From 6774213fcdb93f9c85847a91f78b3ad3bc8884c3 Mon Sep 17 00:00:00 2001
From: Rob Rix <rob.rix@github.com>
Date: Wed, 14 Oct 2015 10:09:38 -0400
Subject: [PATCH] Cofree is a Functor.

---
 prototype/Doubt/Cofree.swift | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/prototype/Doubt/Cofree.swift b/prototype/Doubt/Cofree.swift
index 33288bc9b..ff6d9aaab 100644
--- a/prototype/Doubt/Cofree.swift
+++ b/prototype/Doubt/Cofree.swift
@@ -12,6 +12,15 @@ public enum Cofree<A, B> {
 }
 
 
+// MARK: - Functor
+
+extension Cofree {
+	public func map<Other>(transform: B -> Other) -> Cofree<A, Other> {
+		return .Unroll(transform(extract), unwrap.map { $0.map(transform) })
+	}
+}
+
+
 // MARK: - Comonad
 
 extension Cofree {