ass10 hint tweaks

[lambda.git] / assignment3.mdwn

diff --git a/assignment3.mdwn b/assignment3.mdwn
index 4da627a..e240b73 100644 (file)
--- a/assignment3.mdwn
+++ b/assignment3.mdwn
@@ -10,9 +10,9 @@ originally read
        let tb = (make_list t12 t3) in
 
 This has been corrected below, and in the preloaded evaluator for 
        let tb = (make_list t12 t3) in
 
 This has been corrected below, and in the preloaded evaluator for 

-working on assignment 3.
-
+working on assignment 3, available here: [[assignment 3 evaluator]].

 
 

+<hr>

 
 Once again, the lambda evaluator will make working through this
 assignment much faster and more secure.
 
 Once again, the lambda evaluator will make working through this
 assignment much faster and more secure.


@@ -42,6 +42,7 @@ Recall that version 1 style lists are constructed like this (see
        ; church numerals
        let iszero = \n. n (\x. false) true in
        let succ = \n s z. s (n s z) in
        ; church numerals
        let iszero = \n. n (\x. false) true in
        let succ = \n s z. s (n s z) in

+       let add = \l r. l succ r in

        let mul = \m n s. m (n s) 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 mul = \m n s. m (n s) 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


@@ -50,6 +51,7 @@ Recall that version 1 style lists are constructed like this (see
        ; 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
        ; 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

+       let fold = Y (\f l g z. isempty l z (g (head l)(f (tail l) g z))) in

        
        eq 2 2 yes no
 
        
        eq 2 2 yes no