php curry lambda closures functional

curry.php

<?php
function curry($fn)
{
    if (is_callable($fn)) {

        $fargc = count((new ReflectionFunction($fn))->getParameters());

        return $c = function (...$argv) use (&$c, $fn, $fargc) {

            if (count($argv) >= $fargc) {
                return $fn(...$argv);
            }

            return function (...$argv2) use (&$c, $argv) {
                return $c(...array_merge($argv, $argv2));
            };
        };
    }

    return false;
}

$sum = curry(function ($x, $y, $z) {
    echo $x + $y + $z, "\n";
    return true;
});
// $sum = curry(function () {
//     echo 'xx';
// });
echo memory_get_usage()," ";
echo memory_get_peak_usage()," ";
echo memory_get_usage(true)," ";
echo memory_get_peak_usage(true),"\n";

$sum(1, 2, 3);
$sum(1,2)(3);
$sum(1)(2, 3);
$sum(1, 2, 3, 4, 7);
$sum()()(1,2)()(3);
$sum(1)()()(2, 3);


echo memory_get_usage()," ";
echo memory_get_peak_usage()," ";
echo memory_get_usage(true)," ";
echo memory_get_peak_usage(true),"\n";

消除尾递归.md

function factorial($n, $accumulator = 1) {
    if ($n == 0) {
        return $accumulator;
    }

    return function() use($n, $accumulator) {
        return factorial($n - 1, $accumulator * $n);
    };
}

function trampoline($callback, $params) {
    $result = call_user_func_array($callback, $params);

    while (is_callable($result)) {
        $result = $result();
    }

    return $result;
}

var_dump(trampoline('factorial', array(100)));

引用自 http://n3xtchen.github.io/n3xtchen/2015/04/26/php-functional-programming