let false = \x y. y in
let and = \l r. l (r true false) false in
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
let iszero = \n. n (\x. false) true in
let succ = \n s z. s (n s z) 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 pred = (\shift n. n shift (make\_pair 0 0) get\_snd) (\p. p (\x y. make\_pair (succ x) x)) in
let leq = \m n. iszero(n pred m) in
let eq = \m n. and (leq m n)(leq n m) in
;
;
; synonyms
let makePair = make\_pair in
+let fst = get\_fst in
+let snd = get\_snd in
let nil = empty in
let isNil = isempty in
let makeList = make\_list in