New syntax for GADT-style record declarations, and associated refactoring

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

diff --git a/compiler/typecheck/TcRules.lhs b/compiler/typecheck/TcRules.lhs
index 2909910..a95251d 100644 (file)
--- a/compiler/typecheck/TcRules.lhs
+++ b/compiler/typecheck/TcRules.lhs
@@ -6,17 +6,8 @@
 TcRules: Typechecking transformation rules
 
 \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 TcRules ( tcRules ) where
 
-#include "HsVersions.h"
-
 import HsSyn
 import TcRnMonad
 import TcSimplify
@@ -30,29 +21,29 @@ import Id
 import Name
 import SrcLoc
 import Outputable
+import FastString
 \end{code}
 
 \begin{code}
 tcRules :: [LRuleDecl Name] -> TcM [LRuleDecl TcId]
-tcRules decls = mappM (wrapLocM tcRule) decls
+tcRules decls = mapM (wrapLocM tcRule) decls
 
 tcRule :: RuleDecl Name -> TcM (RuleDecl TcId)
 tcRule (HsRule name act vars lhs fv_lhs rhs fv_rhs)
-  = addErrCtxt (ruleCtxt name)                 $
-    traceTc (ptext SLIT("---- Rule ------")
-                <+> ppr name)                  `thenM_` 
-    newFlexiTyVarTy openTypeKind               `thenM` \ rule_ty ->
+  = addErrCtxt (ruleCtxt name)                 $ do
+    traceTc (ptext (sLit "---- Rule ------") <+> ppr name)
+    rule_ty <- newFlexiTyVarTy openTypeKind
 
        -- Deal with the tyvars mentioned in signatures
-    tcRuleBndrs vars (\ ids ->
+    (ids, lhs', rhs', lhs_lie, rhs_lie) <-
+      tcRuleBndrs vars $ \ ids -> do
                -- Now LHS and RHS
-       getLIE (tcMonoExpr lhs rule_ty) `thenM` \ (lhs', lhs_lie) ->
-       getLIE (tcMonoExpr rhs rule_ty) `thenM` \ (rhs', rhs_lie) ->
-       returnM (ids, lhs', rhs', lhs_lie, rhs_lie)
-    )                          `thenM` \ (ids, lhs', rhs', lhs_lie, rhs_lie) ->
+        (lhs', lhs_lie) <- getLIE (tcMonoExpr lhs rule_ty)
+        (rhs', rhs_lie) <- getLIE (tcMonoExpr rhs rule_ty)
+        return (ids, lhs', rhs', lhs_lie, rhs_lie)
 
                -- Check that LHS has no overloading at all
-    tcSimplifyRuleLhs lhs_lie  `thenM` \ (lhs_dicts, lhs_binds) ->
+    (lhs_dicts, lhs_binds) <- tcSimplifyRuleLhs lhs_lie
 
        -- Gather the template variables and tyvars
     let
@@ -79,23 +70,23 @@ tcRule (HsRule name act vars lhs fv_lhs rhs fv_rhs)
        -- during zonking (see TcHsSyn.zonkRule)
        --
        forall_tvs = tyVarsOfTypes (rule_ty : map idType tpl_ids)
-    in
+
        -- RHS can be a bit more lenient.  In particular,
        -- we let constant dictionaries etc float outwards
        --
        -- NB: tcSimplifyInferCheck zonks the forall_tvs, and 
        --     knocks out any that are constrained by the environment
-    getInstLoc (SigOrigin (RuleSkol name))     `thenM` \ loc -> 
-    tcSimplifyInferCheck loc
-                        forall_tvs
-                        lhs_dicts rhs_lie      `thenM` \ (forall_tvs1, rhs_binds) ->
+    loc <- getInstLoc (SigOrigin (RuleSkol name))
+    (forall_tvs1, rhs_binds) <- tcSimplifyInferCheck loc
+                                        forall_tvs
+                                        lhs_dicts rhs_lie
 
-    returnM (HsRule name act
+    return (HsRule name act
                    (map (RuleBndr . noLoc) (forall_tvs1 ++ tpl_ids))   -- yuk
                    (mkHsDictLet lhs_binds lhs') fv_lhs
                    (mkHsDictLet rhs_binds rhs') fv_rhs)
 
-
+tcRuleBndrs :: [RuleBndr Name] -> ([Id] -> TcM a) -> TcM a
 tcRuleBndrs [] thing_inside = thing_inside []
 tcRuleBndrs (RuleBndr var : vars) thing_inside
   = do         { ty <- newFlexiTyVarTy openTypeKind
@@ -115,7 +106,8 @@ tcRuleBndrs (RuleBndrSig var rn_ty : vars) thing_inside
          tcExtendIdEnv [id] $
          tcRuleBndrs vars (\ids -> thing_inside (id:ids)) }
 
-ruleCtxt name = ptext SLIT("When checking the transformation rule") <+> 
+ruleCtxt :: FastString -> SDoc
+ruleCtxt name = ptext (sLit "When checking the transformation rule") <+> 
                doubleQuotes (ftext name)
 \end{code}