X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcBinds.lhs;h=c4e1b92f6c981640dce050094c6cfaeafa1b4d51;hb=ff818166a0a06e77becad9e28ed116f3b7f5cc8b;hp=7a2ef3f041d14caaa0b11fb196b6f01b9d6f81e2;hpb=97583682f28694366fcefed1e9068e96d710ecbe;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcBinds.lhs b/ghc/compiler/typecheck/TcBinds.lhs index 7a2ef3f..c4e1b92 100644 --- a/ghc/compiler/typecheck/TcBinds.lhs +++ b/ghc/compiler/typecheck/TcBinds.lhs @@ -4,50 +4,54 @@ \section[TcBinds]{TcBinds} \begin{code} -module TcBinds ( tcBindsAndThen, tcTopBinds, tcMonoBinds, tcSpecSigs ) where +module TcBinds ( tcBindsAndThen, tcTopBinds, tcHsBootSigs, tcMonoBinds, tcSpecSigs ) where #include "HsVersions.h" -import {-# SOURCE #-} TcMatches ( tcGRHSs, tcMatchesFun ) -import {-# SOURCE #-} TcExpr ( tcExpr, tcMonoExpr ) +import {-# SOURCE #-} TcMatches ( tcGRHSsPat, tcMatchesFun ) +import {-# SOURCE #-} TcExpr ( tcCheckSigma, tcCheckRho ) -import CmdLineOpts ( DynFlag(Opt_NoMonomorphismRestriction) ) -import HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..), - Match(..), HsMatchContext(..), mkMonoBind, - collectMonoBinders, andMonoBinds, - collectSigTysFromMonoBinds +import CmdLineOpts ( DynFlag(Opt_MonomorphismRestriction) ) +import HsSyn ( HsExpr(..), HsBind(..), LHsBinds, Sig(..), + LSig, Match(..), HsBindGroup(..), IPBind(..), + HsType(..), hsLTyVarNames, isVanillaLSig, + LPat, GRHSs, MatchGroup(..), emptyLHsBinds, isEmptyLHsBinds, + collectHsBindBinders, collectPatBinders, pprPatBind ) -import RnHsSyn ( RenamedHsBinds, RenamedSig, RenamedMonoBinds ) -import TcHsSyn ( TcHsBinds, TcMonoBinds, TcId, zonkId, mkHsLet ) +import TcHsSyn ( TcId, TcDictBinds, zonkId, mkHsLet ) import TcRnMonad -import Inst ( InstOrigin(..), newDicts, newIPDict, instToId ) -import TcEnv ( tcExtendLocalValEnv, tcExtendLocalValEnv2, newLocalName ) -import TcUnify ( unifyTauTyLists, checkSigTyVarsWrt, sigCtxt ) +import Inst ( InstOrigin(..), newDictsAtLoc, newIPDict, instToId ) +import TcEnv ( tcExtendIdEnv, tcExtendIdEnv2, tcExtendTyVarEnv2, + newLocalName, tcLookupLocalIds, pprBinders, + tcGetGlobalTyVars ) +import TcUnify ( Expected(..), tcInfer, unifyTheta, + bleatEscapedTvs, sigCtxt ) import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck, tcSimplifyRestricted, tcSimplifyToDicts, tcSimplifyIPs ) -import TcMonoType ( tcHsSigType, UserTypeCtxt(..), TcSigInfo(..), - tcTySig, maybeSig, tcSigPolyId, tcSigMonoId, tcAddScopedTyVars +import TcHsType ( tcHsSigType, UserTypeCtxt(..), tcAddLetBoundTyVars, + TcSigInfo(..), TcSigFun, lookupSig ) -import TcPat ( tcPat, tcSubPat, tcMonoPatBndr ) +import TcPat ( tcPat, PatCtxt(..) ) import TcSimplify ( bindInstsOfLocalFuns ) -import TcMType ( newTyVar, newTyVarTy, newHoleTyVarTy, - zonkTcTyVarToTyVar, readHoleResult - ) -import TcType ( TcTyVar, mkTyVarTy, mkForAllTys, mkFunTys, tyVarsOfType, - mkPredTy, mkForAllTy, isUnLiftedType, - unliftedTypeKind, liftedTypeKind, openTypeKind, eqKind - ) - -import CoreFVs ( idFreeTyVars ) +import TcMType ( newTyFlexiVarTy, zonkQuantifiedTyVar, + tcInstSigType, zonkTcTypes, zonkTcTyVar ) +import TcType ( TcTyVar, SkolemInfo(SigSkol), + TcTauType, TcSigmaType, + mkTyVarTy, mkForAllTys, mkFunTys, tyVarsOfType, + mkForAllTy, isUnLiftedType, tcGetTyVar, + mkTyVarTys, tidyOpenTyVar, tidyOpenType ) +import Kind ( argTypeKind ) +import VarEnv ( TyVarEnv, emptyVarEnv, lookupVarEnv, extendVarEnv, emptyTidyEnv ) +import TysPrim ( alphaTyVar ) import Id ( mkLocalId, mkSpecPragmaId, setInlinePragma ) import Var ( idType, idName ) -import Name ( Name, getSrcLoc ) +import Name ( Name ) import NameSet -import Var ( tyVarKind ) import VarSet +import SrcLoc ( Located(..), unLoc, noLoc, getLoc ) import Bag -import Util ( isIn, equalLength ) +import Util ( isIn ) import BasicTypes ( TopLevelFlag(..), RecFlag(..), isNonRec, isRec, isNotTopLevel, isAlwaysActive ) import FiniteMap ( listToFM, lookupFM ) @@ -87,114 +91,134 @@ At the top-level the LIE is sure to contain nothing but constant dictionaries, which we resolve at the module level. \begin{code} -tcTopBinds :: RenamedHsBinds -> TcM (TcMonoBinds, TcLclEnv) +tcTopBinds :: [HsBindGroup Name] -> TcM (LHsBinds TcId, TcLclEnv) -- Note: returning the TcLclEnv is more than we really -- want. The bit we care about is the local bindings -- and the free type variables thereof tcTopBinds binds - = tc_binds_and_then TopLevel glue binds $ - getLclEnv `thenM` \ env -> - returnM (EmptyMonoBinds, env) + = tc_binds_and_then TopLevel glue binds $ + do { env <- getLclEnv + ; return (emptyLHsBinds, env) } where -- The top level bindings are flattened into a giant -- implicitly-mutually-recursive MonoBinds - glue binds1 (binds2, env) = (flatten binds1 `AndMonoBinds` binds2, env) - flatten EmptyBinds = EmptyMonoBinds - flatten (b1 `ThenBinds` b2) = flatten b1 `AndMonoBinds` flatten b2 - flatten (MonoBind b _ _) = b - -- Can't have a IPBinds at top level - + glue (HsBindGroup binds1 _ _) (binds2, env) = (binds1 `unionBags` binds2, env) + glue (HsIPBinds _) _ = panic "Top-level HsIpBinds" + -- Can't have a HsIPBinds at top level + +tcHsBootSigs :: [HsBindGroup Name] -> TcM (LHsBinds TcId, TcLclEnv) +-- A hs-boot file has only one BindGroup, and it only has type +-- signatures in it. The renamer checked all this +tcHsBootSigs [HsBindGroup _ sigs _] + = do { ids <- mapM (addLocM tc_sig) (filter isVanillaLSig sigs) + ; tcExtendIdEnv ids $ do + { env <- getLclEnv + ; return (emptyLHsBinds, env) }} + where + tc_sig (Sig (L _ name) ty) + = do { sigma_ty <- tcHsSigType (FunSigCtxt name) ty + ; return (mkLocalId name sigma_ty) } tcBindsAndThen - :: (TcHsBinds -> thing -> thing) -- Combinator - -> RenamedHsBinds + :: (HsBindGroup TcId -> thing -> thing) -- Combinator + -> [HsBindGroup Name] -> TcM thing -> TcM thing tcBindsAndThen = tc_binds_and_then NotTopLevel -tc_binds_and_then top_lvl combiner EmptyBinds do_next - = do_next -tc_binds_and_then top_lvl combiner (MonoBind EmptyMonoBinds sigs is_rec) do_next +tc_binds_and_then top_lvl combiner [] do_next = do_next +tc_binds_and_then top_lvl combiner (group : groups) do_next + = tc_bind_and_then top_lvl combiner group $ + tc_binds_and_then top_lvl combiner groups do_next -tc_binds_and_then top_lvl combiner (ThenBinds b1 b2) do_next - = tc_binds_and_then top_lvl combiner b1 $ - tc_binds_and_then top_lvl combiner b2 $ - do_next - -tc_binds_and_then top_lvl combiner (IPBinds binds is_with) do_next - = getLIE do_next `thenM` \ (result, expr_lie) -> - mapAndUnzipM tc_ip_bind binds `thenM` \ (avail_ips, binds') -> +tc_bind_and_then top_lvl combiner (HsIPBinds binds) do_next + = getLIE do_next `thenM` \ (result, expr_lie) -> + mapAndUnzipM (wrapLocSndM tc_ip_bind) binds `thenM` \ (avail_ips, binds') -> -- If the binding binds ?x = E, we must now -- discharge any ?x constraints in expr_lie tcSimplifyIPs avail_ips expr_lie `thenM` \ dict_binds -> - returnM (combiner (IPBinds binds' is_with) $ - combiner (mkMonoBind Recursive dict_binds) result) + returnM (combiner (HsIPBinds binds') $ + combiner (HsBindGroup dict_binds [] Recursive) result) where -- I wonder if we should do these one at at time -- Consider ?x = 4 -- ?y = ?x + 1 - tc_ip_bind (ip, expr) - = newTyVarTy openTypeKind `thenM` \ ty -> - getSrcLocM `thenM` \ loc -> - newIPDict (IPBind ip) ip ty `thenM` \ (ip', ip_inst) -> - tcMonoExpr expr ty `thenM` \ expr' -> - returnM (ip_inst, (ip', expr')) - -tc_binds_and_then top_lvl combiner (MonoBind bind sigs is_rec) do_next - = -- BRING ANY SCOPED TYPE VARIABLES INTO SCOPE - -- Notice that they scope over - -- a) the type signatures in the binding group - -- b) the bindings in the group - -- c) the scope of the binding group (the "in" part) - tcAddScopedTyVars (collectSigTysFromMonoBinds bind) $ - - tcBindWithSigs top_lvl bind sigs is_rec `thenM` \ (poly_binds, poly_ids) -> - + tc_ip_bind (IPBind ip expr) + = newTyFlexiVarTy argTypeKind `thenM` \ ty -> + newIPDict (IPBindOrigin ip) ip ty `thenM` \ (ip', ip_inst) -> + tcCheckRho expr ty `thenM` \ expr' -> + returnM (ip_inst, (IPBind ip' expr')) + +tc_bind_and_then top_lvl combiner (HsBindGroup binds sigs is_rec) do_next + | isEmptyLHsBinds binds + = do_next + | otherwise + = -- BRING ANY SCOPED TYPE VARIABLES INTO SCOPE + -- Notice that they scope over + -- a) the type signatures in the binding group + -- b) the bindings in the group + -- c) the scope of the binding group (the "in" part) + tcAddLetBoundTyVars binds $ + case top_lvl of - TopLevel -- For the top level don't bother will all this - -- bindInstsOfLocalFuns stuff. All the top level - -- things are rec'd together anyway, so it's fine to - -- leave them to the tcSimplifyTop, and quite a bit faster too - -- - -- Subtle (and ugly) point: furthermore at top level we - -- return the TcLclEnv, which contains the LIE var; we - -- don't want to return the wrong one! - -> tc_body poly_ids `thenM` \ (prag_binds, thing) -> - returnM (combiner (mkMonoBind Recursive (poly_binds `andMonoBinds` prag_binds)) - thing) - - NotTopLevel -- For nested bindings we must - -> getLIE (tc_body poly_ids) `thenM` \ ((prag_binds, thing), lie) -> - - -- Create specialisations of functions bound here - bindInstsOfLocalFuns lie poly_ids `thenM` \ lie_binds -> - - -- We want to keep non-recursive things non-recursive - -- so that we desugar unlifted bindings correctly - if isRec is_rec then - returnM ( - combiner (mkMonoBind Recursive ( - poly_binds `andMonoBinds` - lie_binds `andMonoBinds` - prag_binds)) thing - ) - else - returnM ( - combiner (mkMonoBind NonRecursive poly_binds) $ - combiner (mkMonoBind NonRecursive prag_binds) $ - combiner (mkMonoBind Recursive lie_binds) $ - -- NB: the binds returned by tcSimplify and bindInstsOfLocalFuns - -- aren't guaranteed in dependency order (though we could change - -- that); hence the Recursive marker. - thing) + TopLevel -- For the top level don't bother will all this + -- bindInstsOfLocalFuns stuff. All the top level + -- things are rec'd together anyway, so it's fine to + -- leave them to the tcSimplifyTop, and quite a bit faster too + -> tcBindWithSigs top_lvl binds sigs is_rec `thenM` \ (poly_binds, poly_ids) -> + tc_body poly_ids `thenM` \ (prag_binds, thing) -> + returnM (combiner (HsBindGroup + (poly_binds `unionBags` prag_binds) + [] -- no sigs + Recursive) + thing) + + NotTopLevel -- For nested bindings we must do the bindInstsOfLocalFuns thing. + | not (isRec is_rec) -- Non-recursive group + -> -- We want to keep non-recursive things non-recursive + -- so that we desugar unlifted bindings correctly + tcBindWithSigs top_lvl binds sigs is_rec `thenM` \ (poly_binds, poly_ids) -> + getLIE (tc_body poly_ids) `thenM` \ ((prag_binds, thing), lie) -> + + -- Create specialisations of functions bound here + bindInstsOfLocalFuns lie poly_ids `thenM` \ lie_binds -> + + returnM ( + combiner (HsBindGroup poly_binds [] NonRecursive) $ + combiner (HsBindGroup prag_binds [] NonRecursive) $ + combiner (HsBindGroup lie_binds [] Recursive) $ + -- NB: the binds returned by tcSimplify and + -- bindInstsOfLocalFuns aren't guaranteed in + -- dependency order (though we could change that); + -- hence the Recursive marker. + thing) + + | otherwise + -> -- NB: polymorphic recursion means that a function + -- may use an instance of itself, we must look at the LIE arising + -- from the function's own right hand side. Hence the getLIE + -- encloses the tcBindWithSigs. + + getLIE ( + tcBindWithSigs top_lvl binds sigs is_rec `thenM` \ (poly_binds, poly_ids) -> + tc_body poly_ids `thenM` \ (prag_binds, thing) -> + returnM (poly_ids, poly_binds `unionBags` prag_binds, thing) + ) `thenM` \ ((poly_ids, extra_binds, thing), lie) -> + + bindInstsOfLocalFuns lie poly_ids `thenM` \ lie_binds -> + + returnM (combiner (HsBindGroup + (extra_binds `unionBags` lie_binds) + [] Recursive) thing + ) where tc_body poly_ids -- Type check the pragmas and "thing inside" = -- Extend the environment to bind the new polymorphic Ids - tcExtendLocalValEnv poly_ids $ + tcExtendIdEnv poly_ids $ -- Build bindings and IdInfos corresponding to user pragmas tcSpecSigs sigs `thenM` \ prag_binds -> @@ -223,131 +247,117 @@ so all the clever stuff is in here. as the Name in the tc_ty_sig \begin{code} -tcBindWithSigs - :: TopLevelFlag - -> RenamedMonoBinds - -> [RenamedSig] -- Used solely to get INLINE, NOINLINE sigs - -> RecFlag - -> TcM (TcMonoBinds, [TcId]) - -tcBindWithSigs top_lvl mbind sigs is_rec - = -- TYPECHECK THE SIGNATURES - recoverM (returnM []) ( - mappM tcTySig [sig | sig@(Sig name _ _) <- sigs] - ) `thenM` \ tc_ty_sigs -> +tcBindWithSigs :: TopLevelFlag + -> LHsBinds Name + -> [LSig Name] + -> RecFlag + -> TcM (LHsBinds TcId, [TcId]) + -- The returned TcIds are guaranteed zonked + +tcBindWithSigs top_lvl mbind sigs is_rec = do + { -- TYPECHECK THE SIGNATURES + tc_ty_sigs <- recoverM (returnM []) $ + tcTySigs (filter isVanillaLSig sigs) + ; let lookup_sig = lookupSig tc_ty_sigs -- SET UP THE MAIN RECOVERY; take advantage of any type sigs - recoverM ( - -- If typechecking the binds fails, then return with each - -- signature-less binder given type (forall a.a), to minimise subsequent - -- error messages - newTyVar liftedTypeKind `thenM` \ alpha_tv -> - let - forall_a_a = mkForAllTy alpha_tv (mkTyVarTy alpha_tv) - binder_names = collectMonoBinders mbind - poly_ids = map mk_dummy binder_names - mk_dummy name = case maybeSig tc_ty_sigs name of - Just sig -> tcSigPolyId sig -- Signature - Nothing -> mkLocalId name forall_a_a -- No signature - in - traceTc (text "tcBindsWithSigs: error recovery" <+> ppr binder_names) `thenM_` - returnM (EmptyMonoBinds, poly_ids) - ) $ - - -- TYPECHECK THE BINDINGS - getLIE (tcMonoBinds mbind tc_ty_sigs is_rec) `thenM` \ ((mbind', binder_names, mono_ids), lie_req) -> - let - tau_tvs = foldr (unionVarSet . tyVarsOfType . idType) emptyVarSet mono_ids - in - - -- GENERALISE - -- (it seems a bit crude to have to do getLIE twice, - -- but I can't see a better way just now) - addSrcLoc (minimum (map getSrcLoc binder_names)) $ - addErrCtxt (genCtxt binder_names) $ - getLIE (generalise binder_names mbind tau_tvs lie_req tc_ty_sigs) - `thenM` \ ((tc_tyvars_to_gen, dict_binds, dict_ids), lie_free) -> - - - -- ZONK THE GENERALISED TYPE VARIABLES TO REAL TyVars - -- This commits any unbound kind variables to boxed kind, by unification - -- It's important that the final quanfified type variables - -- are fully zonked, *including boxity*, because they'll be - -- included in the forall types of the polymorphic Ids. - -- At calls