2 files changed, 19 insertions, 0 deletions
diff --git a/Haskell-book/15/orphan-instance/Listy.hs b/Haskell-book/15/orphan-instance/Listy.hs
new file mode 100644
index 0000000..c99720a
--- /dev/null
+++ b/Haskell-book/15/orphan-instance/Listy.hs
@@ -0,0 +1,10 @@
+module Listy where
+
+newtype Listy a =
+    Listy [a]
+    deriving (Eq, Show)
+
+instance Monoid (Listy a) where
+    mempty = Listy []
+    mappend (Listy l) (Listy l') =
+        Listy $ mappend l l'
diff --git a/Haskell-book/15/orphan-instance/ListyInstances.hs b/Haskell-book/15/orphan-instance/ListyInstances.hs
new file mode 100644
index 0000000..39f7210
--- /dev/null
+++ b/Haskell-book/15/orphan-instance/ListyInstances.hs
@@ -0,0 +1,9 @@
+module ListyInstances where
+
+import Data.Monoid
+import Listy
+
+instance Monoid (Listy a) where
+    mempty = Listy []
+    mappend (Listy l) (Listy l') =
+        Listy $ mappend l l'