\section[TcRules]{Typechecking transformation rules}
\begin{code}
-module TcRules ( tcIfaceRules, tcSourceRules ) where
+module TcRules ( tcRules ) where
#include "HsVersions.h"
-import HsSyn ( RuleDecl(..), RuleBndr(..), collectRuleBndrSigTys )
-import CoreSyn ( CoreRule(..) )
-import RnHsSyn ( RenamedRuleDecl )
-import TcHsSyn ( TypecheckedRuleDecl, mkHsLet )
-import TcMonad
+import HsSyn ( RuleDecl(..), LRuleDecl, RuleBndr(..), mkHsDictLet )
+import TcRnMonad
import TcSimplify ( tcSimplifyToDicts, tcSimplifyInferCheck )
-import TcMType ( newTyVarTy )
+import TcMType ( newTyFlexiVarTy, zonkQuantifiedTyVar )
import TcType ( tyVarsOfTypes, openTypeKind )
-import TcIfaceSig ( tcCoreExpr, tcCoreLamBndrs, tcVar )
-import TcMonoType ( tcHsSigType, UserTypeCtxt(..), tcAddScopedTyVars )
-import TcExpr ( tcMonoExpr )
-import TcEnv ( tcExtendLocalValEnv, tcLookupId )
-import Inst ( LIE, plusLIEs, emptyLIE, instToId )
+import TcHsType ( UserTypeCtxt(..), tcHsPatSigType )
+import TcExpr ( tcCheckRho )
+import TcEnv ( tcExtendIdEnv, tcExtendTyVarEnv )
+import Inst ( instToId )
import Id ( idType, mkLocalId )
+import Name ( Name )
+import SrcLoc ( noLoc, unLoc )
import Outputable
\end{code}
\begin{code}
-tcIfaceRules :: [RenamedRuleDecl] -> TcM [TypecheckedRuleDecl]
-tcIfaceRules decls = mapTc tcIfaceRule decls
-
-tcIfaceRule :: RenamedRuleDecl -> TcM TypecheckedRuleDecl
- -- No zonking necessary!
-tcIfaceRule (IfaceRule name act vars fun args rhs src_loc)
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (ruleCtxt name) $
- tcVar fun `thenTc` \ fun' ->
- tcCoreLamBndrs vars $ \ vars' ->
- mapTc tcCoreExpr args `thenTc` \ args' ->
- tcCoreExpr rhs `thenTc` \ rhs' ->
- returnTc (IfaceRuleOut fun' (Rule name act vars' args' rhs'))
-
-tcIfaceRule (IfaceRuleOut fun rule) -- Built-in rules come this way
- = tcVar fun `thenTc` \ fun' ->
- returnTc (IfaceRuleOut fun' rule)
-
-tcSourceRules :: [RenamedRuleDecl] -> TcM (LIE, [TypecheckedRuleDecl])
-tcSourceRules decls
- = mapAndUnzipTc tcSourceRule decls `thenTc` \ (lies, decls') ->
- returnTc (plusLIEs lies, decls')
-
-tcSourceRule (IfaceRuleOut fun rule) -- Built-in rules come this way
- -- if they are from the module being compiled
- = tcLookupId fun `thenTc` \ fun' ->
- returnTc (emptyLIE, IfaceRuleOut fun' rule)
-
-tcSourceRule (HsRule name act vars lhs rhs src_loc)
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (ruleCtxt name) $
- newTyVarTy openTypeKind `thenNF_Tc` \ rule_ty ->
+tcRules :: [LRuleDecl Name] -> TcM [LRuleDecl TcId]
+tcRules decls = mappM (wrapLocM tcRule) decls
- -- Deal with the tyvars mentioned in signatures
- tcAddScopedTyVars (collectRuleBndrSigTys vars) (
+tcRule :: RuleDecl Name -> TcM (RuleDecl TcId)
+tcRule (HsRule name act vars lhs rhs)
+ = addErrCtxt (ruleCtxt name) $
+ traceTc (ptext SLIT("---- Rule ------")
+ <+> ppr name) `thenM_`
+ newTyFlexiVarTy openTypeKind `thenM` \ rule_ty ->
- -- Ditto forall'd variables
- mapNF_Tc new_id vars `thenNF_Tc` \ ids ->
- tcExtendLocalValEnv ids $
-
+ -- Deal with the tyvars mentioned in signatures
+ tcRuleBndrs vars (\ ids ->
-- Now LHS and RHS
- tcMonoExpr lhs rule_ty `thenTc` \ (lhs', lhs_lie) ->
- tcMonoExpr rhs rule_ty `thenTc` \ (rhs', rhs_lie) ->
-
- returnTc (ids, lhs', rhs', lhs_lie, rhs_lie)
- ) `thenTc` \ (ids, lhs', rhs', lhs_lie, 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) ->
-- Check that LHS has no overloading at all
- tcSimplifyToDicts lhs_lie `thenTc` \ (lhs_dicts, lhs_binds) ->
+ getLIE (tcSimplifyToDicts lhs_lie) `thenM` \ (lhs_binds, lhs_dicts) ->
-- Gather the template variables and tyvars
let
-- 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))
--
- -- It's still conceivable that there may be type variables mentioned
- -- in the LHS, but not in the type of the lhs, nor in the binders.
- -- They'll get zapped to (), but that's over-constraining really.
- -- Let's see if we get a problem.
+ -- 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)
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
tcSimplifyInferCheck (text "tcRule")
forall_tvs
- lhs_dicts rhs_lie `thenTc` \ (forall_tvs1, lie', rhs_binds) ->
-
- returnTc (lie', HsRule name act
- (map RuleBndr (forall_tvs1 ++ tpl_ids)) -- yuk
- (mkHsLet lhs_binds lhs')
- (mkHsLet rhs_binds rhs')
- src_loc)
+ lhs_dicts rhs_lie `thenM` \ (forall_tvs1, rhs_binds) ->
+ mappM zonkQuantifiedTyVar forall_tvs1 `thenM` \ forall_tvs2 ->
+ -- This zonk is exactly the same as the one in TcBinds.tcBindWithSigs
+
+ returnM (HsRule name act
+ (map (RuleBndr . noLoc) (forall_tvs2 ++ tpl_ids)) -- yuk
+ (mkHsDictLet lhs_binds lhs')
+ (mkHsDictLet rhs_binds rhs'))
where
- new_id (RuleBndr var) = newTyVarTy openTypeKind `thenNF_Tc` \ ty ->
- returnNF_Tc (mkLocalId var ty)
- new_id (RuleBndrSig var rn_ty) = tcHsSigType (RuleSigCtxt var) rn_ty `thenTc` \ ty ->
- returnNF_Tc (mkLocalId var ty)
+
+tcRuleBndrs [] thing_inside = thing_inside []
+tcRuleBndrs (RuleBndr var : vars) thing_inside
+ = do { ty <- newTyFlexiVarTy 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 $
+ tcExtendIdEnv [id] $
+ tcRuleBndrs vars (\ids -> thing_inside (id:ids)) }
ruleCtxt name = ptext SLIT("When checking the transformation rule") <+>
doubleQuotes (ftext name)
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