(* Standard prelude	*)

let I x = x ;;			(* identity			*)
let A f = I o f ;;		(* P->A functor			*)
let T f x = /f x ;;		(* raising A->P for 1-arg functions *)
let T2 f x y = /f x y ;;	(* -- for 1-2-arg functions	*)

let rec it_list *f = \ [] 		(* list iterator *)
	| [h|t]; f h; it_list f:f t ;;
let rec list_it *f = \ []		(* reverse order *)
	| [h|t]; list_it f:f t; f h ;;
let rec fold *f = \ [] ; /[]
	| [h|t] ; f h; \x ; fold f:f t ; T(cons x) ;;
let rec map *f = \ []; [] | [h|t]; (f h)::map f:f t ;;
let rec while *do *end = end;			
	\ ok:false | ok:true; do ; while do:do end:end ;;
let rec repeat *f = \ 0 | n; f; repeat f:f (n-1);;

let length = A(it_list f:(\_;T(add 1)) 2:0) ;;
let rec append = \ [] ; I | [h|t], l ; h::append t l;;
let rec combine = \ [], [] ; [] | [h|t], [h'|t'] ; <h,h'>::combine t t' ;;