Simon's fixes to the generated type instances in Generics

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

diff --git a/compiler/types/FamInstEnv.lhs b/compiler/types/FamInstEnv.lhs
index 894da34..5b4374a 100644 (file)
--- a/compiler/types/FamInstEnv.lhs
+++ b/compiler/types/FamInstEnv.lhs
@@ -84,7 +84,12 @@ instance Outputable FamInst where
 pprFamInst :: FamInst -> SDoc
 pprFamInst famInst
   = hang (pprFamInstHdr famInst)
-       2 (ptext (sLit "--") <+> pprNameLoc (getName famInst))
+       2 (vcat [ ifPprDebug (ptext (sLit "Coercion axiom:") <+> pp_ax)
+               , ptext (sLit "--") <+> pprNameLoc (getName famInst)])
+  where
+    pp_ax = case tyConFamilyCoercion_maybe (fi_tycon famInst) of
+              Just ax -> ppr ax
+              Nothing -> ptext (sLit "<not there!>")
 
 pprFamInstHdr :: FamInst -> SDoc
 pprFamInstHdr (FamInst {fi_tycon = rep_tc})