diff --git a/src/TypeChecker/TypeCheckerHm.hs b/src/TypeChecker/TypeCheckerHm.hs
index 1fc0ee4..9fe62a4 100644
--- a/src/TypeChecker/TypeCheckerHm.hs
+++ b/src/TypeChecker/TypeCheckerHm.hs
@@ -47,67 +47,6 @@ typecheck = onLeft msg . run . checkPrg
     onLeft f (Left x) = Left $ f x
     onLeft _ (Right x) = Right x
 
-checkData :: Data -> Infer ()
-checkData err@(Data typ injs) = do
-    (name, tvars) <- go typ
-    dataErr (mapM_ (\i -> typecheckInj i name tvars) injs) err
-  where
-    go = \case
-        TData name typs
-            | Right tvars' <- mapM toTVar typs ->
-                pure (name, tvars')
-        TAll _ _ -> uncatchableErr "Explicit foralls not allowed, for now"
-        _ -> uncatchableErr $ unwords ["Bad data type definition: ", printTree typ]
-
-typecheckInj :: Inj -> UIdent -> [TVar] -> Infer ()
-typecheckInj (Inj c inj_typ) name tvars
-    | Right False <- boundTVars tvars inj_typ =
-        catchableErr "Unbound type variables"
-    | TData name' typs <- returnType inj_typ
-    , Right tvars' <- mapM toTVar typs
-    , name' == name
-    , tvars' == tvars = do
-        exist <- existInj (coerce c)
-        case exist of
-            Just t -> uncatchableErr $ Aux.do
-                "Constructor"
-                quote $ coerce name
-                "with type"
-                quote $ printTree t
-                "already exist"
-            Nothing -> insertInj (coerce c) inj_typ
-    | otherwise =
-        uncatchableErr $
-            unwords
-                [ "Bad type constructor: "
-                , show name
-                , "\nExpected: "
-                , printTree . TData name $ map TVar tvars
-                , "\nActual: "
-                , printTree $ returnType inj_typ
-                ]
-  where
-    boundTVars :: [TVar] -> Type -> Either Error Bool
-    boundTVars tvars' = \case
-        TAll{} -> uncatchableErr "Explicit foralls not allowed, for now"
-        TFun t1 t2 -> do
-            t1' <- boundTVars tvars t1
-            t2' <- boundTVars tvars t2
-            return $ t1' && t2'
-        TVar tvar -> return $ tvar `elem` tvars'
-        TData _ typs -> and <$> mapM (boundTVars tvars) typs
-        TLit _ -> return True
-        TEVar _ -> error "TEVar in data type declaration"
-
-toTVar :: Type -> Either Error TVar
-toTVar = \case
-    TVar tvar -> pure tvar
-    _ -> uncatchableErr "Not a type variable"
-
-returnType :: Type -> Type
-returnType (TFun _ t2) = returnType t2
-returnType a = a
-
 checkPrg :: Program -> Infer (T.Program' Type)
 checkPrg (Program bs) = do
     preRun bs
@@ -172,39 +111,66 @@ checkBind (Bind name args e) = do
             insertSig (coerce name) (Just lambda_t)
             return (T.Bind (coerce name, lambda_t) [] (e, lambda_t))
 
-typeEq :: Type -> Type -> Bool
-typeEq (TFun l r) (TFun l' r') = typeEq l l' && typeEq r r'
-typeEq (TLit a) (TLit b) = a == b
-typeEq (TData name a) (TData name' b) =
-    length a == length b
-        && name == name'
-        && and (zipWith typeEq a b)
-typeEq (TAll _ t1) t2 = t1 `typeEq` t2
-typeEq t1 (TAll _ t2) = t1 `typeEq` t2
-typeEq (TVar _) (TVar _) = True
-typeEq _ _ = False
+checkData :: Data -> Infer ()
+checkData err@(Data typ injs) = do
+    (name, tvars) <- go typ
+    dataErr (mapM_ (\i -> checkInj i name tvars) injs) err
+  where
+    go = \case
+        TData name typs
+            | Right tvars' <- mapM toTVar typs ->
+                pure (name, tvars')
+        TAll _ _ -> uncatchableErr "Explicit foralls not allowed, for now"
+        _ -> uncatchableErr $ unwords ["Bad data type definition: ", printTree typ]
 
