[project @ 2003-10-30 09:37:57 by simonpj]

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

diff --git a/ghc/compiler/typecheck/TcRules.lhs b/ghc/compiler/typecheck/TcRules.lhs
index 766266d..27072a2 100644 (file)
--- a/ghc/compiler/typecheck/TcRules.lhs
+++ b/ghc/compiler/typecheck/TcRules.lhs
@@ -8,21 +8,18 @@ module TcRules ( tcRules ) where
 
 #include "HsVersions.h"
 
-import HsSyn           ( RuleDecl(..), RuleBndr(..), HsExpr(..), collectRuleBndrSigTys )
-import CoreSyn         ( CoreRule(..) )
+import HsSyn           ( RuleDecl(..), RuleBndr(..), collectRuleBndrSigTys )
 import RnHsSyn         ( RenamedRuleDecl )
-import TcHsSyn         ( TypecheckedRuleDecl, TcExpr, mkHsLet )
+import TcHsSyn         ( TypecheckedRuleDecl, mkHsLet )
 import TcRnMonad
 import TcSimplify      ( tcSimplifyToDicts, tcSimplifyInferCheck )
 import TcMType         ( newTyVarTy )
-import TcType          ( TcTyVarSet, tyVarsOfTypes, tyVarsOfType, openTypeKind )
-import TcIfaceSig      ( tcCoreExpr, tcCoreLamBndrs, tcVar )
-import TcMonoType      ( tcHsSigType, UserTypeCtxt(..), tcAddScopedTyVars )
-import TcExpr          ( tcMonoExpr )
+import TcType          ( tyVarsOfTypes, openTypeKind )
+import TcHsType                ( tcHsSigType, UserTypeCtxt(..), tcAddScopedTyVars )
+import TcExpr          ( tcCheckRho )
 import TcEnv           ( tcExtendLocalValEnv )
 import Inst            ( instToId )
 import Id              ( idType, mkLocalId )
-import VarSet
 import Outputable
 \end{code}
 
@@ -31,23 +28,12 @@ tcRules :: [RenamedRuleDecl] -> TcM [TypecheckedRuleDecl]
 tcRules decls = mappM tcRule decls
 
 tcRule :: RenamedRuleDecl -> TcM TypecheckedRuleDecl
-tcRule (IfaceRule name act vars fun args rhs src_loc)
-  = addSrcLoc src_loc          $
-    addErrCtxt (ruleCtxt name) $
-    tcVar fun                          `thenM` \ fun' ->
-    tcCoreLamBndrs vars                        $ \ vars' ->
-    mappM tcCoreExpr args              `thenM` \ args' ->
-    tcCoreExpr rhs                     `thenM` \ rhs' ->
-    returnM (IfaceRuleOut fun' (Rule name act vars' args' rhs'))
-
-tcRule (IfaceRuleOut fun rule) -- Built-in rules come this way
-  = tcVar fun                          `thenM` \ fun' ->
-    returnM (IfaceRuleOut fun' rule)   
-
 tcRule (HsRule name act vars lhs rhs src_loc)
   = addSrcLoc src_loc                          $
     addErrCtxt (ruleCtxt name)                 $
-    newTyVarTy openTypeKind                            `thenM` \ rule_ty ->
+    traceTc (ptext SLIT("---- Rule ------")
+                <+> ppr name)                  `thenM_` 
+    newTyVarTy openTypeKind                    `thenM` \ rule_ty ->
 
        -- Deal with the tyvars mentioned in signatures
     tcAddScopedTyVars (collectRuleBndrSigTys vars) (
@@ -57,8 +43,8 @@ tcRule (HsRule name act vars lhs rhs src_loc)
        tcExtendLocalValEnv ids                 $
        
