Grain

module BinaryTree

enum Tree<a> {
  Empty,
  Node(a, Tree<a>, Tree<a>)
}

let rec insert = (value, tree) => {
  match (tree) {
    Empty => Node(value, Empty, Empty),
    Node(val, left, right) => {
      if (value < val) {
        Node(val, insert(value, left), right)
      } else if (value > val) {
        Node(val, left, insert(value, right))
      } else {
        tree
      }
    }
  }
}

let rec contains = (value, tree) => {
  match (tree) {
    Empty => false,
    Node(val, left, right) => {
      if (value == val) {
        true
      } else if (value < val) {
        contains(value, left)
      } else {
        contains(value, right)
      }
    }
  }
}