Fix scoped type variables for expression type signatures

[ghc-hetmet.git] / compiler / basicTypes / DataCon.lhs

diff --git a/compiler/basicTypes/DataCon.lhs b/compiler/basicTypes/DataCon.lhs
index a04f28f..3450602 100644 (file)
--- a/compiler/basicTypes/DataCon.lhs
+++ b/compiler/basicTypes/DataCon.lhs
@@ -11,7 +11,6 @@ module DataCon (
        dataConRepType, dataConSig, dataConFullSig,
        dataConName, dataConTag, dataConTyCon, dataConUserType,
        dataConUnivTyVars, dataConExTyVars, dataConAllTyVars, dataConResTys,
-       dataConInstTys,
        dataConEqSpec, eqSpecPreds, dataConTheta, dataConStupidTheta, 
        dataConInstArgTys, dataConOrigArgTys, 
        dataConInstOrigArgTys, dataConRepArgTys, 
@@ -34,22 +33,21 @@ import Type         ( Type, ThetaType,
                          substTyWith, substTyVar, mkTopTvSubst, 
                          mkForAllTys, mkFunTys, mkTyConApp, mkTyVarTy, mkTyVarTys, 
                          splitTyConApp_maybe, newTyConInstRhs, 
-                         mkPredTys, isStrictPred, pprType, mkPredTy
+                         mkPredTys, isStrictPred, pprType
                        )
 import Coercion                ( isEqPred, mkEqPred )
 import TyCon           ( TyCon, FieldLabel, tyConDataCons, 
                          isProductTyCon, isTupleTyCon, isUnboxedTupleTyCon,
-                          isNewTyCon, isRecursiveTyCon, tyConFamily_maybe )
+                          isNewTyCon, isClosedNewTyCon, isRecursiveTyCon,
+                          tyConFamInst_maybe )
 import Class           ( Class, classTyCon )
-import Name            ( Name, NamedThing(..), nameUnique, mkSysTvName, mkSystemName )
-import Var             ( TyVar, CoVar, Id, mkTyVar, tyVarKind, setVarUnique,
-                          mkCoVar )
+import Name            ( Name, NamedThing(..), nameUnique )
+import Var             ( TyVar, Id )
 import BasicTypes      ( Arity, StrictnessMark(..) )
 import Outputable
 import Unique          ( Unique, Uniquable(..) )
 import ListSetOps      ( assoc, minusList )
 import Util            ( zipEqual, zipWithEqual )
-import List            ( partition )
 import Maybes           ( expectJust )
 import FastString
 \end{code}
@@ -336,13 +334,9 @@ data DataCon
        -- An entirely separate wrapper function is built in TcTyDecls
        dcIds :: DataConIds,
 
-       dcInfix :: Bool,        -- True <=> declared infix
+       dcInfix :: Bool         -- True <=> declared infix
                                -- Used for Template Haskell and 'deriving' only
                                -- The actual fixity is stored elsewhere
-
-        dcInstTys :: Maybe [Type]  -- If this data constructor is part of a
-                                  -- data instance, then these are the type
-                                  -- patterns of the instance.
   }
 
