\section[TcRules]{Typechecking transformation rules}
\begin{code}
-module TcRules ( tcIfaceRules, tcSourceRules ) where
+module TcRules ( tcRules ) where
#include "HsVersions.h"
-import HsSyn ( RuleDecl(..), RuleBndr(..) )
+import HsSyn ( RuleDecl(..), RuleBndr(..), collectRuleBndrSigTys )
import CoreSyn ( CoreRule(..) )
import RnHsSyn ( RenamedRuleDecl )
-import HscTypes ( PackageRuleBase )
import TcHsSyn ( TypecheckedRuleDecl, mkHsLet )
-import TcMonad
-import TcSimplify ( tcSimplifyToDicts, tcSimplifyAndCheck )
-import TcType ( zonkTcTypes, zonkTcTyVarToTyVar, newTyVarTy )
+import TcRnMonad
+import TcSimplify ( tcSimplifyToDicts, tcSimplifyInferCheck )
+import TcMType ( newTyVarTy )
+import TcType ( tyVarsOfTypes, openTypeKind )
import TcIfaceSig ( tcCoreExpr, tcCoreLamBndrs, tcVar )
-import TcMonoType ( kcHsSigType, tcHsSigType, tcTyVars, checkSigTyVars )
-import TcExpr ( tcExpr )
-import TcEnv ( tcExtendLocalValEnv, tcExtendTyVarEnv, tcGetGlobalTyVars, isLocalThing )
-import Rules ( extendRuleBase )
-import Inst ( LIE, plusLIEs, instToId )
-import Id ( idType, idName, mkVanillaId )
-import Module ( Module )
-import VarSet
-import Type ( tyVarsOfTypes, openTypeKind )
-import Bag ( bagToList )
-import List ( partition )
+import TcMonoType ( tcHsSigType, UserTypeCtxt(..), tcAddScopedTyVars )
+import TcExpr ( tcMonoExpr )
+import TcEnv ( tcExtendLocalValEnv )
+import Inst ( instToId )
+import Id ( idType, mkLocalId )
import Outputable
\end{code}
\begin{code}
-tcIfaceRules :: PackageRuleBase -> Module -> [RenamedRuleDecl]
- -> TcM (PackageRuleBase, [TypecheckedRuleDecl])
-tcIfaceRules pkg_rule_base mod decls
- = mapTc tcIfaceRule decls `thenTc` \ new_rules ->
- let
- (local_rules, imported_rules) = partition is_local new_rules
- new_rule_base = foldl add pkg_rule_base imported_rules
- in
- returnTc (new_rule_base, local_rules)
- where
- add rule_base (IfaceRuleOut id rule) = extendRuleBase rule_base (id, rule)
-
- -- When relinking this module from its interface-file decls
- -- we'll have IfaceRules that are in fact local to this module
- is_local (IfaceRuleOut n _) = isLocalThing mod n
- is_local other = True
-
-tcIfaceRule :: RenamedRuleDecl -> TcM TypecheckedRuleDecl
- -- No zonking necessary!
-tcIfaceRule (IfaceRule name vars fun args rhs src_loc)
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (ruleCtxt name) $
- tcVar fun `thenTc` \ fun' ->
+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' ->
- mapTc tcCoreExpr args `thenTc` \ args' ->
- tcCoreExpr rhs `thenTc` \ rhs' ->
- returnTc (IfaceRuleOut fun' (Rule name vars' args' rhs'))
+ 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)
-tcSourceRules :: [RenamedRuleDecl] -> TcM (LIE, [TypecheckedRuleDecl])
-tcSourceRules decls
- = mapAndUnzipTc tcSourceRule decls `thenTc` \ (lies, decls') ->
- returnTc (plusLIEs lies, decls')
-
-tcSourceRule (HsRule name sig_tvs vars lhs rhs src_loc)
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (ruleCtxt name) $
- newTyVarTy openTypeKind `thenNF_Tc` \ rule_ty ->
+tcRule (HsRule name act vars lhs rhs src_loc)
+ = addSrcLoc src_loc $
+ addErrCtxt (ruleCtxt name) $
+ newTyVarTy openTypeKind `thenM` \ rule_ty ->
-- Deal with the tyvars mentioned in signatures
