Fix a bug in functorLikeTraverse, which was giving wrong answer for tuples

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

diff --git a/compiler/typecheck/TcEnv.lhs b/compiler/typecheck/TcEnv.lhs
index b69163c..c51f786 100644 (file)
--- a/compiler/typecheck/TcEnv.lhs
+++ b/compiler/typecheck/TcEnv.lhs
@@ -606,8 +606,8 @@ as well as explicit user written ones.
 \begin{code}
 data InstInfo a
   = InstInfo {
-      iSpec  :: Instance,              -- Includes the dfun id.  Its forall'd type 
-      iBinds :: InstBindings a         -- variables scope over the stuff in InstBindings!
+      iSpec   :: Instance,        -- Includes the dfun id.  Its forall'd type
+      iBinds  :: InstBindings a   -- variables scope over the stuff in InstBindings!
     }
 
 iDFunId :: InstInfo a -> DFunId
@@ -637,7 +637,13 @@ data InstBindings a
                         -- in TcDeriv
 
 pprInstInfo :: InstInfo a -> SDoc
-pprInstInfo info = vcat [ptext (sLit "InstInfo:") <+> ppr (idType (iDFunId info))]
+pprInstInfo info = hang (ptext (sLit "instance"))
+                      2 (sep [ ifPprDebug (pprForAll tvs)
+                             , pprThetaArrow theta, ppr tau
+                             , ptext (sLit "where")])
+  where
+    (tvs, theta, tau) = tcSplitSigmaTy (idType (iDFunId info))
+
 
 pprInstInfoDetails :: OutputableBndr a => InstInfo a -> SDoc
 pprInstInfoDetails info = pprInstInfo info $$ nest 2 (details (iBinds info))