RosettaCodeData/Task/Factorial/Lang/factorial-3.lang

fp.fact = ($n) -> {
	if($n < 0) {
		throw fn.withErrorMessage($LANG_ERROR_INVALID_ARGUMENTS, n must be >= 0)
	}
	
	return fn.arrayReduce(fn.arrayGenerateFrom(fn.inc, $n), 1L, fn.mul)
}