curry.php

<?php

function curry(\Closure $f)
{
    $a = [];
    $t = 'function($%s) use ($f, $a) { $a[] = $%s; return %s };';

    return eval('return '
        .array_reduce(
            array_reverse((new \ReflectionObject($f))->getMethod('__invoke')->getParameters()),
            function($i, $p) use ($t) { return sprintf($t, $p->name, $p->name, $i); },
            'call_user_func_array($f, $a);')
    );
}

function uncurry(\Closure $f)
{
    $getParams = function(\Closure $c) use (&$getParams) {
        $m = (new \ReflectionObject($c))->getMethod('__invoke');
        if ($m->getNumberOfParameters() === 1
            && $f = $m->invoke($c, null)
            and $f instanceof \Closure
        ) {
            return array_merge($m->getParameters(), $getParams($f));
        } else {
            return $m->getParameters();
        }
        
        
    };
    $params = $getParams($f);

    return eval(sprintf(
        'return function(%s) use ($f) { return $f%s; };',
        implode(', ', array_map(function($p) { return '$'.$p->getName(); }, $params)),
        array_reduce($params, function($i, $p) { return $i.'->__invoke($'.$p->getName().')'; }, '')
    ));
}

test1.php

<?php

$c = curry(function($x, $y) { return $x * $y; });
$u = uncurry($c);

// true
var_dump($c->__invoke(2)->__invoke(4) === $u(2, 4));

test2.php

<?php

$c = curry(function($w, $x, $y, $z) { return $w + $x + $y + $z; });
$u = uncurry($c);

// true
var_dump($c->__invoke(1)->__invoke(2)->__invoke(3)->__invoke(4) === $u(1, 2, 3, 4));