diff --git a/README.md b/README.md
index 725c84c50..f07d1faf2 100644
--- a/README.md
+++ b/README.md
@@ -37,7 +37,7 @@ On top of this, this library:
  * uses [S.O.L.I.D. principles][solid on wikipedia],
  * does not have any external dependency,
  * fully tested,
- * type safe (_type safe @ > 98%_),
+ * type safe (_type safe @ > 93%_),
  * framework agnostic.
  
 Except a few methods, most methods are [pure][pure function on wikipedia] and return a
@@ -111,6 +111,12 @@ If you can't contribute to the code, you can also sponsor me on [Github][github
 * [Reddit release 2.0.0 thread][reddit release 2.0.0]
 * [Featured in PHPStorm Annotated August 2020][phpstorm annotated august 2020]
 
+## Changelog
+
+See [CHANGELOG.md][changelog-md] for a changelog based on [git commits][git-commits].
+
+For more detailed changelogs, please read the per release changelogs.
+
 [packagist collection]: https://packagist.org/packages/loophp/collection
 [latest stable version]: https://img.shields.io/packagist/v/loophp/collection.svg?style=flat-square
 [github stars]: https://img.shields.io/github/stars/loophp/collection.svg?style=flat-square
@@ -160,4 +166,6 @@ If you can't contribute to the code, you can also sponsor me on [Github][github
 [paypal sponsor]: https://www.paypal.me/drupol
 [reddit announcement]: https://www.reddit.com/r/PHP/comments/csxw23/a_stateless_and_modular_collection_class/
 [reddit release 2.0.0]: https://www.reddit.com/r/PHP/comments/i2u2le/release_of_version_200_of_loophpcollection/
-[phpstorm annotated august 2020]: https://blog.jetbrains.com/phpstorm/2020/08/php-annotated-august-2020/
\ No newline at end of file
+[phpstorm annotated august 2020]: https://blog.jetbrains.com/phpstorm/2020/08/php-annotated-august-2020/
+[changelog-md]: https://github.com/loophp/collection/blob/master/CHANGELOG.md
+[git-commits]: https://github.com/loophp/collection/commits/master
\ No newline at end of file
diff --git a/docs/pages/api.rst b/docs/pages/api.rst
index 4112f9fd0..9bf8fd4c7 100644
--- a/docs/pages/api.rst
+++ b/docs/pages/api.rst
@@ -159,6 +159,11 @@ Methods (operations)
 
 Operations always returns a new collection object.
 
+all
+~~~
+
+Interface: `Allable`_
+
 append
 ~~~~~~
 
@@ -366,6 +371,11 @@ Signature: ``Collection::compact(...$values);``
     $collection = Collection::with(['a', 1 => 'b', null, false, 0, 'c'];)
         ->compact(null, 0); // ['a', 1 => 'b', 3 => false, 5 => 'c']
 
+contains
+~~~~~~~~
+
+Interface: `Containsable`_
+
 cycle
 ~~~~~
 
@@ -440,6 +450,11 @@ Signature: ``Collection::explode(...$items);``
     $collection = Collection::with($string)
         ->explode('o');
 
+falsy
+~~~~~
+
+Interface: `Falsyable`_
+
 filter
 ~~~~~~
 
@@ -547,6 +562,16 @@ However, when using a collection:
 
 This example will return ``['a', 'b', 'c', 'd', 'a']``.
 
+foldLeft
+~~~~~~~~
+
+Interface: `FoldLeftable`_
+
+foldRight
+~~~~~~~~~
+
+Interface: `FoldRightable`_
+
 forget
 ~~~~~~
 
@@ -578,6 +603,12 @@ Signature: ``Collection::frequency();``
         ->frequency()
         ->all(); // [1 => 'a', 2 => 'b', 3 => 'c'];
 
+get
+~~~
+
+Interface: `Getable`_
+
+
 group
 ~~~~~
 
@@ -607,6 +638,11 @@ Signature: ``Collection::group(callable $callable = null);``
     $collection = Collection::with($callback)
         ->group();
 
+has
+~~~
+
+Interface: `Hasable`_
+
 head
 ~~~~
 
@@ -659,6 +695,11 @@ Signature: ``Collection::ifThenElse(callable $condition, callable $then, ?callab
     Collection::fromIterable($input)
         ->ifThenElse($condition, $then, $else) // [3, 4, 5, 16, 7]
 
+implode
+~~~~~~~
+
+Interface: `Implodeable`_
+
 intersect
 ~~~~~~~~~
 
@@ -849,6 +890,11 @@ Signature: ``Collection::nth(int $step, int $offset = 0);``
     $collection = Collection::with(range(10, 100))
         ->nth(3);
 
+nullsy
+~~~~~~
+
+Interface: `Nullsyable`_
+
 only
 ~~~~
 
@@ -1026,6 +1072,11 @@ Signature: ``Collection::random(int $size = 1);``
     $collection = Collection::with(['4', '5', '6'])
         ->random(); // ['6']
 
+reduce
+~~~~~~
+
+Interface: `Reduceable`_
+
 reduction
 ~~~~~~~~~
 
@@ -1081,7 +1132,6 @@ rsample
 
 Work in progress... sorry.
 
-
 scale
 ~~~~~
 
@@ -1235,7 +1285,6 @@ Signature: ``Collection::sort(?callable $callback = null);``
         ->sort() // Sort the values (which are now the keys)
         ->flip(); // Flip again to put back the keys and values, sorted by keys.
 
-
 split
 ~~~~~
 
@@ -1305,6 +1354,11 @@ Signature: ``Collection::transpose();``
     $result = Collection::with($records)
         ->transpose();
 
+truthy
+~~~~~~
+
+Interface: `Truthyable`_
+
 unpack
 ~~~~~~
 
@@ -1447,77 +1501,7 @@ Signature: ``Collection::zip(iterable ...$iterables);``
         ->limit(100)
         ->flatten();
 
-Methods (transformations)
--------------------------
-
-Transformations might returns something different from a collection.
-
-all
-~~~
-
-Interface: `Allable`_
-
-contains
-~~~~~~~~
-
-Interface: `Containsable`_
-
-falsy
-~~~~~
-
-Interface: `Falsyable`_
-
-foldLeft
-~~~~~~~~
-
-Interface: `FoldLeftable`_
-
-foldRight
-~~~~~~~~~
-
-Interface: `FoldRightable`_
-
-get
-~~~
-
-Interface: `Getable`_
-
-has
-~~~
-
-Interface: `Hasable`_
-
-implode
-~~~~~~~
-
-Interface: `Implodeable`_
-
-nullsy
-~~~~~~
-
-Interface: `Nullsyable`_
-
-reduce
-~~~~~~
-
-Interface: `Reduceable`_
-
-run
-~~~
-
-Interface: `Runable`_
-
-transform
-~~~~~~~~~
-
-Interface: `Transformable`_
-
-truthy
-~~~~~~
-
-Interface: `Truthyable`_
-
-.. _Allable: https://github.com/loophp/collection/blob/master/src/Contract/Transformation/Allable.php
+.. _Allable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Allable.php
 .. _Appendable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Appendable.php
 .. _Applyable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Applyable.php
 .. _Associateable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Associateable.php
@@ -1528,28 +1512,28 @@ Interface: `Truthyable`_
 .. _Combinateable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Combinateable.php
 .. _Combineable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Combineable.php
 .. _Compactable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Compactable.php
-.. _Containsable: https://github.com/loophp/collection/blob/master/src/Contract/Transformation/Containsable.php
+.. _Containsable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Containsable.php
 .. _Cycleable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Cycleable.php
 .. _Diffable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Diffable.php
 .. _Diffkeysable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Diffkeysable.php
 .. _Distinctable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Distinctable.php
 .. _Explodeable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Explodeable.php
-.. _Falsyable: https://github.com/loophp/collection/blob/master/src/Contract/Transformation/Falsyable.php
+.. _Falsyable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Falsyable.php
 .. _Filterable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Filterable.php
 .. _Firstable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Firstable.php
 .. _Flattenable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Flattenable.php
 .. _Flipable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Flipable.php
 .. _array_flip(): https://php.net/array_flip
-.. _FoldLeftable: https://github.com/loophp/collection/blob/master/src/Contract/Transformation/FoldLeftable.php
-.. _FoldRightable: https://github.com/loophp/collection/blob/master/src/Contract/Transformation/FoldRightable.php
+.. _FoldLeftable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/FoldLeftable.php
+.. _FoldRightable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/FoldRightable.php
 .. _Forgetable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Forgetable.php
 .. _Frequencyable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Frequencyable.php
-.. _Getable: https://github.com/loophp/collection/blob/master/src/Contract/Transformation/Getable.php
+.. _Getable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Getable.php
 .. _Groupable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Groupable.php
-.. _Hasable: https://github.com/loophp/collection/blob/master/src/Contract/Transformation/Hasable.php
+.. _Hasable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Hasable.php
 .. _Headable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Headable.php
 .. _IfThenElseable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/IfThenElseable.php
-.. _Implodeable: https://github.com/loophp/collection/blob/master/src/Contract/Transformation/Implodeable.php
+.. _Implodeable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Implodeable.php
 .. _Intersectable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Intersectable.php
 .. _Intersectkeysable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Intersectkeysable.php
 .. _Intersperseable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Intersperseable.php
@@ -1561,7 +1545,7 @@ Interface: `Truthyable`_
 .. _Mergeable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Mergeable.php
 .. _Normalizeable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Normalizeable.php
 .. _Nthable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Nthable.php
-.. _Nullsyable: https://github.com/loophp/collection/blob/master/src/Contract/Transformation/Nullsyable.php
+.. _Nullsyable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Nullsyable.php
 .. _Onlyable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Onlyable.php
 .. _Packable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Packable.php
 .. _Padable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Padable.php
@@ -1571,10 +1555,9 @@ Interface: `Truthyable`_
 .. _Prependable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Prependable.php
 .. _Productable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Productable.php
 .. _Randomable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Randomable.php
-.. _Reduceable: https://github.com/loophp/collection/blob/master/src/Contract/Transformation/Reduceable.php
+.. _Reduceable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Reduceable.php
 .. _Reductionable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Reductionable.php
 .. _Reverseable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Reverseable.php
-.. _Runable: https://github.com/loophp/collection/blob/master/src/Contract/Transformation/Runable.php
 .. _Scaleable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Scaleable.php
 .. _Skipable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Skipable.php
 .. _Sinceable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Sinceable.php
@@ -1582,9 +1565,8 @@ Interface: `Truthyable`_
 .. _Sortable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Sortable.php
 .. _Splitable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Splitable.php
 .. _Tailable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Tailable.php
-.. _Transformable: https://github.com/loophp/collection/blob/master/src/Contract/Transformation/Transformable.php
 .. _Transposeable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Transposeable.php
-.. _Truthyable: https://github.com/loophp/collection/blob/master/src/Contract/Transformation/Truthyable.php
+.. _Truthyable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Truthyable.php
 .. _Unpackable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Unpackagle.php
 .. _Unpairable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Unpairable.php
 .. _Untilable: https://github.com/loophp/collection/blob/master/src/Contract/Operation/Untilable.php
diff --git a/spec/loophp/collection/CollectionSpec.php b/spec/loophp/collection/CollectionSpec.php
index c38a1883a..259385eac 100644
--- a/spec/loophp/collection/CollectionSpec.php
+++ b/spec/loophp/collection/CollectionSpec.php
@@ -13,7 +13,6 @@
 use JsonSerializable;
 use loophp\collection\Collection;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Contract\Transformation;
 use loophp\collection\Operation\AbstractOperation;
 use PhpSpec\ObjectBehavior;
 use stdClass;
@@ -238,17 +237,6 @@ public function it_can_be_json_encoded()
 
         $this
             ->shouldImplement(JsonSerializable::class);
-
-        $this
-            ->transform(
-                new class() implements Transformation {
-                    public function __invoke(Iterator $collection)
-                    {
-                        return '{"a":"A","b":"B","c":"C"}';
-                    }
-                }
-            )
-            ->shouldReturn(json_encode($this->getWrappedObject()));
     }
 
     public function it_can_be_returned_as_an_array(): void
@@ -1212,12 +1200,14 @@ public function it_can_intersperse(): void
             ->shouldIterateAs($generator());
 
         $this::fromIterable(range('A', 'F'))
+            ->intersperse('foo', -1, 1)
             ->shouldThrow(Exception::class)
-            ->during('intersperse', ['foo', -1, 1]);
+            ->during('all');
 
         $this::fromIterable(range('A', 'F'))
+            ->intersperse('foo', 1, -1)
             ->shouldThrow(Exception::class)
-            ->during('intersperse', ['foo', 1, -1]);
+            ->during('all');
     }
 
     public function it_can_iterate(): void
@@ -1673,7 +1663,7 @@ public function __invoke(): Closure
         };
 
         $this::fromIterable(range(1, 5))
-            ->run($square, $sqrt, $map)
+            ->run($square(), $sqrt(), $map())
             ->shouldIterateAs(range(1, 5));
     }
 
@@ -2087,6 +2077,10 @@ public function it_can_use_times_with_a_callback(): void
             return range(1, 5);
         })
             ->shouldIterateAs($a);
+
+        $this::times(-1, 'count')
+            ->shouldThrow(InvalidArgumentException::class)
+            ->during('all');
     }
 
     public function it_can_use_times_without_a_callback(): void
@@ -2094,9 +2088,9 @@ public function it_can_use_times_without_a_callback(): void
         $this::times(10)
             ->shouldIterateAs(range(1, 10));
 
-        $this::times(10)
+        $this::times(-5)
             ->shouldThrow(InvalidArgumentException::class)
-            ->during('times', [-5]);
+            ->during('all');
 
         $this::times(1)
             ->shouldIterateAs([1]);
diff --git a/src/Collection.php b/src/Collection.php
index 36f3b20ae..2dbdc5b48 100644
--- a/src/Collection.php
+++ b/src/Collection.php
@@ -8,7 +8,6 @@
 use Generator;
 use loophp\collection\Contract\Collection as CollectionInterface;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Contract\Transformation;
 use loophp\collection\Iterator\ClosureIterator;
 use loophp\collection\Iterator\IterableIterator;
 use loophp\collection\Iterator\ResourceIterator;
@@ -23,20 +22,28 @@
 use loophp\collection\Operation\Combinate;
 use loophp\collection\Operation\Combine;
 use loophp\collection\Operation\Compact;
+use loophp\collection\Operation\Compose;
+use loophp\collection\Operation\Contains;
 use loophp\collection\Operation\Cycle;
 use loophp\collection\Operation\Diff;
 use loophp\collection\Operation\DiffKeys;
 use loophp\collection\Operation\Distinct;
 use loophp\collection\Operation\Explode;
+use loophp\collection\Operation\Falsy;
 use loophp\collection\Operation\Filter;
 use loophp\collection\Operation\First;
 use loophp\collection\Operation\Flatten;
 use loophp\collection\Operation\Flip;
+use loophp\collection\Operation\FoldLeft;
+use loophp\collection\Operation\FoldRight;
 use loophp\collection\Operation\Forget;
 use loophp\collection\Operation\Frequency;
+use loophp\collection\Operation\Get;
 use loophp\collection\Operation\Group;
+use loophp\collection\Operation\Has;
 use loophp\collection\Operation\Head;
 use loophp\collection\Operation\IfThenElse;
+use loophp\collection\Operation\Implode;
 use loophp\collection\Operation\Intersect;
 use loophp\collection\Operation\IntersectKeys;
 use loophp\collection\Operation\Intersperse;
@@ -49,6 +56,7 @@
 use loophp\collection\Operation\Merge;
 use loophp\collection\Operation\Normalize;
 use loophp\collection\Operation\Nth;
+use loophp\collection\Operation\Nullsy;
 use loophp\collection\Operation\Only;
 use loophp\collection\Operation\Pack;
 use loophp\collection\Operation\Pad;
@@ -59,9 +67,11 @@
 use loophp\collection\Operation\Product;
 use loophp\collection\Operation\Random;
 use loophp\collection\Operation\Range;
+use loophp\collection\Operation\Reduce;
 use loophp\collection\Operation\Reduction;
 use loophp\collection\Operation\Reverse;
 use loophp\collection\Operation\RSample;
+use loophp\collection\Operation\Run;
 use loophp\collection\Operation\Scale;
 use loophp\collection\Operation\Shuffle;
 use loophp\collection\Operation\Since;
@@ -72,6 +82,7 @@
 use loophp\collection\Operation\Tail;
 use loophp\collection\Operation\Times;
 use loophp\collection\Operation\Transpose;
+use loophp\collection\Operation\Truthy;
 use loophp\collection\Operation\Unpack;
 use loophp\collection\Operation\Unpair;
 use loophp\collection\Operation\Until;
@@ -79,20 +90,6 @@
 use loophp\collection\Operation\Window;
 use loophp\collection\Operation\Wrap;
 use loophp\collection\Operation\Zip;
-use loophp\collection\Transformation\All;
-use loophp\collection\Transformation\Contains;
-use loophp\collection\Transformation\Count;
-use loophp\collection\Transformation\Falsy;
-use loophp\collection\Transformation\FoldLeft;
-use loophp\collection\Transformation\FoldRight;
-use loophp\collection\Transformation\Get;
-use loophp\collection\Transformation\Has;
-use loophp\collection\Transformation\Implode;
-use loophp\collection\Transformation\Nullsy;
-use loophp\collection\Transformation\Reduce;
-use loophp\collection\Transformation\Run;
-use loophp\collection\Transformation\Transform;
-use loophp\collection\Transformation\Truthy;
 use Psr\Cache\CacheItemPoolInterface;
 use Symfony\Component\Cache\Adapter\ArrayAdapter;
 
@@ -120,7 +117,7 @@ final class Collection implements CollectionInterface
 
     /**
      * @var Closure
-     * @psalm-var Closure(Closure|callable|iterable|mixed|resource|scalar|T):(T)
+     * @psalm-var Closure((Closure|callable|iterable|mixed|resource|scalar|T)...):Generator
      */
     private $source;
 
@@ -226,89 +223,89 @@ static function ($data): Generator {
 
     public function all(): array
     {
-        return $this->transform(new All());
+        return iterator_to_array($this);
     }
 
     public function append(...$items): CollectionInterface
     {
-        return $this->run(new Append(...$items));
+        return $this->run(Append::of()(...$items));
     }
 
     public function apply(callable ...$callables): CollectionInterface
     {
-        return $this->run(new Apply(...$callables));
+        return $this->run(Apply::of()(...$callables));
     }
 
     public function associate(
         ?callable $callbackForKeys = null,
         ?callable $callbackForValues = null
     ): CollectionInterface {
-        return $this->run(new Associate($callbackForKeys, $callbackForValues));
+        return $this->run(Associate::of()($callbackForKeys)($callbackForValues));
     }
 
     public function cache(?CacheItemPoolInterface $cache = null): CollectionInterface
     {
-        return $this->run(new Cache($cache ?? new ArrayAdapter()));
+        return $this->run(Cache::of()($cache ?? new ArrayAdapter()));
     }
 
     public function chunk(int ...$sizes): CollectionInterface
     {
-        return $this->run(new Chunk(...$sizes));
+        return $this->run(Chunk::of()(...$sizes));
     }
 
     public function collapse(): CollectionInterface
     {
-        return $this->run(new Collapse());
+        return $this->run(Collapse::of());
     }
 
     public function column($column): CollectionInterface
     {
-        return $this->run(new Column($column));
+        return $this->run(Column::of()($column));
     }
 
     public function combinate(?int $length = null): CollectionInterface
     {
-        return $this->run(new Combinate($length));
+        return $this->run(Combinate::of()($length));
     }
 
     public function combine(...$keys): CollectionInterface
     {
-        return $this->run(new Combine(...$keys));
+        return $this->run(Combine::of()(...$keys));
     }
 
     public function compact(...$values): CollectionInterface
     {
-        return $this->run(new Compact(...$values));
+        return $this->run(Compact::of()(...$values));
     }
 
     public function contains(...$value): bool
     {
-        return $this->transform(new Contains(...$value));
+        return $this->run(Contains::of()(...$value))->getIterator()->current();
     }
 
     public function count(): int
     {
-        return $this->transform(new Count());
+        return iterator_count($this);
     }
 
     public function cycle(int $length = 0): CollectionInterface
     {
-        return $this->run(new Cycle($length));
+        return $this->run(Cycle::of()($length));
     }
 
     public function diff(...$values): CollectionInterface
     {
-        return $this->run(new Diff(...$values));
+        return $this->run(Diff::of()(...$values));
     }
 
     public function diffKeys(...$values): CollectionInterface
     {
-        return $this->run(new DiffKeys(...$values));
+        return $this->run(DiffKeys::of()(...$values));
     }
 
     public function distinct(): CollectionInterface
     {
-        return $this->run(new Distinct());
+        return $this->run(Distinct::of());
     }
 
     public static function empty(): Collection
@@ -318,52 +315,52 @@ public static function empty(): Collection
 
     public function explode(...$explodes): CollectionInterface
     {
-        return $this->run(new Explode(...$explodes));
+        return $this->run(Explode::of()(...$explodes));
     }
 
     public function falsy(): bool
     {
-        return $this->transform(new Falsy());
+        return $this->run(Falsy::of())->getIterator()->current();
     }
 
     public function filter(callable ...$callbacks): CollectionInterface
     {
-        return $this->run(new Filter(...$callbacks));
+        return $this->run(Filter::of()(...$callbacks));
     }
 
     public function first(?callable $callback = null, int $size = 1): CollectionInterface
     {
-        return $this->run(new First($callback, $size));
+        return $this->run(First::of()($callback)($size));
     }
 
     public function flatten(int $depth = PHP_INT_MAX): CollectionInterface
     {
-        return $this->run(new Flatten($depth));
+        return $this->run(Flatten::of()($depth));
     }
 
     public function flip(): CollectionInterface
     {
-        return $this->run(new Flip());
+        return $this->run(Flip::of());
     }
 
     public function foldLeft(callable $callback, $initial = null)
     {
-        return $this->transform(new FoldLeft($callback, $initial));
+        return $this->run(FoldLeft::of()($callback)($initial))->getIterator()->current();
     }
 
     public function foldRight(callable $callback, $initial = null)
     {
-        return $this->transform(new FoldRight($callback, $initial));
+        return $this->run(Foldright::of()($callback)($initial))->getIterator()->current();
     }
 
     public function forget(...$keys): CollectionInterface
     {
-        return $this->run(new Forget(...$keys));
+        return $this->run(Forget::of()(...$keys));
     }
 
     public function frequency(): CollectionInterface
     {
-        return $this->run(new Frequency());
+        return $this->run(Frequency::of());
     }
 
     public static function fromCallable(callable $callable, ...$parameters): Collection
@@ -390,6 +387,11 @@ static function (iterable $iterable): Generator {
     public static function fromResource($resource): Collection
     {
         return new self(
+            /**
+             * @psalm-param resource $resource
+             *
+             * @param mixed $resource
+             */
             static function ($resource): Generator {
                 return yield from new ResourceIterator($resource);
             },
@@ -400,6 +402,9 @@ static function ($resource): Generator {
     public static function fromString(string $string, string $delimiter = ''): Collection
     {
         return new self(
+            /**
+             * @psalm-return Generator<int, string>
+             */
             static function (string $string, string $delimiter): Generator {
                 return yield from new StringIterator($string, $delimiter);
             },
@@ -410,7 +415,7 @@ static function (string $string, string $delimiter): Generator {
 
     public function get($key, $default = null)
     {
-        return $this->transform(new Get($key, $default));
+        return $this->run(Get::of()($key)($default))->getIterator()->current();
     }
 
     public function getIterator(): ClosureIterator
@@ -420,51 +425,61 @@ public function getIterator(): ClosureIterator
 
     public function group(?callable $callable = null): CollectionInterface
     {
-        return $this->run(new Group($callable));
+        return $this->run(Group::of()($callable));
     }
 
     public function has(callable $callback): bool
     {
-        return $this->transform(new Has($callback));
+        return $this->run(Has::of()($callback))->getIterator()->current();
     }
 
     public function head(): CollectionInterface
     {
-        return $this->run(new Head());
+        return $this->run(Head::of());
     }
 
     public function ifThenElse(callable $condition, callable $then, ?callable $else = null): CollectionInterface
     {
-        $else = $else ?? static function ($value, $key) {
-            return $value;
-        };
+        $else = $else ??
+            /**
+             * @psalm-param T $value
+             * @psalm-param TKey $key
+             *
+             * @psalm-return T
+             *
+             * @param mixed $value
+             * @param mixed $key
+             */
+            static function ($value, $key) {
+                return $value;
+            };
 
-        return $this->run(new IfThenElse($condition, $then, $else));
+        return $this->run(IfThenElse::of()($condition)($then)($else));
     }
 
     public function implode(string $glue = ''): string
     {
-        return $this->transform(new Implode($glue));
+        return $this->run(Implode::of()($glue))->getIterator()->current();
     }
 
     public function intersect(...$values): CollectionInterface
     {
-        return $this->run(new Intersect(...$values));
+        return $this->run(Intersect::of()(...$values));
     }
 
     public function intersectKeys(...$values): CollectionInterface
     {
-        return $this->run(new IntersectKeys(...$values));
+        return $this->run(IntersectKeys::of()(...$values));
     }
 
     public function intersperse($element, int $every = 1, int $startAt = 0): CollectionInterface
     {
-        return $this->run(new Intersperse($element, $every, $startAt));
+        return $this->run(Intersperse::of()($element)($every)($startAt));
     }
 
     public static function iterate(callable $callback, ...$parameters): CollectionInterface
     {
-        return (new self())->run(new Iterate($callback, $parameters));
+        return (new self())->run(Iterate::of()($callback)(...$parameters));
     }
 
     /**
@@ -477,122 +492,125 @@ public function jsonSerialize(): array
 
     public function keys(): CollectionInterface
     {
-        return $this->run(new Keys());
+        return $this->run(Keys::of());
     }
 
     public function last(?callable $callback = null, int $size = 1): CollectionInterface
     {
-        return $this->run(new Last($callback, $size));
+        return $this->run(Last::of()($callback)($size));
     }
 
     public function limit(int $limit = -1, int $offset = 0): CollectionInterface
     {
-        return $this->run(new Limit($limit, $offset));
+        return $this->run(Limit::of()($limit)($offset));
     }
 
     public function loop(): CollectionInterface
     {
-        return $this->run(new Loop());
+        return $this->run(Loop::of());
     }
 
     public function map(callable ...$callbacks): CollectionInterface
     {
-        return $this->run(new Map(...$callbacks));
+        return $this->run(Map::of()(...$callbacks));
     }
 
     public function merge(iterable ...$sources): CollectionInterface
     {
-        return $this->run(new Merge(...$sources));
+        return $this->run(Merge::of()(...$sources));
     }
 
     public function normalize(): CollectionInterface
     {
-        return $this->run(new Normalize());
+        return $this->run(Normalize::of());
     }
 
     public function nth(int $step, int $offset = 0): CollectionInterface
     {
-        return $this->run(new Nth($step, $offset));
+        return $this->run(Nth::of()($step)($offset));
     }
 
     public function nullsy(): bool
     {
-        return $this->transform(new Nullsy());
+        return $this->run(Nullsy::of())->getIterator()->current();
     }
 
     public function only(...$keys): CollectionInterface
     {
-        return $this->run(new Only(...$keys));
+        return $this->run(Only::of()(...$keys));
     }
 
     public function pack(): CollectionInterface
     {
-        return $this->run(new Pack());
+        return $this->run(Pack::of());
     }
 
     public function pad(int $size, $value): CollectionInterface
     {
-        return $this->run(new Pad($size, $value));
+        return $this->run(Pad::of()($size)($value));
     }
 
     public function pair(): CollectionInterface
     {
-        return $this->run(new Pair());
+        return $this->run(Pair::of());
     }
 
     public function permutate(): CollectionInterface
     {
-        return $this->run(new Permutate());
+        return $this->run(Permutate::of());
     }
 
     public function pluck($pluck, $default = null): CollectionInterface
     {
-        return $this->run(new Pluck($pluck, $default));
+        return $this->run(Pluck::of()($pluck)($default));
     }
 
     public function prepend(...$items): CollectionInterface
     {
-        return $this->run(new Prepend(...$items));
+        return $this->run(Prepend::of()(...$items));
     }
 
     public function product(iterable ...$iterables): CollectionInterface
     {
-        return $this->run(new Product(...$iterables));
+        return $this->run(Product::of()(...$iterables));
     }
 
     public function random(int $size = 1): CollectionInterface
     {
-        return $this->run(new Random($size));
+        return $this->run(Random::of()($size));
     }
 
     public static function range(float $start = 0.0, float $end = INF, float $step = 1.0): CollectionInterface
     {
-        return (new self())->run(new Range($start, $end, $step));
+        return (new self())->run(Range::of()($start)($end)($step));
     }
 
     public function reduce(callable $callback, $initial = null)
     {
-        return $this->transform(new Reduce($callback, $initial));
+        return $this->run(Reduce::of()($callback)($initial))->getIterator()->current();
     }
 
     public function reduction(callable $callback, $initial = null): CollectionInterface
     {
-        return $this->run(new Reduction($callback, $initial));
+        return $this->run(Reduction::of()($callback)($initial));
     }
 
     public function reverse(): CollectionInterface
     {
-        return $this->run(new Reverse());
+        return $this->run(Reverse::of());
     }
 
     public function rsample(float $probability): CollectionInterface
     {
-        return $this->run(new RSample($probability));
+        return $this->run(RSample::of()($probability));
     }
 
-    public function run(Operation ...$operations)
+    public function run(callable ...$operations): CollectionInterface
     {
-        return self::fromIterable((new Run(...$operations))($this->getIterator()));
+        return self::fromCallable(
+            Compose::of()(...$operations),
+            $this->getIterator()
+        );
     }
 
     public function scale(
@@ -602,87 +620,82 @@ public function scale(
         float $wantedUpperBound = 1.0,
         float $base = 0.0
     ): CollectionInterface {
-        return $this->run(new Scale($lowerBound, $upperBound, $wantedLowerBound, $wantedUpperBound, $base));
+        return $this->run(Scale::of()($lowerBound)($upperBound)($wantedLowerBound)($wantedUpperBound)($base));
     }
 
     public function shuffle(): CollectionInterface
     {
-        return $this->run(new Shuffle());
+        return $this->run(Shuffle::of());
     }
 
     public function since(callable ...$callbacks): CollectionInterface
     {
-        return $this->run(new Since(...$callbacks));
+        return $this->run(Since::of()(...$callbacks));
     }
 
     public function skip(int ...$counts): CollectionInterface
     {
-        return $this->run(new Skip(...$counts));
+        return $this->run(Skip::of()(...$counts));
     }
 
     public function slice(int $offset, int $length = -1): CollectionInterface
     {
-        return $this->run(new Slice($offset, $length));
+        return $this->run(Slice::of()($offset)($length));
     }
 
     public function sort(int $type = Operation\Sortable::BY_VALUES, ?callable $callback = null): CollectionInterface
     {
-        return $this->run(new Sort($type, $callback));
+        return $this->run(Sort::of()($type)($callback));
     }
 
     public function split(callable ...$callbacks): CollectionInterface
     {
-        return $this->run(new Split(...$callbacks));
+        return $this->run(Split::of()(...$callbacks));
     }
 
     public function tail(): CollectionInterface
     {
-        return $this->run(new Tail());
+        return $this->run(Tail::of());
     }
 
     public static function times(int $number = 0, ?callable $callback = null): CollectionInterface
     {
-        return (new self())->run(new Times($number, $callback));
-    }
-
-    public function transform(Transformation ...$transformers)
-    {
-        return (new Transform(...$transformers))($this->getIterator());
+        return (new self())->run(Times::of()($number)($callback));
     }
 
     public function transpose(): CollectionInterface
     {
-        return $this->run(new Transpose());
+        return $this->run(Transpose::of());
     }
 
     public function truthy(): bool
     {
-        return $this->transform(new Truthy());
+        return $this->run(Truthy::of())->getIterator()->current();
     }
 
     public function unpack(): CollectionInterface
     {
-        return $this->run(new Unpack());
+        return $this->run(Unpack::of());
     }
 
     public function unpair(): CollectionInterface
     {
-        return $this->run(new Unpair());
+        return $this->run(Unpair::of());
     }
 
     public function until(callable ...$callbacks): CollectionInterface
     {
-        return $this->run(new Until(...$callbacks));
+        return $this->run(Until::of()(...$callbacks));
     }
 
     public function unwrap(): CollectionInterface
     {
-        return $this->run(new Unwrap());
+        return $this->run(Unwrap::of());
     }
 
     public function window(int ...$length): CollectionInterface
     {
-        return $this->run(new Window(...$length));
+        return $this->run(Window::of()(...$length));
     }
 
     public static function with($data = [], ...$parameters): Collection
@@ -692,11 +705,11 @@ public static function with($data = [], ...$parameters): Collection
 
     public function wrap(): CollectionInterface
     {
-        return $this->run(new Wrap());
+        return $this->run(Wrap::of());
     }
 
     public function zip(iterable ...$iterables): CollectionInterface
     {
-        return $this->run(new Zip(...$iterables));
+        return $this->run(Zip::of()(...$iterables));
     }
 }
diff --git a/src/Contract/Collection.php b/src/Contract/Collection.php
index b8f59047f..ce4f11a4a 100644
--- a/src/Contract/Collection.php
+++ b/src/Contract/Collection.php
@@ -6,6 +6,7 @@
 
 use IteratorAggregate;
 use JsonSerializable;
+use loophp\collection\Contract\Operation\Allable;
 use loophp\collection\Contract\Operation\Appendable;
 use loophp\collection\Contract\Operation\Applyable;
 use loophp\collection\Contract\Operation\Associateable;
@@ -16,20 +17,27 @@
 use loophp\collection\Contract\Operation\Combinateable;
 use loophp\collection\Contract\Operation\Combineable;
 use loophp\collection\Contract\Operation\Compactable;
+use loophp\collection\Contract\Operation\Containsable;
 use loophp\collection\Contract\Operation\Cycleable;
 use loophp\collection\Contract\Operation\Diffable;
 use loophp\collection\Contract\Operation\Diffkeysable;
 use loophp\collection\Contract\Operation\Distinctable;
 use loophp\collection\Contract\Operation\Explodeable;
+use loophp\collection\Contract\Operation\Falsyable;
 use loophp\collection\Contract\Operation\Filterable;
 use loophp\collection\Contract\Operation\Firstable;
 use loophp\collection\Contract\Operation\Flattenable;
 use loophp\collection\Contract\Operation\Flipable;
+use loophp\collection\Contract\Operation\FoldLeftable;
+use loophp\collection\Contract\Operation\FoldRightable;
 use loophp\collection\Contract\Operation\Forgetable;
 use loophp\collection\Contract\Operation\Frequencyable;
+use loophp\collection\Contract\Operation\Getable;
 use loophp\collection\Contract\Operation\Groupable;
+use loophp\collection\Contract\Operation\Hasable;
 use loophp\collection\Contract\Operation\Headable;
 use loophp\collection\Contract\Operation\IfThenElseable;
+use loophp\collection\Contract\Operation\Implodeable;
 use loophp\collection\Contract\Operation\Intersectable;
 use loophp\collection\Contract\Operation\Intersectkeysable;
 use loophp\collection\Contract\Operation\Intersperseable;
@@ -42,6 +50,7 @@
 use loophp\collection\Contract\Operation\Mergeable;
 use loophp\collection\Contract\Operation\Normalizeable;
 use loophp\collection\Contract\Operation\Nthable;
+use loophp\collection\Contract\Operation\Nullsyable;
 use loophp\collection\Contract\Operation\Onlyable;
 use loophp\collection\Contract\Operation\Padable;
 use loophp\collection\Contract\Operation\Pairable;
@@ -51,9 +60,11 @@
 use loophp\collection\Contract\Operation\Productable;
 use loophp\collection\Contract\Operation\Randomable;
 use loophp\collection\Contract\Operation\Rangeable;
+use loophp\collection\Contract\Operation\Reduceable;
 use loophp\collection\Contract\Operation\Reductionable;
 use loophp\collection\Contract\Operation\Reverseable;
 use loophp\collection\Contract\Operation\RSampleable;
+use loophp\collection\Contract\Operation\Runable;
 use loophp\collection\Contract\Operation\Scaleable;
 use loophp\collection\Contract\Operation\Shuffleable;
 use loophp\collection\Contract\Operation\Sinceable;
@@ -64,25 +75,14 @@
 use loophp\collection\Contract\Operation\Tailable;
 use loophp\collection\Contract\Operation\Timesable;
 use loophp\collection\Contract\Operation\Transposeable;
+use loophp\collection\Contract\Operation\Truthyable;
 use loophp\collection\Contract\Operation\Unpairable;
 use loophp\collection\Contract\Operation\Untilable;
 use loophp\collection\Contract\Operation\Unwrapable;
 use loophp\collection\Contract\Operation\Windowable;
 use loophp\collection\Contract\Operation\Wrapable;
 use loophp\collection\Contract\Operation\Zipable;
-use loophp\collection\Contract\Transformation\Allable;
-use loophp\collection\Contract\Transformation\Containsable;
-use loophp\collection\Contract\Transformation\Falsyable;
-use loophp\collection\Contract\Transformation\FoldLeftable;
-use loophp\collection\Contract\Transformation\FoldRightable;
-use loophp\collection\Contract\Transformation\Getable;
-use loophp\collection\Contract\Transformation\Hasable;
-use loophp\collection\Contract\Transformation\Implodeable;
-use loophp\collection\Contract\Transformation\Nullsyable;
-use loophp\collection\Contract\Transformation\Reduceable;
-use loophp\collection\Contract\Transformation\Runable;
-use loophp\collection\Contract\Transformation\Transformable;
-use loophp\collection\Contract\Transformation\Truthyable;
+use loophp\collection\Iterator\ClosureIterator;
 
 /**
  * @psalm-template TKey
@@ -159,7 +159,6 @@
  * @template-extends Zipable<TKey, T>
  * @template-extends \IteratorAggregate<TKey, T>
  * @template-extends Runable<TKey, T>
- * @template-extends Transformable<TKey, T>
  */
 interface Collection extends
     Allable,
@@ -222,7 +221,6 @@ interface Collection extends
     Reductionable,
     Reverseable,
     RSampleable,
-    Runable,
     Scaleable,
     Shuffleable,
     Sinceable,
@@ -232,7 +230,6 @@ interface Collection extends
     Splitable,
     Tailable,
     Timesable,
-    Transformable,
     Transposeable,
     Truthyable,
     Unpairable,
@@ -277,25 +274,22 @@ public static function fromCallable(callable $callable, ...$parameters): \loophp
     public static function fromIterable(iterable $iterable): \loophp\collection\Collection;
 
     /**
-     * @psalm-template NewTKey
-     * @psalm-template NewTKey of array-key
-     * @psalm-template NewT
-     *
      * @param resource $resource
      *
-     * @psalm-return \loophp\collection\Collection<NewTKey, NewT>
+     * @psalm-return \loophp\collection\Collection<int, string>
      */
     public static function fromResource($resource): \loophp\collection\Collection;
 
     /**
-     * @psalm-template NewTKey
-     * @psalm-template NewTKey of array-key
-     * @psalm-template NewT
-     *
-     * @psalm-return \loophp\collection\Collection<NewTKey, NewT>
+     * @psalm-return \loophp\collection\Collection<int, string>
      */
     public static function fromString(string $string, string $delimiter = ''): \loophp\collection\Collection;
 
+    /**
+     * @psalm-return \loophp\collection\Iterator\ClosureIterator<TKey, T>
+     */
+    public function getIterator(): ClosureIterator;
+
     /**
      * @psalm-template NewTKey
      * @psalm-template NewTKey of array-key
diff --git a/src/Contract/Operation.php b/src/Contract/Operation.php
index 102c419d7..5646618a3 100644
--- a/src/Contract/Operation.php
+++ b/src/Contract/Operation.php
@@ -10,8 +10,5 @@ interface Operation
 {
     public function __invoke(): Closure;
 
-    /**
-     * @return array<string, mixed>
-     */
-    public function getArguments(): array;
+    public static function of(): Closure;
 }
diff --git a/src/Contract/Transformation/Allable.php b/src/Contract/Operation/Allable.php
similarity index 86%
rename from src/Contract/Transformation/Allable.php
rename to src/Contract/Operation/Allable.php
index e1db99e93..7b8a40c4b 100644
--- a/src/Contract/Transformation/Allable.php
+++ b/src/Contract/Operation/Allable.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace loophp\collection\Contract\Transformation;
+namespace loophp\collection\Contract\Operation;
 
 /**
  * @psalm-template TKey
diff --git a/src/Contract/Transformation/Containsable.php b/src/Contract/Operation/Containsable.php
similarity index 80%
rename from src/Contract/Transformation/Containsable.php
rename to src/Contract/Operation/Containsable.php
index 4c1ccc3af..b78e7779b 100644
--- a/src/Contract/Transformation/Containsable.php
+++ b/src/Contract/Operation/Containsable.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace loophp\collection\Contract\Transformation;
+namespace loophp\collection\Contract\Operation;
 
 /**
  * @psalm-template T
diff --git a/src/Contract/Transformation/Falsyable.php b/src/Contract/Operation/Falsyable.php
similarity index 63%
rename from src/Contract/Transformation/Falsyable.php
rename to src/Contract/Operation/Falsyable.php
index 93e5b4c3e..9e7ffd649 100644
--- a/src/Contract/Transformation/Falsyable.php
+++ b/src/Contract/Operation/Falsyable.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace loophp\collection\Contract\Transformation;
+namespace loophp\collection\Contract\Operation;
 
 interface Falsyable
 {
diff --git a/src/Contract/Transformation/FoldLeftable.php b/src/Contract/Operation/FoldLeftable.php
similarity index 88%
rename from src/Contract/Transformation/FoldLeftable.php
rename to src/Contract/Operation/FoldLeftable.php
index 540d5833b..a4db77e6b 100644
--- a/src/Contract/Transformation/FoldLeftable.php
+++ b/src/Contract/Operation/FoldLeftable.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace loophp\collection\Contract\Transformation;
+namespace loophp\collection\Contract\Operation;
 
 /**
  * @psalm-template TKey
diff --git a/src/Contract/Transformation/FoldRightable.php b/src/Contract/Operation/FoldRightable.php
similarity index 88%
rename from src/Contract/Transformation/FoldRightable.php
rename to src/Contract/Operation/FoldRightable.php
index ab534aade..2c78afab8 100644
--- a/src/Contract/Transformation/FoldRightable.php
+++ b/src/Contract/Operation/FoldRightable.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace loophp\collection\Contract\Transformation;
+namespace loophp\collection\Contract\Operation;
 
 /**
  * @psalm-template TKey
diff --git a/src/Contract/Transformation/Getable.php b/src/Contract/Operation/Getable.php
similarity index 89%
rename from src/Contract/Transformation/Getable.php
rename to src/Contract/Operation/Getable.php
index ef497b4dc..d556d2900 100644
--- a/src/Contract/Transformation/Getable.php
+++ b/src/Contract/Operation/Getable.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace loophp\collection\Contract\Transformation;
+namespace loophp\collection\Contract\Operation;
 
 /**
  * @psalm-template TKey
diff --git a/src/Contract/Transformation/Hasable.php b/src/Contract/Operation/Hasable.php
similarity index 83%
rename from src/Contract/Transformation/Hasable.php
rename to src/Contract/Operation/Hasable.php
index 6da78652a..b4804c26a 100644
--- a/src/Contract/Transformation/Hasable.php
+++ b/src/Contract/Operation/Hasable.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace loophp\collection\Contract\Transformation;
+namespace loophp\collection\Contract\Operation;
 
 /**
  * @psalm-template TKey
diff --git a/src/Contract/Transformation/Implodeable.php b/src/Contract/Operation/Implodeable.php
similarity index 68%
rename from src/Contract/Transformation/Implodeable.php
rename to src/Contract/Operation/Implodeable.php
index ce0bf4d9a..d906ebfda 100644
--- a/src/Contract/Transformation/Implodeable.php
+++ b/src/Contract/Operation/Implodeable.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace loophp\collection\Contract\Transformation;
+namespace loophp\collection\Contract\Operation;
 
 interface Implodeable
 {
diff --git a/src/Contract/Transformation/Nullsyable.php b/src/Contract/Operation/Nullsyable.php
similarity index 64%
rename from src/Contract/Transformation/Nullsyable.php
rename to src/Contract/Operation/Nullsyable.php
index 74cdf626e..214cb2d3e 100644
--- a/src/Contract/Transformation/Nullsyable.php
+++ b/src/Contract/Operation/Nullsyable.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace loophp\collection\Contract\Transformation;
+namespace loophp\collection\Contract\Operation;
 
 interface Nullsyable
 {
diff --git a/src/Contract/Transformation/Reduceable.php b/src/Contract/Operation/Reduceable.php
similarity index 88%
rename from src/Contract/Transformation/Reduceable.php
rename to src/Contract/Operation/Reduceable.php
index e23432271..fdc294bdd 100644
--- a/src/Contract/Transformation/Reduceable.php
+++ b/src/Contract/Operation/Reduceable.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace loophp\collection\Contract\Transformation;
+namespace loophp\collection\Contract\Operation;
 
