function composition and array concat

Author: brianium

src/Brianium/Phunc/Arrays.php

@@ -9,4 +9,14 @@
  */
 function rest(array $array) {
     return array_slice($array, 1);
+}
+
+/**
+ * Concat all supplied arrays
+ *
+ * @return array|mixed
+ */
+function concat(/** arrays **/) {
+    $arrays = array_filter(func_get_args(), 'is_array');
+    return call_user_func_array('array_merge', $arrays);
 }

src/Brianium/Phunc/Functions.php

@@ -13,7 +13,7 @@
 function partial(callable $func /** args **/) {
     $rest = _array\rest(func_get_args());
     return function() use ($func, $rest) {
-        return call_user_func_array($func, array_merge($rest, func_get_args()));
+        return call_user_func_array($func, _array\concat($rest, func_get_args()));
     };
 }
 
@@ -26,7 +26,7 @@ function partial(callable $func /** args **/) {
 function partialRight(callable $func /** args **/) {
     $rest = _array\rest(func_get_args());
     return function() use ($func, $rest) {
-        return call_user_func_array($func, array_merge(func_get_args(), $rest));
+        return call_user_func_array($func, _array\concat(func_get_args(), array_reverse($rest)));
     };
 }
 
@@ -61,7 +61,7 @@ function curry1(callable $func) {
 function curry2(callable $func, $order = 0) {
     return function($arg1) use ($func, $order) {
         return function() use ($func, $arg1, $order) {
-            $args = ($order > 0) ? array_merge(func_get_args(), [$arg1]) : array_merge([$arg1], func_get_args());
+            $args = ($order > 0) ? _array\concat(func_get_args(), [$arg1]) : _array\concat([$arg1], func_get_args());
             return call_user_func_array($func, $args);
         };
     };
@@ -78,7 +78,7 @@ function curry3(callable $func, $order = 0) {
     return function($arg1) use ($func, $order) {
         return function($arg2) use ($func, $arg1, $order) {
             return function() use ($func, $arg1, $arg2, $order) {
-                $args = ($order > 0) ? array_merge(func_get_args(), [$arg2, $arg1]) : array_merge([$arg1, $arg2], func_get_args());
+                $args = ($order > 0) ? _array\concat(func_get_args(), [$arg2, $arg1]) : _array\concat([$arg1, $arg2], func_get_args());
                 return call_user_func_array($func, $args);
             };
         };
@@ -107,4 +107,21 @@ function curry(callable $func, $arity = 1) {
 function curryRight(callable $func, $arity = 1) {
     $fn = __NAMESPACE__ . '\\' . "curry$arity";
     return (function_exists($fn)) ? call_user_func_array($fn, [$func, 1]) : false;
+}
+
+/**
+ * Compose a group of functions such that every
+ * function is called with the result of the function to
+ * it's right
+ *
+ * @return callable
+ */
+function compose(/** functions */) {
+    $functions = array_filter(func_get_args(), 'is_callable');
+    return function () use ($functions) {
+        $result = func_get_args();
+        while ($fn = array_pop($functions))
+            $result = [call_user_func_array($fn, $result)];
+        return $result[0];
+    };
 }

test/Brianium/Phunc/Functions/ComposeTest.php

@@ -0,0 +1,17 @@
+<?php
+namespace Brianium\Phunc\Functions;
+loadModule('Functions');
+
+class ComposeTest extends \PHPUnit_Framework_TestCase
+{
+    public function test_compose_passes_results_from_end_to_first()
+    {
+        $makeCool = function($name) {
+            return $name . ' is cool.';
+        };
+        $subject = 'brian:scaturro';
+        $findNameAndMakeItCool = compose($makeCool, 'ucfirst', partialRight('strstr', true, ':'));
+        $result = $findNameAndMakeItCool($subject);
+        $this->assertEquals('Brian is cool.', $result);
+    }
+}