X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FbasicTypes%2FVarEnv.lhs;h=d65ec5face4dddd9d2cdcc630cbe9e69a51a2203;hp=0b2553a3d4dac90818d05d788c909c74a19f0f9b;hb=206b4dec78250efef3cd927d64dc6cbc54a16c3d;hpb=59264221c24a17e7c8ecde3e289882b9620bd5a8

diff --git a/compiler/basicTypes/VarEnv.lhs b/compiler/basicTypes/VarEnv.lhs
index 0b2553a..d65ec5f 100644
--- a/compiler/basicTypes/VarEnv.lhs
+++ b/compiler/basicTypes/VarEnv.lhs
@@ -4,6 +4,13 @@
 %
 
 \begin{code}
+{-# OPTIONS -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+--     http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
+-- for details
+
 module VarEnv (
 	VarEnv, IdEnv, TyVarEnv,
 	emptyVarEnv, unitVarEnv, mkVarEnv,
@@ -28,7 +35,7 @@ module VarEnv (
 	-- RnEnv2 and its operations
 	RnEnv2, mkRnEnv2, rnBndr2, rnBndrs2, rnOccL, rnOccR, inRnEnvL, inRnEnvR,
 		rnBndrL, rnBndrR, nukeRnEnvL, nukeRnEnvR, extendRnInScopeList,
-		rnInScope, lookupRnInScope,
+		rnInScope, rnInScopeSet, lookupRnInScope,
 
 	-- TidyEnvs
 	TidyEnv, emptyTidyEnv
@@ -65,16 +72,16 @@ instance Outputable InScopeSet where
   ppr (InScope s i) = ptext SLIT("InScope") <+> ppr s
 
 emptyInScopeSet :: InScopeSet
-emptyInScopeSet = InScope emptyVarSet 1#
+emptyInScopeSet = InScope emptyVarSet (_ILIT(1))
 
 getInScopeVars ::  InScopeSet -> VarEnv Var
 getInScopeVars (InScope vs _) = vs
 
 mkInScopeSet :: VarEnv Var -> InScopeSet
-mkInScopeSet in_scope = InScope in_scope 1#
+mkInScopeSet in_scope = InScope in_scope (_ILIT(1))
 
 extendInScopeSet :: InScopeSet -> Var -> InScopeSet
-extendInScopeSet (InScope in_scope n) v = InScope (extendVarEnv in_scope v v) (n +# 1#)
+extendInScopeSet (InScope in_scope n) v = InScope (extendVarEnv in_scope v v) (n +# _ILIT(1))
 
 extendInScopeSetList :: InScopeSet -> [Var] -> InScopeSet
 extendInScopeSetList (InScope in_scope n) vs
@@ -88,7 +95,7 @@ extendInScopeSetSet (InScope in_scope n) vs
 modifyInScopeSet :: InScopeSet -> Var -> Var -> InScopeSet
 -- Exploit the fact that the in-scope "set" is really a map
 -- 	Make old_v map to new_v
-modifyInScopeSet (InScope in_scope n) old_v new_v = InScope (extendVarEnv in_scope old_v new_v) (n +# 1#)
+modifyInScopeSet (InScope in_scope n) old_v new_v = InScope (extendVarEnv in_scope old_v new_v) (n +# _ILIT(1))
 
 delInScopeSet :: InScopeSet -> Var -> InScopeSet
 delInScopeSet (InScope in_scope n) v = InScope (in_scope `delVarEnv` v) n
@@ -127,17 +134,17 @@ uniqAway in_scope var
 uniqAway' :: InScopeSet -> Var -> Var
 -- This one *always* makes up a new variable
 uniqAway' (InScope set n) var
-  = try 1#
+  = try (_ILIT(1))
   where
     orig_unique = getUnique var
     try k 
 #ifdef DEBUG
-	  | k ># 1000#
+	  | k ># _ILIT(1000)
 	  = pprPanic "uniqAway loop:" (ppr (iBox k) <+> text "tries" <+> ppr var <+> int (iBox n)) 
 #endif			    
-	  | uniq `elemVarSetByKey` set = try (k +# 1#)
+	  | uniq `elemVarSetByKey` set = try (k +# _ILIT(1))
 #ifdef DEBUG
-	  | opt_PprStyle_Debug && k ># 3#
+	  | opt_PprStyle_Debug && k ># _ILIT(3)
 	  = pprTrace "uniqAway:" (ppr (iBox k) <+> text "tries" <+> ppr var <+> int (iBox n)) 
 	    setVarUnique var uniq
 #endif			    
@@ -196,6 +203,9 @@ extendRnInScopeList env vs
 rnInScope :: Var -> RnEnv2 -> Bool
 rnInScope x env = x `elemInScopeSet` in_scope env
 
+rnInScopeSet :: RnEnv2 -> InScopeSet
+rnInScopeSet = in_scope
+
 rnBndrs2 :: RnEnv2 -> [Var] -> [Var] -> RnEnv2
 -- Arg lists must be of equal length
 rnBndrs2 env bsL bsR = foldl2 rnBndr2 env bsL bsR 
@@ -226,20 +236,34 @@ rnBndr2 (RV2 { envL = envL, envR = envR, in_scope = in_scope }) bL bR
 rnBndrL, rnBndrR :: RnEnv2 -> Var -> (RnEnv2, Var)
 -- Used when there's a binder on one side or the other only
 -- Useful when eta-expanding
+-- 
 rnBndrL (RV2 { envL = envL, envR = envR, in_scope = in_scope }) bL
   = (RV2 { envL     = extendVarEnv envL bL new_b
-	 , envR     = envR
+	 , envR     = extendVarEnv envR new_b new_b 	-- Note [rnBndrLR]
 	 , in_scope = extendInScopeSet in_scope new_b }, new_b)
   where
     new_b = uniqAway in_scope bL
 
 rnBndrR (RV2 { envL = envL, envR = envR, in_scope = in_scope }) bR
-  = (RV2 { envL     = envL
+  = (RV2 { envL     = extendVarEnv envL new_b new_b	-- Note [rnBndrLR]
 	 , envR     = extendVarEnv envR bR new_b
 	 , in_scope = extendInScopeSet in_scope new_b }, new_b)
   where
     new_b = uniqAway in_scope bR
 
+-- Note [rnBndrLR] 
+-- ~~~~~~~~~~~~~~~
+-- Notice that in rnBndrL, rnBndrR, we extend envR, envL respectively
+-- with a binding [new_b -> new_b], where new_b is the new binder.
+-- This is important when doing eta expansion; e.g. matching (\x.M) ~ N
+-- In effect we switch to (\x'.M) ~ (\x'.N x'), where x' is new_b
+-- So we must add x' to the env of both L and R.  (x' is fresh, so it
+-- can't capture anything in N.)  
+--
+-- If we don't do this, we can get silly matches like
+--	forall a.  \y.a  ~   v
+-- succeeding with [x -> v y], which is bogus of course 
+
 rnOccL, rnOccR :: RnEnv2 -> Var -> Var
 -- Look up the renaming of an occurrence in the left or right term
 rnOccL (RV2 { envL = env }) v = lookupVarEnv env v `orElse` v