<?php
/*
span :: (a -> Bool) -> [a] -> ([a],[a])
span _ xs@[] = (xs, xs)
span p xs@(x:xs')
| p x = let (ys,zs) = span p xs' in (x:ys,zs)
| otherwise = ([],xs)
*/
function span($p, $xs) {
if (empty($xs)) {
return [[], []];
}
$xs_ = $xs;
$x = array_shift($xs_);
if ($p($x)) {
list($ys, $zs) = span($p, $xs_);
return [array_unshift($ys, $x), $zs];
}
return [[], $xs];
}
/*
groupBy :: (a -> a -> Bool) -> [a] -> [[a]]
groupBy _ [] = []
groupBy eq (x:xs) = (x:ys) : groupBy eq zs
where (ys,zs) = span (eq x) xs
*/
function array_group(callable $eq, array $xs) {
if (empty($xs)) {
return [];
}
$x = array_shift($xs);
list($ys, $zs) = span($eq($x), $xs);
}
function it($m,$p){echo ($p?'✔︎':'✘')." It $m\n"; if(!$p){$GLOBALS['f']=1;}}function done(){if(@$GLOBALS['f'])die(1);}
it('spans elements', span(function ($x) { return $x < 2; }, [1, 2, 3]) === [[1, 2], [3]]);
preferences:
33.6 ms | 402 KiB | 5 Q