 /**
  * @psalm-template TKey
diff --git a/src/Contract/Transformation/Truthyable.php b/src/Contract/Operation/Truthyable.php
similarity index 64%
rename from src/Contract/Transformation/Truthyable.php
rename to src/Contract/Operation/Truthyable.php
index ced83bad9..9d7f7b521 100644
--- a/src/Contract/Transformation/Truthyable.php
+++ b/src/Contract/Operation/Truthyable.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace loophp\collection\Contract\Transformation;
+namespace loophp\collection\Contract\Operation;
 
 interface Truthyable
 {
diff --git a/src/Contract/Transformation.php b/src/Contract/Transformation.php
deleted file mode 100644
index 1b92ae10d..000000000
--- a/src/Contract/Transformation.php
+++ /dev/null
@@ -1,24 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Contract;
-
-use Iterator;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- */
-interface Transformation
-{
-    /**
-     * @param iterable<mixed> $collection
-     * @psalm-param \Iterator<TKey, T> $collection
-     *
-     * @return mixed
-     * @psalm-return T|scalar|\Iterator<TKey, T>|array<TKey, T>|null
-     */
-    public function __invoke(Iterator $collection);
-}
diff --git a/src/Contract/Transformation/Runable.php b/src/Contract/Transformation/Runable.php
deleted file mode 100644
index dff0e8e32..000000000
--- a/src/Contract/Transformation/Runable.php
+++ /dev/null
@@ -1,20 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Contract\Transformation;
-
-use loophp\collection\Contract\Operation;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- */
-interface Runable
-{
-    /**
-     * @psalm-return \loophp\collection\Contract\Collection<TKey, T>
-     */
-    public function run(Operation ...$operations);
-}
diff --git a/src/Contract/Transformation/Transformable.php b/src/Contract/Transformation/Transformable.php
deleted file mode 100644
index 0a70fb783..000000000
--- a/src/Contract/Transformation/Transformable.php
+++ /dev/null
@@ -1,23 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Contract\Transformation;
-
-use loophp\collection\Contract\Transformation;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- */
-interface Transformable
-{
-    /**
-     * @param \loophp\collection\Contract\Transformation ...$transformers
-     * @psalm-param \loophp\collection\Contract\Transformation<TKey, T> ...$transformers
-     *
-     * @return \loophp\collection\Iterator\ClosureIterator|mixed
-     */
-    public function transform(Transformation ...$transformers);
-}
diff --git a/src/Iterator/StringIterator.php b/src/Iterator/StringIterator.php
index 10c682294..5478d5d60 100644
--- a/src/Iterator/StringIterator.php
+++ b/src/Iterator/StringIterator.php
@@ -14,7 +14,7 @@
  * @psalm-template T of string
  *
  * @extends ProxyIterator<TKey, T>
- * @implements \Iterator<TKey, T>
+ * @implements Iterator<TKey, T>
  */
 final class StringIterator extends ProxyIterator implements Iterator, OuterIterator
 {
@@ -22,7 +22,7 @@ public function __construct(string $data, string $delimiter = '')
     {
         $this->iterator = new ClosureIterator(
             /**
-             * @psalm-return \Generator<int, string>
+             * @psalm-return Generator<int, string>
              */
             static function (string $input, string $delimiter): Generator {
                 $offset = 0;
diff --git a/src/Operation/AbstractOperation.php b/src/Operation/AbstractOperation.php
index a9bf47445..5a3a781f5 100644
--- a/src/Operation/AbstractOperation.php
+++ b/src/Operation/AbstractOperation.php
@@ -4,18 +4,17 @@
 
 namespace loophp\collection\Operation;
 
-abstract class AbstractOperation
+use Closure;
+use loophp\collection\Contract\Operation;
+
+abstract class AbstractOperation implements Operation
 {
-    /**
-     * @var array<string, mixed>
-     */
-    protected $storage = [];
+    final public function __construct()
+    {
+    }
 
-    /**
-     * @return array<string, mixed>
-     */
-    public function getArguments(): array
+    public static function of(): Closure
     {
-        return $this->storage;
+        return (new static())->__invoke();
     }
 }
diff --git a/src/Operation/Append.php b/src/Operation/Append.php
index 9a992dd4d..16aa1e261 100644
--- a/src/Operation/Append.php
+++ b/src/Operation/Append.php
@@ -17,31 +17,28 @@
 final class Append extends AbstractOperation implements Operation
 {
     /**
-     * @param mixed ...$items
-     * @psalm-param T ...$items
+     * @psalm-return Closure(T...): Closure(Iterator<TKey, T>): Generator<int|TKey, T>
      */
-    public function __construct(...$items)
-    {
-        $this->storage['items'] = $items;
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<T> $items
-             *
-             * @psalm-return Generator<TKey|int, T>
+             * @psalm-param T ...$items
              */
-            static function (Iterator $iterator, array $items): Generator {
-                foreach ($iterator as $key => $value) {
-                    yield $key => $value;
-                }
+            static function (...$items): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     */
+                    static function (Iterator $iterator) use ($items): Generator {
+                        foreach ($iterator as $key => $value) {
+                            yield $key => $value;
+                        }
 
-                foreach ($items as $key => $item) {
-                    yield $key => $item;
-                }
+                        foreach ($items as $key => $item) {
+                            yield $key => $item;
+                        }
+                    };
             };
     }
 }
diff --git a/src/Operation/Apply.php b/src/Operation/Apply.php
index 88d40d3a8..e4bf5c5d7 100644
--- a/src/Operation/Apply.php
+++ b/src/Operation/Apply.php
@@ -17,36 +17,34 @@
 final class Apply extends AbstractOperation implements Operation
 {
     /**
-     * @param callable ...$callbacks
-     * @psalm-param callable(T, TKey):(bool) ...$callbacks
-     */
-    public function __construct(callable ...$callbacks)
-    {
-        $this->storage['callbacks'] = $callbacks;
-    }
-
-    /**
-     * @psalm-return Closure(Iterator<TKey, T>, list<callable(T, TKey):(bool)>):(Generator<TKey, T>)
+     * @psalm-return Closure((callable(T, TKey):(bool))...): Closure(Iterator<TKey, T>): Generator<TKey, T>
      */
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<callable(T, TKey):(bool)> $callbacks
+             * @psalm-param callable(T, TKey):(bool) ...$callbacks
              */
-            static function (Iterator $iterator, array $callbacks): Generator {
-                foreach ($iterator as $key => $value) {
-                    foreach ($callbacks as $callback) {
-                        if (true === $callback($value, $key)) {
-                            continue;
-                        }
+            static function (callable ...$callbacks): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     *
+                     * @psalm-return Generator<TKey, T>
+                     */
+                    static function (Iterator $iterator) use ($callbacks): Generator {
+                        foreach ($iterator as $key => $value) {
+                            foreach ($callbacks as $callback) {
+                                if (true === $callback($value, $key)) {
+                                    continue;
+                                }
 
-                        break;
-                    }
+                                break;
+                            }
 
-                    yield $key => $value;
-                }
+                            yield $key => $value;
+                        }
+                    };
             };
     }
 }
diff --git a/src/Operation/Associate.php b/src/Operation/Associate.php
index 349552bbf..10b02fa89 100644
--- a/src/Operation/Associate.php
+++ b/src/Operation/Associate.php
@@ -17,36 +17,40 @@
 final class Associate extends AbstractOperation implements Operation
 {
     /**
-     * @psalm-param null|callable(TKey, T):(TKey) $callbackForKeys
-     * @psalm-param null|callable(TKey, T):(T) $callbackForValues
-     */
-    public function __construct(?callable $callbackForKeys = null, ?callable $callbackForValues = null)
-    {
-        $this->storage = [
-            'callbackForKeys' => $callbackForKeys ?? static function ($key, $value) {
-                return $key;
-            },
-            'callbackForValues' => $callbackForValues ?? static function ($key, $value) {
-                return $value;
-            },
-        ];
-    }
-
-    /**
-     * @psalm-return Closure(Iterator<TKey, T>, callable(TKey, T):(TKey), callable(TKey, T):(T)):(Generator<TKey, T>)
+     * @psalm-return Closure(null|callable(TKey, T):(TKey)): Closure(null|callable(TKey, T):(T)): Generator<TKey, T>
      */
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param callable(TKey, T):(TKey) $callbackForKeys
-             * @psalm-param callable(TKey, T):(T) $callbackForValues
+             * @psalm-param null|callable(TKey, T):(TKey) $callbackForKeys
              */
-            static function (Iterator $iterator, callable $callbackForKeys, callable $callbackForValues): Generator {
-                foreach ($iterator as $key => $value) {
-                    yield $callbackForKeys($key, $value) => $callbackForValues($key, $value);
-                }
+            static function (?callable $callbackForKeys = null): Closure {
+                $callbackForKeys = $callbackForKeys ?? static function ($key, $value) {
+                    return $key;
+                };
+
+                return
+                    /**
+                     * @psalm-param null|callable(TKey, T):(T) $callbackForValues
+                     */
+                    static function (?callable $callbackForValues = null) use ($callbackForKeys): Closure {
+                        $callbackForValues = $callbackForValues ?? static function ($key, $value) {
+                            return $value;
+                        };
+
+                        return
+                            /**
+                             * @psalm-param Iterator<TKey, T> $iterator
+                             *
+                             * @psalm-return Generator<TKey, T>
+                             */
+                            static function (Iterator $iterator) use ($callbackForKeys, $callbackForValues): Generator {
+                                foreach ($iterator as $key => $value) {
+                                    yield $callbackForKeys($key, $value) => $callbackForValues($key, $value);
+                                }
+                            };
+                    };
             };
     }
 }
diff --git a/src/Operation/Cache.php b/src/Operation/Cache.php
index 43c6a1c69..85f0358da 100644
--- a/src/Operation/Cache.php
+++ b/src/Operation/Cache.php
@@ -18,21 +18,21 @@
  */
 final class Cache extends AbstractOperation implements Operation
 {
-    public function __construct(CacheItemPoolInterface $cache)
-    {
-        $this->storage['cache'] = $cache;
-    }
-
+    /**
+     * @psalm-return Closure(CacheItemPoolInterface): Closure(Iterator<TKey, T>): Generator<TKey, T>
+     */
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             *
-             * @psalm-return Generator<TKey, T>
-             */
-            static function (Iterator $iterator, CacheItemPoolInterface $cache): Generator {
-                return yield from new CacheIterator($iterator, $cache);
-            };
+        return static function (CacheItemPoolInterface $cache): Closure {
+            return
+                /**
+                 * @psalm-param Iterator<TKey, T> $iterator
+                 *
+                 * @psalm-return Generator<TKey, T>
+                 */
+                static function (Iterator $iterator) use ($cache): Generator {
+                    return yield from new CacheIterator($iterator, $cache);
+                };
+        };
     }
 }
diff --git a/src/Operation/Chunk.php b/src/Operation/Chunk.php
index 7e7983574..002ff7a81 100644
--- a/src/Operation/Chunk.php
+++ b/src/Operation/Chunk.php
@@ -9,7 +9,6 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\Run;
 
 use function count;
 
@@ -20,47 +19,48 @@
  */
 final class Chunk extends AbstractOperation implements Operation
 {
-    public function __construct(int ...$sizes)
-    {
-        $this->storage['sizes'] = new ArrayIterator($sizes);
-    }
-
     /**
-     * @psalm-return Closure(Iterator<TKey, T>, list<int>):(Generator<int, list<T>>)
+     * @psalm-return Closure(int...): Closure(Iterator<TKey, T>): Generator<int, list<T>>
      */
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param ArrayIterator<int, int> $sizes
-             *
-             * @psalm-return Generator<int, list<T>>
+             * @psalm-param int ...$sizes
              */
-            static function (Iterator $iterator, ArrayIterator $sizes): Generator {
-                $sizesIterator = (new Run(new Loop()))($sizes);
+            static function (int ...$sizes): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     *
+                     * @psalm-return Generator<int, list<T>>
+                     */
+                    static function (Iterator $iterator) use ($sizes): Generator {
+                        /** @psalm-var Iterator<int, int> $sizesIterator */
+                        $sizesIterator = Loop::of()(new ArrayIterator($sizes));
 
-                $values = [];
+                        $values = [];
 
-                foreach ($iterator as $value) {
-                    if (0 >= $sizesIterator->current()) {
-                        return yield from [];
-                    }
+                        foreach ($iterator as $value) {
+                            if (0 >= $sizesIterator->current()) {
+                                return yield from [];
+                            }
 
-                    if (count($values) !== $sizesIterator->current()) {
-                        $values[] = $value;
+                            if (count($values) !== $sizesIterator->current()) {
+                                $values[] = $value;
 
-                        continue;
-                    }
+                                continue;
+                            }
 
-                    $sizesIterator->next();
+                            $sizesIterator->next();
 
-                    yield $values;
+                            yield $values;
 
-                    $values = [$value];
-                }
+                            $values = [$value];
+                        }
 
-                return yield $values;
+                        return yield $values;
+                    };
             };
     }
 }
diff --git a/src/Operation/Collapse.php b/src/Operation/Collapse.php
index a5eb37977..89495e02c 100644
--- a/src/Operation/Collapse.php
+++ b/src/Operation/Collapse.php
@@ -16,6 +16,9 @@
  */
 final class Collapse extends AbstractOperation implements Operation
 {
+    /**
+     * @psalm-return Closure(Iterator<TKey, T>): Generator<TKey, T>
+     */
     public function __invoke(): Closure
     {
         return
diff --git a/src/Operation/Column.php b/src/Operation/Column.php
index 5b1df8481..d6451864a 100644
--- a/src/Operation/Column.php
+++ b/src/Operation/Column.php
@@ -8,7 +8,6 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\Run;
 
 /**
  * @psalm-template TKey
@@ -17,15 +16,6 @@
  */
 final class Column extends AbstractOperation implements Operation
 {
-    /**
-     * @param int|string $column
-     * @psalm-param array-key $column
-     */
-    public function __construct($column)
-    {
-        $this->storage['column'] = $column;
-    }
-
     /**
      * @psalm-return Closure(Iterator<TKey, T>, array-key):(Generator<int, iterable<TKey, T>>)
      */
@@ -33,23 +23,28 @@ public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param array-key $column
+             * @param int|string $column
              *
-             * @psalm-return Generator<int, iterable<TKey, T>>
-             *
-             * @param mixed $column
+             * @psalm-param array-key $column
              */
-            static function (Iterator $iterator, $column): Generator {
-                /**
-                 * @psalm-var array-key $key
-                 * @psalm-var iterable<TKey, T> $value
-                 */
-                foreach ((new Run(new Transpose()))($iterator) as $key => $value) {
-                    if ($key === $column) {
-                        return yield from $value;
-                    }
-                }
+            static function ($column): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     *
+                     * @psalm-return Generator<int, iterable<TKey, T>>
+                     */
+                    static function (Iterator $iterator) use ($column): Generator {
+                        /**
+                         * @psalm-var array-key $key
+                         * @psalm-var iterable<TKey, T> $value
+                         */
+                        foreach (Transpose::of()($iterator) as $key => $value) {
+                            if ($key === $column) {
+                                return yield from $value;
+                            }
+                        }
+                    };
             };
     }
 }
diff --git a/src/Operation/Combinate.php b/src/Operation/Combinate.php
index 662c14c5f..815bb9943 100644
--- a/src/Operation/Combinate.php
+++ b/src/Operation/Combinate.php
@@ -19,65 +19,57 @@
  */
 final class Combinate extends AbstractOperation implements Operation
 {
-    public function __construct(?int $length = null)
-    {
-        $this->storage = [
-            'length' => $length,
-            'getCombinations' => function (array $dataset, int $length): Generator {
-                return $this->getCombinations($dataset, $length);
-            },
-        ];
-    }
-
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param callable(array<int, T>, int): (array<int, T>) $getCombinations
-             *
-             * @psalm-return Generator<int, list<T>>
-             */
-            static function (Iterator $iterator, ?int $length, callable $getCombinations): Generator {
-                $dataset = iterator_to_array($iterator);
+        return static function (?int $length = null): Closure {
+            $getCombinations =
+                /**
+                 * @param array<mixed> $dataset
+                 * @psalm-param array<int, T> $dataset
+                 *
+                 * @return Generator<array<mixed>>
+                 * @psalm-return Generator<array<int, T>>
+                 */
+                static function (array $dataset, int $length) use (&$getCombinations): Generator {
+                    for ($i = 0; count($dataset) - $length >= $i; ++$i) {
+                        if (1 === $length) {
+                            yield [$dataset[$i]];
 
-                if (0 < $length) {
-                    return yield from $getCombinations($dataset, $length);
-                }
+                            continue;
+                        }
 
-                $collectionSize = count($dataset);
+                        /** @psalm-var array<int, T> $permutation */
+                        foreach ($getCombinations(array_slice($dataset, $i + 1), $length - 1) as $permutation) {
+                            array_unshift($permutation, $dataset[$i]);
 
-                if (0 === $length) {
-                    return yield from $getCombinations($dataset, $collectionSize);
-                }
+                            yield $permutation;
+                        }
+                    }
+                };
 
-                for ($i = 1; $i <= $collectionSize; ++$i) {
-                    yield from $getCombinations($dataset, $i);
-                }
-            };
-    }
+            return
+                /**
+                 * @psalm-param Iterator<TKey, T> $iterator
+                 *
+                 * @psalm-return Generator<int, array<int, T>>
+                 */
+                static function (Iterator $iterator) use ($length, $getCombinations): Generator {
+                    $dataset = iterator_to_array($iterator);
 
-    /**
-     * @param array<mixed> $dataset
-     * @psalm-param array<int, T> $dataset
-     *
-     * @return Generator<array<mixed>>
-     * @psalm-return Generator<array<int, T>>
-     */
-    private function getCombinations(array $dataset, int $length): Generator
-    {
-        for ($i = 0; count($dataset) - $length >= $i; ++$i) {
-            if (1 === $length) {
-                yield [$dataset[$i]];
+                    if (0 < $length) {
+                        return yield from $getCombinations($dataset, $length);
+                    }
 
-                continue;
-            }
+                    $collectionSize = count($dataset);
 
-            foreach ($this->getCombinations(array_slice($dataset, $i + 1), $length - 1) as $permutation) {
-                array_unshift($permutation, $dataset[$i]);
+                    if (0 === $length) {
+                        return yield from $getCombinations($dataset, $collectionSize);
+                    }
 
-                yield $permutation;
-            }
-        }
+                    for ($i = 1; $i <= $collectionSize; ++$i) {
+                        yield from $getCombinations($dataset, $i);
+                    }
+                };
+        };
     }
 }
diff --git a/src/Operation/Combine.php b/src/Operation/Combine.php
index 21c9e62f9..214ae4b5c 100644
--- a/src/Operation/Combine.php
+++ b/src/Operation/Combine.php
@@ -20,36 +20,37 @@
 final class Combine extends AbstractOperation implements Operation
 {
     /**
-     * Combine constructor.
-     *
-     * @param mixed ...$keys
-     * @psalm-param TKey ...$keys
+     * @return Closure(T...): Closure(Iterator<TKey, T>): Generator<T, T>
      */
-    public function __construct(...$keys)
-    {
-        $this->storage['keys'] = new ArrayIterator($keys);
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param ArrayIterator<int, TKey> $keys
+             * @psalm-param T ...$keys
              *
-             * @psalm-return Generator<TKey, T>
+             * @psalm-return Closure(Iterator<TKey, T>): Generator<T, T>
              */
-            static function (Iterator $iterator, ArrayIterator $keys): Generator {
-                while ($iterator->valid() && $keys->valid()) {
-                    yield $keys->current() => $iterator->current();
-
-                    $iterator->next();
-                    $keys->next();
-                }
-
-                if ($iterator->valid() !== $keys->valid()) {
-                    trigger_error('Both keys and values must have the same amount of items.', E_USER_WARNING);
-                }
+            static function (...$keys): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     *
+                     * @psalm-retur Generator<T, T>
+                     */
+                    static function (Iterator $iterator) use ($keys): Generator {
+                        $keys = new ArrayIterator($keys);
+
+                        while ($iterator->valid() && $keys->valid()) {
+                            yield $keys->current() => $iterator->current();
+
+                            $iterator->next();
+                            $keys->next();
+                        }
+
+                        if ($iterator->valid() !== $keys->valid()) {
+                            trigger_error('Both keys and values must have the same amount of items.', E_USER_WARNING);
+                        }
+                    };
             };
     }
 }
diff --git a/src/Operation/Compact.php b/src/Operation/Compact.php
index f02a6c3b7..fb25ef576 100644
--- a/src/Operation/Compact.php
+++ b/src/Operation/Compact.php
@@ -8,7 +8,6 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\Run;
 
 use function in_array;
 
