From: Jim Pryor Date: Sun, 3 Oct 2010 20:31:55 +0000 (-0400) Subject: week3 evaluator fix X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=5ed8a6c84fad085dfab0bb91621c5a887f8802ef week3 evaluator fix Signed-off-by: Jim Pryor --- diff --git a/assignment_3_evaluator.mdwn b/assignment_3_evaluator.mdwn index 9207c058..c0af5d01 100644 --- a/assignment_3_evaluator.mdwn +++ b/assignment_3_evaluator.mdwn @@ -13,10 +13,10 @@ let isempty = \x. x 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 - +; ; a list of numbers to experiment on let mylist = make\_list 1 (make\_list 2 (make\_list 3 empty)) in - +; ; church numerals let iszero = \n. n (\x. false) true in let succ = \n s z. s (n s z) in @@ -24,12 +24,12 @@ 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 - +; ; synonyms let makePair = make\_pair in let nil = empty in @@ -37,7 +37,7 @@ let isNil = isempty in let makeList = make\_list in let isZero = iszero in let mult = mul in - +; length (tail mylist)