Problem 4.

Please Code in language Ocaml: and complete (b) at the bottom

For the three next problems you will deal with the data type of polymorphic binary trees. The solution to each part is meant to be very short (one to four lines). You may (and should) use functions from earlier parts to solve later parts. Unless otherwise specified, your solutions may utilize functions from the standard OCaml library.

Define a polymorphic data type called a binTree as follows:

type a binTree =

| Leaf

| Node of a * (a binTree) * (a binTree)

Trees of this type will contain a single piece of data of type a at each node, and no data at their leaves.

(b) Define an OCaml function foldT : (a -> b -> b -> b) -> a binTree -> b -> b which operates on trees the same way that foldr operates on lists. In other words, the base item of type b should replace the leaf constructor in the tree, and the function of type a -> b -> b -> b should replace the node constructor in the tree.

starter code:

type 'a binTree = | Leaf | Node of 'a * ('a binTree) * ('a binTree)

let rec foldT (f: 'a -> 'b -> 'b -> 'b) (t: 'a binTree) (base: 'b) : 'b = (* your work here *) base