@@ -20,36 +19,36 @@
 final class Compact extends AbstractOperation implements Operation
 {
     /**
-     * @param mixed ...$values
-     * @psalm-param T ...$values
+     * @psalm-return Closure(T...): Closure(Iterator<TKey, T>): Generator<TKey, T>
      */
-    public function __construct(...$values)
-    {
-        $this->storage['values'] = [] === $values ? [null] : $values;
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<T|null> $values
-             *
-             * @psalm-return Generator<TKey, T>
+             * @psalm-param T ...$values
              */
-            static function (Iterator $iterator, array $values): Generator {
-                return yield from
-                (new Run(
-                    new Filter(
-                        /**
-                         * @param mixed $item
-                         */
-                        static function ($item) use ($values): bool {
-                            return !in_array($item, $values, true);
-                        }
-                    )
-                )
-                )($iterator);
+            static function (...$values): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     * @psalm-return Generator<TKey, T>
+                     */
+                    static function (Iterator $iterator) use ($values): Generator {
+                        $values = [] === $values ? [null] : $values;
+
+                        /** @psalm-var callable(Iterator<TKey, T>):Generator<TKey, T> $filter */
+                        $filter = Filter::of()(
+                            /**
+                             * @param mixed $value
+                             * @psalm-param T $value
+                             */
+                            static function ($value) use ($values): bool {
+                                return !in_array($value, $values, true);
+                            }
+                        );
+
+                        return yield from $filter($iterator);
+                    };
             };
     }
 }
diff --git a/src/Operation/Compose.php b/src/Operation/Compose.php
new file mode 100644
index 000000000..b8887f7c8
--- /dev/null
+++ b/src/Operation/Compose.php
@@ -0,0 +1,52 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Operation;
+
+use Closure;
+use Generator;
+use Iterator;
+use loophp\collection\Contract\Operation;
+
+/**
+ * @psalm-template TKey
+ * @psalm-template TKey of array-key
+ * @psalm-template T
+ */
+final class Compose extends AbstractOperation implements Operation
+{
+    // phpcs:disable
+    /**
+     * @psalm-return Closure((callable(Iterator<TKey, T>):Generator<TKey, T>)...): Closure(Iterator<TKey, T>): Generator<TKey, T>
+     */
+    // phpcs:enable
+    public function __invoke(): Closure
+    {
+        return
+            /**
+             * @psalm-param callable(Iterator<TKey, T>): Generator<TKey, T> ...$operations
+             */
+            static function (callable ...$operations): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     * @psalm-return Generator<TKey, T>
+                     */
+                    static function (Iterator $iterator) use ($operations): Generator {
+                        $callback =
+                            /**
+                             * @psalm-param Iterator<TKey, T> $iterator
+                             * @psalm-param callable(Iterator<TKey, T>): Generator<TKey, T> $fn
+                             *
+                             * @psalm-return Generator<TKey, T>
+                             */
+                            static function (Iterator $iterator, callable $fn): Generator {
+                                return $fn($iterator);
+                            };
+
+                        return yield from array_reduce($operations, $callback, $iterator);
+                    };
+            };
+    }
+}
diff --git a/src/Operation/Contains.php b/src/Operation/Contains.php
new file mode 100644
index 000000000..6cd1d10cd
--- /dev/null
+++ b/src/Operation/Contains.php
@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Operation;
+
+use Closure;
+use Generator;
+use Iterator;
+use loophp\collection\Contract\Operation;
+
+/**
+ * @psalm-template TKey
+ * @psalm-template TKey of array-key
+ * @psalm-template T
+ */
+final class Contains extends AbstractOperation implements Operation
+{
+    public function __invoke(): Closure
+    {
+        return
+            /**
+             * @psalm-param T ...$values
+             */
+            static function (...$values): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     *
+                     * @psalm-return Generator<int, bool>
+                     */
+                    static function (Iterator $iterator) use ($values): Generator {
+                        foreach ($iterator as $key => $value) {
+                            foreach ($values as $k => $v) {
+                                if ($v === $value) {
+                                    unset($values[$k]);
+                                }
+
+                                if ([] === $values) {
+                                    return yield true;
+                                }
+                            }
+                        }
+
+                        return yield false;
+                    };
+            };
+    }
+}
diff --git a/src/Operation/Cycle.php b/src/Operation/Cycle.php
index 99d1bad71..7a707c9e2 100644
--- a/src/Operation/Cycle.php
+++ b/src/Operation/Cycle.php
@@ -18,29 +18,29 @@
  */
 final class Cycle extends AbstractOperation implements Operation
 {
-    public function __construct(int $length)
-    {
-        $this->storage['length'] = $length;
-    }
-
+    /**
+     * @psalm-return Closure(int): Closure(Iterator<TKey, T>): Generator<TKey, T>
+     */
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             *
-             * @psalm-return Generator<TKey, T>
-             */
-            static function (Iterator $iterator, int $length): Generator {
-                if (0 === $length) {
-                    return yield from [];
-                }
+        return static function (int $length): Closure {
+            return
+                /**
+                 * @psalm-param Iterator<TKey, T> $iterator
+                 *
+                 * @psalm-return Generator<TKey, T>
+                 */
+                static function (Iterator $iterator) use ($length): Generator {
+                    if (0 === $length) {
+                        return yield from [];
+                    }
 
-                return yield from new LimitIterator(
-                    new InfiniteIterator($iterator),
-                    0,
-                    $length
-                );
-            };
+                    return yield from new LimitIterator(
+                        new InfiniteIterator($iterator),
+                        0,
+                        $length
+                    );
+                };
+        };
     }
 }
diff --git a/src/Operation/Diff.php b/src/Operation/Diff.php
index c1b364869..cdd147f3f 100644
--- a/src/Operation/Diff.php
+++ b/src/Operation/Diff.php
@@ -19,29 +19,28 @@
 final class Diff extends AbstractOperation implements Operation
 {
     /**
-     * @param mixed ...$values
-     * @psalm-param T ...$values
+     * @psalm-return Closure(T...): Closure(Iterator<TKey, T>): Generator<TKey, T>
      */
-    public function __construct(...$values)
-    {
-        $this->storage['values'] = $values;
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<T> $values
-             *
-             * @psalm-return Generator<TKey, T>
+             * @psalm-param T ...$values
              */
-            static function (Iterator $iterator, array $values): Generator {
-                foreach ($iterator as $key => $value) {
-                    if (false === in_array($value, $values, true)) {
-                        yield $key => $value;
-                    }
-                }
+            static function (...$values): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     *
+                     * @psalm-return Generator<TKey, T>
+                     */
+                    static function (Iterator $iterator) use ($values): Generator {
+                        foreach ($iterator as $key => $value) {
+                            if (false === in_array($value, $values, true)) {
+                                yield $key => $value;
+                            }
+                        }
+                    };
             };
     }
 }
diff --git a/src/Operation/DiffKeys.php b/src/Operation/DiffKeys.php
index ea9e21bb0..096a3b1fe 100644
--- a/src/Operation/DiffKeys.php
+++ b/src/Operation/DiffKeys.php
@@ -19,31 +19,26 @@
 final class DiffKeys extends AbstractOperation implements Operation
 {
     /**
-     * @param mixed ...$values
-     * @psalm-param TKey ...$values
+     * @psalm-return Closure(TKey...): Closure(Iterator<TKey, T>): Generator<TKey, T>
      */
-    public function __construct(...$values)
-    {
-        $this->storage['values'] = $values;
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<TKey> $values
-             *
-             * @psalm-return Generator<TKey, T>
-             *
-             * @param mixed $values
+             * @psalm-param T ...$values
              */
-            static function (Iterator $iterator, array $values): Generator {
-                foreach ($iterator as $key => $value) {
-                    if (false === in_array($key, $values, true)) {
-                        yield $key => $value;
-                    }
-                }
+            static function (...$values): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     */
+                    static function (Iterator $iterator) use ($values): Generator {
+                        foreach ($iterator as $key => $value) {
+                            if (false === in_array($key, $values, true)) {
+                                yield $key => $value;
+                            }
+                        }
+                    };
             };
     }
 }
diff --git a/src/Operation/Distinct.php b/src/Operation/Distinct.php
index 4dfdb84c6..0d9b1d38d 100644
--- a/src/Operation/Distinct.php
+++ b/src/Operation/Distinct.php
@@ -18,6 +18,9 @@
  */
 final class Distinct extends AbstractOperation implements Operation
 {
+    /**
+     * @psalm-return Closure(Iterator<TKey, T>): Generator<TKey, T>
+     */
     public function __invoke(): Closure
     {
         return
diff --git a/src/Operation/Explode.php b/src/Operation/Explode.php
index 7cb2f6123..1f58eb7d6 100644
--- a/src/Operation/Explode.php
+++ b/src/Operation/Explode.php
@@ -8,7 +8,6 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\Run;
 
 /**
  * @psalm-template TKey
@@ -17,46 +16,40 @@
  */
 final class Explode extends AbstractOperation implements Operation
 {
-    /**
-     * @param mixed ...$explodes
-     * @psalm-param T ...$explodes
-     */
-    public function __construct(...$explodes)
-    {
-        $this->storage['explodes'] = $explodes;
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<T> $explodes
-             *
-             * @psalm-return Generator<int, list<T>>
+             * @psalm-param T ...$explodes
              */
-            static function (Iterator $iterator, array $explodes): Generator {
-                return yield from (new Run(
-                    new Split(
-                        ...array_map(
-                            /**
-                             * @param mixed $explode
-                             * @psalm-param T $explode
-                             */
-                            static function ($explode): Closure {
-                                return
-                                    /**
-                                     * @param mixed $value
-                                     * @psalm-param T $value
-                                     */
-                                    static function ($value) use ($explode): bool {
-                                        return $value === $explode;
-                                    };
-                            },
-                            $explodes
-                        )
-                    )
-                ))($iterator);
+            static function (...$explodes): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     *
+                     * @psalm-return Generator<int, list<T>>
+                     */
+                    static function (Iterator $iterator) use ($explodes): Generator {
+                        return yield from Split::of()(
+                            ...array_map(
+                                /**
+                                 * @param mixed $explode
+                                 * @psalm-param T $explode
+                                 */
+                                static function ($explode): Closure {
+                                    return
+                                        /**
+                                         * @param mixed $value
+                                         * @psalm-param T $value
+                                         */
+                                        static function ($value) use ($explode): bool {
+                                            return $value === $explode;
+                                        };
+                                },
+                                $explodes
+                            )
+                        )($iterator);
+                    };
             };
     }
 }
diff --git a/src/Operation/Falsy.php b/src/Operation/Falsy.php
new file mode 100644
index 000000000..a8d3d0fbe
--- /dev/null
+++ b/src/Operation/Falsy.php
@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Operation;
+
+use Closure;
+use Generator;
+use Iterator;
+use loophp\collection\Contract\Operation;
+
+/**
+ * @psalm-template TKey
+ * @psalm-template TKey of array-key
+ * @psalm-template T
+ */
+final class Falsy extends AbstractOperation implements Operation
+{
+    /**
+     * @psalm-return Closure(Iterator<TKey, T>): Generator<int, bool>
+     */
+    public function __invoke(): Closure
+    {
+        return
+            /**
+             * @psalm-param Iterator<TKey, T> $iterator
+             * @psalm-return Generator<int, bool> $iterator
+             */
+            static function (Iterator $iterator): Generator {
+                foreach ($iterator as $key => $value) {
+                    if (false !== (bool) $value) {
+                        return yield false;
+                    }
+                }
+
+                return yield true;
+            };
+    }
+}
diff --git a/src/Operation/Filter.php b/src/Operation/Filter.php
index cef23d1f1..baea1c623 100644
--- a/src/Operation/Filter.php
+++ b/src/Operation/Filter.php
@@ -17,42 +17,48 @@
  */
 final class Filter extends AbstractOperation implements Operation
 {
-    public function __construct(callable ...$callbacks)
-    {
-        $defaultCallback =
-            /**
-             * @param mixed $value
-             * @param mixed $key
-             * @psalm-param T $value
-             * @psalm-param TKey $key
-             * @psalm-param Iterator<TKey, T> $iterator
-             */
-            static function ($value, $key, Iterator $iterator): bool {
-                return (bool) $value;
-            };
-
-        $this->storage['callbacks'] = [] === $callbacks ?
-            [$defaultCallback] :
-            $callbacks;
-    }
-
+    // phpcs:disable
+    /**
+     * @psalm-return Closure((callable(T, TKey, Iterator<TKey, T>): bool)...): Closure(Iterator<TKey, T>): Generator<TKey, T>
+     */
+    // phpcs:enable
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<callable(T, TKey, Iterator<TKey, T>):(bool)> $callbacks
-             *
-             * @psalm-return Generator<TKey, T>
+             * @psalm-param callable(T, TKey, Iterator<TKey, T>): bool ...$callbacks
              */
-            static function (Iterator $iterator, array $callbacks): Generator {
-                return yield from array_reduce(
-                    $callbacks,
-                    static function (Iterator $carry, callable $callback): CallbackFilterIterator {
-                        return new CallbackFilterIterator($carry, $callback);
-                    },
-                    $iterator
-                );
+            static function (callable ...$callbacks): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     * @psalm-return Generator<TKey, T>
+                     */
+                    static function (Iterator $iterator) use ($callbacks): Generator {
+                        $defaultCallback =
+                            /**
+                             * @param mixed $value
+                             * @param mixed $key
+                             * @psalm-param T $value
+                             * @psalm-param TKey $key
+                             * @psalm-param Iterator<TKey, T> $iterator
+                             */
+                            static function ($value, $key, Iterator $iterator): bool {
+                                return (bool) $value;
+                            };
+
+                        $callbacks = [] === $callbacks ?
+                            [$defaultCallback] :
+                            $callbacks;
+
+                        return yield from array_reduce(
+                            $callbacks,
+                            static function (Iterator $carry, callable $callback): CallbackFilterIterator {
+                                return new CallbackFilterIterator($carry, $callback);
+                            },
+                            $iterator
+                        );
+                    };
             };
     }
 }
diff --git a/src/Operation/First.php b/src/Operation/First.php
index e352feb4f..33bf3da64 100644
--- a/src/Operation/First.php
+++ b/src/Operation/First.php
@@ -8,70 +8,47 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\Run;
 
 /**
  * @psalm-template TKey
  * @psalm-template TKey of array-key
  * @psalm-template T
- *
- * @implements Operation<TKey, T>
  */
 final class First extends AbstractOperation implements Operation
 {
-    /**
-     * @var callable
-     * @psalm-var callable(T, TKey):(bool)
-     */
-    private $callback;
-
-    /**
-     * @psalm-param callable(T, TKey):(bool)|null $callback
-     *
-     * @psalm-param T|null $default
-     */
-    public function __construct(?callable $callback = null, int $size = 1)
-    {
-        $defaultCallback =
-            /**
-             * @param mixed $value
-             * @param mixed $key
-             * @psalm-param T $value
-             * @psalm-param TKey $key
-             * @psalm-param Iterator<TKey, T> $iterator
-             */
-            static function ($value, $key, Iterator $iterator): bool {
-                return true;
-            };
-
-        $this->storage = [
-            'callback' => $callback ?? $defaultCallback,
-            'size' => $size,
-        ];
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             *
-             * @psalm-return Generator<TKey, T>
+             * @psalm-param callable(T, TKey):(bool)|null $callback
              */
-            static function (Iterator $iterator, callable $callback, int $size): Generator {
-                $callback =
+            static function (?callable $callback = null): Closure {
+                return static function (int $size = 1) use ($callback): Closure {
+                    return
                     /**
-                     * @param mixed $value
-                     * @param mixed $key
-                     * @psalm-param T $value
-                     * @psalm-param TKey $key
                      * @psalm-param Iterator<TKey, T> $iterator
                      */
-                    static function ($value, $key, Iterator $iterator) use ($callback): bool {
-                        return true === $callback($value, $key, $iterator);
+                    static function (Iterator $iterator) use ($callback, $size): Generator {
+                        $defaultCallback =
+                            /**
+                             * @param mixed $value
+                             * @param mixed $key
+                             * @psalm-param T $value
+                             * @psalm-param TKey $key
+                             * @psalm-param Iterator<TKey, T> $iterator
+                             */
+                            static function ($value, $key, Iterator $iterator): bool {
+                                return true;
+                            };
+
+                        $callback = $callback ?? $defaultCallback;
+
+                        return yield from Compose::of()(
+                            Filter::of()($callback),
+                            Limit::of()($size)(0)
+                        )($iterator);
                     };
-
-                return yield from (new Run(new Filter($callback), new Limit($size)))($iterator);
+                };
             };
     }
 }
diff --git a/src/Operation/Flatten.php b/src/Operation/Flatten.php
index 5b45e73b0..d6eb7b63a 100644
--- a/src/Operation/Flatten.php
+++ b/src/Operation/Flatten.php
@@ -9,7 +9,6 @@
 use Iterator;
 use loophp\collection\Contract\Operation;
 use loophp\collection\Iterator\IterableIterator;
-use loophp\collection\Transformation\Run;
 
 /**
  * @psalm-template TKey
@@ -18,37 +17,42 @@
  */
 final class Flatten extends AbstractOperation implements Operation
 {
-    public function __construct(int $depth)
-    {
-        $this->storage['depth'] = $depth;
-    }
-
+    /**
+     * @psalm-return Closure(int): Closure(Iterator<TKey, T>): Generator<int, T>
+     */
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             *
-             * @psalm-return Generator<int, T>
-             */
-            static function (Iterator $iterator, int $depth): Generator {
-                foreach ($iterator as $key => $value) {
-                    if (false === is_iterable($value)) {
-                        yield $key => $value;
-                    } elseif (1 === $depth) {
-                        /** @psalm-var T $subValue */
-                        foreach ($value as $subKey => $subValue) {
-                            yield $subKey => $subValue;
-                        }
-                    } else {
-                        /** @psalm-var IterableIterator<TKey, T> $iterable */
-                        $iterable = (new Run(new Flatten($depth - 1)))(new IterableIterator($value));
+        return static function (int $depth): Closure {
+            return
+                /**
+                 * @psalm-param Iterator<TKey, T> $iterator
+                 *
+                 * @psalm-return Generator<int, T>
+                 */
+                static function (Iterator $iterator) use ($depth): Generator {
+                    foreach ($iterator as $key => $value) {
+                        if (false === is_iterable($value)) {
+                            yield $key => $value;
+                        } elseif (1 === $depth) {
+                            /** @psalm-var TKey $subKey */
+                            /** @psalm-var T $subValue */
+                            foreach ($value as $subKey => $subValue) {
+                                yield $subKey => $subValue;
+                            }
+                        } else {
+                            /** @psalm-var callable(Iterator<TKey, T>): Generator<TKey, T> $flatten */
+                            $flatten = Flatten::of()($depth - 1);
 
-                        foreach ($iterable as $subKey => $subValue) {
-                            yield $subKey => $subValue;
+                            /**
+                             * @psalm-var TKey $subKey
+                             * @psalm-var T $subValue
+                             */
+                            foreach ($flatten(new IterableIterator($value)) as $subKey => $subValue) {
+                                yield $subKey => $subValue;
+                            }
                         }
                     }
-                }
-            };
+                };
+        };
     }
 }
diff --git a/src/Operation/FoldLeft.php b/src/Operation/FoldLeft.php
new file mode 100644
index 000000000..2af8b323a
--- /dev/null
+++ b/src/Operation/FoldLeft.php
@@ -0,0 +1,54 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Operation;
+
+use Closure;
+use Generator;
+use Iterator;
+use loophp\collection\Contract\Operation;
+
+/**
+ * @psalm-template TKey
+ * @psalm-template TKey of array-key
+ * @psalm-template T
+ */
+final class FoldLeft extends AbstractOperation implements Operation
+{
+    // phpcs:disable
+    /**
+     * @psalm-return Closure(callable(T|null, T, TKey, Iterator<TKey, T>): T): Closure(T|null): Closure(Iterator<TKey, T>): T|null
+     */
+    // phpcs:enable
+    public function __invoke(): Closure
+    {
+        return
+            /**
+             * @psalm-param callable(T|null, T, TKey, Iterator<TKey, T>): T
+             */
+            static function (callable $callback): Closure {
+                return
+                    /**
+                     * @psalm-param T|null $initial
+                     *
+                     * @param mixed|null $initial
+                     */
+                    static function ($initial = null) use ($callback): Closure {
+                        return
+                            /**
+                             * @psalm-param Iterator<TKey, T> $iterator
+                             *
+                             * @psalm-return Generator<int, T|null>
+                             */
+                            static function (Iterator $iterator) use ($callback, $initial): Generator {
+                                foreach ($iterator as $key => $value) {
+                                    $initial = $callback($initial, $value, $key, $iterator);
+                                }
+
+                                return yield $initial;
+                            };
+                    };
+            };
+    }
+}
diff --git a/src/Operation/FoldRight.php b/src/Operation/FoldRight.php
new file mode 100644
index 000000000..f09a4f381
--- /dev/null
+++ b/src/Operation/FoldRight.php
@@ -0,0 +1,55 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Operation;
+
+use Closure;
+use Generator;
+use Iterator;
+use loophp\collection\Contract\Operation;
+
+/**
+ * @psalm-template TKey
+ * @psalm-template TKey of array-key
+ * @psalm-template T
+ */
+final class FoldRight extends AbstractOperation implements Operation
+{
+    // phpcs:disable
+    /**
+     * @psalm-return Closure(callable(T|null, T, TKey, Iterator<TKey, T>): T): Closure(T|null): Closure(Iterator<TKey, T>): T|null
+     */
+    // phpcs:enable
+    public function __invoke(): Closure
+    {
+        return
+            /**
+             * @psalm-param callable(T|null, T, TKey, Iterator<TKey, T>): T
+             */
+            static function (callable $callback): Closure {
+                return
+                    /**
+                     * @param mixed|null $initial
+                     * @psalm-param T|null $initial
+                     */
+                    static function ($initial = null) use ($callback): Closure {
+                        return
+                            /**
+                             * @psalm-param Iterator<TKey, T> $iterator
+                             *
+                             * @psalm-return Generator<int, T|null>
+                             */
+                            static function (Iterator $iterator) use ($callback, $initial): Generator {
+                                /** @psalm-var callable(Iterator<TKey, T>): Generator<TKey, T> $foldRight */
+                                $foldRight = Compose::of()(
+                                    Reverse::of(),
+                                    FoldLeft::of()($callback)($initial)
+                                );
+
+                                return yield from $foldRight($iterator);
+                            };
+                    };
+            };
+    }
+}
diff --git a/src/Operation/Forget.php b/src/Operation/Forget.php
index 32cd3cc9e..1268f4054 100644
--- a/src/Operation/Forget.php
+++ b/src/Operation/Forget.php
@@ -19,31 +19,30 @@
 final class Forget extends AbstractOperation implements Operation
 {
     /**
-     * @param mixed ...$keys
-     * @psalm-param TKey ...$keys
+     * @psalm-return Closure(TKey...): Closure(Iterator<TKey, T>): Generator<TKey, T>
      */
-    public function __construct(...$keys)
-    {
-        $this->storage['keys'] = $keys;
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<TKey> $keys
-             *
-             * @psalm-return Generator<TKey, T>
+             * @psalm-param TKey ...$keys
              */
-            static function (Iterator $iterator, array $keys): Generator {
-                $keys = array_flip($keys);
+            static function (...$keys): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     *
+                     * @psalm-return Generator<TKey, T>
+                     */
+                    static function (Iterator $iterator) use ($keys): Generator {
+                        $keys = array_flip($keys);
 
-                foreach ($iterator as $key => $value) {
-                    if (false === array_key_exists($key, $keys)) {
-                        yield $key => $value;
-                    }
-                }
+                        foreach ($iterator as $key => $value) {
+                            if (false === array_key_exists($key, $keys)) {
+                                yield $key => $value;
+                            }
+                        }
+                    };
             };
     }
 }
diff --git a/src/Operation/Get.php b/src/Operation/Get.php
new file mode 100644
index 000000000..59579f0b0
--- /dev/null
+++ b/src/Operation/Get.php
@@ -0,0 +1,53 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Operation;
+
+use Closure;
+use Generator;
+use Iterator;
+use loophp\collection\Contract\Operation;
+
+/**
+ * @psalm-template TKey
+ * @psalm-template TKey of array-key
+ * @psalm-template T
+ */
+final class Get extends AbstractOperation implements Operation
+{
+    public function __invoke(): Closure
+    {
+        return
+            /**
+             * @psalm-param array-key $keyToGet
+             *
+             * @param mixed $keyToGet
+             */
+            static function ($keyToGet): Closure {
+                return
+                    /**
+                     * @psalm-param T $default
+                     *
+                     * @param mixed $default
+                     */
+                    static function ($default) use ($keyToGet): Closure {
+                        return
+                            /**
+                             * @psalm-param Iterator<TKey, T> $iterator
+                             *
+                             * @psalm-return Generator<int, T>
+                             */
+                            static function (Iterator $iterator) use ($keyToGet, $default): Generator {
+                                foreach ($iterator as $key => $value) {
+                                    if ($key === $keyToGet) {
+                                        return yield $value;
+                                    }
+                                }
+
+                                return yield $default;
+                            };
+                    };
+            };
+    }
+}
diff --git a/src/Operation/Group.php b/src/Operation/Group.php
index b834c298d..cdae76aea 100644
--- a/src/Operation/Group.php
+++ b/src/Operation/Group.php
@@ -8,8 +8,6 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\FoldLeft;
-use loophp\collection\Transformation\Transform;
 
 /**
  * @psalm-template TKey
@@ -18,57 +16,65 @@
  */
 final class Group extends AbstractOperation implements Operation
 {
-    public function __construct(?callable $callable = null)
-    {
-        $this->storage['callable'] = $callable ??
-            /**
-             * @param mixed $key
-             * @psalm-param TKey $key
-             *
-             * @param mixed $value
-             * @psalm-param T $value
-             *
-             * @return mixed
-             * @psalm-return TKey
-             */
-            static function ($value, $key) {
-                return $key;
-            };
-    }
-
+    /**
+     * @psalm-return Closure(null|callable(TKey, T):(TKey)): Closure(Iterator<TKey, T>): Generator<int, list<T>>
+     */
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param callable(TKey, T):(TKey) $callable
-             *
-             * @psalm-return Generator<int, list<T>>
+             * @psalm-param null|callable(TKey, T):(T|TKey) $callable
              */
-            static function (Iterator $iterator, callable $callable): Generator {
-                $callback =
+            static function (?callable $callable = null): Closure {
+                return
                     /**
-                     * @psalm-param array<TKey, list<T>> $collect
+                     * @psalm-param Iterator<TKey, T> $iterator
                      *
-                     * @param mixed $value
-                     * @psalm-param T $value
-                     *
-                     * @param mixed $key
-                     * @psalm-param TKey $key
-                     *
-                     * @psalm-return array<TKey, list<T>>
+                     * @psalm-return Generator<int, list<T>>
                      */
-                    static function (array $collect, $value, $key) use ($callable): array {
-                        if (null !== $groupKey = $callable($value, $key)) {
-                            $collect[$groupKey][] = $value;
-                        } else {
-                            $collect[$key] = $value;
-                        }
+                    static function (Iterator $iterator) use ($callable): Generator {
+                        $callable = $callable ??
+                            /**
+                             * @param mixed $key
+                             * @psalm-param TKey $key
+                             *
+                             * @param mixed $value
+                             * @psalm-param T $value
+                             *
+                             * @return mixed
+                             * @psalm-return TKey
+                             */
+                            static function ($value, $key) {
+                                return $key;
+                            };
 
-                        return $collect;
-                    };
+                        $callback =
+                            /**
+                             * @psalm-param array<TKey, list<T>> $collect
+                             *
+                             * @param mixed $value
+                             * @psalm-param T $value
+                             *
+                             * @param mixed $key
+                             * @psalm-param TKey $key
+                             *
+                             * @psalm-return array<TKey, list<T>>
+                             */
+                            static function (array $collect, $value, $key) use ($callable): array {
+                                if (null !== $groupKey = $callable($value, $key)) {
+                                    $collect[$groupKey][] = $value;
+                                } else {
+                                    $collect[$key] = $value;
+                                }
 
-                return yield from (new Transform(new FoldLeft($callback, [])))($iterator);
+                                return $collect;
+                            };
+
+                        /** @psalm-var callable(Iterator<TKey, T>): Generator<TKey, T> $foldLeft */
+                        $foldLeft = FoldLeft::of()($callback)([]);
+
+                        return yield from ($foldLeft($iterator))->current();
+                    };
             };
     }
 }
diff --git a/src/Operation/Has.php b/src/Operation/Has.php
new file mode 100644
index 000000000..519261cae
--- /dev/null
+++ b/src/Operation/Has.php
@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Operation;
+
+use Closure;
+use Generator;
+use Iterator;
+use loophp\collection\Contract\Operation;
+
+/**
+ * @psalm-template TKey
+ * @psalm-template TKey of array-key
+ * @psalm-template T
+ */
+final class Has extends AbstractOperation implements Operation
+{
+    /**
+     * @psalm-return Closure(callable(TKey, T):(bool)): Closure(Iterator<TKey, T>): bool
+     */
+    public function __invoke(): Closure
+    {
+        return
+            /**
+             * @psalm-param callable(TKey, T):(bool) $callback
+             */
+            static function (callable $callback): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     * @psalm-return Generator<int, bool>
+                     */
+                    static function (Iterator $iterator) use ($callback): Generator {
+                        foreach ($iterator as $key => $value) {
+                            if ($callback($key, $value) === $value) {
+                                return yield true;
+                            }
+                        }
+
+                        return yield false;
+                    };
+            };
+    }
+}
diff --git a/src/Operation/IfThenElse.php b/src/Operation/IfThenElse.php
index fbce20e58..eb8e70cfb 100644
--- a/src/Operation/IfThenElse.php
+++ b/src/Operation/IfThenElse.php
@@ -16,33 +16,43 @@
  */
 final class IfThenElse extends AbstractOperation implements Operation
 {
-    /**
-     * @psalm-param callable(T, TKey): bool $condition
-     * @psalm-param callable(T, TKey): (T|TKey) $then
-     * @psalm-param callable(T, TKey): (T|TKey) $else
-     */
-    public function __construct(callable $condition, callable $then, callable $else)
-    {
-        $this->storage = [
-            'condition' => $condition,
-            'then' => $then,
-            'else' => $else,
-        ];
-    }
-
     // phpcs:disable
     /**
-     * @psalm-return Closure(Iterator<TKey, T>, callable(T, TKey): bool, callable(T, TKey): (T|TKey), callable(T, TKey): (T|TKey)): Generator<TKey, T>
+     * @psalm-return Closure(callable(T, TKey): bool): Closure(callable(T, TKey): (T)): Closure(callable(T, TKey): (T)): Generator<TKey, T>
      */
     // phpcs:enable
     public function __invoke(): Closure
     {
-        return static function (Iterator $iterator, callable $condition, callable $then, callable $else): Generator {
-            foreach ($iterator as $key => $value) {
-                yield $key => $condition($value, $key) ?
-                    $then($value, $key) :
-                    $else($value, $key);
-            }
-        };
+        return
+            /**
+             * @psalm-param callable(T, TKey): bool $condition
+             */
+            static function (callable $condition): Closure {
+                return
+                    /**
+                     * @psalm-param callable(T, TKey): (T) $then
+                     */
+                    static function (callable $then) use ($condition): Closure {
+                        return
+                            /**
+                             * @psalm-param callable(T, TKey): (T) $else
+                             */
+                            static function (callable $else) use ($condition, $then): Closure {
+                                return
+                                    /**
+                                     * @psalm-param Iterator<TKey, T> $iterator
+                                     *
+                                     * @psalm-return Generator<TKey, T>
+                                     */
+                                    static function (Iterator $iterator) use ($condition, $then, $else): Generator {
+                                        foreach ($iterator as $key => $value) {
+                                            yield $key => $condition($value, $key) ?
+                                                $then($value, $key) :
+                                                $else($value, $key);
+                                        }
+                                    };
+                            };
+                    };
+            };
     }
 }
diff --git a/src/Operation/Implode.php b/src/Operation/Implode.php
new file mode 100644
index 000000000..4a1d830a4
--- /dev/null
+++ b/src/Operation/Implode.php
@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Operation;
+
+use CachingIterator;
+use Closure;
+use Generator;
+use Iterator;
+use loophp\collection\Contract\Operation;
+
+/**
+ * @psalm-template TKey
+ * @psalm-template TKey of array-key
+ * @psalm-template T
+ */
+final class Implode extends AbstractOperation implements Operation
+{
+    public function __invoke(): Closure
+    {
+        return static function (string $glue): Closure {
+            return static function (Iterator $iterator) use ($glue): Generator {
+                $callback =
+                    /**
+                     * @psalm-param TKey $key
+                     * @psalm-param CachingIterator $iterator
+                     *
+                     * @param mixed $key
+                     * @param mixed $iterator
+                     */
+                    static function (string $carry, string $item, $key, CachingIterator $iterator) use ($glue): string {
+                        $carry .= $item;
+
+                        if ($iterator->hasNext()) {
+                            $carry .= $glue;
+                        }
+
+                        return $carry;
+                    };
+
+                return yield from FoldLeft::of()($callback)('')(new CachingIterator($iterator));
+            };
+        };
+    }
+}
diff --git a/src/Operation/Intersect.php b/src/Operation/Intersect.php
index e64ccb3a0..38e173682 100644
--- a/src/Operation/Intersect.php
+++ b/src/Operation/Intersect.php
@@ -19,31 +19,30 @@
 final class Intersect extends AbstractOperation implements Operation
 {
     /**
-     * @param mixed ...$values
-     * @psalm-param T ...$values
+     * @psalm-return Closure(T...): Closure(Iterator<TKey, T>): Generator<TKey, T>
      */
-    public function __construct(...$values)
-    {
-        $this->storage['values'] = $values;
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<T> $values
-             *
-             * @psalm-return Generator<TKey, T>
+             * @psalm-param T ...$values
              */
-            static function (Iterator $iterator, array $values): Generator {
-                foreach ($iterator as $key => $value) {
-                    if (false === in_array($value, $values, true)) {
-                        continue;
-                    }
+            static function (...$values): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     *
+                     * @psalm-return Generator<TKey, T>
+                     */
+                    static function (Iterator $iterator) use ($values): Generator {
+                        foreach ($iterator as $key => $value) {
+                            if (false === in_array($value, $values, true)) {
+                                continue;
+                            }
 
-                    yield $key => $value;
-                }
+                            yield $key => $value;
+                        }
+                    };
             };
     }
 }
diff --git a/src/Operation/IntersectKeys.php b/src/Operation/IntersectKeys.php
index 3188fc1a9..7ef16770c 100644
--- a/src/Operation/IntersectKeys.php
+++ b/src/Operation/IntersectKeys.php
@@ -19,33 +19,30 @@
 final class IntersectKeys extends AbstractOperation implements Operation
 {
     /**
-     * @param mixed ...$values
-     * @psalm-param TKey ...$values
+     * @psalm-return Closure(TKey...): Closure(Iterator<TKey, T>): Generator<TKey, T>
      */
-    public function __construct(...$values)
-    {
-        $this->storage['values'] = $values;
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<TKey> $values
-             *
-             * @psalm-return Generator<TKey, T>
-             *
-             * @param mixed $values
+             * @psalm-param TKey ...$values
              */
-            static function (Iterator $iterator, array $values): Generator {
-                foreach ($iterator as $key => $value) {
-                    if (false === in_array($key, $values, true)) {
-                        continue;
-                    }
+            static function (...$values): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     *
+                     * @psalm-return Generator<TKey, T>
+                     */
+                    static function (Iterator $iterator) use ($values): Generator {
+                        foreach ($iterator as $key => $value) {
+                            if (false === in_array($key, $values, true)) {
+                                continue;
+                            }
 
-                    yield $key => $value;
-                }
+                            yield $key => $value;
+                        }
+                    };
             };
     }
 }
diff --git a/src/Operation/Intersperse.php b/src/Operation/Intersperse.php
index f22e92544..86a4b2c88 100644
--- a/src/Operation/Intersperse.php
+++ b/src/Operation/Intersperse.php
@@ -11,11 +11,6 @@
 use loophp\collection\Contract\Operation;
 
 /**
- * Class Intersperse.
- *
- * Insert a given value between each element of a collection.
- * Indices are not preserved.
- *
  * @psalm-template TKey
  * @psalm-template TKey of array-key
  * @psalm-template T
@@ -23,45 +18,48 @@
 final class Intersperse extends AbstractOperation implements Operation
 {
     /**
-     * @param mixed $element
-     * @psalm-param T $element
+     * @psalm-return Closure(T): Closure(int): Closure(int): Closure(Iterator<TKey, T>): Generator<int|TKey, T>
      */
-    public function __construct($element, int $atEvery, int $startAt)
-    {
-        if (0 > $atEvery) {
-            throw new InvalidArgumentException('The second parameter must be a positive integer.');
-        }
-
-        if (0 > $startAt) {
-            throw new InvalidArgumentException('The third parameter must be a positive integer.');
-        }
-
-        $this->storage = [
-            'element' => $element,
-            'atEvery' => $atEvery,
-            'startAt' => $startAt,
-        ];
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             *
-             * @param mixed $element
              * @psalm-param T $element
              *
-             * @psalm-return Generator<int|TKey, T>
+             * @param mixed $element
              */
-            static function (Iterator $iterator, $element, int $every, int $startAt): Generator {
-                foreach ($iterator as $key => $value) {
-                    if (0 === $startAt++ % $every) {
-                        yield $element;
-                    }
+            static function ($element): Closure {
+                return static function (int $atEvery) use ($element): Closure {
+                    return static function (int $startAt) use ($element, $atEvery): Closure {
+                        return
+                            /**
+                             * @psalm-param Iterator<TKey, T> $iterator
+                             *
+                             * @psalm-return Generator<int|TKey, T>
+                             */
+                            static function (Iterator $iterator) use ($element, $atEvery, $startAt): Generator {
+                                if (0 > $atEvery) {
+                                    throw new InvalidArgumentException(
+                                        'The second parameter must be a positive integer.'
+                                    );
+                                }
+
+                                if (0 > $startAt) {
+                                    throw new InvalidArgumentException(
+                                        'The third parameter must be a positive integer.'
+                                    );
+                                }
+
+                                foreach ($iterator as $key => $value) {
+                                    if (0 === $startAt++ % $atEvery) {
+                                        yield $element;
+                                    }
 
-                    yield $key => $value;
-                }
+                                    yield $key => $value;
+                                }
+                            };
+                    };
+                };
             };
     }
 }
diff --git a/src/Operation/Iterate.php b/src/Operation/Iterate.php
index 2bdd4738a..3bed2512c 100644
--- a/src/Operation/Iterate.php
+++ b/src/Operation/Iterate.php
@@ -17,35 +17,34 @@
 final class Iterate extends AbstractOperation implements Operation
 {
     /**
-     * @param array<mixed, mixed> $parameters
-     * @psalm-param array<array-key, T> $parameters
-     *
-     * @psalm-param callable(...list<T>):(array<array-key, T>) $callback
+     * @psalm-return Closure(callable(T...):(array<TKey, T>)): Closure(T...): Generator<TKey, T>
      */
-    public function __construct(callable $callback, array $parameters = [])
-    {
-        $this->storage = [
-            'callback' => $callback,
-            'parameters' => $parameters,
-        ];
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param callable(...list<T>):(array<array-key, T>) $callback
-             *
-             * @param array<int, mixed> $parameters
-             * @psalm-param array<array-key, T> $parameters
+             * @psalm-param callable(T...):(array<TKey, T>) $callback
              */
-            static function (Iterator $iterator, callable $callback, array $parameters): Generator {
-                while (true) {
-                    yield current(
-                        $parameters = (array) $callback(...array_values((array) $parameters))
-                    );
-                }
+            static function (callable $callback): Closure {
+                return
+                    /**
+                     * @psalm-param T ...$parameters
+                     */
+                    static function (...$parameters) use ($callback): Closure {
+                        return
+                            /**
+                             * @psalm-param Iterator<TKey, T> $iterator
+                             *
+                             * @psalm-return Generator<TKey, T>
+                             */
+                            static function (Iterator $iterator) use ($callback, $parameters): Generator {
+                                while (true) {
+                                    yield current(
+                                        $parameters = (array) $callback(...array_values((array) $parameters))
+                                    );
+                                }
+                            };
+                    };
             };
     }
 }
diff --git a/src/Operation/Last.php b/src/Operation/Last.php
index 4394b5573..193359e2f 100644
--- a/src/Operation/Last.php
+++ b/src/Operation/Last.php
@@ -8,7 +8,6 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\Run;
 
 /**
  * @psalm-template TKey
@@ -17,58 +16,38 @@
  */
 final class Last extends AbstractOperation implements Operation
 {
-    /**
-     * @var callable|Closure
-     * @psalm-var callable(T, TKey):(bool)|Closure(T, TKey):(bool)
-     */
-    private $callback;
-
-    /**
-     * @psalm-param Closure(T, TKey):(bool)|callable(T, TKey):(bool)|null $callback
-     * @psalm-param T|null $default
-     */
-    public function __construct(?callable $callback = null, int $size = 1)
-    {
-        $defaultCallback =
-            /**
-             * @param mixed $value
-             * @param mixed $key
-             * @psalm-param T $value
-             * @psalm-param TKey $key
-             * @psalm-param Iterator<TKey, T> $iterator
-             */
-            static function ($value, $key, Iterator $iterator): bool {
-                return true;
-            };
-
-        $this->storage = [
-            'callback' => $callback ?? $defaultCallback,
-            'size' => $size,
-        ];
-    }
-
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             *
-             * @psalm-return Generator<TKey, T>
-             */
-            static function (Iterator $iterator, callable $callback, int $size): Generator {
-                $callback =
+        return static function (?callable $callback = null): Closure {
+            return static function (int $size) use ($callback): Closure {
+                return
                     /**
-                     * @param mixed $value
-                     * @param mixed $key
-                     * @psalm-param T $value
-                     * @psalm-param TKey $key
                      * @psalm-param Iterator<TKey, T> $iterator
+                     *
+                     * @psalm-return Generator<TKey, T>
                      */
-                    static function ($value, $key, Iterator $iterator) use ($callback): bool {
-                        return true === $callback($value, $key, $iterator);
+                    static function (Iterator $iterator) use ($callback, $size): Generator {
+                        $defaultCallback =
+                            /**
+                             * @param mixed $value
+                             * @param mixed $key
+                             * @psalm-param T $value
+                             * @psalm-param TKey $key
+                             * @psalm-param Iterator<TKey, T> $iterator
+                             */
+                            static function ($value, $key, Iterator $iterator): bool {
+                                return true;
+                            };
+
+                        $callback = $callback ?? $defaultCallback;
+
+                        return yield from Compose::of()(
+                            Filter::of()($callback),
+                            Reverse::of(),
+                            Limit::of()($size)(0)
+                        )($iterator);
                     };
-
-                return yield from (new Run(new Filter($callback), new Reverse(), new Limit($size)))($iterator);
             };
+        };
     }
 }
diff --git a/src/Operation/Limit.php b/src/Operation/Limit.php
index 9c625ecf4..175dec154 100644
--- a/src/Operation/Limit.php
+++ b/src/Operation/Limit.php
@@ -17,28 +17,27 @@
  */
 final class Limit extends AbstractOperation implements Operation
 {
-    public function __construct(int $limit, int $offset = 0)
-    {
-        $this->storage = [
-            'limit' => $limit,
-            'offset' => $offset,
-        ];
-    }
-
+    /**
+     * @psalm-return Closure(int): Closure(int=): Closure(Iterator<TKey, T>): Generator<TKey, T>
+     */
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             *
-             * @psalm-return Generator<TKey, T>
-             */
-            static function (Iterator $iterator, int $limit, int $offset): Generator {
-                if (0 === $limit) {
-                    return yield from [];
-                }
+        return static function (int $limit): Closure {
+            return static function (int $offset = 0) use ($limit): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     *
+                     * @psalm-return Generator<TKey, T>
+                     */
+                    static function (Iterator $iterator) use ($limit, $offset): Generator {
+                        if (0 === $limit) {
+                            return yield from [];
+                        }
 
-                return yield from new LimitIterator($iterator, $offset, $limit);
+                        return yield from new LimitIterator($iterator, $offset, $limit);
+                    };
             };
+        };
     }
 }
diff --git a/src/Operation/Loop.php b/src/Operation/Loop.php
index 31ce8b1b6..04cef3e13 100644
--- a/src/Operation/Loop.php
+++ b/src/Operation/Loop.php
@@ -17,13 +17,16 @@
  */
 final class Loop extends AbstractOperation implements Operation
 {
+    /**
+     * @psalm-return Closure(Iterator<TKey, T>): Generator<TKey, T>
+     */
     public function __invoke(): Closure
     {
         return
             /**
              * @psalm-param Iterator<TKey, T> $iterator
              *
-             * @psalm-return Generator<TKey, T>
+             * @psalm-return Iterator<TKey, T>
              */
             static function (Iterator $iterator): Generator {
                 return yield from new InfiniteIterator($iterator);
diff --git a/src/Operation/Map.php b/src/Operation/Map.php
index 9376bb3a2..e8f0245f9 100644
--- a/src/Operation/Map.php
+++ b/src/Operation/Map.php
@@ -16,35 +16,40 @@
  */
 final class Map extends AbstractOperation implements Operation
 {
-    public function __construct(callable ...$callbacks)
-    {
-        $this->storage['callbacks'] = $callbacks;
-    }
-
+    /**
+     * @psalm-return Closure((callable(T, TKey): T)...): Closure(Iterator<TKey, T>): Generator<TKey, T>
+     */
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<callable(T, TKey): T> $callbacks
-             *
-             * @psalm-return Generator<TKey, T>
+             * @psalm-param callable(T, TKey): T ...$callbacks
              */
-            static function (Iterator $iterator, array $callbacks): Generator {
-                foreach ($iterator as $key => $value) {
-                    $callback =
-                        /**
-                         * @param mixed $carry
-                         * @psalm-param T $carry
-                         * @psalm-param callable(T, TKey): T $callback
-                         * @psalm-return T
-                         */
-                        static function ($carry, callable $callback) use ($value, $key) {
-                            return $callback($value, $key);
-                        };
+            static function (callable ...$callbacks): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     *
+                     * @psalm-return Generator<TKey, T>
+                     */
+                    static function (Iterator $iterator) use ($callbacks): Generator {
+                        foreach ($iterator as $key => $value) {
+                            $callback =
+                                /**
+                                 * @param mixed $carry
+                                 * @psalm-param T $carry
+                                 *
+                                 * @psalm-param callable(T, TKey): T $callback
+                                 *
+                                 * @psalm-return T
+                                 */
+                                static function ($carry, callable $callback) use ($value, $key) {
+                                    return $callback($value, $key);
+                                };
 
