Playing around with Functional PHP

Collection.php

<?php

class Collection
{
  private $data;

  public function __construct($data)
  {
    $this->data = $data;
  }

  public function __invoke()
  {
    return $this->data;
  }

  public function concat($data)
  {
    $this->data = array_merge($this->data, $data);
    return $this;
  }

  public function every($callback)
  {
    $this->data = sizeof($this->data) === sizeof(array_filter($this->data, $callback));
    return $this;
  }

  public function filter($callback)
  {
    $this->data = array_filter($this->data, $callback);
    return $this;
  }

  public function in($data)
  {
    $this->data = in_array($data, $this->data);
    return $this;
  }

  public function key($data)
  {
    $this->data = array_key_exists($data, $this->data);
    return $this;
  }

  public function map($callback)
  {
    $this->data = array_map($callback, $this->data);
    return $this;
  }

  public function reduce($callback, $initial = null)
  {
    $this->data = array_reduce($this->data, $callback, $initial);
    return $this;
  }

  public function remove($data)
  {
    $this->data = array_diff($this->data, $data);
    return $this;
  }

  public function slice($start, $length = null)
  {
    $this->data = array_slice($this->data, $start, $length);
    return $this->data;
  }

  public function some($callback)
  {
    $this->data = sizeof(array_filter($this->data, $callback)) > 0;
    return $this;
  }
}

Filtering.php

<?php

class Filtering
{
  public static function isType($comparator)
  {
    return function ($value) use ($comparator) {
      $type = gettype($value);
      if ($type !== 'resource')
        return $type === $comparator;
      return get_resource_type($value) === $comparator;
    };
  }

  public static function isValue($comparator)
  {
    return function ($value) use ($comparator) {
      return $value === $comparator;
    };
  }
}

Mapping.php

<?php

class Mapping
{
  public static function extract($key)
  {
    return function ($array) use ($key) {
      return $array[$key];
    };
  }
}

Reducing.php

<?php

class Reducing
{
  public static function sumLength()
  {
    return function ($carry, $item) {
      return $carry + strlen($item);
    };
  }
}