Changed constant function name to identity

docs/docs.md

@@ -9,7 +9,6 @@
  * [butlast](functions/butlast.md):  Returns all the elements of a collection except the last preserving the keys
  * [complement](functions/complement.md): Returns another function that takes the same arguments and has the opposite truth value.
  * [compose](functions/compose.md): Combine multiple function calls in one function
- * [constant](functions/constant.md): It wraps a value into a Closure, which return the same value whenever is called
  * [dissoc](functions/dissoc.md): Dissociate a value of a key in a collection
  * [do_if](functions/do_if.md): Returns a callable that will call the given function if the result of applying the callable arguments to the predicates is true for all of them
  * [each](functions/each.md): Apply a function over all the items of a collection
@@ -20,6 +19,7 @@
  * [get](functions/get.md): Returns the value of an item in a collection or a default value in the case it does not exists
  * [get_in](functions/get_in.md): Returns the value in a nested associative structure or a default value in the case it does not exists
  * [key](functions/key.md): Returns the key of an item value in a collection or a default value in the case it does not exists
+ * [identity](functions/identity.md): Returns a closure which always return the same value that is passed as argument
  * [instance_of](functions/instance_of.md): Returns a checker that validated if an element is an instance of a class
  * [last](functions/last.md): Returns the last element of a collection
  * [map](functions/map.md): Apply a function over all the items of a collection and returns an array with the results

docs/functions/identity.md

@@ -0,0 +1,29 @@
+# identity
+
+## Description
+
+It wraps a value into a closure, which return the same value that is passed as argument whenever is called.
+
+## Parameters
+
+<dl>
+  <dt>value</dt>
+  <dd>Any type of value that will be returned</dd>
+</dl>
+
+## Examples
+
+Fill an array with zeros:
+
+```php
+<?php
+
+use function Lambdish\Phunctional\map;
+use function Lambdish\Phunctional\identity;
+
+$numbers = [1,2,3,4,5];
+
+map(identity(0), $numbers);
+
+// => [0,0,0,0,0]
+```

src/_bootstrap.php

@@ -7,7 +7,6 @@
 require __DIR__ . '/butlast.php';
 require __DIR__ . '/complement.php';
 require __DIR__ . '/compose.php';
-require __DIR__ . '/constant.php';
 require __DIR__ . '/dissoc.php';
 require __DIR__ . '/do_if.php';
 require __DIR__ . '/each.php';
@@ -18,6 +17,7 @@
 require __DIR__ . '/get.php';
 require __DIR__ . '/get_in.php';
 require __DIR__ . '/key.php';
+require __DIR__ . '/identity.php';
 require __DIR__ . '/instance_of.php';
 require __DIR__ . '/last.php';
 require __DIR__ . '/map.php';

src/constant.php → src/identity.php

@@ -3,15 +3,15 @@
 namespace Lambdish\Phunctional;
 
 /**
- * It wraps a value into a Closure, which return the same value whenever is called
+ * It wraps a value into a Closure, which return the same value that is passed as argument whenever is called
  *
  * @since v1.0.7
  *
  * @param mixed $value any type of value
  *
  * @return \Closure
  */
-function constant($value)
+function identity($value)
 {
     return function () use ($value) {
         return $value;

tests/IdentityTest.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace Lambdish\Phunctional\Tests;
+
+use PHPUnit_Framework_TestCase;
+use function Lambdish\Phunctional\identity;
+
+final class IdentityTest extends PHPUnit_Framework_TestCase
+{
+    /** @test */
+    public function it_should_return_a_value()
+    {
+        $value = 5;
+        $identityClosure  = identity($value);
+
+        $this->assertSame($value, $identityClosure());
+    }
+
+    /** @test */
+    public function it_should_return_same_value_if_called_twice()
+    {
+        $value = 5;
+        $identityClosure  = identity($value);
+
+        $identityClosure();
+
+        $this->assertSame($value, $identityClosure());
+    }
+}