-                    yield $key => array_reduce($callbacks, $callback, $value);
-                }
+                            yield $key => array_reduce($callbacks, $callback, $value);
+                        }
+                    };
             };
     }
 }
diff --git a/src/Operation/Merge.php b/src/Operation/Merge.php
index 016bf1171..85d7f7d1e 100644
--- a/src/Operation/Merge.php
+++ b/src/Operation/Merge.php
@@ -17,33 +17,31 @@
 final class Merge extends AbstractOperation implements Operation
 {
     /**
-     * @param iterable<int|string, mixed> ...$sources
-     * @psalm-param Iterator<TKey, T> ...$sources
+     * @psalm-return Closure(iterable<TKey, T>...): Closure(Iterator<TKey, T>): Generator<TKey, T>
      */
-    public function __construct(iterable ...$sources)
-    {
-        $this->storage['sources'] = $sources;
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<iterable<TKey, T>> $sources
-             *
-             * @psalm-return Generator<TKey, T>
+             * @psalm-param iterable<TKey, T> ...$sources
              */
-            static function (Iterator $iterator, array $sources): Generator {
-                foreach ($iterator as $key => $value) {
-                    yield $key => $value;
-                }
-
-                foreach ($sources as $source) {
-                    foreach ($source as $key => $value) {
+            static function (iterable ...$sources): Closure {
+                return
+                /**
+                 * @psalm-param Iterator<TKey, T> $iterator
+                 * @psalm-return Generator<TKey, T>
+                 */
+                static function (Iterator $iterator) use ($sources): Generator {
+                    foreach ($iterator as $key => $value) {
                         yield $key => $value;
                     }
-                }
+
+                    foreach ($sources as $source) {
+                        foreach ($source as $key => $value) {
+                            yield $key => $value;
+                        }
+                    }
+                };
             };
     }
 }
diff --git a/src/Operation/Normalize.php b/src/Operation/Normalize.php
index 259d48bfb..1162cd978 100644
--- a/src/Operation/Normalize.php
+++ b/src/Operation/Normalize.php
@@ -16,13 +16,16 @@
  */
 final class Normalize extends AbstractOperation implements Operation
 {
+    /**
+     * @psalm-return Closure(Iterator<TKey, T>): Generator<int, T, mixed, void>
+     */
     public function __invoke(): Closure
     {
         return
             /**
              * @psalm-param Iterator<TKey, T> $iterator
              *
-             * @psalm-return Generator<int, T>
+             * @psalm-return Generator<int, T, mixed, void>
              */
             static function (Iterator $iterator): Generator {
                 foreach ($iterator as $value) {
diff --git a/src/Operation/Nth.php b/src/Operation/Nth.php
index 8de721c94..7c27e8dcc 100644
--- a/src/Operation/Nth.php
+++ b/src/Operation/Nth.php
@@ -16,32 +16,30 @@
  */
 final class Nth extends AbstractOperation implements Operation
 {
-    public function __construct(int $step, int $offset)
-    {
-        $this->storage = [
-            'step' => $step,
-            'offset' => $offset,
-        ];
-    }
-
+    /**
+     * @psalm-return Closure(int): Closure(int): Closure(Iterator<TKey, T>): Generator<TKey, T>
+     */
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             *
-             * @psalm-return Generator<TKey, T>
-             */
-            static function (Iterator $iterator, int $step, int $offset): Generator {
-                $position = 0;
+        return static function (int $step): Closure {
+            return static function (int $offset) use ($step): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     * @psalm-return Generator<TKey, T>
+                     */
+                    static function (Iterator $iterator) use ($step, $offset): Generator {
+                        $position = 0;
 
-                foreach ($iterator as $key => $value) {
-                    if ($position++ % $step !== $offset) {
-                        continue;
-                    }
+                        foreach ($iterator as $key => $value) {
+                            if ($position++ % $step !== $offset) {
+                                continue;
+                            }
 
-                    yield $key => $value;
-                }
+                            yield $key => $value;
+                        }
+                    };
             };
+        };
     }
 }
diff --git a/src/Operation/Nullsy.php b/src/Operation/Nullsy.php
new file mode 100644
index 000000000..c4e45f385
--- /dev/null
+++ b/src/Operation/Nullsy.php
@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Operation;
+
+use Closure;
+use Generator;
+use Iterator;
+use loophp\collection\Contract\Operation;
+
+/**
+ * @psalm-template TKey
+ * @psalm-template TKey of array-key
+ * @psalm-template T
+ */
+final class Nullsy extends AbstractOperation implements Operation
+{
+    /**
+     * @psalm-return Closure(Iterator<TKey, T>): Generator<int, bool>
+     */
+    public function __invoke(): Closure
+    {
+        return
+            /**
+             * @psalm-param Iterator<TKey, T> $iterator
+             * @psalm-return Generator<int, bool>
+             */
+            static function (Iterator $iterator): Generator {
+                foreach ($iterator as $key => $value) {
+                    if (null !== $value) {
+                        return yield false;
+                    }
+                }
+
+                return yield true;
+            };
+    }
+}
diff --git a/src/Operation/Only.php b/src/Operation/Only.php
index d8a996b28..58d83d32a 100644
--- a/src/Operation/Only.php
+++ b/src/Operation/Only.php
@@ -19,39 +19,36 @@
 final class Only extends AbstractOperation implements Operation
 {
     /**
-     * @param mixed ...$keys
-     * @psalm-param TKey ...$keys
+     * @psalm-return Closure(TKey...): Closure(Iterator<TKey, T>): Generator<TKey, T>
      */
-    public function __construct(...$keys)
-    {
-        $this->storage = [
-            'keys' => $keys,
-        ];
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<TKey> $keys
-             *
-             * @psalm-return Generator<TKey, T>
+             * @psalm-param TKey ...$keys
              */
-            static function (Iterator $iterator, array $keys): Generator {
-                if ([] === $keys) {
-                    return yield from $iterator;
-                }
-
-                $keys = array_flip($keys);
-
-                foreach ($iterator as $key => $value) {
-                    if (false === array_key_exists($key, $keys)) {
-                        continue;
-                    }
-
-                    yield $key => $value;
-                }
+            static function (...$keys): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     *
+                     * @psalm-return Generator<TKey, T>
+                     */
+                    static function (Iterator $iterator) use ($keys): Generator {
+                        if ([] === $keys) {
+                            return yield from $iterator;
+                        }
+
+                        $keys = array_flip($keys);
+
+                        foreach ($iterator as $key => $value) {
+                            if (false === array_key_exists($key, $keys)) {
+                                continue;
+                            }
+
+                            yield $key => $value;
+                        }
+                    };
             };
     }
 }
diff --git a/src/Operation/Pack.php b/src/Operation/Pack.php
index 615f78c64..965fd0997 100644
--- a/src/Operation/Pack.php
+++ b/src/Operation/Pack.php
@@ -16,6 +16,9 @@
  */
 final class Pack extends AbstractOperation implements Operation
 {
+    /**
+     * @psalm-return Closure(Iterator<TKey, T>): Generator<int, array{0:TKey, 1:T}>
+     */
     public function __invoke(): Closure
     {
         return
diff --git a/src/Operation/Pad.php b/src/Operation/Pad.php
index db684956b..6bd7df8f9 100644
--- a/src/Operation/Pad.php
+++ b/src/Operation/Pad.php
@@ -17,40 +17,38 @@
 final class Pad extends AbstractOperation implements Operation
 {
     /**
-     * @param mixed $value
-     * @psalm-param T $value
+     * @return Closure(int): Closure(T): Closure(Iterator<TKey, T>): Generator<int|TKey, T>
      */
-    public function __construct(int $size, $value)
-    {
-        $this->storage = [
-            'size' => $size,
-            'value' => $value,
-        ];
-    }
-
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param T $padValue
-             *
-             * @psalm-return Generator<TKey|int, T>
-             *
-             * @param mixed $padValue
-             */
-            static function (Iterator $iterator, int $size, $padValue): Generator {
-                $y = 0;
-
-                foreach ($iterator as $key => $value) {
-                    ++$y;
-
-                    yield $key => $value;
-                }
-
-                while ($y++ < $size) {
-                    yield $padValue;
-                }
-            };
+        return static function (int $size): Closure {
+            return
+                /**
+                 * @psalm-param T $padValue
+                 *
+                 * @param mixed $padValue
+                 */
+                static function ($padValue) use ($size): Closure {
+                    return
+                        /**
+                         * @psalm-param Iterator<TKey, T> $iterator
+                         *
+                         * @psalm-return Generator<int|TKey, T>
+                         */
+                        static function (Iterator $iterator) use ($size, $padValue): Generator {
+                            $y = 0;
+
+                            foreach ($iterator as $key => $value) {
+                                ++$y;
+
+                                yield $key => $value;
+                            }
+
+                            while ($y++ < $size) {
+                                yield $padValue;
+                            }
+                        };
+                };
+        };
     }
 }
diff --git a/src/Operation/Pair.php b/src/Operation/Pair.php
index 1d536d717..96ecb52f2 100644
--- a/src/Operation/Pair.php
+++ b/src/Operation/Pair.php
@@ -8,7 +8,6 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\Run;
 
 /**
  * @psalm-template TKey
@@ -17,6 +16,9 @@
  */
 final class Pair extends AbstractOperation implements Operation
 {
+    /**
+     * @psalm-return Closure(Iterator<TKey, T>): Generator<TKey, T>
+     */
     public function __invoke(): Closure
     {
         return
@@ -27,7 +29,7 @@ public function __invoke(): Closure
              */
             static function (Iterator $iterator): Generator {
                 /** @psalm-var list<T> $chunk */
-                foreach ((new Run(new Chunk(2)))($iterator) as $chunk) {
+                foreach (Chunk::of()(2)($iterator) as $chunk) {
                     $chunk = array_values($chunk);
 
                     yield $chunk[0] => $chunk[1];
diff --git a/src/Operation/Pluck.php b/src/Operation/Pluck.php
index 39f5618b0..a3e675b0e 100644
--- a/src/Operation/Pluck.php
+++ b/src/Operation/Pluck.php
@@ -11,93 +11,116 @@
 use Iterator;
 use loophp\collection\Contract\Collection;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Iterator\IterableIterator;
-use loophp\collection\Transformation\Get;
-use loophp\collection\Transformation\Run;
-use loophp\collection\Transformation\Transform;
 use ReflectionClass;
-use ReflectionException;
 
 use function array_key_exists;
 use function in_array;
 use function is_array;
 use function is_object;
 
+/**
+ * @psalm-template TKey
+ * @psalm-template TKey of array-key
+ * @psalm-template T
+ */
 final class Pluck extends AbstractOperation implements Operation
 {
     /**
-     * Pluck constructor.
-     *
-     * @param array<int, string>|string $key
-     * @param mixed $default
+     * @psalm-return Closure(T): Closure(T): Closure(Iterator<TKey, T>): Generator<int, T>
      */
-    public function __construct($key, $default)
-    {
-        $this->storage = [
-            'key' => $key,
-            'default' => $default,
-            'operation' => Closure::fromCallable([$this, 'pick']),
-        ];
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @param array<int, string>|string $key
-             * @param mixed $default
+             * @psalm-param T $key
+             *
+             * @psalm-return Closure(T): Closure(Iterator<TKey, T>): Generator<int, T|iterable<int, T>, mixed, void>
+             *
+             * @param mixed $key
              */
-            static function (Iterator $iterator, $key, $default, callable $pick): Generator {
-                $key = true === is_scalar($key) ? explode('.', trim((string) $key, '.')) : $key;
+            static function ($key): Closure {
+                return
+                    /**
+                     * @psalm-param T $default
+                     *
+                     * @psalm-return Closure(Iterator<TKey, T>): Generator<int, T|iterable<int, T>, mixed, void>
+                     *
+                     * @param mixed $default
+                     */
+                    static function ($default) use ($key): Closure {
+                        return
+                            /**
+                             * @psalm-param Iterator<TKey, T> $iterator
+                             *
+                             * @psalm-return Generator<int, T|iterable<int, T>, mixed, void>
+                             */
+                            static function (Iterator $iterator) use ($key, $default): Generator {
+                                $pick =
+                                    // phpcs:disable
+                                    /**
+                                     * @psalm-param Iterator<TKey, T> $iterator
+                                     * @psalm-param T|iterable<TKey, T> $target
+                                     * @psalm-param array<int, string> $key
+                                     * @psalm-param T $default
+                                     *
+                                     * @psalm-return T|iterable<int, T>
+                                     *
+                                     * @param mixed $target
+                                     * @param mixed|null $default
+                                     */
+                                    static function (Iterator $iterator, $target, array $key, $default = null) use (&$pick) {
+                                        // phpcs:enable
+                                        while (null !== $segment = array_shift($key)) {
+                                            if ('*' === $segment) {
+                                                if (false === is_iterable($target)) {
+                                                    return $default;
+                                                }
 
-                foreach ($iterator as $value) {
-                    yield $pick($iterator, $value, $key, $default);
-                }
-            };
-    }
+                                                /** @psalm-var array<int, T> $result */
+                                                $result = [];
 
-    /**
-     * Get an item from an array or object using "dot" notation.
-     *
-     * @param Iterator<mixed> $iterator
-     * @param mixed $target
-     * @param array<string> $key
-     * @param mixed $default
-     *
-     * @throws ReflectionException
-     *
-     * @return mixed
-     */
-    private function pick(Iterator $iterator, $target, array $key, $default = null)
-    {
-        while (null !== $segment = array_shift($key)) {
-            if ('*' === $segment) {
-                if (false === is_iterable($target)) {
-                    return $default;
-                }
+                                                foreach ($target as $item) {
+                                                    $result[] = $pick($iterator, $item, $key);
+                                                }
 
-                $result = [];
+                                                /** @psalm-var Generator<TKey, T> $collapse */
+                                                $collapse = Collapse::of()(new ArrayIterator($result));
 
-                foreach ($target as $item) {
-                    $result[] = $this->pick($iterator, $item, $key);
-                }
+                                                return in_array('*', $key, true) ? $collapse : $result;
+                                            }
 
-                return in_array('*', $key, true) ? (new Run((new Collapse())))(new ArrayIterator($result)) : $result;
-            }
+                                            // phpcs:disable
+                                            if ((true === is_array($target)) && (true === array_key_exists($segment, $target))) {
+                                                /** @psalm-var T $target */
+                                                $target = $target[$segment];
+                                            } elseif (($target instanceof ArrayAccess) && (true === $target->offsetExists($segment))) {
+                                                /** @psalm-var T $target */
+                                                $target = $target[$segment];
+                                            } elseif ($target instanceof Collection) {
+                                                /** @psalm-var T $target */
+                                                $target = (Get::of()($segment)($default)($target->getIterator()))->current();
+                                            } elseif ((true === is_object($target)) && (true === property_exists($target, $segment))) {
+                                                /** @psalm-var T $target */
+                                                $target = (new ReflectionClass($target))->getProperty($segment)->getValue($target);
+                                            } else {
+                                                /** @psalm-var T $target */
+                                                $target = $default;
+                                            }
+                                            // phpcs:enable
+                                        }
 
-            if ((true === is_array($target)) && (true === array_key_exists($segment, $target))) {
-                $target = $target[$segment];
-            } elseif (($target instanceof ArrayAccess) && (true === $target->offsetExists($segment))) {
-                $target = $target[$segment];
-            } elseif ($target instanceof Collection) {
-                $target = (new Transform(new Get($segment, $default)))(new IterableIterator($target));
-            } elseif ((true === is_object($target)) && (true === property_exists($target, $segment))) {
-                $target = (new ReflectionClass($target))->getProperty($segment)->getValue($target);
-            } else {
-                $target = $default;
-            }
-        }
+                                        return $target;
+                                    };
 
-        return $target;
+                                $key = true === is_scalar($key) ? explode('.', trim((string) $key, '.')) : $key;
+
+                                // phpcs:disable
+                                foreach ($iterator as $value) {
+                                    yield $pick($iterator, $value, $key, $default);
+                                }
+                                // phpcs:enable
+                            };
+                    };
+            };
     }
 }
diff --git a/src/Operation/Prepend.php b/src/Operation/Prepend.php
index 1a92729a6..8db15f4c1 100644
--- a/src/Operation/Prepend.php
+++ b/src/Operation/Prepend.php
@@ -17,31 +17,28 @@
 final class Prepend extends AbstractOperation implements Operation
 {
     /**
-     * @param mixed ...$items
-     * @psalm-param T ...$items
+     * @psalm-return Closure(T...): Closure(Iterator<TKey, T>): Generator<int|TKey, T>
      */
-    public function __construct(...$items)
-    {
-        $this->storage['items'] = $items;
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<T> $items
-             *
-             * @psalm-return Generator<TKey|int, T>
+             * @psalm-param T ...$items
              */
-            static function (Iterator $iterator, array $items): Generator {
-                foreach ($items as $key => $item) {
-                    yield $key => $item;
-                }
+            static function (...$items): Closure {
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     */
+                    static function (Iterator $iterator) use ($items): Generator {
+                        foreach ($items as $key => $item) {
+                            yield $key => $item;
+                        }
 
-                foreach ($iterator as $key => $value) {
-                    yield $key => $value;
-                }
+                        foreach ($iterator as $key => $value) {
+                            yield $key => $value;
+                        }
+                    };
             };
     }
 }
diff --git a/src/Operation/Product.php b/src/Operation/Product.php
index 518498700..e4eb970e1 100644
--- a/src/Operation/Product.php
+++ b/src/Operation/Product.php
@@ -19,37 +19,14 @@
  */
 final class Product extends AbstractOperation implements Operation
 {
-    /**
-     * @param iterable<mixed> ...$iterables
-     * @psalm-param Iterator<TKey, T> ...$iterables
-     */
-    public function __construct(iterable ...$iterables)
-    {
-        $this->storage = [
-            'iterables' => $iterables,
-            'cartesian' =>
-                /**
-                 * @param array<int, mixed> $input
-                 * @psalm-param array<int, Iterator<TKey, T>> $input
-                 *
-                 * @psalm-return Generator<array<int, T>>
-                 */
-                function (array $input): Generator {
-                    return $this->cartesian($input);
-                },
-        ];
-    }
-
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param array<int, iterable<TKey, T>> $iterables
-             *
-             * @psalm-return Generator<int, array<int, T>>
-             */
-            static function (Iterator $iterator, array $iterables, callable $cartesian): Generator {
+        $cartesian = function (array $input): Generator {
+            return $this->cartesian($input);
+        };
+
+        return static function (iterable ...$iterables) use ($cartesian): Closure {
+            return static function (Iterator $iterator) use ($cartesian, $iterables): Generator {
                 $its = [$iterator];
 
                 foreach ($iterables as $iterable) {
@@ -58,6 +35,7 @@ static function (Iterator $iterator, array $iterables, callable $cartesian): Gen
 
                 return yield from $cartesian($its);
             };
+        };
     }
 
     /**
diff --git a/src/Operation/RSample.php b/src/Operation/RSample.php
index 581df41f3..47cc70027 100644
--- a/src/Operation/RSample.php
+++ b/src/Operation/RSample.php
@@ -8,7 +8,6 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\Run;
 
 /**
  * @psalm-template TKey
@@ -17,27 +16,16 @@
  */
 final class RSample extends AbstractOperation implements Operation
 {
-    public function __construct(float $probability)
-    {
-        $this->storage['probability'] = $probability;
-    }
-
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             *
-             * @psalm-return Generator<TKey, T>
-             */
-            static function (Iterator $iterator, float $probability): Generator {
-                return yield from (new Run(
-                    new Filter(
-                        static function () use ($probability): bool {
-                            return (mt_rand() / mt_getrandmax()) < $probability;
-                        }
-                    )
-                ))($iterator);
+        return static function (float $probability): Closure {
+            return static function (Iterator $iterator) use ($probability): Generator {
+                $callback = static function () use ($probability): bool {
+                    return (mt_rand() / mt_getrandmax()) < $probability;
+                };
+
+                return yield from Filter::of()($callback)($iterator);
             };
+        };
     }
 }
diff --git a/src/Operation/Random.php b/src/Operation/Random.php
index 9e373510e..61a42f4c0 100644
--- a/src/Operation/Random.php
+++ b/src/Operation/Random.php
@@ -8,7 +8,6 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\Run;
 
 /**
  * @psalm-template TKey
@@ -17,23 +16,15 @@
  */
 final class Random extends AbstractOperation implements Operation
 {
-    public function __construct(int $size)
-    {
-        $this->storage = [
-            'size' => $size,
-        ];
-    }
-
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             *
-             * @psalm-return Generator<TKey, T>
-             */
-            static function (Iterator $iterator, int $size): Generator {
-                return yield from (new Run(new Limit($size), new Shuffle()))($iterator);
+        return static function (int $size): Closure {
+            return static function (Iterator $iterator) use ($size): Generator {
+                return yield from (Compose::of()(
+                    Limit::of()($size)(0),
+                    Shuffle::of()
+                )($iterator));
             };
+        };
     }
 }
diff --git a/src/Operation/Range.php b/src/Operation/Range.php
index 6988ff30c..11798d9d3 100644
--- a/src/Operation/Range.php
+++ b/src/Operation/Range.php
@@ -13,21 +13,18 @@
 
 final class Range extends AbstractOperation implements Operation
 {
-    public function __construct(float $start = 0.0, float $end = INF, float $step = 1.0)
-    {
-        $this->storage = [
-            'start' => $start,
-            'end' => $end,
-            'step' => $step,
-        ];
-    }
-
     public function __invoke(): Closure
     {
-        return static function (Iterator $iterator, float $start, float $end, float $step): Generator {
-            for ($current = $start; $current < $end; $current += $step) {
-                yield $current;
-            }
+        return static function (float $start = 0.0): Closure {
+            return static function (float $end = INF) use ($start): Closure {
+                return static function (float $step = 1.0) use ($start, $end): Closure {
+                    return static function (Iterator $iterator) use ($start, $end, $step): Generator {
+                        for ($current = $start; $current < $end; $current += $step) {
+                            yield $current;
+                        }
+                    };
+                };
+            };
         };
     }
 }
diff --git a/src/Operation/Reduce.php b/src/Operation/Reduce.php
new file mode 100644
index 000000000..0aaa16b42
--- /dev/null
+++ b/src/Operation/Reduce.php
@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Operation;
+
+use Closure;
+use Iterator;
+use loophp\collection\Contract\Operation;
+
+/**
+ * @psalm-template TKey
+ * @psalm-template TKey of array-key
+ * @psalm-template T
+ */
+final class Reduce extends AbstractOperation implements Operation
+{
+    /**
+     * @psalm-param \Iterator<TKey, T> $collection
+     *
+     * @return mixed|null
+     * @psalm-return T|scalar|null|\Iterator<TKey, T>
+     */
+    public function __invoke(): Closure
+    {
+        return static function (callable $callback): Closure {
+            return static function ($initial = null) use ($callback): Closure {
+                return static function (Iterator $iterator) use ($callback, $initial) {
+                    return yield from FoldLeft::of()($callback)($initial)($iterator);
+                };
+            };
+        };
+    }
+}
diff --git a/src/Operation/Reduction.php b/src/Operation/Reduction.php
index bf6f6c51c..0250a9e05 100644
--- a/src/Operation/Reduction.php
+++ b/src/Operation/Reduction.php
@@ -16,35 +16,36 @@
  */
 final class Reduction extends AbstractOperation implements Operation
 {
+    // phpcs:disable
     /**
-     * @param mixed|null $initial
-     * @psalm-param T|null $initial
-     * @psalm-param callable(T|null, T, TKey):(T|null) $callback
+     * @psalm-return Closure(callable(T|null, T, TKey):(T|null)): Closure(T|null): Closure(Iterator<TKey, T>): Generator<TKey, T>
      */
-    public function __construct(callable $callback, $initial = null)
-    {
-        $this->storage = [
-            'callback' => $callback,
-            'initial' => $initial,
-        ];
-    }
-
+    // phpcs:enable
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
              * @psalm-param callable(T|null, T, TKey):(T|null) $callback
-             *
-             * @param mixed $initial
-             * @psalm-param T|null $initial
-             *
-             * @psalm-return Generator<TKey, T|null>
              */
-            static function (Iterator $iterator, callable $callback, $initial): Generator {
-                foreach ($iterator as $key => $value) {
-                    yield $key => ($initial = $callback($initial, $value, $key));
-                }
+            static function (callable $callback): Closure {
+                return
+                    /**
+                     * @param mixed|null $initial
+                     * @psalm-param T|null $initial
+                     */
+                    static function ($initial = null) use ($callback): Closure {
+                        return
+                            /**
+                             * @psalm-param Iterator<TKey, T> $iterator
+                             *
+                             * @psalm-return Generator<TKey, T|null>
+                             */
+                            static function (Iterator $iterator) use ($callback, $initial): Generator {
+                                foreach ($iterator as $key => $value) {
+                                    yield $key => ($initial = $callback($initial, $value, $key));
+                                }
+                            };
+                    };
             };
     }
 }
diff --git a/src/Operation/Reverse.php b/src/Operation/Reverse.php
index d089b1dc2..44990a2c3 100644
--- a/src/Operation/Reverse.php
+++ b/src/Operation/Reverse.php
@@ -8,7 +8,6 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\Run;
 
