X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcSimplify.lhs;h=932cb68f425ba706a4114cbd1a1c2e3396a72c60;hp=b5bcc5b45e3e741650432870b89ebc0bd06d5011;hb=e79c9ce01d0ce4412bd4bcd99c8c728a6a2ec569;hpb=e47c481d3e69601d902ce525f54de9246a80bcda

diff --git a/compiler/typecheck/TcSimplify.lhs b/compiler/typecheck/TcSimplify.lhs
index b5bcc5b..932cb68 100644
--- a/compiler/typecheck/TcSimplify.lhs
+++ b/compiler/typecheck/TcSimplify.lhs
@@ -16,6 +16,8 @@ module TcSimplify (
 
 	tcSimplifyDeriv, tcSimplifyDefault,
 	bindInstsOfLocalFuns, 
+	
+        tcSimplifyStagedExpr,
 
         misMatchMsg
     ) where
@@ -58,6 +60,7 @@ import Util
 import SrcLoc
 import DynFlags
 import FastString
+
 import Control.Monad
 import Data.List
 \end{code}
@@ -861,7 +864,7 @@ Note [NO TYVARS]
 
 The excitement comes when simplifying the bindings for h.  Initially
 try to simplify {y @ [[t1]] t2, 0 @ t1}, with initial qtvs = {t2}.
-From this we get t1:=:t2, but also various bindings.  We can't forget
+From this we get t1~t2, but also various bindings.  We can't forget
 the bindings (because of [LOOP]), but in fact t1 is what g is
 polymorphic in.  
 
@@ -977,7 +980,7 @@ makeImplicationBind :: InstLoc -> [TcTyVar]
 --	(ir1, .., irn) = f qtvs givens
 -- where f is (evidence for) the new implication constraint
 --	f :: forall qtvs. givens => (ir1, .., irn)
--- qtvs includes coercion variables.
+-- qtvs includes coercion variables
 --
 -- This binding must line up the 'rhs' in reduceImplication
 makeImplicationBind loc all_tvs
@@ -997,7 +1000,7 @@ makeImplicationBind loc all_tvs
 	      name = mkInternalName uniq (mkVarOcc "ic") span
 	      implic_inst = ImplicInst { tci_name = name,
 					 tci_tyvars = all_tvs, 
-					 tci_given = (eq_givens ++ dict_givens),
+					 tci_given = eq_givens ++ dict_givens,
                                                        -- same order as binders
 					 tci_wanted = irreds, 
                                          tci_loc = loc }
@@ -1412,7 +1415,7 @@ tcSimplifyRestricted 	-- Used for restricted binding groups
 tcSimplifyRestricted doc top_lvl bndrs tau_tvs wanteds
 	-- Zonk everything in sight
   = do	{ traceTc (text "tcSimplifyRestricted")
-	; wanteds' <- zonkInsts wanteds
+	; wanteds_z <- zonkInsts wanteds
 
    	-- 'ReduceMe': Reduce as far as we can.  Don't stop at
 	-- dicts; the idea is to get rid of as many type
@@ -1424,7 +1427,7 @@ tcSimplifyRestricted doc top_lvl bndrs tau_tvs wanteds
 	-- HOWEVER, some unification may take place, if we instantiate
 	-- 	    a method Inst with an equality constraint
 	; let env = mkNoImproveRedEnv doc (\_ -> ReduceMe)
-	; (_imp, _binds, constrained_dicts) <- reduceContext env wanteds'
+	; (_imp, _binds, constrained_dicts) <- reduceContext env wanteds_z
 
 	-- Next, figure out the tyvars we will quantify over
 	; tau_tvs' <- zonkTcTyVarsAndFV (varSetElems tau_tvs)
@@ -1452,6 +1455,13 @@ tcSimplifyRestricted doc top_lvl bndrs tau_tvs wanteds
 		ppr _binds,
 		ppr constrained_tvs', ppr tau_tvs', ppr qtvs ])
 
+          -- Zonk wanteds again!  The first call to reduceContext may have
+          -- instantiated some variables. 
+          -- FIXME: If red_improve would work, we could propagate that into
+          --        the equality solver, too, to prevent instantating any
+          --        variables.
+	; wanteds_zz <- zonkInsts wanteds_z
+
 	-- The first step may have squashed more methods than
 	-- necessary, so try again, this time more gently, knowing the exact
 	-- set of type variables to quantify over.
@@ -1473,7 +1483,7 @@ tcSimplifyRestricted doc top_lvl bndrs tau_tvs wanteds
 			   (is_nested_group || isDict inst) = Stop
 		          | otherwise  	                    = ReduceMe 
 	      env = mkNoImproveRedEnv doc try_me
-	; (_imp, binds, irreds) <- reduceContext env wanteds'
+	; (_imp, binds, irreds) <- reduceContext env wanteds_zz
 
 	-- See "Notes on implicit parameters, Question 4: top level"
 	; ASSERT( all (isFreeWrtTyVars qtvs) irreds )	-- None should be captured
@@ -3007,6 +3017,26 @@ tcSimplifyDefault theta = do
     doc = ptext (sLit "default declaration")
 \end{code}
 
+@tcSimplifyStagedExpr@ performs a simplification but does so at a new
+stage. This is used when typechecking annotations and splices.
+
+\begin{code}
+
+tcSimplifyStagedExpr :: ThStage -> TcM a -> TcM (a, TcDictBinds)
+-- Type check an expression that runs at a top level stage as if
+--   it were going to be spliced and then simplify it
+tcSimplifyStagedExpr stage tc_action
+  = setStage stage $ do { 
+        -- Typecheck the expression
+	  (thing', lie) <- getLIE tc_action
+	
+	-- Solve the constraints
+	; const_binds <- tcSimplifyTop lie
+	
+	; return (thing', const_binds) }
+
+\end{code}
+
 
 %************************************************************************
 %*									*