musique/examples/church.mq

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-- 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]);