//  Copyright (c) 2015 Rob Rix. All rights reserved.

/// A binary tree with leaves of type `T`.
public enum BinaryTree<T> {
	// MARK: Constructors

	/// Constructs an empty instance.
	public init() {
		self = Nil
	}


	case Branch(Box<BinaryTree>?, Box<T>, Box<BinaryTree>?)
	case Nil
}


import Box

//  Copyright (c) 2015 Rob Rix. All rights reserved.

/// A binary tree with leaves of type `T`.
public enum BinaryTree<T> {
	case Branch(Box<BinaryTree>?, Box<T>, Box<BinaryTree>?)
	case Nil
}


import Box

--- 
+++ 
@@ -2,6 +2,14 @@
 
 /// A binary tree with leaves of type `T`.
 public enum BinaryTree<T> {
+	// MARK: Constructors
+
+	/// Constructs an empty instance.
+	public init() {
+		self = Nil
+	}
+
+
 	case Branch(Box<BinaryTree>?, Box<T>, Box<BinaryTree>?)
 	case Nil
 }
Add a constructor for the nil case.
