Once again, the lambda evaluator will make working through this
assignment much faster and more secure.
-*Writing recursive functions on version 1 style lists*
+##Writing recursive functions on version 1 style lists##
Recall that version 1 style lists are constructed like this:
Then `length mylist` evaluates to 3.
-1. What does `head (tail (tail mylist))` evaluate to?
+1. Warm-up: What does `head (tail (tail mylist))` evaluate to?
2. Using the `length` function as a model, and using the predecessor
function, write a function that computes factorials. (Recall that n!,
same length. That is,
listLenEq mylist (makeList meh (makeList meh (makeList meh nil))) ~~> true
+
listLenEq mylist (makeList meh (makeList meh nil))) ~~> false
+4. Now write the same function, but don't use the length function (hint: use `leq` as a model).
+
+##Trees##
+
+Since we'll be working with linguistic objects, let's approximate
+trees as follows: a tree is a version 1 list
+a Church number is a tree, and
+if A and B are trees, then (make-pair A B) is a tree.
+
-4. Now write the same function (true iff two lists have the same
-length) but don't use the length function (hint: use `leq` as a model).
- That is, (makeList 1 (makeList 2 (makeList 3 nil)))
[The following should be correct, but won't run in my browser: