Last updated: 2015-10-09 05:33:28 +0100

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Contents of follows

= PHP Core Extensions =

This is a "polyfill" which provides some core language functionality not offered by PHP 'out of the box'. Includes:

== Callable Operators ==

In regular PHP, we can't treat operators as functions, eg.

$total = array_reduce($penalties,
                      function($x, $y) { return $x - $y; },
if ($errors) { throw current($errors); }

PHP Core provides an 'op' function to work around this:

$total = array_reduce($penalties, op('-'), $score);
array_map(op('throw'), $errors);

Core's higher-order functions apply 'op' automatically.

== Partial Application ==

By default, PHP's functions are all-or-nothing: you can either call them now, with whatever values you have, or you must wait until later:

$r1 = func($a, $b, $c, null, null, null);

$r2 = function($d, $e, $f) use ($a, $b, $c) {
  return func($a, $b, $c, $d, $e, $f);

Partial application lets you pass in some arguments now and the rest later:

$r3 = papply('func', $a, $b, $c);

== Currying ==

Curried functions don't need partial application: they collect up the right number of arguments automatically:

$f = curry(function($w, $x, $y, $z) { return func_get_args(); });
$g = $f(10);
$h = $g(20);
$i = $h(30, 40); // $i === [10, 20, 30, 40]

They also pass surplus arguments to their return value:

$action = curry(function($action) { return "ldap_{$action}"; });
$action('bind', $connection, $dn, $password);

Some of Core's higher-order functions will automatically curry their arguments and results.

== Named Closures ==

PHP separates functions into those which are named (AKA 'global functions') and those which are anonymous (AKA 'Closure instances'):

function i_am_named($x) { return $x; }
$i_am_anonymous = function($x) { return $x; };

PHP allows named functions to be treated like anonymous functions:

$i_act_anonymously = 'i_am_named';

Core allows anonymous functions to be named:

defun('i_act_named', $i_am_anonymous);

== Extras ==

A few handy functions are provided too: