Template Haskell: make reify aware of type families

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

diff --git a/compiler/basicTypes/DataCon.lhs b/compiler/basicTypes/DataCon.lhs
index d8fdfb5..af30dd1 100644 (file)
--- a/compiler/basicTypes/DataCon.lhs
+++ b/compiler/basicTypes/DataCon.lhs
@@ -15,9 +15,11 @@ module DataCon (
        
        -- ** Type deconstruction
        dataConRepType, dataConSig, dataConFullSig,
-       dataConName, dataConIdentity, dataConTag, dataConTyCon, dataConUserType,
+       dataConName, dataConIdentity, dataConTag, dataConTyCon, 
+        dataConOrigTyCon, dataConUserType,
        dataConUnivTyVars, dataConExTyVars, dataConAllTyVars, 
-       dataConEqSpec, eqSpecPreds, dataConEqTheta, dataConDictTheta, dataConStupidTheta, 
+       dataConEqSpec, eqSpecPreds, dataConEqTheta, dataConDictTheta,
+       dataConStupidTheta,  
        dataConInstArgTys, dataConOrigArgTys, dataConOrigResTy,
        dataConInstOrigArgTys, dataConRepArgTys, 
        dataConFieldLabels, dataConFieldType,
@@ -563,6 +565,14 @@ dataConTag  = dcTag
 dataConTyCon :: DataCon -> TyCon
 dataConTyCon = dcRepTyCon
 
+-- | The original type constructor used in the definition of this data
+-- constructor.  In case of a data family instance, that will be the family
+-- type constructor.
+dataConOrigTyCon :: DataCon -> TyCon
+dataConOrigTyCon dc 
+  | Just (tc, _) <- tyConFamInst_maybe (dcRepTyCon dc) = tc
+  | otherwise                                          = dcRepTyCon dc
+
 -- | The representation type of the data constructor, i.e. the sort
 -- type that will represent values of this type at runtime
 dataConRepType :: DataCon -> Type