isDataTyCon should be False for all type families, even data type families

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

diff --git a/compiler/types/TyCon.lhs b/compiler/types/TyCon.lhs
index 50d76cf..90ac71c 100644 (file)
--- a/compiler/types/TyCon.lhs
+++ b/compiler/types/TyCon.lhs
@@ -616,9 +616,14 @@ isDataTyCon :: TyCon -> Bool
 --     True for all @data@ types
 --     False for newtypes
 --               unboxed tuples
+--               type families
+-- 
+-- NB: for a data type family, T, only the *instance* tycons are
+--     get an info table etc.  The family tycon does not.
+--     Hence False for OpenTyCon
 isDataTyCon tc@(AlgTyCon {algTcRhs = rhs})  
   = case rhs of
-        OpenTyCon {}  -> not (otIsNewtype rhs)
+        OpenTyCon {}  -> False
        DataTyCon {}  -> True
        NewTyCon {}   -> False
        AbstractTyCon -> False   -- We don't know, so return False