X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=assignment3.mdwn;h=e91eeee58765ddf36d5f331b42de2d8e6ee84c5e;hp=c7c5be41755bf6c0f28e7ca860474d53884e0489;hb=cbb48495bd8cd6cdcbebd1bcd8c3051148c8b0a6;hpb=34983e83fd449a9856d571ddf4f5290ab6a25bad

diff --git a/assignment3.mdwn b/assignment3.mdwn
index c7c5be41..e91eeee5 100644
--- a/assignment3.mdwn
+++ b/assignment3.mdwn
@@ -70,7 +70,7 @@ same length.  That is,
 5. In assignment 2, we discovered that version 3-type lists (the ones that
 work like Church numerals) made it much easier to define operations
 like `map` and `filter`.  But now that we have recursion in our toolbox,
-reasonable map and filter functions for version 3 lists are within our
+reasonable map and filter functions for version 1 lists are within our
 reach.  Give definitions for `map` and a `filter` for verson 1 type lists.
 
 #Computing with trees#
@@ -89,7 +89,7 @@ Then we have the following representations:
    (a)           (b)             (c)  
     .
    /|\            /\              /\
-  / | \          /\ 3             1/\
+  / | \          /\ 3            1 /\
   1 2  3        1  2               2 3
 
 [[1];[2];[3]]  [[[1];[2]];[3]]   [[1];[[2];[3]]]
@@ -111,23 +111,23 @@ trees.
 Expected behavior:
 
 <pre>
-let t1 = (make-list 1 nil) in
-let t2 = (make-list 2 nil) in
-let t3 = (make-list 3 nil) in
-let t12 = (make-list t1 (make-list t2 nil)) in
-let t23 = (make-list t2 (make-list t3 nil)) in
-let ta = (make-list t1 t23) in
-let tb = (make-list t12 t3) in
-let tc = (make-list t1 (make-list t23 nil)) in
-
-count-leaves t1 ~~> 1
-count-leaves t2 ~~> 2
-count-leaves t3 ~~> 3
-count-leaves t12 ~~> 3
-count-leaves t23 ~~> 5
-count-leaves ta ~~> 6
-count-leaves tb ~~> 6
-count-leaves tc ~~> 6
+let t1 = (makeList 1 nil) in
+let t2 = (makeList 2 nil) in
+let t3 = (makeList 3 nil) in
+let t12 = (makeList t1 (makeList t2 nil)) in
+let t23 = (makeList t2 (makeList t3 nil)) in
+let ta = (makeList t1 t23) in
+let tb = (makeList t12 t3) in
+let tc = (makeList t1 (makeList t23 nil)) in
+
+sum-leaves t1 ~~> 1
+sum-leaves t2 ~~> 2
+sum-leaves t3 ~~> 3
+sum-leaves t12 ~~> 3
+sum-leaves t23 ~~> 5
+sum-leaves ta ~~> 6
+sum-leaves tb ~~> 6
+sum-leaves tc ~~> 6
 </pre>
 
 2.   Write a function that counts the number of leaves.