let false = \x y. y in
let and = \l r. l (r true false) false in
- ; version 1 lists
let make_pair = \f s g. g f s in
- let fst = true in
- let snd = false in
+ let get_fst = true in
+ let get_snd = false in
let empty = make_pair true junk in
- let isempty = \x. x fst in
+ let isempty = \x. x get_fst in
let make_list = \h t. make_pair false (make_pair h t) in
- let head = \l. isempty l err (l snd fst) in
- let tail = \l. isempty l err (l snd snd) in
-
+ let head = \l. isempty l err (l get_snd get_fst) in
+ let tail = \l. isempty l err (l get_snd get_snd) in
+
; a list of numbers to experiment on
let mylist = make_list 1 (make_list 2 (make_list 3 empty)) in
-
- ; a fixed-point combinator for defining recursive functions
- let Y = \f. (\h. f (h h)) (\h. f (h h)) in
-
+
; church numerals
let iszero = \n. n (\x. false) true in
let succ = \n s z. s (n s z) in
- let mult = \m n s. m (n s) in
- let length = Y (\length l. isempty l 0 (succ (length (tail l)))) in
- let pred = \n. iszero n 0 (length (tail (n (\p. make_list junk p) empty)))
- in
+ let mul = \m n s. m (n s) in
+ let pred = \n. iszero n 0 (length (tail (n (\p. make_list junk p) empty))) in
let leq = \m n. iszero(n pred m) in
let eq = \m n. and (leq m n)(leq n m) in
-
+
+ ; a fixed-point combinator for defining recursive functions
+ let Y = \f. (\h. f (h h)) (\h. f (h h)) in
+ let length = Y (\length l. isempty l 0 (succ (length (tail l)))) in
+
eq 2 2 yes no