musique/examples/church.mq

-- PAIR definition
var pair = [x y | [z | z x y]];
var car = [p | p [x y | x]];
var cdr = [p | p [x y | y]];

var x = pair 100 200;
say (car x);
say (cdr x);

-- LIST definition
var null = pair true true;
var is_empty = car;
var head = [list | car (cdr list)];
var tail = [list | cdr (cdr list)];
var cons = [head tail | pair false (pair head tail)];

var for_each = [list iterator |
	if (is_empty list) [ nil ] [
		iterator (head list);
		for_each (tail list) iterator ]];

var map = [list iterator |
	if (is_empty list) [ null ] [|
		cons (iterator (head list)) (map (tail list) iterator) ]];

var foldr = [list init folder |
	if (is_empty list)
		[ init ]
		[ foldr (tail list) (folder (head list) init) folder ]];

var range = [start stop | if (start >= stop) [cons start null] [cons start (range (start+1) stop)]];

var xs = range 1 5;
say (foldr xs 1 [x y|x*y]);