[project @ 2006-01-18 12:15:37 by simonpj]

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

diff --git a/ghc/compiler/typecheck/TcSimplify.lhs b/ghc/compiler/typecheck/TcSimplify.lhs
index 0660a68..8ff7474 100644 (file)
--- a/ghc/compiler/typecheck/TcSimplify.lhs
+++ b/ghc/compiler/typecheck/TcSimplify.lhs
@@ -31,7 +31,7 @@ import Inst           ( lookupInst, LookupInstResult(..),
                          isMethodFor, isMethod,
                          instToId, tyVarsOfInsts,  cloneDict,
                          ipNamesOfInsts, ipNamesOfInst, dictPred,
-                         instBindingRequired, fdPredsOfInst,
+                         fdPredsOfInst,
                          newDictsAtLoc, tcInstClassOp,
                          getDictClassTys, isTyVarDict, instLoc,
                          zonkInst, tidyInsts, tidyMoreInsts,
@@ -1350,10 +1350,6 @@ data Avail
                        -- e.g. those "given" in a signature
          Bool          -- True <=> actually consumed (splittable IPs only)
 
-  | NoRhs              -- Used for Insts like (CCallable f)
-                       -- where no witness is required.
-                       -- ToDo: remove?
-
   | Rhs                -- Used when there is a RHS
        (LHsExpr TcId)  -- The RHS
        [Inst]          -- Insts free in the RHS; we need these too
@@ -1375,7 +1371,6 @@ pprAvails avails = vcat [sep [ppr inst, nest 2 (equals <+> pprAvail avail)]
 instance Outputable Avail where
     ppr = pprAvail
 
-pprAvail NoRhs         = text "<no rhs>"
 pprAvail IsFree                = text "Free"
 pprAvail Irred         = text "Irred"
 pprAvail (Given x b)           = text "Given" <+> ppr x <+> 
@@ -1409,7 +1404,6 @@ extractResults avails wanteds
          Nothing    -> pprTrace "Urk: extractResults" (ppr w) $
                        go avails binds irreds frees ws
 
-         Just NoRhs  -> go avails               binds irreds     frees     ws
          Just IsFree -> go (add_free avails w)  binds irreds     (w:frees) ws
          Just Irred  -> go (add_given avails w) binds (w:irreds) frees     ws
 
@@ -1443,11 +1437,7 @@ extractResults avails wanteds
     get_root irreds frees IsFree       w = cloneDict w `thenM` \ w' ->
                                           returnM (irreds, w':frees, instToId w')
 
-    add_given avails w 
-       | instBindingRequired w = addToFM avails w (Given (instToId w) True)
-       | otherwise             = addToFM avails w NoRhs
-       -- NB: make sure that CCallable/CReturnable use NoRhs rather
-       --      than Given, else we end up with bogus bindings.
+    add_given avails w = addToFM avails w (Given (instToId w) True)
 
     add_free avails w | isMethod w = avails
                      | otherwise  = add_given avails w
@@ -1828,8 +1818,7 @@ addWanted :: WantSCs -> Avails -> Inst -> LHsExpr TcId -> [Inst] -> TcM Avails
 addWanted want_scs avails wanted rhs_expr wanteds
   = addAvailAndSCs want_scs avails wanted avail
   where
-    avail | instBindingRequired wanted = Rhs rhs_expr wanteds
-         | otherwise                  = ASSERT( null wanteds ) NoRhs
+    avail = Rhs rhs_expr wanteds
 
 addGiven :: Avails -> Inst -> TcM Avails
 addGiven avails given = addAvailAndSCs AddSCs avails given (Given (instToId given) False)
@@ -2197,9 +2186,7 @@ get_default_tys
 
 When typechecking _ccall_s, TcExpr ensures that the external
 function is only passed arguments (and in the other direction,
-results) of a restricted set of 'native' types. This is
-implemented via the help of the pseudo-type classes,
-@CReturnable@ (CR) and @CCallable@ (CC.)
+results) of a restricted set of 'native' types.
 
 The interaction between the defaulting mechanism for numeric
 values and CC & CR can be a bit puzzling to the user at times.
@@ -2218,10 +2205,6 @@ is not an instance of CR. If the default list is equal to
 Haskell 1.4's default-default of (Int, Double), 'x' has type
 Int.
 
-To try to minimise the potential for surprises here, the
-defaulting mechanism is turned off in the presence of
-CCallable and CReturnable.
-
 End of aside]