From 025eac26d8c2302ce9f5762662a3e7ca36206a09 Mon Sep 17 00:00:00 2001
From: Harry Garrood <harry@garrood.me>
Date: Mon, 8 Dec 2014 18:44:34 +0000
Subject: [PATCH 1/2] Add semigroup instance

---
 README.md         | 2 ++
 src/Data/Map.purs | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/README.md b/README.md
index e79be4f6..8ff0b8b9 100644
--- a/README.md
+++ b/README.md
@@ -15,6 +15,8 @@
 
     instance functorMap :: P.Functor (Map k)
 
+    instance semigroupMap :: (P.Ord k) => P.Semigroup (Map k v)
+
     instance showMap :: (P.Show k, P.Show v) => P.Show (Map k v)
 
     instance traversableMap :: (P.Ord k) => Traversable (Map k)
diff --git a/src/Data/Map.purs b/src/Data/Map.purs
index fd60efd4..b2ecc758 100644
--- a/src/Data/Map.purs
+++ b/src/Data/Map.purs
@@ -47,6 +47,9 @@ instance eqMap :: (P.Eq k, P.Eq v) => P.Eq (Map k v) where
 instance showMap :: (P.Show k, P.Show v) => P.Show (Map k v) where
   show m = "fromList " P.++ P.show (toList m)
 
+instance semigroupMap :: (P.Ord k) => P.Semigroup (Map k v) where
+  (<>) = union
+
 instance functorMap :: P.Functor (Map k) where
   (<$>) _ Leaf = Leaf
   (<$>) f (Two left k v right) = Two (f P.<$> left) k (f v) (f P.<$> right)

From 166e3a064e6c7218acb5920e292b7fedaf133155 Mon Sep 17 00:00:00 2001
From: Harry Garrood <harry@garrood.me>
Date: Mon, 8 Dec 2014 21:12:45 +0000
Subject: [PATCH 2/2] Add Monoid instance for Map k v

---
 README.md         | 2 ++
 src/Data/Map.purs | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/README.md b/README.md
index 8ff0b8b9..43f5ce35 100644
--- a/README.md
+++ b/README.md
@@ -15,6 +15,8 @@
 
     instance functorMap :: P.Functor (Map k)
 
+    instance monoidMap :: (P.Ord k) => Monoid (Map k v)
+
     instance semigroupMap :: (P.Ord k) => P.Semigroup (Map k v)
 
     instance showMap :: (P.Show k, P.Show v) => P.Show (Map k v)
diff --git a/src/Data/Map.purs b/src/Data/Map.purs
index b2ecc758..1a75b137 100644
--- a/src/Data/Map.purs
+++ b/src/Data/Map.purs
@@ -32,6 +32,7 @@ import qualified Prelude as P
 import qualified Data.Array as A
 import Data.Maybe
 import Data.Tuple
+import Data.Monoid (Monoid)
 import Data.Foldable (foldl, foldMap, foldr, Foldable)
 import Data.Traversable (traverse, Traversable)
 
@@ -50,6 +51,9 @@ instance showMap :: (P.Show k, P.Show v) => P.Show (Map k v) where
 instance semigroupMap :: (P.Ord k) => P.Semigroup (Map k v) where
   (<>) = union
 
+instance monoidMap :: (P.Ord k) => Monoid (Map k v) where
+  mempty = empty
+
 instance functorMap :: P.Functor (Map k) where
   (<$>) _ Leaf = Leaf
   (<$>) f (Two left k v right) = Two (f P.<$> left) k (f v) (f P.<$> right)