 data DataConIds
@@ -438,7 +432,6 @@ mkDataCon :: Name
          -> [TyVar] -> [TyVar] 
          -> [(TyVar,Type)] -> ThetaType
          -> [Type] -> TyCon
-         -> Maybe [Type]
          -> ThetaType -> DataConIds
          -> DataCon
   -- Can get the tag from the TyCon
@@ -449,17 +442,22 @@ mkDataCon name declared_infix
          univ_tvs ex_tvs 
          eq_spec theta
          orig_arg_tys tycon
-         mb_typats
          stupid_theta ids
+-- Warning: mkDataCon is not a good place to check invariants. 
+-- If the programmer writes the wrong result type in the decl, thus:
+--     data T a where { MkT :: S }
+-- then it's possible that the univ_tvs may hit an assertion failure
+-- if you pull on univ_tvs.  This case is checked by checkValidDataCon,
+-- so the error is detected properly... it's just that asaertions here
+-- are a little dodgy.
+
   = ASSERT( not (any isEqPred theta) )
        -- We don't currently allow any equality predicates on
        -- a data constructor (apart from the GADT ones in eq_spec)
     con
   where
     is_vanilla = null ex_tvs && null eq_spec && null theta
-    con = ASSERT( is_vanilla || not (isNewTyCon tycon) )
-               -- Invariant: newtypes have a vanilla data-con
-         MkData {dcName = name, dcUnique = nameUnique name, 
+    con = MkData {dcName = name, dcUnique = nameUnique name, 
                  dcVanilla = is_vanilla, dcInfix = declared_infix,
                  dcUnivTyVars = univ_tvs, dcExTyVars = ex_tvs, 
                  dcEqSpec = eq_spec, 
@@ -469,8 +467,7 @@ mkDataCon name declared_infix
                  dcStrictMarks = arg_stricts, 
                  dcRepStrictness = rep_arg_stricts,
                  dcFields = fields, dcTag = tag, dcRepType = ty,
-                 dcIds = ids,
-                 dcInstTys = mb_typats }
+                 dcIds = ids }
 
        -- Strictness marks for source-args
        --      *after unboxing choices*, 
@@ -609,9 +606,6 @@ dataConResTys dc = [substTyVar env tv | tv <- dcUnivTyVars dc]
   where
     env = mkTopTvSubst (dcEqSpec dc)
 
-dataConInstTys :: DataCon -> Maybe [Type]
-dataConInstTys = dcInstTys
-
 dataConUserType :: DataCon -> Type
 -- The user-declared type of the data constructor
 -- in the nice-to-read form 
@@ -623,18 +617,13 @@ dataConUserType :: DataCon -> Type
 dataConUserType  (MkData { dcUnivTyVars = univ_tvs, 
                           dcExTyVars = ex_tvs, dcEqSpec = eq_spec,
                           dcTheta = theta, dcOrigArgTys = arg_tys,
-                          dcTyCon = tycon, dcInstTys = mb_insttys })
+                          dcTyCon = tycon })
   = mkForAllTys ((univ_tvs `minusList` map fst eq_spec) ++ ex_tvs) $
     mkFunTys (mkPredTys theta) $
     mkFunTys arg_tys $
-    case mb_insttys of
-      Nothing      -> mkTyConApp tycon (map (substTyVar subst) univ_tvs)
-      Just insttys -> mkTyConApp ftycon insttys            -- data instance
-        where
-         ftycon = case tyConFamily_maybe tycon of
-                    Just ftycon -> ftycon
-                    Nothing     -> panic err
-          err    = "dataConUserType: type patterns without family tycon"
+    case tyConFamInst_maybe tycon of
+      Nothing             -> mkTyConApp tycon (map (substTyVar subst) univ_tvs)
+      Just (ftc, insttys) -> mkTyConApp ftc insttys        -- data instance
   where
     subst = mkTopTvSubst eq_spec
 
@@ -743,9 +732,10 @@ splitProductType str ty
 deepSplitProductType_maybe ty
   = do { (res@(tycon, tycon_args, _, _)) <- splitProductType_maybe ty
        ; let {result 
-             | isNewTyCon tycon && not (isRecursiveTyCon tycon)
+             | isClosedNewTyCon tycon && not (isRecursiveTyCon tycon)
              = deepSplitProductType_maybe (newTyConInstRhs tycon tycon_args)
-             | isNewTyCon tycon = Nothing  -- cannot unbox through recursive newtypes
+             | isNewTyCon tycon = Nothing  -- cannot unbox through recursive
+                                          -- newtypes nor through families
              | otherwise = Just res}
        ; result
        }
@@ -767,6 +757,6 @@ computeRep stricts tys
     unbox MarkedStrict    ty = [(MarkedStrict,    ty)]
     unbox MarkedUnboxed   ty = zipEqual "computeRep" (dataConRepStrictness arg_dc) arg_tys
                                where
-                                 (tycon, tycon_args, arg_dc, arg_tys) 
+                                 (_tycon, _tycon_args, arg_dc, arg_tys) 
                                      = deepSplitProductType "unbox_strict_arg_ty" ty
 \end{code}