Fix family instance bug due to the name parent elimination

[ghc-hetmet.git] / compiler / types / TyCon.lhs

diff --git a/compiler/types/TyCon.lhs b/compiler/types/TyCon.lhs
index eb0474b..2e7427c 100644 (file)
--- a/compiler/types/TyCon.lhs
+++ b/compiler/types/TyCon.lhs
@@ -13,7 +13,7 @@ module TyCon(
        tyConPrimRep,
 
        AlgTyConRhs(..), visibleDataCons, 
-        AlgTyConParent(..), hasParent,
+        AlgTyConParent(..), 
        SynTyConRhs(..),
 
        isFunTyCon, isUnLiftedTyCon, isProductTyCon, 
@@ -114,6 +114,8 @@ data TyCon
                                        -- argument list (starting from 0).
                                        -- NB: Length is less than tyConArity
                                        --     if higher kind signature.
+                                       -- NB: Just _ <=> associated (not
+                                       --                toplevel) family
        
        algTcSelIds :: [Id],            -- Its record selectors (empty if none)
 
@@ -279,10 +281,6 @@ data AlgTyConParent = -- An ordinary type constructor has no parent.
                                                -- the representation type
                                                -- with the type instance
 
-hasParent :: AlgTyConParent -> Bool
-hasParent NoParentTyCon = False
-hasParent _other        = True
-
 data SynTyConRhs
   = OpenSynTyCon Kind  -- Type family: *result* kind given
   | SynonymTyCon Type   -- Mentioning head type vars.  Acts as a template for
@@ -674,11 +672,24 @@ isCoercionTyCon :: TyCon -> Bool
 isCoercionTyCon (CoercionTyCon {}) = True
 isCoercionTyCon other              = False
 
+-- Identifies implicit tycons that, in particular, do not go into interface
+-- files (because they are implicitly reconstructed when the interface is
+-- read).
+--
+-- Note that 
+--
+-- * associated families are implicit, as they are re-constructed from
+--   the class declaration in which they reside, and 
+-- * family instances are *not* implicit as they represent the instance body
+--   (similar to a dfun does that for a class instance).
+--
 isImplicitTyCon :: TyCon -> Bool
-isImplicitTyCon SynTyCon{}                     = False
-isImplicitTyCon AlgTyCon{algTcParent = parent} = hasParent parent
-isImplicitTyCon other                          = True
-        -- catches: FunTyCon, TupleTyCon, PrimTyCon, 
+isImplicitTyCon tycon | isTyConAssoc tycon           = True
+                     | isSynTyCon tycon             = False
+                     | isAlgTyCon tycon             = isClassTyCon tycon ||
+                                                      isTupleTyCon tycon
+isImplicitTyCon _other                               = True
+        -- catches: FunTyCon, PrimTyCon, 
         -- CoercionTyCon, SuperKindTyCon
 \end{code}