在Ocaml的树中添加元素

Question

So, here is my problem.. I need to write a function that will add elements in a tree and it is a binary tree, so it must be well organized. The problem is in how is my tree defined. I have this tree:

type 'a tree = {
  mutable cont:'a;
  mutable left:'a bin_tree;
  mutable right:'a bin_tree
  }
  and 'a bin_tree = 
  Empty
  |Node of 'a bin_tree;;

So, when I write the function to add elements in this tree it says that the tree is of type 'a tree and I am using function for 'a bin_tree.

I tried a lot of different ways to write that function and I get the same error. The function I used last is:

let rec dodajVDrevo x = function
Empty -> Node{cont=x; left=Empty; right=Empty}
|Node{cont; left; right} -> if x < cont then Node{cont; left= dodajVDrevo x left; right}
else if x > cont then Node{cont; left; right = dodajVDrevo x right}
else Node{cont; left; right};;

Please help me and give some clues.

Thank you!

Answer 1

Node构造函数应采用'a tree而不是'a bin_tree 。