diff --git a/hs2ats.cabal b/hs2ats.cabal
--- a/hs2ats.cabal
+++ b/hs2ats.cabal
@@ -1,5 +1,5 @@
 name:                hs2ats
-version:             0.2.1.2
+version:             0.2.1.3
 synopsis:            Create ATS types from Haskell types
 description:         This package enables scanning Haskell source files for data types and then generating [ATS](http://www.ats-lang.org/) types from them.
 homepage:            https://github.com/vmchale/hs2ats#readme
diff --git a/src/Language/ATS/Generate.hs b/src/Language/ATS/Generate.hs
--- a/src/Language/ATS/Generate.hs
+++ b/src/Language/ATS/Generate.hs
@@ -17,7 +17,7 @@
 import           Control.Lens                 (over, _head)
 import           Data.Char                    (toUpper)
 import           Data.Either                  (lefts, rights)
-import           Data.Maybe                   (fromJust)
+import           Data.Maybe
 import qualified Data.Text                    as T
 import           Language.ATS                 as ATS
 import           Language.ATS.Generate.Error
@@ -52,17 +52,18 @@
 stringTypeConv "CString" = Right "Strptr1"
 stringTypeConv "Word"    = Right "uint"
 stringTypeConv "CUInt"   = Right "uint"
+stringTypeConv "Int"     = Right "int"
+stringTypeConv "CInt"    = Right "int"
+stringTypeConv "Float"   = Right "float"
+stringTypeConv "CFloat"  = Right "float"
+stringTypeConv "Double"  = Right "double"
+stringTypeConv "Bool"    = Right "bool"
+stringTypeConv "CBool"   = Right "bool"
 stringTypeConv _         = unsupported "stringTypeConv"
 
 toStringATS' :: QName a -> ErrM ATS.Type
-toStringATS' (QNamed _ _ "Int")    = Right ATS.Int
-toStringATS' (QNamed _ _ "CInt")   = Right ATS.Int
-toStringATS' (QNamed _ _ "Float")  = Right ATS.Float
-toStringATS' (QNamed _ _ "CFloat") = Right ATS.Float
-toStringATS' (QNamed _ _ "Bool")   = Right ATS.Bool
-toStringATS' (QNamed _ _ "CBool")  = Right ATS.Bool
-toStringATS' (QNamed _ _ s)        = Named . Unqualified <$> stringTypeConv s
-toStringATS' _                     = unsupported "toStringATS'"
+toStringATS' (QNamed _ _ s) = Named . Unqualified <$> stringTypeConv s
+toStringATS' _              = unsupported "toStringATS'"
 
 typeToType :: HS.Type a -> ErrM ATS.Type
 typeToType (TyCon _ qn)                       = toStringATS' qn
@@ -89,15 +90,15 @@
 toStringATS (Ident _ s) = s
 toStringATS _           = undefined
 
-tyvarToArg :: Bool -> TyVarBind a -> ErrM Arg
-tyvarToArg False (UnkindedVar _ n) = Right $ Arg (Both (toStringATS n) (Vt0p None))
-tyvarToArg True (UnkindedVar _ n)  = Right $ Arg (Both (toStringATS n) (Vt0p Plus))
+tyvarToArg :: Bool -> TyVarBind a -> ErrM SortArg
+tyvarToArg False (UnkindedVar _ n) = Right $ SortArg (toStringATS n) (Vt0p None)
+tyvarToArg True (UnkindedVar _ n)  = Right $ SortArg (toStringATS n) (Vt0p Plus)
 tyvarToArg _ _                     = unsupported "tyvarToArg"
 
 consM :: (Monad m) => m a -> m [a] -> m [a]
 consM x xs = (:) <$> x <*> xs
 
-asATSName :: DeclHead a -> ErrM (String, [Arg])
+asATSName :: DeclHead a -> ErrM (String, [SortArg])
 asATSName (DHead _ n)    = Right (convertConventions $ toStringATS n, [])
 asATSName (DHParen _ d)  = (,) . fst <$> asATSName d <*> pure []
 asATSName (DHApp _ d tb) = (,) . fst <$> asATSName d <*> consM (tyvarToArg False tb) (snd <$> asATSName d)
@@ -111,16 +112,16 @@
 qualConDeclToLeaf (EmptyQualCon _ cd) = Leaf [] <$> (over _head toUpper . convertConventions . fst <$> conDeclToType cd) <*> pure [] <*> (snd <$> conDeclToType cd)
 qualConDeclToLeaf _                   = unsupported "qualConDeclToLeaf"
 
-addNils :: [Arg] -> [Arg]
-addNils [] = [NoArgs]
-addNils x  = x
+pruneATSNils :: [SortArg] -> Maybe [SortArg]
+pruneATSNils [] = Nothing
+pruneATSNils x  = Just x
 
 -- TODO if it derives functor, use +
 asATSType :: Decl a -> ErrM Declaration
-asATSType (TypeDecl _ dh t) = ViewTypeDef undefined <$> (fst <$> asATSName dh) <*> (addNils . snd <$> asATSName dh) <*> typeToType t
-asATSType (DataDecl _ NewType{} _ dh [qcd] _)  = ViewTypeDef undefined <$> (fst <$> asATSName dh) <*> (addNils . snd <$> asATSName dh) <*> qualConDeclToType qcd
-asATSType (DataDecl _ DataType{} _ dh [qcd] _) = ViewTypeDef undefined <$> (fst <$> asATSName dh) <*> (addNils . snd <$> asATSName dh) <*> qualConDeclToType qcd
-asATSType (DataDecl _ DataType{} _ dh qcds _)  = SumViewType <$> (fst <$> asATSName dh) <*> (addNils . snd <$> asATSName dh) <*> mapM qualConDeclToLeaf (reverse qcds)
+asATSType (TypeDecl _ dh t) = ViewTypeDef undefined <$> (fst <$> asATSName dh) <*> (pruneATSNils . snd <$> asATSName dh) <*> typeToType t
+asATSType (DataDecl _ NewType{} _ dh [qcd] _)  = ViewTypeDef undefined <$> (fst <$> asATSName dh) <*> (pruneATSNils . snd <$> asATSName dh) <*> qualConDeclToType qcd
+asATSType (DataDecl _ DataType{} _ dh [qcd] _) = ViewTypeDef undefined <$> (fst <$> asATSName dh) <*> (pruneATSNils . snd <$> asATSName dh) <*> qualConDeclToType qcd
+asATSType (DataDecl _ DataType{} _ dh qcds _)  = SumViewType <$> (fst <$> asATSName dh) <*> (pruneATSNils . snd <$> asATSName dh) <*> mapM qualConDeclToLeaf (reverse qcds)
 asATSType _                                    = unsupported "asATSType"
 
 -- TODO GDataDecl and DataFamDecl