 /**
  * @psalm-template TKey
@@ -26,8 +25,9 @@ public function __invoke(): Closure
              * @psalm-return Generator<TKey, T, mixed, void>
              */
             static function (Iterator $iterator): Generator {
-                /** @psalm-var array<int, array{0: TKey, 1: T}> $all */
-                $all = iterator_to_array((new Run(new Pack()))($iterator));
+                /** @psalm-var Generator<int, array{0: TKey, 1: T}> $pack */
+                $pack = Pack::of()($iterator);
+                $all = iterator_to_array($pack);
 
                 for (end($all); null !== key($all); prev($all)) {
                     $item = current($all);
diff --git a/src/Operation/Scale.php b/src/Operation/Scale.php
index 66fb9b996..33fc60484 100644
--- a/src/Operation/Scale.php
+++ b/src/Operation/Scale.php
@@ -8,7 +8,6 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\Run;
 
 use const INF;
 
@@ -19,51 +18,61 @@
  */
 final class Scale extends AbstractOperation implements Operation
 {
-    public function __construct(
-        float $lowerBound,
-        float $upperBound,
-        float $wantedLowerBound = 0.0,
-        float $wantedUpperBound = 1.0,
-        float $base = 0.0
-    ) {
-        $wantedLowerBound = (0.0 === $wantedLowerBound) ? (0.0 === $base ? 0.0 : 1.0) : $wantedLowerBound; // phpcs:ignore
-        $wantedUpperBound = (1.0 === $wantedUpperBound) ? (0.0 === $base ? 1.0 : $base) : $wantedUpperBound; // phpcs:ignore
+    // phpcs:disable
+    /**
+     * @psalm-return Closure(float): Closure(float): Closure(float): Closure(float): Closure(float): Closure(Iterator<TKey, float|int>): Generator<TKey, float|int>
+     */
+    // phpcs:enable
+    public function __invoke(): Closure
+    {
+        return static function (float $lowerBound): Closure {
+            return static function (float $upperBound) use ($lowerBound): Closure {
+                return static function (float $wantedLowerBound = 0.0) use ($lowerBound, $upperBound): Closure {
+                    return static function (float $wantedUpperBound = 1.0) use ($lowerBound, $upperBound, $wantedLowerBound): Closure {  // phpcs:ignore
+                        return static function (float $base = 0.0) use ($lowerBound, $upperBound, $wantedLowerBound, $wantedUpperBound): Closure { // phpcs:ignore
+                            return static function (Iterator $iterator) use ($lowerBound, $upperBound, $wantedLowerBound, $wantedUpperBound, $base): Generator { // phpcs:ignore
+                                $wantedLowerBound = (0.0 === $wantedLowerBound) ? (0.0 === $base ? 0.0 : 1.0) : $wantedLowerBound; // phpcs:ignore
+                                $wantedUpperBound = (1.0 === $wantedUpperBound) ? (0.0 === $base ? 1.0 : $base) : $wantedUpperBound; // phpcs:ignore
 
-        $this->storage['mapper'] = new Map(
-            /**
-             * @param float|int $v
-             */
-            static function ($v) use ($lowerBound, $upperBound, $wantedLowerBound, $wantedUpperBound, $base): float { // phpcs:ignore
-                $mx = 0.0 === $base ?
-                    ($v - $lowerBound) / ($upperBound - $lowerBound) :
-                    log($v - $lowerBound, $base) / log($upperBound - $lowerBound, $base);
+                                /** @psalm-var callable(Generator<TKey, float|int>): Generator<TKey, float> $mapper */
+                                $mapper = Map::of()(
+                                    /**
+                                     * @param mixed $v
+                                     * @psalm-param float|int $v
+                                     */
+                                    static function ($v) use ($lowerBound, $upperBound, $wantedLowerBound, $wantedUpperBound, $base): float { // phpcs:ignore
+                                        $mx = 0.0 === $base ?
+                                            ($v - $lowerBound) / ($upperBound - $lowerBound) :
+                                            log($v - $lowerBound, $base) / log($upperBound - $lowerBound, $base);
 
-                $mx = $mx === -INF ? 0 : $mx;
+                                        $mx = $mx === -INF ? 0 : $mx;
 
-                return $wantedLowerBound + $mx * ($wantedUpperBound - $wantedLowerBound);
-            }
-        );
+                                        return $wantedLowerBound + $mx * ($wantedUpperBound - $wantedLowerBound);
+                                    }
+                                );
 
-        $this->storage['filter'] = new Filter(
-            /**
-             * @param float|int $item
-             */
-            static function ($item) use ($lowerBound): bool {
-                return $item >= $lowerBound;
-            },
-            /**
-             * @param float|int $item
-             */
-            static function ($item) use ($upperBound): bool {
-                return $item <= $upperBound;
-            }
-        );
-    }
+                                /** @psalm-var callable(Iterator<TKey, float|int>): Generator<TKey, float|int> $filter */
+                                $filter = Filter::of()(
+                                    /**
+                                     * @param float|int $item
+                                     */
+                                    static function ($item) use ($lowerBound): bool {
+                                        return $item >= $lowerBound;
+                                    },
+                                    /**
+                                     * @param float|int $item
+                                     */
+                                    static function ($item) use ($upperBound): bool {
+                                        return $item <= $upperBound;
+                                    }
+                                );
 
-    public function __invoke(): Closure
-    {
-        return static function (Iterator $iterator, Map $mapper, Filter $filter): Generator {
-            return yield from (new Run($filter, $mapper))($iterator);
+                                return yield from Compose::of()($filter, $mapper)($iterator);
+                            };
+                        };
+                    };
+                };
+            };
         };
     }
 }
diff --git a/src/Operation/Shuffle.php b/src/Operation/Shuffle.php
index 7c549ca77..cfe1f4d19 100644
--- a/src/Operation/Shuffle.php
+++ b/src/Operation/Shuffle.php
@@ -8,7 +8,6 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\Run;
 
 /**
  * @psalm-template TKey
@@ -26,8 +25,9 @@ public function __invoke(): Closure
              * @psalm-return Generator<TKey, T, mixed, void>
              */
             static function (Iterator $iterator): Generator {
-                /** @psalm-var array<int, array{0: TKey, 1: T}>  $data */
-                $data = iterator_to_array((new Run(new Pack()))($iterator));
+                /** @psalm-var Iterator<int, array{0: TKey, 1: T}> $pack */
+                $pack = Pack::of()($iterator);
+                $data = iterator_to_array($pack);
 
                 while ([] !== $data) {
                     $randomKey = array_rand($data);
diff --git a/src/Operation/Since.php b/src/Operation/Since.php
index a7d0a4436..18303c754 100644
--- a/src/Operation/Since.php
+++ b/src/Operation/Since.php
@@ -16,25 +16,10 @@
  */
 final class Since extends AbstractOperation implements Operation
 {
-    /**
-     * @param callable ...$callbacks
-     * @psalm-param callable(T, TKey):(bool) ...$callbacks
-     */
-    public function __construct(callable ...$callbacks)
-    {
-        $this->storage['callbacks'] = $callbacks;
-    }
-
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<callable(T, TKey):(bool)> $callbacks
-             *
-             * @psalm-return Generator<TKey, T>
-             */
-            static function (Iterator $iterator, array $callbacks): Generator {
+        return static function (callable ...$callbacks): Closure {
+            return static function (Iterator $iterator) use ($callbacks): Generator {
                 while ($iterator->valid()) {
                     $result = array_reduce(
                         $callbacks,
@@ -57,5 +42,6 @@ static function (bool $carry, callable $callable) use ($iterator): bool {
                     yield $iterator->key() => $iterator->current();
                 }
             };
+        };
     }
 }
diff --git a/src/Operation/Skip.php b/src/Operation/Skip.php
index 6e3172a79..873d9af34 100644
--- a/src/Operation/Skip.php
+++ b/src/Operation/Skip.php
@@ -16,30 +16,29 @@
  */
 final class Skip extends AbstractOperation implements Operation
 {
-    public function __construct(int ...$skip)
-    {
-        $this->storage['skip'] = $skip;
-    }
-
+    /**
+     * @psalm-return Closure(int...): Closure(Iterator<TKey, T>): Generator<TKey, T>
+     */
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<int> $skip
-             *
-             * @psalm-return Generator<TKey, T>
-             */
-            static function (Iterator $iterator, array $skip): Generator {
-                $skip = array_sum($skip);
+        return static function (int ...$skip): Closure {
+            return
+                /**
+                 * @psalm-param Iterator<TKey, T> $iterator
+                 *
+                 * @psalm-return Generator<TKey, T>
+                 */
+                static function (Iterator $iterator) use ($skip): Generator {
+                    $skip = array_sum($skip);
 
-                foreach ($iterator as $key => $value) {
-                    if (0 < $skip--) {
-                        continue;
-                    }
+                    foreach ($iterator as $key => $value) {
+                        if (0 < $skip--) {
+                            continue;
+                        }
 
-                    yield $key => $value;
-                }
-            };
+                        yield $key => $value;
+                    }
+                };
+        };
     }
 }
diff --git a/src/Operation/Slice.php b/src/Operation/Slice.php
index f3983727a..0dc46411a 100644
--- a/src/Operation/Slice.php
+++ b/src/Operation/Slice.php
@@ -8,7 +8,6 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\Run;
 
 /**
  * @psalm-template TKey
@@ -17,30 +16,36 @@
  */
 final class Slice extends AbstractOperation implements Operation
 {
-    public function __construct(int $offset, int $length = -1)
-    {
-        $this->storage = [
-            'offset' => $offset,
-            'length' => $length,
-        ];
-    }
-
+    /**
+     * @psalm-return Closure(int): Closure(int|null): Generator<TKey, T>
+     */
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             *
-             * @psalm-return Generator<TKey, T>
-             */
-            static function (Iterator $iterator, int $offset, int $length): Generator {
-                $skip = (new Run(new Skip($offset)))($iterator);
+        return static function (int $offset): Closure {
+            return
+                /**
+                 * @psalm-param int|null $length
+                 *
+                 * @psalm-return Closure(Iterator<TKey, T>): Generator<TKey, T>
+                 */
+                static function (int $length = -1) use ($offset): Closure {
+                    return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     *
+                     * @psalm-return Generator<TKey, T>
+                     */
+                    static function (Iterator $iterator) use ($offset, $length): Generator {
+                        /** @psalm-var callable(Iterator<TKey, T>): Generator<TKey, T> $skip */
+                        $skip = Skip::of()($offset);
 
-                if (-1 === $length) {
-                    return yield from $skip;
-                }
+                        if (-1 === $length) {
+                            return yield from $skip($iterator);
+                        }
 
-                return yield from (new Run(new Limit($length)))($skip);
-            };
+                        return yield from Compose::of()($skip, Limit::of()($length)(0))($iterator);
+                    };
+                };
+        };
     }
 }
diff --git a/src/Operation/Sort.php b/src/Operation/Sort.php
index 666600da7..35ebeb7d1 100644
--- a/src/Operation/Sort.php
+++ b/src/Operation/Sort.php
@@ -10,7 +10,6 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\Run;
 
 /**
  * @psalm-template TKey
@@ -19,63 +18,61 @@
  */
 final class Sort extends AbstractOperation implements Operation
 {
-    public function __construct(int $type = Operation\Sortable::BY_VALUES, ?callable $callback = null)
-    {
-        $this->storage = [
-            'type' => $type,
-            'callback' => $callback ?? Closure::fromCallable([$this, 'compare']),
-        ];
-    }
-
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param callable(T, T):(int) $callback
-             *
-             * @psalm-return Generator<TKey, T>
-             */
-            static function (Iterator $iterator, int $type, callable $callback): Generator {
-                if (Operation\Sortable::BY_VALUES !== $type && Operation\Sortable::BY_KEYS !== $type) {
-                    throw new Exception('Invalid sort type.');
-                }
-
-                $operations = Operation\Sortable::BY_VALUES === $type ?
-                    [
-                        'before' => [new Pack()],
-                        'after' => [new Unpack()],
-                    ] :
-                    [
-                        'before' => [new Flip(), new Pack()],
-                        'after' => [new Unpack(), new Flip()],
-                    ];
-
-                $callback =
+        return static function (int $type = Operation\Sortable::BY_VALUES): Closure {
+            return static function (?callable $callback = null) use ($type): Closure {
+                $callback = $callback ??
                     /**
-                     * @psalm-param array{0:TKey, 1:T} $left
-                     * @psalm-param array{0:TKey, 1:T} $right
+                     * @param mixed $left
+                     * @psalm-param T|TKey $left
+                     *
+                     * @param mixed $right
+                     * @psalm-param T|TKey $right
                      */
-                    static function (array $left, array $right) use ($callback): int {
-                        return $callback($left[1], $right[1]);
+                    static function ($left, $right): int {
+                        return $left <=> $right;
                     };
 
-                $arrayIterator = new ArrayIterator(iterator_to_array((new Run(...$operations['before']))($iterator)));
-                $arrayIterator->uasort($callback);
+                return
+                    /**
+                     * @psalm-param Iterator<TKey, T> $iterator
+                     * @psalm-param callable(T, T):(int) $callback
+                     *
+                     * @psalm-return Generator<TKey, T>
+                     */
+                    static function (Iterator $iterator) use ($type, $callback): Generator {
+                        if (Operation\Sortable::BY_VALUES !== $type && Operation\Sortable::BY_KEYS !== $type) {
+                            throw new Exception('Invalid sort type.');
+                        }
+
+                        $operations = Operation\Sortable::BY_VALUES === $type ?
+                            [
+                                'before' => [Pack::of()],
+                                'after' => [Unpack::of()],
+                            ] :
+                            [
+                                'before' => [Flip::of(), Pack::of()],
+                                'after' => [Unpack::of(), Flip::of()],
+                            ];
 
-                return yield from (new Run(...$operations['after']))($arrayIterator);
-            };
-    }
+                        /** @psalm-var callable(Iterator<TKey, T>): Generator<int, array{0:TKey, 1:T}> | callable(Iterator<TKey, T>): Generator<int, array{0:T, 1:TKey}> $before */
+                        $before = Compose::of()(...$operations['before']);
 
-    /**
-     * @psalm-param T $left
-     * @psalm-param T $right
-     *
-     * @param mixed $left
-     * @param mixed $right
-     */
-    private function compare($left, $right): int
-    {
-        return $left <=> $right;
+                        $arrayIterator = new ArrayIterator(iterator_to_array($before($iterator)));
+                        $arrayIterator->uasort(
+                            /**
+                             * @psalm-param array{0:TKey|T, 1:T|TKey} $left
+                             * @psalm-param array{0:TKey|T, 1:T|TKey} $right
+                             */
+                            static function (array $left, array $right) use ($callback): int {
+                                return $callback($left[1], $right[1]);
+                            }
+                        );
+
+                        return yield from Compose::of()(...$operations['after'])($arrayIterator);
+                    };
+            };
+        };
     }
 }
diff --git a/src/Operation/Split.php b/src/Operation/Split.php
index 090ecd0ac..2ec57e485 100644
--- a/src/Operation/Split.php
+++ b/src/Operation/Split.php
@@ -16,44 +16,41 @@
  */
 final class Split extends AbstractOperation implements Operation
 {
-    public function __construct(callable ...$callbacks)
-    {
-        $this->storage['callbacks'] = $callbacks;
-    }
-
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<callable(T, TKey):(bool)> $callbacks
-             *
-             * @psalm-return Generator<int, list<T>>
-             */
-            static function (Iterator $iterator, array $callbacks): Generator {
-                $carry = [];
-
-                foreach ($iterator as $key => $value) {
-                    $callbackReturn = array_reduce(
-                        $callbacks,
-                        static function (bool $carry, callable $callback) use ($key, $value): bool {
-                            return $callback($value, $key) !== $carry;
-                        },
-                        false
-                    );
-
-                    if (true === $callbackReturn && [] !== $carry) {
-                        yield $carry;
-
-                        $carry = [];
+        return static function (callable ...$callbacks): Closure {
+            return
+                /**
+                 * @psalm-param Iterator<TKey, T> $iterator
+                 * @psalm-param list<callable(T, TKey):(bool)> $callbacks
+                 *
+                 * @psalm-return Generator<int, list<T>>
+                 */
+                static function (Iterator $iterator) use ($callbacks): Generator {
+                    $carry = [];
+
+                    foreach ($iterator as $key => $value) {
+                        $callbackReturn = array_reduce(
+                            $callbacks,
+                            static function (bool $carry, callable $callback) use ($key, $value): bool {
+                                return $callback($value, $key) !== $carry;
+                            },
+                            false
+                        );
+
+                        if (true === $callbackReturn && [] !== $carry) {
+                            yield $carry;
+
+                            $carry = [];
+                        }
+
+                        $carry[] = $value;
                     }
 
-                    $carry[] = $value;
-                }
-
-                if ([] !== $carry) {
-                    yield $carry;
-                }
-            };
+                    if ([] !== $carry) {
+                        yield $carry;
+                    }
+                };
+        };
     }
 }
diff --git a/src/Operation/Tail.php b/src/Operation/Tail.php
index db6fdade5..2efc69972 100644
--- a/src/Operation/Tail.php
+++ b/src/Operation/Tail.php
@@ -8,7 +8,6 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\Run;
 
 /**
  * @psalm-template TKey
@@ -17,16 +16,19 @@
  */
 final class Tail extends AbstractOperation implements Operation
 {
+    /**
+     * @psalm-return Closure(Iterator<TKey, T>): Generator<TKey, T>
+     */
     public function __invoke(): Closure
     {
         return
             /**
              * @psalm-param Iterator<TKey, T> $iterator
              *
-             * @psalm-return Generator<Tkey, T>
+             * @psalm-return Generator<TKey, T>
              */
             static function (Iterator $iterator): Generator {
-                return yield from (new Run(new Skip(1)))($iterator);
+                return yield from Skip::of()(1)($iterator);
             };
     }
 }
diff --git a/src/Operation/Times.php b/src/Operation/Times.php
index c73aa14d9..bf4cd5d27 100644
--- a/src/Operation/Times.php
+++ b/src/Operation/Times.php
@@ -17,35 +17,24 @@
  */
 final class Times extends AbstractOperation implements Operation
 {
-    public function __construct(?int $number = null, ?callable $callback = null)
+    public function __invoke(): Closure
     {
-        $number = $number ?? 0;
-
-        if (1 > $number) {
-            throw new InvalidArgumentException('Invalid parameter. $number must be greater than 1.');
-        }
+        return static function (int $number = 0): Closure {
+            return static function (?callable $callback = null) use ($number): Closure {
+                return static function (Iterator $iterator) use ($number, $callback): Generator {
+                    if (1 > $number) {
+                        throw new InvalidArgumentException('Invalid parameter. $number must be greater than 1.');
+                    }
 
-        $this->storage = [
-            'number' => $number,
-            'callback' => $callback ?? static function (int $value): int {
-                return $value;
-            },
-        ];
-    }
+                    $callback = $callback ?? static function (int $value): int {
+                        return $value;
+                    };
 
-    public function __invoke(): Closure
-    {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param callable(int):(int) $callback
-             *
-             * @psalm-return Generator<int, int>
-             */
-            static function (Iterator $iterator, ?int $number, callable $callback): Generator {
-                for ($current = 1; $current <= $number; ++$current) {
-                    yield $callback($current);
-                }
+                    for ($current = 1; $current <= $number; ++$current) {
+                        yield $callback($current);
+                    }
+                };
             };
+        };
     }
 }
diff --git a/src/Operation/Transpose.php b/src/Operation/Transpose.php
index bdf770ad4..219b38c9a 100644
--- a/src/Operation/Transpose.php
+++ b/src/Operation/Transpose.php
@@ -18,6 +18,9 @@
  */
 final class Transpose extends AbstractOperation implements Operation
 {
+    /**
+     * @psalm-return Closure(Iterator<TKey, T>): Generator<TKey, list<T>>
+     */
     public function __invoke(): Closure
     {
         return
diff --git a/src/Operation/Truthy.php b/src/Operation/Truthy.php
new file mode 100644
index 000000000..2f7020f69
--- /dev/null
+++ b/src/Operation/Truthy.php
@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Operation;
+
+use Closure;
+use Generator;
+use Iterator;
+use loophp\collection\Contract\Operation;
+
+/**
+ * @psalm-template TKey
+ * @psalm-template TKey of array-key
+ * @psalm-template T
+ */
+final class Truthy extends AbstractOperation implements Operation
+{
+    /**
+     * @psalm-return Closure(Iterator<TKey, T>): Generator<int, bool>
+     */
+    public function __invoke(): Closure
+    {
+        return
+            /**
+             * @psalm-param Iterator<TKey, T> $iterator
+             * @psalm-return Generator<int, bool> $iterator
+             */
+            static function (Iterator $iterator): Generator {
+                foreach ($iterator as $key => $value) {
+                    if (false === (bool) $value) {
+                        return yield false;
+                    }
+                }
+
+                return yield true;
+            };
+    }
+}
diff --git a/src/Operation/Unpack.php b/src/Operation/Unpack.php
index 63ec06a30..e2dcab460 100644
--- a/src/Operation/Unpack.php
+++ b/src/Operation/Unpack.php
@@ -9,7 +9,6 @@
 use Iterator;
 use loophp\collection\Contract\Operation;
 use loophp\collection\Iterator\IterableIterator;
-use loophp\collection\Transformation\Run;
 
