Straightened out implicit coercions for indexed types

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

diff --git a/compiler/types/TyCon.lhs b/compiler/types/TyCon.lhs
index d536f59..723a790 100644 (file)
--- a/compiler/types/TyCon.lhs
+++ b/compiler/types/TyCon.lhs
@@ -14,11 +14,12 @@ module TyCon(
        SynTyConRhs(..),
 
        isFunTyCon, isUnLiftedTyCon, isProductTyCon, 
-       isAlgTyCon, isDataTyCon, isSynTyCon, isNewTyCon, isPrimTyCon,
+       isAlgTyCon, isDataTyCon, isSynTyCon, isNewTyCon, isClosedNewTyCon,
+       isPrimTyCon, 
        isEnumerationTyCon, isGadtSyntaxTyCon, isOpenTyCon,
        assocTyConArgPoss_maybe, isTyConAssoc, setTyConArgPoss,
        isTupleTyCon, isUnboxedTupleTyCon, isBoxedTupleTyCon, tupleTyConBoxity,
-       isRecursiveTyCon, newTyConRep, newTyConRhs, newTyConCo,
+       isRecursiveTyCon, newTyConRep, newTyConRhs, newTyConCo_maybe,
        isHiBootTyCon, isSuperKindTyCon,
         isCoercionTyCon_maybe, isCoercionTyCon,
 
@@ -49,6 +50,7 @@ module TyCon(
        tyConArity,
        isClassTyCon, tyConClass_maybe,
        isFamInstTyCon, tyConFamInst_maybe, tyConFamilyCoercion_maybe,
+       tyConFamInstIndex,
        synTyConDefn, synTyConRhs, synTyConType, synTyConResKind,
        tyConExtName,           -- External name for foreign types
 
@@ -273,6 +275,9 @@ data AlgTyConParent = -- An ordinary type constructor has no parent.
                                    TyCon       -- a *coercion* identifying
                                                -- the representation type
                                                -- with the type instance
+                                    Int         -- index to generate unique
+                                               -- name (needed here to put
+                                               -- into iface)
 
 data SynTyConRhs
   = OpenSynTyCon Kind  -- Type family: *result* kind given
@@ -560,6 +565,14 @@ isNewTyCon (AlgTyCon {algTcRhs = rhs}) = case rhs of
                                           _            -> False
 isNewTyCon other                       = False
 
+-- This is an important refinement as typical newtype optimisations do *not*
+-- hold for newtype families.  Why?  Given a type `T a', if T is a newtype
+-- family, there is no unique right hand side by which `T a' can be replaced
+-- by a cast.
+--
+isClosedNewTyCon :: TyCon -> Bool
+isClosedNewTyCon tycon = isNewTyCon tycon && not (isOpenTyCon tycon)
+
 isProductTyCon :: TyCon -> Bool
 -- A "product" tycon
 --     has *one* constructor, 
@@ -747,12 +760,9 @@ newTyConRep :: TyCon -> ([TyVar], Type)
 newTyConRep (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon { nt_rep = rep }}) = (tvs, rep)
 newTyConRep tycon = pprPanic "newTyConRep" (ppr tycon)
 
-newTyConCo :: TyCon -> Maybe TyCon
-newTyConCo (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon { nt_co = co }})
-  = co
-newTyConCo (AlgTyCon {tyConTyVars = tvs, algTcRhs = OpenNewTyCon})
-  = Nothing
-newTyConCo tycon = pprPanic "newTyConCo" (ppr tycon)
+newTyConCo_maybe :: TyCon -> Maybe TyCon
+newTyConCo_maybe (AlgTyCon {algTcRhs = NewTyCon { nt_co = co }}) = co
+newTyConCo_maybe _                                              = Nothing
 
 tyConPrimRep :: TyCon -> PrimRep
 tyConPrimRep (PrimTyCon {primTyConRep = rep}) = rep
@@ -807,20 +817,25 @@ tyConClass_maybe (AlgTyCon {algTcParent = ClassTyCon clas}) = Just clas
 tyConClass_maybe ther_tycon                                = Nothing
 
 isFamInstTyCon :: TyCon -> Bool
-isFamInstTyCon (AlgTyCon {algTcParent = FamilyTyCon _ _ _}) = True
-isFamInstTyCon other_tycon                                 = False
+isFamInstTyCon (AlgTyCon {algTcParent = FamilyTyCon _ _ _ _}) = True
+isFamInstTyCon other_tycon                                   = False
 
 tyConFamInst_maybe :: TyCon -> Maybe (TyCon, [Type])
-tyConFamInst_maybe (AlgTyCon {algTcParent = FamilyTyCon fam instTys _}) = 
+tyConFamInst_maybe (AlgTyCon {algTcParent = FamilyTyCon fam instTys _ _}) = 
   Just (fam, instTys)
-tyConFamInst_maybe ther_tycon                                          = 
+tyConFamInst_maybe ther_tycon                                            = 
   Nothing
 
 tyConFamilyCoercion_maybe :: TyCon -> Maybe TyCon
-tyConFamilyCoercion_maybe (AlgTyCon {algTcParent = FamilyTyCon _ _ coe}) = 
+tyConFamilyCoercion_maybe (AlgTyCon {algTcParent = FamilyTyCon _ _ coe _}) = 
   Just coe
-tyConFamilyCoercion_maybe ther_tycon                                    = 
+tyConFamilyCoercion_maybe ther_tycon                                      = 
   Nothing
+
+tyConFamInstIndex :: TyCon -> Int
+tyConFamInstIndex (AlgTyCon {algTcParent = FamilyTyCon _ _ _ index}) = index
+tyConFamInstIndex _                                                 = 
+  panic "tyConFamInstIndex"
 \end{code}