of these Ids we'll instantiate fresh type variables from - -- them, and we use their boxity then. - mappM zonkTcTyVarToTyVar tc_tyvars_to_gen `thenM` \ real_tyvars_to_gen -> - - -- ZONK THE Ids - -- It's important that the dict Ids are zonked, including the boxity set - -- in the previous step, because they are later used to form the type of - -- the polymorphic thing, and forall-types must be zonked so far as - -- their bound variables are concerned - mappM zonkId dict_ids `thenM` \ zonked_dict_ids -> - mappM zonkId mono_ids `thenM` \ zonked_mono_ids -> + ; recoverM (recoveryCode mbind lookup_sig) $ do + + { traceTc (ptext SLIT("--------------------------------------------------------")) + ; traceTc (ptext SLIT("Bindings for") <+> ppr (collectHsBindBinders mbind)) + + -- TYPECHECK THE BINDINGS + ; ((mbind', mono_bind_infos), lie_req) + <- getLIE (tcMonoBinds mbind lookup_sig is_rec) + + -- CHECK FOR UNLIFTED BINDINGS + -- These must be non-recursive etc, and are not generalised + -- They desugar to a case expression in the end + ; zonked_mono_tys <- zonkTcTypes (map getMonoType mono_bind_infos) + ; if any isUnLiftedType zonked_mono_tys then + do { -- Unlifted bindings + checkUnliftedBinds top_lvl is_rec mbind + ; extendLIEs lie_req + ; let exports = zipWith mk_export mono_bind_infos zonked_mono_tys + mk_export (name, Nothing, mono_id) mono_ty = ([], mkLocalId name mono_ty, mono_id) + mk_export (name, Just sig, mono_id) mono_ty = ([], sig_id sig, mono_id) + + ; return ( unitBag $ noLoc $ AbsBinds [] [] exports emptyNameSet mbind', + [poly_id | (_, poly_id, _) <- exports]) } -- Guaranteed zonked + + else do -- The normal lifted case: GENERALISE + { is_unres <- isUnRestrictedGroup mbind tc_ty_sigs + ; (tyvars_to_gen, dict_binds, dict_ids) + <- setSrcSpan (getLoc (head (bagToList mbind))) $ + -- TODO: location a bit awkward, but the mbinds have been + -- dependency analysed and may no longer be adjacent + addErrCtxt (genCtxt (bndrNames mono_bind_infos)) $ + generalise top_lvl is_unres mono_bind_infos tc_ty_sigs lie_req + + -- FINALISE THE QUANTIFIED TYPE VARIABLES + -- The quantified type variables often include meta type variables + -- we want to freeze them into ordinary type variables, and + -- default their kind (e.g. from OpenTypeKind to TypeKind) + ; tyvars_to_gen' <- mappM zonkQuantifiedTyVar tyvars_to_gen -- BUILD THE POLYMORPHIC RESULT IDs - let - exports = zipWith mk_export binder_names zonked_mono_ids + ; let + exports = map mk_export mono_bind_infos poly_ids = [poly_id | (_, poly_id, _) <- exports] - dict_tys = map idType zonked_dict_ids + dict_tys = map idType dict_ids - inlines = mkNameSet [name | InlineSig True name _ loc <- sigs] + inlines = mkNameSet [ name + | L _ (InlineSig True (L _ name) _) <- sigs] -- Any INLINE sig (regardless of phase control) -- makes the RHS look small - inline_phases = listToFM [(name, phase) | InlineSig _ name phase _ <- sigs, - not (isAlwaysActive phase)] + inline_phases = listToFM [ (name, phase) + | L _ (InlineSig _ (L _ name) phase) <- sigs, + not (isAlwaysActive phase)] -- Set the IdInfo field to control the inline phase -- AlwaysActive is the default, so don't bother with them + add_inlines id = attachInlinePhase inline_phases id - mk_export binder_name zonked_mono_id - = (tyvars, - attachInlinePhase inline_phases poly_id, - zonked_mono_id) + mk_export (binder_name, mb_sig, mono_id) + = case mb_sig of + Just sig -> (sig_tvs sig, add_inlines (sig_id sig), mono_id) + Nothing -> (tyvars_to_gen', add_inlines new_poly_id, mono_id) where - (tyvars, poly_id) = - case maybeSig tc_ty_sigs binder_name of - Just (TySigInfo