 /**
  * @psalm-template TKey
@@ -33,7 +32,7 @@ static function (Iterator $iterator): Generator {
                     }
 
                     /** @psalm-var array<int, array<TKey, T>> $chunks */
-                    $chunks = (new Run((new Chunk(2))))(new IterableIterator($value));
+                    $chunks = Chunk::of()(2)(new IterableIterator($value));
 
                     foreach ($chunks as [$k, $v]) {
                         yield $k => $v;
diff --git a/src/Operation/Unpair.php b/src/Operation/Unpair.php
index ef34231c4..968408e15 100644
--- a/src/Operation/Unpair.php
+++ b/src/Operation/Unpair.php
@@ -16,6 +16,9 @@
  */
 final class Unpair extends AbstractOperation implements Operation
 {
+    /**
+     * @psalm-return Closure(Iterator<TKey, T>): Generator<int, array{TKey, T}>
+     */
     public function __invoke(): Closure
     {
         return
diff --git a/src/Operation/Until.php b/src/Operation/Until.php
index ab870fd1f..9af366b9c 100644
--- a/src/Operation/Until.php
+++ b/src/Operation/Until.php
@@ -17,41 +17,40 @@
 final class Until extends AbstractOperation implements Operation
 {
     /**
-     * @param callable ...$callbacks
-     * @psalm-param callable(T, TKey):(bool) ...$callbacks
+     * @psalm-return Closure((callable(T, TKey):(bool))...): Closure(Iterator<TKey, T>): Generator<TKey, T>
      */
-    public function __construct(callable ...$callbacks)
-    {
-        $this->storage['callbacks'] = $callbacks;
-    }
-
     public function __invoke(): Closure
     {
         return
             /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<callable(T, TKey):(bool)> $callbacks
-             *
-             * @psalm-return Generator<TKey, T>
+             * @psalm-param callable(T, TKey):(bool) ...$callbacks
              */
-            static function (Iterator $iterator, array $callbacks): Generator {
-                foreach ($iterator as $key => $value) {
-                    yield $key => $value;
+            static function (callable ...$callbacks): Closure {
+                return
+                /**
+                 * @psalm-param Iterator<TKey, T> $iterator
+                 *
+                 * @psalm-return Generator<TKey, T>
+                 */
+                static function (Iterator $iterator) use ($callbacks): Generator {
+                    foreach ($iterator as $key => $value) {
+                        yield $key => $value;
 
-                    $result = array_reduce(
-                        $callbacks,
-                        static function (bool $carry, callable $callable) use ($key, $value): bool {
-                            return ($callable($value, $key)) ?
+                        $result = array_reduce(
+                            $callbacks,
+                            static function (bool $carry, callable $callable) use ($key, $value): bool {
+                                return ($callable($value, $key)) ?
                                 $carry :
                                 false;
-                        },
-                        true
-                    );
+                            },
+                            true
+                        );
 
-                    if (false !== $result) {
-                        break;
+                        if (false !== $result) {
+                            break;
+                        }
                     }
-                }
+                };
             };
     }
 }
diff --git a/src/Operation/Window.php b/src/Operation/Window.php
index c9f130d43..47e475c97 100644
--- a/src/Operation/Window.php
+++ b/src/Operation/Window.php
@@ -9,7 +9,6 @@
 use Generator;
 use Iterator;
 use loophp\collection\Contract\Operation;
-use loophp\collection\Transformation\Run;
 
 /**
  * @psalm-template TKey
@@ -18,30 +17,32 @@
  */
 final class Window extends AbstractOperation implements Operation
 {
-    public function __construct(int ...$length)
-    {
-        $this->storage['length'] = new ArrayIterator($length);
-    }
-
+    /**
+     * @psalm-return Closure(int...): Closure(Iterator<TKey, T>): Generator<int, list<T>>
+     */
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param ArrayIterator<int, int> $length
-             *
-             * @psalm-return Generator<int, list<T>>
-             */
-            static function (Iterator $iterator, ArrayIterator $length): Generator {
-                /** @psalm-var Iterator<int, int> $length */
-                $length = (new Run(new Loop()))($length);
+        return static function (int ...$lengths): Closure {
+            return
+                /**
+                 * @psalm-param Iterator<TKey, T> $iterator
+                 * @psalm-param ArrayIterator<int, int> $length
+                 *
+                 * @psalm-return Generator<int, list<T>>
+                 */
+                static function (Iterator $iterator) use ($lengths): Generator {
+                    /** @psalm-var Iterator<int, int> $lengths */
+                    $lengths = Loop::of()(new ArrayIterator($lengths));
+
+                    for ($i = 0; iterator_count($iterator) > $i; ++$i) {
+                        /** @psalm-var Generator<TKey, T> $slice */
+                        $slice = Slice::of()($i)($lengths->current())($iterator);
 
-                for ($i = 0; iterator_count($iterator) > $i; ++$i) {
-                    /** @psalm-var list<T> $window */
-                    yield iterator_to_array((new Run(new Slice($i, $length->current())))($iterator));
+                        yield iterator_to_array($slice);
 
-                    $length->next();
-                }
-            };
+                        $lengths->next();
+                    }
+                };
+        };
     }
 }
diff --git a/src/Operation/Zip.php b/src/Operation/Zip.php
index 71d510238..489af2dd0 100644
--- a/src/Operation/Zip.php
+++ b/src/Operation/Zip.php
@@ -18,36 +18,28 @@
  */
 final class Zip extends AbstractOperation implements Operation
 {
-    /**
-     * Zip constructor.
-     *
-     * @param iterable<mixed> ...$iterables
-     */
-    public function __construct(iterable ...$iterables)
-    {
-        $this->storage['iterables'] = $iterables;
-    }
-
     public function __invoke(): Closure
     {
-        return
-            /**
-             * @psalm-param Iterator<TKey, T> $iterator
-             * @psalm-param list<iterable<TKey, T>> $iterables
-             *
-             * @psalm-return Generator<int, list<T>>
-             */
-            static function (Iterator $iterator, array $iterables): Generator {
-                $mit = new MultipleIterator(MultipleIterator::MIT_NEED_ANY);
-                $mit->attachIterator($iterator);
+        return static function (iterable ...$iterables): Closure {
+            return
+                /**
+                 * @psalm-param Iterator<TKey, T> $iterator
+                 * @psalm-param list<iterable<TKey, T>> $iterables
+                 *
+                 * @psalm-return Generator<int, list<T>>
+                 */
+                static function (Iterator $iterator) use ($iterables): Generator {
+                    $mit = new MultipleIterator(MultipleIterator::MIT_NEED_ANY);
+                    $mit->attachIterator($iterator);
 
-                foreach ($iterables as $iterableIterator) {
-                    $mit->attachIterator(new IterableIterator($iterableIterator));
-                }
+                    foreach ($iterables as $iterableIterator) {
+                        $mit->attachIterator(new IterableIterator($iterableIterator));
+                    }
 
-                foreach ($mit as $values) {
-                    yield $values;
-                }
-            };
+                    foreach ($mit as $values) {
+                        yield $values;
+                    }
+                };
+        };
     }
 }
diff --git a/src/Transformation/All.php b/src/Transformation/All.php
deleted file mode 100644
index bac2f6844..000000000
--- a/src/Transformation/All.php
+++ /dev/null
@@ -1,28 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Transformation;
-
-use Iterator;
-use loophp\collection\Contract\Transformation;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- *
- * @implements Transformation<TKey, T>
- */
-final class All implements Transformation
-{
-    /**
-     * @return array<TKey, T>
-     * @phpstan-return array<TKey, T>
-     * @psalm-return array<TKey, T>
-     */
-    public function __invoke(Iterator $collection): array
-    {
-        return iterator_to_array($collection);
-    }
-}
diff --git a/src/Transformation/Contains.php b/src/Transformation/Contains.php
deleted file mode 100644
index 4ffb76288..000000000
--- a/src/Transformation/Contains.php
+++ /dev/null
@@ -1,58 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Transformation;
-
-use ArrayIterator;
-use Iterator;
-use loophp\collection\Contract\Transformation;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- *
- * @implements Transformation<TKey, T>
- */
-final class Contains implements Transformation
-{
-    /**
-     * @var ArrayIterator<int, mixed>
-     * @psalm-var ArrayIterator<int, T>
-     */
-    private $values;
-
-    /**
-     * @param mixed ...$values
-     * @psalm-param T ...$values
-     */
-    public function __construct(...$values)
-    {
-        $this->values = new ArrayIterator($values);
-    }
-
-    /**
-     * @param Iterator<TKey, T> $collection
-     *
-     * @return bool
-     */
-    public function __invoke(Iterator $collection)
-    {
-        $values = $this->values;
-
-        foreach ($collection as $key => $value) {
-            foreach ($values as $k => $v) {
-                if ($v === $value) {
-                    unset($values[$k]);
-                }
-
-                if (0 === $values->count()) {
-                    return true;
-                }
-            }
-        }
-
-        return false;
-    }
-}
diff --git a/src/Transformation/Count.php b/src/Transformation/Count.php
deleted file mode 100644
index de48eb9bf..000000000
--- a/src/Transformation/Count.php
+++ /dev/null
@@ -1,24 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Transformation;
-
-use Iterator;
-use loophp\collection\Contract\Transformation;
-use loophp\collection\Iterator\IterableIterator;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- *
- * @implements Transformation<TKey, T>
- */
-final class Count implements Transformation
-{
-    public function __invoke(Iterator $collection)
-    {
-        return iterator_count(new IterableIterator($collection));
-    }
-}
diff --git a/src/Transformation/Falsy.php b/src/Transformation/Falsy.php
deleted file mode 100644
index 4dfb8861b..000000000
--- a/src/Transformation/Falsy.php
+++ /dev/null
@@ -1,29 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Transformation;
-
-use Iterator;
-use loophp\collection\Contract\Transformation;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- *
- * @implements Transformation<TKey, T>
- */
-final class Falsy implements Transformation
-{
-    public function __invoke(Iterator $collection): bool
-    {
-        foreach ($collection as $key => $value) {
-            if (false !== (bool) $value) {
-                return false;
-            }
-        }
-
-        return true;
-    }
-}
diff --git a/src/Transformation/FoldLeft.php b/src/Transformation/FoldLeft.php
deleted file mode 100644
index 371d9aa17..000000000
--- a/src/Transformation/FoldLeft.php
+++ /dev/null
@@ -1,60 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Transformation;
-
-use Iterator;
-use loophp\collection\Contract\Transformation;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- *
- * @implements Transformation<TKey, T>
- */
-final class FoldLeft implements Transformation
-{
-    /**
-     * @var callable
-     * @psalm-var callable(T|null, T, TKey, \Iterator<TKey, T>):(T|null)
-     */
-    private $callback;
-
-    /**
-     * @var mixed|null
-     * @psalm-var T|null
-     */
-    private $initial;
-
-    /**
-     * @psalm-param callable(T|null, T, TKey, \Iterator<TKey, T>):(T|null) $callback
-     *
-     * @param mixed|null $initial
-     * @psalm-param T|null $initial
-     */
-    public function __construct(callable $callback, $initial = null)
-    {
-        $this->callback = $callback;
-        $this->initial = $initial;
-    }
-
-    /**
-     * @psalm-param Iterator<TKey, T> $collection
-     *
-     * @return mixed|null
-     * @psalm-return T|null
-     */
-    public function __invoke(Iterator $collection)
-    {
-        $callback = $this->callback;
-        $initial = $this->initial;
-
-        foreach ($collection as $key => $value) {
-            $initial = $callback($initial, $value, $key, $collection);
-        }
-
-        return $initial;
-    }
-}
diff --git a/src/Transformation/FoldRight.php b/src/Transformation/FoldRight.php
deleted file mode 100644
index a3d2f41ad..000000000
--- a/src/Transformation/FoldRight.php
+++ /dev/null
@@ -1,57 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Transformation;
-
-use Iterator;
-use loophp\collection\Contract\Transformation;
-use loophp\collection\Operation\Reverse;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- *
- * @implements Transformation<TKey, T>
- */
-final class FoldRight implements Transformation
-{
-    /**
-     * @var callable
-     * @psalm-var callable(T|null, T|null, TKey, \Iterator<TKey, T>):(T|null)
-     */
-    private $callback;
-
-    /**
-     * @var mixed|null
-     * @psalm-var T|null
-     */
-    private $initial;
-
-    /**
-     * @psalm-param callable(T|null, T|null, TKey, \Iterator<TKey, T>):(T|null) $callback
-     *
-     * @param mixed|null $initial
-     * @psalm-param T|null $initial
-     */
-    public function __construct(callable $callback, $initial = null)
-    {
-        $this->callback = $callback;
-        $this->initial = $initial;
-    }
-
-    /**
-     * @psalm-param Iterator<TKey, T> $collection
-     *
-     * @return mixed|null
-     * @psalm-return T|null
-     */
-    public function __invoke(Iterator $collection)
-    {
-        $callback = $this->callback;
-        $initial = $this->initial;
-
-        return (new Transform(new FoldLeft($callback, $initial)))((new Run(new Reverse()))($collection));
-    }
-}
diff --git a/src/Transformation/Get.php b/src/Transformation/Get.php
deleted file mode 100644
index 131227465..000000000
--- a/src/Transformation/Get.php
+++ /dev/null
@@ -1,59 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Transformation;
-
-use Iterator;
-use loophp\collection\Contract\Transformation;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- *
- * @implements Transformation<TKey, T>
- */
-final class Get implements Transformation
-{
-    /**
-     * @var mixed
-     * @psalm-var T
-     */
-    private $default;
-
-    /**
-     * @var int|string
-     */
-    private $key;
-
-    /**
-     * @param int|string $key
-     * @param mixed $default
-     * @psalm-param T $default
-     */
-    public function __construct($key, $default)
-    {
-        $this->key = $key;
-        $this->default = $default;
-    }
-
-    /**
-     * @param Iterator<TKey, T> $collection
-     *
-     * @return T
-     */
-    public function __invoke(Iterator $collection)
-    {
-        $keyToGet = $this->key;
-        $default = $this->default;
-
-        foreach ($collection as $key => $value) {
-            if ($key === $keyToGet) {
-                return $value;
-            }
-        }
-
-        return $default;
-    }
-}
diff --git a/src/Transformation/Has.php b/src/Transformation/Has.php
deleted file mode 100644
index d7a5be92a..000000000
--- a/src/Transformation/Has.php
+++ /dev/null
@@ -1,50 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Transformation;
-
-use Iterator;
-use loophp\collection\Contract\Transformation;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- *
- * @implements Transformation<TKey, T>
- */
-final class Has implements Transformation
-{
-    /**
-     * @var callable
-     * @psalm-var callable(TKey, T):(bool)
-     */
-    private $callback;
-
-    /**
-     * @psalm-param callable(TKey, T):(bool) $callback
-     */
-    public function __construct(callable $callback)
-    {
-        $this->callback = $callback;
-    }
-
-    /**
-     * @param Iterator<TKey, T> $collection
-     *
-     * @return bool
-     */
-    public function __invoke(Iterator $collection)
-    {
-        $callback = $this->callback;
-
-        foreach ($collection as $key => $value) {
-            if ($callback($key, $value) === $value) {
-                return true;
-            }
-        }
-
-        return false;
-    }
-}
diff --git a/src/Transformation/Implode.php b/src/Transformation/Implode.php
deleted file mode 100644
index aedaf15c3..000000000
--- a/src/Transformation/Implode.php
+++ /dev/null
@@ -1,54 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Transformation;
-
-use CachingIterator;
-use Iterator;
-use loophp\collection\Contract\Transformation;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- *
- * @implements Transformation<TKey, T>
- */
-final class Implode implements Transformation
-{
-    /**
-     * @var string
-     */
-    private $glue;
-
-    public function __construct(string $glue)
-    {
-        $this->glue = $glue;
-    }
-
-    public function __invoke(Iterator $collection): string
-    {
-        $glue = $this->glue;
-
-        $callback =
-            /**
-             * @psalm-param TKey $key
-             * @psalm-param CachingIterator $iterator
-             *
-             * @param mixed $key
-             * @param mixed $iterator
-             */
-            static function (string $carry, string $item, $key, CachingIterator $iterator) use ($glue): string {
-                $carry .= $item;
-
-                if ($iterator->hasNext()) {
-                    $carry .= $glue;
-                }
-
-                return $carry;
-            };
-
-        return (string) (new Transform(new FoldLeft($callback, '')))(new CachingIterator($collection));
-    }
-}
diff --git a/src/Transformation/Nullsy.php b/src/Transformation/Nullsy.php
deleted file mode 100644
index 8b6d46aa4..000000000
--- a/src/Transformation/Nullsy.php
+++ /dev/null
@@ -1,32 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Transformation;
-
-use Iterator;
-use loophp\collection\Contract\Transformation;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- *
- * @implements Transformation<TKey, T>
- */
-final class Nullsy implements Transformation
-{
-    /**
-     * @psalm-param Iterator<TKey, T|null> $collection
-     */
-    public function __invoke(Iterator $collection): bool
-    {
-        foreach ($collection as $key => $value) {
-            if (null !== $value) {
-                return false;
-            }
-        }
-
-        return true;
-    }
-}
diff --git a/src/Transformation/Reduce.php b/src/Transformation/Reduce.php
deleted file mode 100644
index b777c0369..000000000
--- a/src/Transformation/Reduce.php
+++ /dev/null
@@ -1,56 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Transformation;
-
-use Iterator;
-use loophp\collection\Contract\Transformation;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- *
- * @implements Transformation<TKey, T>
- */
-final class Reduce implements Transformation
-{
-    /**
-     * @var callable
-     * @psalm-var callable(T|null, T|null, TKey):(T|null)
-     */
-    private $callback;
-
-    /**
-     * @var mixed|null
-     * @psalm-var T|null
-     */
-    private $initial;
-
-    /**
-     * @psalm-param callable(T|null, T|null, TKey):(T|null) $callback
-     *
-     * @param mixed|null $initial
-     * @psalm-param T|null $initial
-     */
-    public function __construct(callable $callback, $initial = null)
-    {
-        $this->callback = $callback;
-        $this->initial = $initial;
-    }
-
-    /**
-     * @psalm-param Iterator<TKey, T> $collection
-     *
-     * @return mixed|null
-     * @psalm-return T|scalar|null|\Iterator<TKey, T>
-     */
-    public function __invoke(Iterator $collection)
-    {
-        $callback = $this->callback;
-        $initial = $this->initial;
-
-        return (new Transform(new FoldLeft($callback, $initial)))($collection);
-    }
-}
diff --git a/src/Transformation/Run.php b/src/Transformation/Run.php
deleted file mode 100644
index 43ed7682f..000000000
--- a/src/Transformation/Run.php
+++ /dev/null
@@ -1,47 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Transformation;
-
-use ArrayIterator;
-use Iterator;
-use loophp\collection\Contract\Operation;
-use loophp\collection\Contract\Transformation;
-use loophp\collection\Iterator\ClosureIterator;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- *
- * @implements Transformation<TKey, T>
- */
-final class Run implements Transformation
-{
-    /**
-     * @var ArrayIterator<int, \loophp\collection\Contract\Operation>
-     */
-    private $operations;
-
-    public function __construct(Operation ...$operations)
-    {
-        $this->operations = new ArrayIterator($operations);
-    }
-
-    public function __invoke(Iterator $collection): Iterator
-    {
-        return (
-            new FoldLeft(
-                static function (Iterator $collection, Operation $operation): ClosureIterator {
-                    return new ClosureIterator(
-                        $operation(),
-                        $collection,
-                        ...array_values($operation->getArguments())
-                    );
-                },
-                $collection
-            )
-        )($this->operations);
-    }
-}
diff --git a/src/Transformation/Transform.php b/src/Transformation/Transform.php
deleted file mode 100644
index e316c7d50..000000000
--- a/src/Transformation/Transform.php
+++ /dev/null
@@ -1,57 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Transformation;
-
-use ArrayIterator;
-use Iterator;
-use loophp\collection\Contract\Transformation;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- *
- * @implements Transformation<TKey, T>
- */
-final class Transform implements Transformation
-{
-    /**
-     * @var ArrayIterator<int, \loophp\collection\Contract\Transformation<TKey, T>>
-     */
-    private $transformers;
-
-    /**
-     * @param \loophp\collection\Contract\Transformation<TKey, T> ...$transformers
-     */
-    public function __construct(Transformation ...$transformers)
-    {
-        $this->transformers = new ArrayIterator($transformers);
-    }
-
-    /**
-     * @psalm-param Iterator<TKey, T> $collection
-     *
-     * @return mixed|null
-     * @psalm-return Iterator<TKey, T>|T
-     */
-    public function __invoke(Iterator $collection)
-    {
-        return (new FoldLeft(
-            /**
-             * @psalm-param Iterator<TKey, T> $collection
-             * @psalm-param Transformation<TKey, T> $transformer
-             * @psalm-param TKey $key
-             *
-             * @param mixed $key
-             *
-             * @psalm-return T
-             */
-            static function (Iterator $collection, Transformation $transformer, $key) {
-                return $transformer($collection);
-            },
-            $collection
-        ))($this->transformers);
-    }
-}
diff --git a/src/Transformation/Truthy.php b/src/Transformation/Truthy.php
deleted file mode 100644
index c643a27b2..000000000
--- a/src/Transformation/Truthy.php
+++ /dev/null
@@ -1,29 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace loophp\collection\Transformation;
-
-use Iterator;
-use loophp\collection\Contract\Transformation;
-
-/**
- * @psalm-template TKey
- * @psalm-template TKey of array-key
- * @psalm-template T
- *
- * @implements Transformation<TKey, T>
- */
-final class Truthy implements Transformation
-{
-    public function __invoke(Iterator $collection): bool
-    {
-        foreach ($collection as $key => $value) {
-            if (false === (bool) $value) {
-                return false;
-            }
-        }
-
-        return true;
-    }
-}