refactor: Update Implode operation.

BREAKING CHANGE: yes

spec/loophp/collection/CollectionSpec.php

@@ -167,8 +167,8 @@ public function it_can_be_constructed_from_a_stream(): void
 
         $stream = fopen('data://text/plain,' . $string, 'rb');
         $this::fromResource($stream)
-            ->implode('')
-            ->shouldReturn($string);
+            ->implode()
+            ->shouldIterateAs([55 => $string]);
     }
 
     public function it_can_be_constructed_from_array(): void
@@ -1126,11 +1126,11 @@ public function it_can_implode(): void
     {
         $this::fromIterable(range('A', 'C'))
             ->implode('-')
-            ->shouldReturn('A-B-C');
+            ->shouldIterateAs([2 => 'A-B-C']);
 
         $this::fromIterable(range('A', 'C'))
             ->implode()
-            ->shouldReturn('ABC');
+            ->shouldIterateAs([2 => 'ABC']);
     }
 
     public function it_can_init(): void
@@ -2621,7 +2621,7 @@ public function it_can_use_with(): void
             ->last()
             ->unwrap()
             ->implode()
-            ->shouldReturn('indent_size = 4');
+            ->shouldIterateAs([14 => 'indent_size = 4']);
 
         $stream = fopen(__DIR__ . '/../../fixtures/sample.txt', 'rb');
 

src/Collection.php

@@ -546,9 +546,9 @@ static function ($value, $key) {
         return $this->pipe(IfThenElse::of()($condition)($then)($else));
     }
 
-    public function implode(string $glue = ''): string
+    public function implode(string $glue = ''): CollectionInterface
     {
-        return $this->pipe(Implode::of()($glue))->getIterator()->current();
+        return $this->pipe(Implode::of()($glue));
     }
 
     public function init(): CollectionInterface

src/Contract/Operation/Implodeable.php

@@ -4,7 +4,17 @@
 
 namespace loophp\collection\Contract\Operation;
 
+use loophp\collection\Contract\Collection;
+
+/**
+ * @psalm-template TKey
+ * @psalm-template TKey of array-key
+ * @psalm-template T
+ */
 interface Implodeable
 {
-    public function implode(string $glue = ''): string;
+    /**
+     * @psalm-return \loophp\collection\Contract\Collection<int, string>
+     */
+    public function implode(string $glue = ''): Collection;
 }