[project @ 2004-03-17 10:12:31 by simonpj]

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

diff --git a/ghc/compiler/typecheck/Inst.lhs b/ghc/compiler/typecheck/Inst.lhs
index eaf433e..655684a 100644 (file)
--- a/ghc/compiler/typecheck/Inst.lhs
+++ b/ghc/compiler/typecheck/Inst.lhs
@@ -5,10 +5,11 @@
 
 \begin{code}
 module Inst ( 
-       showLIE,
-
        Inst, 
-       pprInst, pprInsts, pprDFuns, pprDictsTheta, pprDictsInFull,
+
+       pprDFuns, pprDictsTheta, pprDictsInFull,        -- User error messages
+       showLIE, pprInst, pprInsts, pprInstInFull,      -- Debugging messages
+
        tidyInsts, tidyMoreInsts,
 
        newDictsFromOld, newDicts, cloneDict, 
@@ -705,8 +706,9 @@ lookupInst dict@(Dict _ pred@(ClassP clas tys) loc)
        ; case lookupInstEnv dflags (pkg_ie, tcg_inst_env tcg_env) clas tys of {
            ([(tenv, (_,_,dfun_id))], []) -> instantiate_dfun tenv dfun_id pred loc ;
            (matches, unifs)              -> do
-       { traceTc (text "lookupInst" <+> vcat [text "matches" <+> ppr matches,
-                                              text "unifs" <+> ppr unifs])
+       { traceTc (text "lookupInst fail" <+> vcat [text "dict" <+> ppr pred,
+                                                   text "matches" <+> ppr matches,
+                                                   text "unifs" <+> ppr unifs])
        ; return NoInstance } } } }
                -- In the case of overlap (multiple matches) we report
                -- NoInstance here.  That has the effect of making the 
@@ -718,7 +720,10 @@ lookupInst (Dict _ _ _) = returnM NoInstance
 
 -----------------
 instantiate_dfun tenv dfun_id pred loc
-  =    -- Record that this dfun is needed
+  = traceTc (text "lookupInst success" <+> 
+               vcat [text "dict" <+> ppr pred, 
+                     text "witness" <+> ppr dfun_id <+> ppr (idType dfun_id) ]) `thenM_`
+       -- Record that this dfun is needed
     record_dfun_usage dfun_id          `thenM_`
 
        -- It's possible that not all the tyvars are in