at we will manipulate trees (binary or otherwise). For any type a, a binary tree over a is either empty or consists of a value of type a and exactly two sub-binary trees over a (either or both of which might be empty). Recall that we defined binary trees in HASKELL as follows: data BinTree a = Empty | Node a (BinTree a) (BinTree a) 1. For any type a, a tree over a consists of a root value of type a and a (finite, possibly empty) sequence of sub-trees over a. For example, the following is a pictorial representation of a tree over Integer; it has root value 2 and three sub-trees, the first and third of which have no sub-trees, and the second of which has two sub-trees: 5 7 8 9 A forest is then a set of trees. Define the HASKELL types Tree and Forest such that, for any type a, Tree a and Forest a are suitable for representing trees and forests over a, respectively.

at we will manipulate trees (binary or otherwise). For any type a, a binary tree over a is either empty or consists of a value of type a and exactly two sub-binary trees over a (either or both of which might be empty). Recall that we defined binary trees in HASKELL as follows: data BinTree a = Empty | Node a (BinTree a) (BinTree a) 1. For any type a, a tree over a consists of a root value of type a and a (finite, possibly empty) sequence of sub-trees over a. For example, the following is a pictorial representation of a tree over Integer; it has root value 2 and three sub-trees, the first and third of which have no sub-trees, and the second of which has two sub-trees: 5 7 8 9 A forest is then a set of trees. Define the HASKELL types Tree and Forest such that, for any type a, Tree a and Forest a are suitable for representing trees and forests over a, respectively.