Swift Functional Programming - Second Edition

Size

To make this BST a little more complete, let's implement a property to check for its size:

var size: Int {     switch self {     case .leaf:         return 0     case .node(let lhs, _, let rhs):         return 1 + lhs.size + rhs.size     } } 

This computed property is going to provide the size of the BST, and we can use it as follows:

print(functionalBST.size) // prints "3"