Rename minor stuff.

README.md

@@ -31,7 +31,7 @@ On top of this, this library:
  * is [immutable](https://en.wikipedia.org/wiki/Immutable_object),
  * is extendable,
  * leverages the power of PHP [generators](https://www.php.net/manual/en/class.generator.php) and [iterators](https://www.php.net/manual/en/class.iterator.php),
- * uses [S.O.L.I.D principles](https://en.wikipedia.org/wiki/SOLID),
+ * uses [S.O.L.I.D. principles](https://en.wikipedia.org/wiki/SOLID),
  * doesn't depends or require any other library or framework.
 
 Except a few methods, most of methods are [pure](https://en.wikipedia.org/wiki/Pure_function) and return a
@@ -119,7 +119,7 @@ Collection::with(['A' => 'A', 'B' => 'B', 'C' => 'C', 'D' => 'D', 'E' => 'E'])
     )
     ->all(); // ['A' => 'a', B => 'b', 'C' => 'c', 'D' = >'d', 'E' => 'e']
 
-// Infinitely loop over numbers, square them, filter those that are not divisible by 5, take the first 100 of them.
+// Infinitely loop over numbers, cube them, filter those that are not divisible by 5, take the first 100 of them.
 Collection::range(0, INF)
     ->map(
         static function ($value, $key) {

src/Operation/Combine.php

@@ -44,14 +44,17 @@ static function () use ($collection) {
             );
             $keysIterator = new \ArrayIterator($keys);
 
-            for (; true === ($original->valid() && $keysIterator->valid()); $original->next(), $keysIterator->next()
-                ) {
+            while ($original->valid() && $keysIterator->valid()) {
                 yield $keysIterator->current() => $original->current();
+
+                $original->next();
+                $keysIterator->next();
             }
 
-            if ((true === $original->valid() && false === $keysIterator->valid()) ||
-                    (false === $original->valid() && true === $keysIterator->valid())
-                ) {
+            $predicate1 = (true === $original->valid() && false === $keysIterator->valid());
+            $predicate2 = (false === $original->valid() && true === $keysIterator->valid());
+
+            if ($predicate1 || $predicate2) {
                 \trigger_error('Both keys and values must have the same amount of items.', \E_USER_WARNING);
             }
         };

src/Operation/Merge.php

@@ -16,6 +16,11 @@ final class Merge implements Operation
      */
     private $sources;
 
+    /**
+     * Merge constructor.
+     *
+     * @param iterable ...$sources
+     */
     public function __construct(iterable ...$sources)
     {
         $this->sources = $sources;

src/Transformation/All.php

@@ -19,11 +19,9 @@ public function on(iterable $collection)
         $result = [];
 
         foreach ($collection as $key => $value) {
-            if (true === \is_iterable($value)) {
-                $result[$key] = $this->on($value);
-            } else {
-                $result[$key] = $value;
-            }
+            $result[$key] = \is_iterable($value) ?
+                $this->on($value) :
+                $value;
         }
 
         return $result;

src/Transformation/Implode.php

@@ -31,6 +31,12 @@ public function __construct(string $glue = '')
      */
     public function on(iterable $collection): string
     {
-        return \implode($this->glue, (new All())->on($collection));
+        $result = '';
+
+        foreach ($collection as $value) {
+            $result .= $value . $this->glue;
+        }
+
+        return \rtrim($result, $this->glue);
     }
 }

src/Transformation/Reduce.php

@@ -41,12 +41,10 @@ public function on(iterable $collection)
         $callback = $this->callback;
         $initial = $this->initial;
 
-        $carry = $initial;
-
         foreach ($collection as $key => $value) {
-            $carry = $callback($carry, $value, $key);
+            $initial = $callback($initial, $value, $key);
         }
 
-        return $carry;
+        return $initial;
     }
 }

src/Transformation/Run.php

@@ -4,7 +4,7 @@
 
 namespace drupol\collection\Transformation;
 
-use drupol\collection\Contract\Operation as OperationInterface;
+use drupol\collection\Contract\Operation;
 use drupol\collection\Contract\Transformation;
 use drupol\collection\Iterator\ClosureIterator;
 
@@ -23,7 +23,7 @@ final class Run implements Transformation
      *
      * @param \drupol\collection\Contract\Operation ...$operations
      */
-    public function __construct(OperationInterface ...$operations)
+    public function __construct(Operation ...$operations)
     {
         $this->operations = $operations;
     }
@@ -33,22 +33,10 @@ public function __construct(OperationInterface ...$operations)
      */
     public function on(iterable $collection)
     {
-        return \array_reduce($this->operations, [$this, 'doRun'], $collection);
-    }
+        $callback = static function (iterable $collection, Operation $operation) {
+            return new ClosureIterator($operation->on($collection));
+        };
 
-    /**
-     * Run an operation on the collection.
-     *
-     * @param iterable $collection
-     *   The collection.
-     * @param \drupol\collection\Contract\Operation $operation
-     *   The operation.
-     *
-     * @return mixed
-     *   The operation result.
-     */
-    private function doRun(iterable $collection, OperationInterface $operation)
-    {
-        return new ClosureIterator($operation->on($collection));
+        return (new Reduce($callback, $collection))->on($this->operations);
     }
 }

src/Transformation/Transform.php

@@ -31,21 +31,10 @@ public function __construct(Transformation ...$transformers)
      */
     public function on(iterable $collection)
     {
-        return \array_reduce($this->transformers, [$this, 'doRun'], $collection);
-    }
+        $callback = static function (iterable $collection, Transformation $transformer) {
+            return $transformer->on($collection);
+        };
 
-    /**
-     * Run an operation on the collection.
-     *
-     * @param iterable $collection
-     *   The collection.
-     * @param \drupol\collection\Contract\Transformation $transformer
-     *
-     * @return mixed
-     *   The operation result.
-     */
-    private function doRun(iterable $collection, Transformation $transformer)
-    {
-        return $transformer->on($collection);
+        return (new Reduce($callback, $collection))->on($this->transformers);
     }
 }