                -- Now LHS and RHS
-       getLIE (tcMonoExpr lhs rule_ty)         `thenM` \ (lhs', lhs_lie) ->
-       getLIE (tcMonoExpr rhs rule_ty)         `thenM` \ (rhs', rhs_lie) ->
+       getLIE (tcCheckRho lhs rule_ty) `thenM` \ (lhs', lhs_lie) ->
+       getLIE (tcCheckRho rhs rule_ty) `thenM` \ (rhs', rhs_lie) ->
        
        returnM (ids, lhs', rhs', lhs_lie, rhs_lie)
     )                          `thenM` \ (ids, lhs', rhs', lhs_lie, rhs_lie) ->
@@ -87,12 +73,10 @@ tcRule (HsRule name act vars lhs rhs src_loc)
        --      RULE:  forall v. fst (ss v) = fst v
        -- The type of the rhs of the rule is just a, but v::(a,(b,c))
        --
-       -- We also need to get the free tyvars of the LHS; see notes 
-       -- below with ruleLhsTvs.
+       -- We also need to get the free tyvars of the LHS; but we do that
+       -- during zonking (see TcHsSyn.zonkRule)
        --
        forall_tvs = tyVarsOfTypes (rule_ty : map idType tpl_ids)
-                       `unionVarSet`
-                    ruleLhsTvs lhs'
     in
        -- RHS can be a bit more lenient.  In particular,
        -- we let constant dictionaries etc float outwards
@@ -114,48 +98,6 @@ tcRule (HsRule name act vars lhs rhs src_loc)
     new_id (RuleBndrSig var rn_ty) = tcHsSigType (RuleSigCtxt var) rn_ty       `thenM` \ ty ->
                                     returnM (mkLocalId var ty)
 
-ruleLhsTvs :: TcExpr -> TcTyVarSet
--- We need to gather the type variables mentioned on the LHS so we can 
--- quantify over them.  Example:
---   data T a = C
--- 
---   foo :: T a -> Int
---   foo C = 1
---
---   {-# RULES "myrule"  foo C = 1 #-}
--- 
--- After type checking the LHS becomes (foo a (C a))
--- and we do not want to zap the unbound tyvar 'a' to (), because
--- that limits the applicability of the rule.  Instead, we
--- want to quantify over it!  
---
--- Fortunately the form of the LHS is pretty limited (see RnSource.validRuleLhs)
--- so we don't need to deal with the whole of HsSyn.
---
--- Uh oh!  validRuleLhs only checks the function part of rule LHSs!
-
-ruleLhsTvs (HsPar e)     = ruleLhsTvs e
-ruleLhsTvs (HsLit e)     = emptyVarSet
-ruleLhsTvs (HsOverLit e) = emptyVarSet
-ruleLhsTvs (HsVar v)     = emptyVarSet -- I don't think we need the tyvars of the Id
-
-ruleLhsTvs (OpApp e1 op _ e2)   = ruleLhsTvs e1 `unionVarSet` ruleLhsTvs op 
-                                 `unionVarSet` ruleLhsTvs e2
-ruleLhsTvs (HsApp e1 e2)       = ruleLhsTvs e1 `unionVarSet` ruleLhsTvs e2
-ruleLhsTvs (TyApp e1 tys)      = ruleLhsTvs e1 `unionVarSet` tyVarsOfTypes tys
-ruleLhsTvs (DictApp e ds)      = ruleLhsTvs e
-ruleLhsTvs (NegApp e _)        = ruleLhsTvs e
-ruleLhsTvs (ExplicitList ty es) = tyVarsOfType ty `unionVarSet` ruleLhsTvs_s es
-ruleLhsTvs (ExplicitTuple es _) = ruleLhsTvs_s es
-
--- Type abstractions can occur in rules like 
---     "foldr k z (build g) = g k z"
-ruleLhsTvs (TyLam tvs e)   = ruleLhsTvs e `delVarSetList` tvs
-ruleLhsTvs (DictLam ids e) = ruleLhsTvs e
-ruleLhsTvs e = pprPanic "ruleLhsTvs" (ppr e)
-
-ruleLhsTvs_s es = foldr (unionVarSet . ruleLhsTvs) emptyVarSet es
-
 ruleCtxt name = ptext SLIT("When checking the transformation rule") <+> 
                doubleQuotes (ftext name)
 \end{code}