haskell: TH support and refactoring

haskell/test/UserData.hs

@@ -0,0 +1,19 @@
+{-# Language TemplateHaskell #-}
+
+import Data.MessagePack
+import Data.MessagePack.Derive
+
+data T
+  = A Int String
+  | B Double
+  deriving (Show)
+
+$(deriveObject ''T)
+
+main = do
+  let bs = pack $ A 123 "hoge"
+  print bs
+  print (unpack bs :: T)
+  let cs = pack $ B 3.14
+  print cs
+  print (unpack cs :: T)