musique/examples/church.mq

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

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

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

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

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

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

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

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