From: Jim Pryor Date: Sun, 3 Oct 2010 20:45:35 +0000 (-0400) Subject: more assignment3 name cleanup X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=6a60dbeb81ccc4949724a6db13a264a0b322a22d more assignment3 name cleanup Signed-off-by: Jim Pryor --- diff --git a/assignment3.mdwn b/assignment3.mdwn index 8c22dfa4..df06d526 100644 --- a/assignment3.mdwn +++ b/assignment3.mdwn @@ -14,32 +14,30 @@ Recall that version 1 style lists are constructed like this (see 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 diff --git a/assignment_3_evaluator.mdwn b/assignment_3_evaluator.mdwn index c0af5d01..496003d0 100644 --- a/assignment_3_evaluator.mdwn +++ b/assignment_3_evaluator.mdwn @@ -6,13 +6,13 @@ let true = \x y. x in 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 @@ -32,6 +32,8 @@ let length = Y (\length l. isempty l 0 (succ (length (tail l)))) 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