X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=assignment3.mdwn;h=e91eeee58765ddf36d5f331b42de2d8e6ee84c5e;hp=568a5c5310808d9a62cabd368721898cbda3c5aa;hb=4b32ef1b335f61cabb654b2e5c91ba3611b42650;hpb=63896de25bdcf571e788507695448675dc395ecc diff --git a/assignment3.mdwn b/assignment3.mdwn index 568a5c53..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]]] @@ -111,24 +111,24 @@ trees. Expected behavior:
```-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
```
-2. Write a function that counts the number of leaves.# +2. Write a function that counts the number of leaves.