slifin

<?php
function tea_and_biscuits($tea, $biscuit) {
  return $tea + ' ' + $biscuit;
}
$tea = 'tea';
$tea_and_biscuits = partial($tea, (new _));
$biscuits = ['chocolate', 'plain', 'hobnob'];
$tea_and_biscuits = array_map($tea_and_biscuits, $biscuits);

slifin

<?php
function cond($condition, callable $true, $false = NULL) {
  if ($condition) {
    return $true();
  }
  if ($false !== NULL) {
    if (is_callable($false)) {
      return $false(); 
    }
    throw new InvalidArgumentException('False not callable');

slifin

<?php
namespace _;
/**
 * Data type to signify a placeholder.
 */
class Placeholder {}
class_alias('Placeholder', '_');

/**
 * Creates a callback at the element of $iterator->current()

slifin

<?php $counter = (int) ($_GET['counter'] ?? 0); ?>
<form>
  <button name="counter" value="<?= $counter + 1 ?>">Number <?= $counter ?></button>
</form>

slifin

<?php
function recursive_filter($data, callable $selector_function, $iterator = NULL) {
  $iterator = $iterator ?? new RecursiveIteratorIterator(
    new RecursiveArrayIterator($data),
    RecursiveIteratorIterator::CHILD_FIRST
  );
  foreach ($iterator as $key => $value) {
    if ($selector_function($value, $key, $iterator)) {

      $depth = $iterator->getDepth();

slifin

<?php
namespace _;
/**
 * Data type to signify a placeholder.
 */
class Placeholder {}
class_alias('Placeholder', '_');

/**
 * Creates a callback at the element of $iterator->current()

slifin

<?php
/**
 * @file
 * Collection of functional tools.
 */

namespace _;

/**
 * Creates a callback at the element of $iterator->current()

slifin

<?php
class struct {
    function __invoke(callable $callback) {
        return $callback(...array_values($this->props));
    }
}
class box extends struct {
    function __construct($a, $b) {
        $this->props = get_defined_vars();
    }

slifin

<?php

class Struct {
    private $args;
    function __construct(array $args) {
        $this->args = $args;
    }
    function __invoke(callable $signature) {    
        return $signature(...array_values($this->args));
    }

slifin

<?php

// Event storage.
function event_storage(callable $callback) {
    static $storage = array();
    return $storage = $callback($storage);
}

// Retrieve events.
function event_get(callable $filter) {