newtype fixes, coercions for non-recursive newtypes now optional

[ghc-hetmet.git] / compiler / typecheck / TcEnv.lhs

diff --git a/compiler/typecheck/TcEnv.lhs b/compiler/typecheck/TcEnv.lhs
index 19deca9..936ec5b 100644 (file)
--- a/compiler/typecheck/TcEnv.lhs
+++ b/compiler/typecheck/TcEnv.lhs
@@ -565,7 +565,9 @@ data InstBindings
        [LSig Name]             -- User pragmas recorded for generating 
                                -- specialised instances
 
-  | NewTypeDerived             -- Used for deriving instances of newtypes, where the
+  | NewTypeDerived             
+        (Maybe TyCon)           -- maybe a coercion for the newtype
+                                -- Used for deriving instances of newtypes, where the
        [Type]                  -- witness dictionary is identical to the argument 
                                -- dictionary.  Hence no bindings, no pragmas
        -- The [Type] are the representation types
@@ -576,7 +578,7 @@ pprInstInfo info = vcat [ptext SLIT("InstInfo:") <+> ppr (idType (iDFunId info))
 pprInstInfoDetails info = pprInstInfo info $$ nest 2 (details (iBinds info))
   where
     details (VanillaInst b _)  = pprLHsBinds b
-    details (NewTypeDerived _) = text "Derived from the representation type"
+    details (NewTypeDerived _  _) = text "Derived from the representation type"
 
 simpleInstInfoClsTy :: InstInfo -> (Class, Type)
 simpleInstInfoClsTy info = case instanceHead (iSpec info) of