$iterable * @param (Closure(Ts, Tk, Tv): Ts) $function * @param Ts $initial * * @return list */ function reductions(iterable $iterable, Closure $function, $initial): array { $accumulators = []; $accumulator = $initial; foreach ($iterable as $k => $v) { $accumulator = $function($accumulator, $k, $v); $accumulators[] = $accumulator; } return $accumulators; }