sequence :: [m a] -> m [a] like function for PHP array

combinations.php

<?php
function combinations()
{
    $xss = func_get_args();
    return array_reduce($xss, function($yss, $xs) {
        $zs = [];
        foreach ($yss as $ys) {
            foreach ($xs as $x) {
                $zs[] = array_merge($ys, array($x));
            }
        }
        return $zs;
    }, [[]]); 
}

$paramsSet = combinations(
    [1,2,3],
    ['http://www.example.com/', null],
    ['male', 'female', 'none']
);

foreach($paramsSet as $params) {
    list($a, $b, $c) = $params;
    echo "f($a, $b, $c)\n";
}

f(1, http://www.example.com/, male)
f(1, http://www.example.com/, female)
f(1, http://www.example.com/, none)
f(1, , male)
f(1, , female)
f(1, , none)
f(2, http://www.example.com/, male)
f(2, http://www.example.com/, female)
f(2, http://www.example.com/, none)
f(2, , male)
f(2, , female)
f(2, , none)
f(3, http://www.example.com/, male)
f(3, http://www.example.com/, female)
f(3, http://www.example.com/, none)
f(3, , male)
f(3, , female)
f(3, , none)

でもこれパターンが多いと遅延じゃなきゃ実用になんないね。。