Refactor part of the renamer to fix Trac #3901

[ghc-hetmet.git] / compiler / rename / RnEnv.lhs

diff --git a/compiler/rename/RnEnv.lhs b/compiler/rename/RnEnv.lhs
index 2f5743a..c3b5592 100644 (file)
--- a/compiler/rename/RnEnv.lhs
+++ b/compiler/rename/RnEnv.lhs
@@ -26,8 +26,8 @@ module RnEnv (
        bindTyVarsRn, extendTyVarEnvFVRn,
 
        checkDupRdrNames, checkDupAndShadowedRdrNames,
-        checkDupAndShadowedNames, 
-       mapFvRn, mapFvRnCPS,
+        checkDupNames, checkDupAndShadowedNames, 
+       addFvRn, mapFvRn, mapMaybeFvRn, mapFvRnCPS,
        warnUnusedMatches, warnUnusedModules, warnUnusedImports, 
        warnUnusedTopBinds, warnUnusedLocalBinds,
        dataTcOccs, unknownNameErr, kindSigErr, perhapsForallMsg
@@ -651,7 +651,6 @@ type MiniFixityEnv = FastStringEnv (Located Fixity)
 --------------------------------
 -- Used for nested fixity decls to bind names along with their fixities.
 -- the fixities are given as a UFM from an OccName's FastString to a fixity decl
--- Also check for unused binders
 bindLocalNamesFV_WithFixities :: [Name]
                              -> MiniFixityEnv
                              -> RnM (a, FreeVars) -> RnM (a, FreeVars)
@@ -990,11 +989,19 @@ checkShadowedOccs (global_env,local_env) loc_occs
 
 \begin{code}
 -- A useful utility
+addFvRn :: FreeVars -> RnM (thing, FreeVars) -> RnM (thing, FreeVars)
+addFvRn fvs1 thing_inside = do { (res, fvs2) <- thing_inside
+                               ; return (res, fvs1 `plusFV` fvs2) }
+
 mapFvRn :: (a -> RnM (b, FreeVars)) -> [a] -> RnM ([b], FreeVars)
 mapFvRn f xs = do stuff <- mapM f xs
                   case unzip stuff of
                       (ys, fvs_s) -> return (ys, plusFVs fvs_s)
 
+mapMaybeFvRn :: (a -> RnM (b, FreeVars)) -> Maybe a -> RnM (Maybe b, FreeVars)
+mapMaybeFvRn _ Nothing = return (Nothing, emptyFVs)
+mapMaybeFvRn f (Just x) = do { (y, fvs) <- f x; return (Just y, fvs) }
+
 -- because some of the rename functions are CPSed:
 -- maps the function across the list from left to right; 
 -- collects all the free vars into one set