From: Jim Pryor Date: Sun, 3 Oct 2010 20:27:34 +0000 (-0400) Subject: week3 evaluator fix X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=ca367b32e54d5816fcea12dd590a76306901d1ae week3 evaluator fix Signed-off-by: Jim Pryor --- diff --git a/assignment_3_evaluator.mdwn b/assignment_3_evaluator.mdwn index 64bebb58..35b012e6 100644 --- a/assignment_3_evaluator.mdwn +++ b/assignment_3_evaluator.mdwn @@ -14,10 +14,10 @@ monospace; height: 3in; overflow: auto; padding: 0.5em; width: 100%;"> 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 @@ -25,12 +25,12 @@ monospace; height: 3in; overflow: auto; padding: 0.5em; width: 100%;"> 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 @@ -38,7 +38,7 @@ monospace; height: 3in; overflow: auto; padding: 0.5em; width: 100%;"> let makeList = make_list in let isZero = iszero in let mult = mul in - + length (tail mylist)