-skolemize :: Type -> Type
-skolemize (TVar (MkTVar a)) = TEVar (MkTEVar $ coerce a)
-skolemize (TAll x t) = TAll x (skolemize t)
-skolemize (TFun t1 t2) = (TFun `on` skolemize) t1 t2
-skolemize t = t
+checkInj :: Inj -> UIdent -> [TVar] -> Infer ()
+checkInj (Inj c inj_typ) name tvars
+    | Right False <- boundTVars tvars inj_typ =
+        catchableErr "Unbound type variables"
+    | TData name' typs <- returnType inj_typ
+    , Right tvars' <- mapM toTVar typs
+    , name' == name
+    , tvars' == tvars = do
+        exist <- existInj (coerce c)
+        case exist of
+            Just t -> uncatchableErr $ Aux.do
+                "Constructor"
+                quote $ coerce name
+                "with type"
+                quote $ printTree t
+                "already exist"
+            Nothing -> insertInj (coerce c) inj_typ
+    | otherwise =
+        uncatchableErr $
+            unwords
+                [ "Bad type constructor: "
+                , show name
+                , "\nExpected: "
+                , printTree . TData name $ map TVar tvars
+                , "\nActual: "
+                , printTree $ returnType inj_typ
+                ]
+  where
+    boundTVars :: [TVar] -> Type -> Either Error Bool
+    boundTVars tvars' = \case
+        TAll{} -> uncatchableErr "Explicit foralls not allowed, for now"
+        TFun t1 t2 -> do
+            t1' <- boundTVars tvars t1
+            t2' <- boundTVars tvars t2
+            return $ t1' && t2'
+        TVar tvar -> return $ tvar `elem` tvars'
+        TData _ typs -> and <$> mapM (boundTVars tvars) typs
+        TLit _ -> return True
+        TEVar _ -> error "TEVar in data type declaration"
 
-isMoreSpecificOrEq :: Type -> Type -> Bool
-isMoreSpecificOrEq t1 (TAll _ t2) = isMoreSpecificOrEq t1 t2
-isMoreSpecificOrEq (TFun a b) (TFun c d) =
-    isMoreSpecificOrEq a c && isMoreSpecificOrEq b d
-isMoreSpecificOrEq (TData n1 ts1) (TData n2 ts2) =
-    n1 == n2
-        && length ts1 == length ts2
-        && and (zipWith isMoreSpecificOrEq ts1 ts2)
-isMoreSpecificOrEq _ (TVar _) = True
-isMoreSpecificOrEq a b = a == b
+toTVar :: Type -> Either Error TVar
+toTVar = \case
+    TVar tvar -> pure tvar
+    _ -> uncatchableErr "Not a type variable"
 
-isPoly :: Type -> Bool
-isPoly (TAll _ _) = True
-isPoly (TVar _) = True
-isPoly _ = False
+returnType :: Type -> Type
+returnType (TFun _ t2) = returnType t2
+returnType a = a
 
 inferExp :: Exp -> Infer (T.ExpT' Type)
 inferExp e = do
@@ -724,6 +690,40 @@ unzip4 =
         )
         ([], [], [], [])
 
+-- typeEq :: Type -> Type -> Bool
+-- typeEq (TFun l r) (TFun l' r') = typeEq l l' && typeEq r r'
+-- typeEq (TLit a) (TLit b) = a == b
+-- typeEq (TData name a) (TData name' b) =
+--     length a == length b
+--         && name == name'
+--         && and (zipWith typeEq a b)
+-- typeEq (TAll _ t1) t2 = t1 `typeEq` t2
+-- typeEq t1 (TAll _ t2) = t1 `typeEq` t2
+-- typeEq (TVar _) (TVar _) = True
+-- typeEq _ _ = False
+
+-- skolemize :: Type -> Type
+-- skolemize (TVar (MkTVar a)) = TEVar (MkTEVar $ coerce a)
+-- skolemize (TAll x t) = TAll x (skolemize t)
+-- skolemize (TFun t1 t2) = (TFun `on` skolemize) t1 t2
+-- skolemize t = t
+
+-- isMoreSpecificOrEq :: Type -> Type -> Bool
+-- isMoreSpecificOrEq t1 (TAll _ t2) = isMoreSpecificOrEq t1 t2
+-- isMoreSpecificOrEq (TFun a b) (TFun c d) =
+--     isMoreSpecificOrEq a c && isMoreSpecificOrEq b d
+-- isMoreSpecificOrEq (TData n1 ts1) (TData n2 ts2) =
+--     n1 == n2
+--         && length ts1 == length ts2
+--         && and (zipWith isMoreSpecificOrEq ts1 ts2)
+-- isMoreSpecificOrEq _ (TVar _) = True
+-- isMoreSpecificOrEq a b = a == b
+
+-- isPoly :: Type -> Bool
+-- isPoly (TAll _ _) = True
+-- isPoly (TVar _) = True
+-- isPoly _ = False
+
 newtype Ctx = Ctx {vars :: Map T.Ident Type}
     deriving (Show)