Revised kind signatures

[ghc-hetmet.git] / compiler / parser / RdrHsSyn.lhs

diff --git a/compiler/parser/RdrHsSyn.lhs b/compiler/parser/RdrHsSyn.lhs
index 1867ce6..980c7f7 100644 (file)
--- a/compiler/parser/RdrHsSyn.lhs
+++ b/compiler/parser/RdrHsSyn.lhs
@@ -38,7 +38,7 @@ module RdrHsSyn (
        checkTyClHdr,         -- LHsContext RdrName -> LHsType RdrName -> P (LHsContext RdrName, Located RdrName, [LHsTyVarBndr RdrName], [LHsType RdrName])
        checkTyVars,          -- [LHsType RdrName] -> Bool -> P ()
        checkSynHdr,          -- LHsType RdrName -> P (Located RdrName, [LHsTyVarBndr RdrName], Maybe [LHsType RdrName])
-       checkTopTyClD,        -- LTyClDecl RdrName -> P (HsDecl RdrName)
+       checkTopTypeD,        -- LTyClDecl RdrName -> P (HsDecl RdrName)
        checkInstType,        -- HsType -> P HsType
        checkPattern,         -- HsExp -> P HsPat
        checkPatterns,        -- SrcLoc -> [HsExp] -> P [HsPat]
@@ -433,7 +433,7 @@ checkTyClHdr :: LHsContext RdrName -> LHsType RdrName
 -- result.  Eg, for
 --      T Int [a]
 -- we return
---      ('()', 'T', ['a'], Just ['Int', '[a]'])
+--      ('()', 'T', ['a'], ['Int', '[a]'])
 checkTyClHdr (L l cxt) ty
   = do (tc, tvs, parms) <- gol ty []
        mapM_ chk_pred cxt
@@ -506,16 +506,21 @@ extractTyVars tvs = collects [] tvs
                            tvs' <- collects tvs ts
                            collect tvs' t
 
--- Wrap a toplevel type or class declaration into 'TyClDecl' after ensuring
--- that all type parameters are variables only (which is in contrast to
--- associated type declarations).
+-- Wrap a toplevel type or data declaration into 'TyClD' and ensure for 
+-- data declarations that all type parameters are variables only (which is in
+-- contrast to type functions and associated type declarations).
 --
-checkTopTyClD :: LTyClDecl RdrName -> P (HsDecl RdrName)
-checkTopTyClD (L _ d@TyData {tcdTyPats = Just typats}) = 
+checkTopTypeD :: LTyClDecl RdrName -> P (HsDecl RdrName)
+checkTopTypeD (L _ d@TyData {tcdTyPats = Just typats}) = 
   do
+    -- `tcdTyPats' will only be of the form `Just typats' if `typats' contains
+    -- a non-variable pattern.  We call `checkTyPats' instead of raising an
+    -- error straight away, as `checkTyPats' raises the error at the location
+    -- of that non-variable pattern.
+    --
     checkTyVars typats False
-    return $ TyClD d {tcdTyPats = Nothing}
-checkTopTyClD (L _ d)                             = return $ TyClD d
+    panic "checkTopTypeD: check on previous line should fail w/ a parse error"
+checkTopTypeD (L _ d) = return $ TyClD d
 
 checkContext :: LHsType RdrName -> P (LHsContext RdrName)
 checkContext (L l t)