- tcTyVars sig_tvs (mapTc_ kcHsSigType sig_tys) `thenTc` \ sig_tyvars ->
- tcExtendTyVarEnv sig_tyvars (
+ tcAddScopedTyVars (collectRuleBndrSigTys vars) (
-- Ditto forall'd variables
- mapNF_Tc new_id vars `thenNF_Tc` \ ids ->
- tcExtendLocalValEnv [(idName id, id) | id <- ids] $
+ mappM new_id vars `thenM` \ ids ->
+ tcExtendLocalValEnv ids $
-- Now LHS and RHS
- tcExpr lhs rule_ty `thenTc` \ (lhs', lhs_lie) ->
- tcExpr rhs rule_ty `thenTc` \ (rhs', rhs_lie) ->
+ getLIE (tcMonoExpr lhs rule_ty) `thenM` \ (lhs', lhs_lie) ->
+ getLIE (tcMonoExpr rhs rule_ty) `thenM` \ (rhs', rhs_lie) ->
- returnTc (sig_tyvars, ids, lhs', rhs', lhs_lie, rhs_lie)
- ) `thenTc` \ (sig_tyvars, ids, lhs', rhs', lhs_lie, 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) ->
- checkSigTyVars sig_tyvars emptyVarSet `thenTc_`
+ getLIE (tcSimplifyToDicts lhs_lie) `thenM` \ (lhs_binds, lhs_dicts) ->
-- Gather the template variables and tyvars
let
- tpl_ids = map instToId (bagToList lhs_dicts) ++ ids
+ tpl_ids = map instToId lhs_dicts ++ ids
-- IMPORTANT! We *quantify* over any dicts that appear in the LHS
-- Reason:
-- b) We'd like to make available the dictionaries bound
-- on the LHS in the RHS, so quantifying over them is good
-- See the 'lhs_dicts' in tcSimplifyAndCheck for the RHS
- in
- -- Gather type variables to quantify over
- -- and turn them into real TyVars (just as in TcBinds.tcBindWithSigs)
- zonkTcTypes (rule_ty : map idType tpl_ids) `thenNF_Tc` \ zonked_tys ->
- tcGetGlobalTyVars `thenNF_Tc` \ free_tyvars ->
- let
- poly_tyvars = tyVarsOfTypes zonked_tys `minusVarSet` free_tyvars
- -- There can be tyvars free in the environment, if there are
- -- monomorphic overloaded top-level bindings. Sigh.
+ -- We initially quantify over any tyvars free in *either* the rule
+ -- *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))
+ --
+ -- 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
- mapTc zonkTcTyVarToTyVar (varSetElems poly_tyvars) `thenTc` \ tvs ->
-
-- RHS can be a bit more lenient. In particular,
-- we let constant dictionaries etc float outwards
- tcSimplifyAndCheck (text "tcRule") (mkVarSet tvs)
- lhs_dicts rhs_lie `thenTc` \ (lie', rhs_binds) ->
-
- returnTc (lie', HsRule name tvs
- (map RuleBndr tpl_ids) -- yuk
- (mkHsLet lhs_binds lhs')
- (mkHsLet rhs_binds rhs')
- src_loc)
+ --
+ -- 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 `thenM` \ (forall_tvs1, rhs_binds) ->
+
+ returnM (HsRule name act
+ (map RuleBndr (forall_tvs1 ++ tpl_ids)) -- yuk
+ (mkHsLet lhs_binds lhs')
+ (mkHsLet rhs_binds rhs')
+ src_loc)
where
- sig_tys = [t | RuleBndrSig _ t <- vars]
-
- new_id (RuleBndr var) = newTyVarTy openTypeKind `thenNF_Tc` \ ty ->
- returnNF_Tc (mkVanillaId var ty)
- new_id (RuleBndrSig var rn_ty) = tcHsSigType rn_ty `thenTc` \ ty ->
- returnNF_Tc (mkVanillaId var ty)
+ new_id (RuleBndr var) = newTyVarTy openTypeKind `thenM` \ ty ->
+ returnM (mkLocalId var ty)
+ new_id (RuleBndrSig var rn_ty) = tcHsSigType (RuleSigCtxt var) rn_ty `thenM` \ ty ->
+ returnM (mkLocalId var ty)
ruleCtxt name = ptext SLIT("When checking the transformation rule") <+>
- doubleQuotes (ptext name)
+ doubleQuotes (ftext name)
\end{code}
projects / ghc-hetmet.git / blobdiff