Fix bug that type declarations weren't syntax checked

CHANGELOG.md

@@ -13,6 +13,7 @@ Under development (0.4.1)
   * Consider parenthesized type expressions in the Curry AST (by Katharina Rahf)
   * Added syntax extension `ExistentialQuantification` that allows the use
     of existentially quantified types in data and newtype constructors
+  * Fixed bug that type declarations weren't syntax checked
 
 Version 0.4.0
 =============

src/Checks/SyntaxCheck.hs

@@ -331,10 +331,10 @@ checkModule :: Module -> SCM (Module, [KnownExtension])
 checkModule (Module ps m es is ds) = do
   mapM_ checkPragma ps
   mapM_ bindTypeDecl tds
-  ds' <- (tds ++) <$> checkTopDecls vds
+  ds' <- checkTopDecls ds
   exts <- getExtensions
   return (Module ps m es is ds', exts)
-  where (tds, vds) = partition isTypeDecl ds
+  where tds = filter isTypeDecl ds
 
 checkPragma :: ModulePragma -> SCM ()
 checkPragma (LanguagePragma _ exts) = mapM_ checkExtension exts