#include "HsVersions.h"
-import HsSyn ( RuleDecl(..), LRuleDecl, RuleBndr(..), mkHsLet )
+import HsSyn ( RuleDecl(..), LRuleDecl, RuleBndr(..), mkHsDictLet )
import TcRnMonad
import TcSimplify ( tcSimplifyToDicts, tcSimplifyInferCheck )
-import TcMType ( newTyFlexiVarTy, zonkQuantifiedTyVar )
-import TcType ( tyVarsOfTypes, openTypeKind )
+import TcMType ( newFlexiTyVarTy, zonkQuantifiedTyVar, tcSkolSigTyVars )
+import TcType ( tyVarsOfTypes, openTypeKind, SkolemInfo(..), substTyWith, mkTyVarTys )
import TcHsType ( UserTypeCtxt(..), tcHsPatSigType )
-import TcExpr ( tcCheckRho )
+import TcExpr ( tcMonoExpr )
import TcEnv ( tcExtendIdEnv, tcExtendTyVarEnv )
import Inst ( instToId )
import Id ( idType, mkLocalId )
= addErrCtxt (ruleCtxt name) $
traceTc (ptext SLIT("---- Rule ------")
<+> ppr name) `thenM_`
- newTyFlexiVarTy openTypeKind `thenM` \ rule_ty ->
+ newFlexiTyVarTy openTypeKind `thenM` \ rule_ty ->
-- Deal with the tyvars mentioned in signatures
tcRuleBndrs vars (\ ids ->
-- Now LHS and RHS
- getLIE (tcCheckRho lhs rule_ty) `thenM` \ (lhs', lhs_lie) ->
- getLIE (tcCheckRho rhs rule_ty) `thenM` \ (rhs', rhs_lie) ->
+ 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) ->
-- See the 'lhs_dicts' in tcSimplifyAndCheck for the RHS
-- We initially quantify over any tyvars free in *either* the rule
- -- *or* the bound variables. The latter is important. Consider
+ -- *or* the bound variables. The latter is important. Consider
-- ss (x,(y,z)) = (x,z)
-- RULE: forall v. fst (ss v) = fst v
-- The type of the rhs of the rule is just a, but v::(a,(b,c))
returnM (HsRule name act
(map (RuleBndr . noLoc) (forall_tvs2 ++ tpl_ids)) -- yuk
- (mkHsLet lhs_binds lhs')
- (mkHsLet rhs_binds rhs'))
+ (mkHsDictLet lhs_binds lhs')
+ (mkHsDictLet rhs_binds rhs'))
where
tcRuleBndrs [] thing_inside = thing_inside []
tcRuleBndrs (RuleBndr var : vars) thing_inside
- = do { ty <- newTyFlexiVarTy openTypeKind
+ = do { ty <- newFlexiTyVarTy openTypeKind
; let id = mkLocalId (unLoc var) ty
; tcExtendIdEnv [id] $
tcRuleBndrs vars (\ids -> thing_inside (id:ids)) }
tcRuleBndrs (RuleBndrSig var rn_ty : vars) thing_inside
- = do { (tyvars, ty) <- tcHsPatSigType (RuleSigCtxt (unLoc var)) rn_ty
- ; let id = mkLocalId (unLoc var) ty
- ; tcExtendTyVarEnv tyvars $
+-- e.g x :: a->a
+-- The tyvar 'a' is brought into scope first, just as if you'd written
+-- a::*, x :: a->a
+ = do { let ctxt = RuleSigCtxt (unLoc var)
+ ; (tyvars, ty) <- tcHsPatSigType ctxt rn_ty
+ ; let skol_tvs = tcSkolSigTyVars (SigSkol ctxt) tyvars
+ id_ty = substTyWith tyvars (mkTyVarTys skol_tvs) ty
+ id = mkLocalId (unLoc var) id_ty
+ ; tcExtendTyVarEnv skol_tvs $
tcExtendIdEnv [id] $
tcRuleBndrs vars (\ids -> thing_inside (id:ids)) }