sig_poly_id sig_tyvars _ _ _ _ _) -> - (sig_tyvars, sig_poly_id) - Nothing -> (real_tyvars_to_gen, new_poly_id) - new_poly_id = mkLocalId binder_name poly_ty - poly_ty = mkForAllTys real_tyvars_to_gen + poly_ty = mkForAllTys tyvars_to_gen' $ mkFunTys dict_tys - $ idType zonked_mono_id - -- It's important to build a fully-zonked poly_ty, because - -- we'll slurp out its free type variables when extending the - -- local environment (tcExtendLocalValEnv); if it's not zonked - -- it appears to have free tyvars that aren't actually free - -- at all. - in - - traceTc (text "binding:" <+> ppr ((zonked_dict_ids, dict_binds), - exports, map idType poly_ids)) `thenM_` - - -- Check for an unlifted, non-overloaded group - -- In that case we must make extra checks - if any (isUnLiftedType . idType) zonked_mono_ids && null zonked_dict_ids - then -- Some bindings are unlifted - checkUnliftedBinds top_lvl is_rec real_tyvars_to_gen mbind `thenM_` - - extendLIEs lie_req `thenM_` - returnM ( - AbsBinds [] [] exports inlines mbind', - -- Do not generate even any x=y bindings - poly_ids + $ idType mono_id + + -- ZONK THE poly_ids, because they are used to extend the type + -- environment; see the invariant on TcEnv.tcExtendIdEnv + ; zonked_poly_ids <- mappM zonkId poly_ids + + ; traceTc (text "binding:" <+> ppr ((dict_ids, dict_binds), + exports, map idType zonked_poly_ids)) + + ; return ( + unitBag $ noLoc $ + AbsBinds tyvars_to_gen' + dict_ids + exports + inlines + (dict_binds `unionBags` mbind'), + zonked_poly_ids ) - - else -- The normal case - extendLIEs lie_free `thenM_` - returnM ( - AbsBinds real_tyvars_to_gen - zonked_dict_ids - exports - inlines - (dict_binds `andMonoBinds` mbind'), - poly_ids - ) + } } } + +-- If typechecking the binds fails, then return with each +-- signature-less binder given type (forall a.a), to minimise +-- subsequent error messages +recoveryCode mbind lookup_sig + = do { traceTc (text "tcBindsWithSigs: error recovery" <+> ppr binder_names) + ; return (emptyLHsBinds, poly_ids) } + where + forall_a_a = mkForAllTy alphaTyVar (mkTyVarTy alphaTyVar) + binder_names = collectHsBindBinders mbind + poly_ids = map mk_dummy binder_names + mk_dummy name = case lookup_sig name of + Just sig -> sig_id sig -- Signature + Nothing -> mkLocalId name forall_a_a -- No signature attachInlinePhase inline_phases bndr = case lookupFM inline_phases (idName bndr) of @@ -357,31 +367,15 @@ attachInlinePhase inline_phases bndr -- Check that non-overloaded unlifted bindings are -- a) non-recursive, -- b) not top level, --- c) non-polymorphic --- d) not a multiple-binding group (more or less implied by (a)) - -checkUnliftedBinds top_lvl is_rec real_tyvars_to_gen mbind - = ASSERT( not (any ((eqKind unliftedTypeKind) . tyVarKind) real_tyvars_to_gen) ) - -- The instCantBeGeneralised stuff in tcSimplify should have - -- already raised an error if we're trying to generalise an - -- unboxed tyvar (NB: unboxed tyvars are always introduced - -- along with a class constraint) and it's better done there - -- because we have more precise origin information. - -- That's why we just use an ASSERT here. - - checkTc (isNotTopLevel top_lvl) +-- c) not a multiple-binding group (more or less implied by (a)) + +checkUnliftedBinds top_lvl is_rec mbind + = checkTc (isNotTopLevel top_lvl) (unliftedBindErr "Top-level" mbind) `thenM_` checkTc (isNonRec is_rec) (unliftedBindErr "Recursive" mbind) `thenM_` - checkTc (single_bind mbind) - (unliftedBindErr "Multiple" mbind) `thenM_` - checkTc (null real_tyvars_to_gen) - (unliftedBindErr "Polymorphic" mbind) - - where - single_bind (PatMonoBind _ _ _) = True - single_bind (FunMonoBind _ _ _ _) = True - single_bind other = False + checkTc (isSingletonBag mbind) + (unliftedBindErr "Multiple" mbind) \end{code} @@ -443,112 +437,293 @@ is doing. %************************************************************************ %* * -\subsection{getTyVarsToGen} +\subsection{tcMonoBind} %* * %************************************************************************ +@tcMonoBinds@ deals with a single @MonoBind@. +The signatures have been dealt with already. + \begin{code} -generalise binder_names mbind tau_tvs lie_req sigs = +tcMonoBinds :: LHsBinds Name + -> TcSigFun -> RecFlag + -> TcM (LHsBinds TcId, [MonoBindInfo]) + +tcMonoBinds binds lookup_sig is_rec + = do { tc_binds <- mapBagM (wrapLocM (tcLhs lookup_sig)) binds + + -- Bring (a) the scoped type variables, and (b) the Ids, into scope for the RHSs + -- For (a) it's ok to bring them all into scope at once, even + -- though each type sig should scope only over its own RHS, + -- because the renamer has sorted all that out. + ; let mono_info = getMonoBindInfo tc_binds + rhs_tvs = [ (name, mkTyVarTy tv) + | (_, Just sig, _) <- mono_info, + (name, tv) <- sig_scoped sig `zip` sig_tvs sig ] + rhs_id_env = map mk mono_info -- A binding for each term variable + + ; binds' <- tcExtendTyVarEnv2 rhs_tvs $ + tcExtendIdEnv2 rhs_id_env $ + traceTc (text "tcMonoBinds" <+> vcat [ppr n <+> ppr id <+> ppr (idType id) | (n,id) <- rhs_id_env]) `thenM_` + mapBagM (wrapLocM tcRhs) tc_binds + ; return (binds', mono_info) } + where + mk (name, Just sig, _) = (name, sig_id sig) -- Use the type sig if there is one + mk (name, Nothing, mono_id) = (name, mono_id) -- otherwise use a monomorphic version + +------------------------ +-- tcLhs typechecks the LHS of the bindings, to construct the environment in which +-- we typecheck the RHSs. Basically what we are doing is this: for each binder: +-- if there's a signature for it, use the instantiated signature type +-- otherwise invent a type variable +-- You see that quite directly in the FunBind case. +-- +-- But there's a complication for pattern bindings: +-- data T = MkT (forall a. a->a) +-- MkT f = e +-- Here we can guess a type variable for the entire LHS (which will be refined to T) +-- but we want to get (f::forall a. a->a) as the RHS environment. +-- The simplest way to do this is to typecheck the pattern, and then look up the +-- bound mono-ids. Then we want to retain the typechecked pattern to avoid re-doing +-- it; hence the TcMonoBind data type in which the LHS is done but the RHS isn't + +data TcMonoBind -- Half completed; LHS done, RHS not done + = TcFunBind MonoBindInfo (Located TcId) Bool (MatchGroup Name) + | TcPatBind [MonoBindInfo] (LPat TcId) (GRHSs Name) TcSigmaType + +type MonoBindInfo = (Name, Maybe TcSigInfo, TcId) + -- Type signature (if any), and + -- the monomorphic bound things + +bndrNames :: [MonoBindInfo] -> [Name] +bndrNames mbi = [n | (n,_,_) <- mbi] + +getMonoType :: MonoBindInfo -> TcTauType +getMonoType (_,_,mono_id) = idType mono_id + +tcLhs :: TcSigFun -> HsBind Name -> TcM TcMonoBind +tcLhs lookup_sig (FunBind (L nm_loc name) inf matches) + = do { let mb_sig = lookup_sig name + ; mono_name <- newLocalName name + ; mono_ty <- mk_mono_ty mb_sig + ; let mono_id = mkLocalId mono_name mono_ty + ; return (TcFunBind (name, mb_sig, mono_id) (L nm_loc mono_id) inf matches) } + where + mk_mono_ty (Just sig) = return (sig_tau sig) + mk_mono_ty Nothing = newTyFlexiVarTy argTypeKind - -- check for -fno-monomorphism-restriction - doptM Opt_NoMonomorphismRestriction `thenM` \ no_MR -> - let is_unrestricted | no_MR = True - | otherwise = isUnRestrictedGroup tysig_names mbind - in +tcLhs lookup_sig bind@(PatBind pat grhss _) + = do { let tc_pat exp_ty = tcPat (LetPat lookup_sig) pat exp_ty lookup_infos + ; ((pat', ex_tvs, infos), pat_ty) + <- addErrCtxt (patMonoBindsCtxt pat grhss) + (tcInfer tc_pat) - if not is_unrestricted then -- RESTRICTED CASE - -- Check signature contexts are empty - checkTc (all is_mono_sig sigs) - (restrictedBindCtxtErr binder_names) `thenM_` + -- Don't know how to deal with pattern-bound existentials yet + ; checkTc (null ex_tvs) (existentialExplode bind) + + ; return (TcPatBind infos pat' grhss pat_ty) } + where + names = collectPatBinders pat + + -- After typechecking the pattern, look up the binder + -- names, which the pattern has brought into scope. + lookup_infos :: TcM [MonoBindInfo] + lookup_infos = do { mono_ids <- tcLookupLocalIds names + ; return [ (name, lookup_sig name, mono_id) + | (name, mono_id) <- names `zip` mono_ids] } + +------------------- +tcRhs :: TcMonoBind -> TcM (HsBind TcId) +tcRhs (TcFunBind info fun'@(L _ mono_id) inf matches) + = do { matches' <- tcMatchesFun (idName mono_id) matches + (Check (idType mono_id)) + ; return (FunBind fun' inf matches') } + +tcRhs bind@(TcPatBind _ pat' grhss pat_ty) + = do { grhss' <- addErrCtxt (patMonoBindsCtxt pat' grhss) $ + tcGRHSsPat grhss (Check pat_ty) + ; return (PatBind pat' grhss' pat_ty) } + + +--------------------- +getMonoBindInfo :: Bag (Located TcMonoBind) -> [MonoBindInfo] +getMonoBindInfo tc_binds + = foldrBag (get_info . unLoc) [] tc_binds + where + get_info (TcFunBind info _ _ _) rest = info : rest + get_info (TcPatBind infos _ _ _) rest = infos ++ rest +\end{code} + + +%************************************************************************ +%* * +\subsection{getTyVarsToGen} +%* * +%************************************************************************ + +Type signatures are tricky. See Note [Signature skolems] in TcType + +\begin{code} +tcTySigs :: [LSig Name] -> TcM [TcSigInfo] +-- The trick here is that all the signatures should have the same +-- context, and we want to share type variables for that context, so that +-- all the right hand sides agree a common vocabulary for their type +-- constraints +tcTySigs [] = return [] + +tcTySigs sigs + = do { (tc_sig1 : tc_sigs) <- mappM tcTySig sigs + ; mapM (check_ctxt tc_sig1) tc_sigs + ; return (tc_sig1 : tc_sigs) } + where + -- Check tha all the signature contexts are the same + -- The type signatures on a mutually-recursive group of definitions + -- must all have the same context (or none). + -- + -- We unify them because, with polymorphic recursion, their types + -- might not otherwise be related. This is a rather subtle issue. + check_ctxt :: TcSigInfo -> TcSigInfo -> TcM () + check_ctxt sig1@(TcSigInfo { sig_theta = theta1 }) sig@(TcSigInfo { sig_theta = theta }) + = setSrcSpan (instLocSrcSpan (sig_loc sig)) $ + addErrCtxt (sigContextsCtxt sig1 sig) $ + unifyTheta theta1 theta + + +tcTySig :: LSig Name -> TcM TcSigInfo +tcTySig (L span (Sig (L _ name) ty)) + = setSrcSpan span $ + do { sigma_ty <- tcHsSigType (FunSigCtxt name) ty + ; (tvs, theta, tau) <- tcInstSigType name sigma_ty + ; loc <- getInstLoc (SigOrigin (SigSkol name)) + + ; let poly_id = mkLocalId name sigma_ty + + -- The scoped names are the ones explicitly mentioned + -- in the HsForAll. (There may be more in sigma_ty, because + -- of nested type synonyms. See Note [Scoped] with TcSigInfo.) + scoped_names = case ty of + L _ (HsForAllTy _ tvs _ _) -> hsLTyVarNames tvs + other -> [] + + ; return (TcSigInfo { sig_id = poly_id, sig_scoped = scoped_names, + sig_tvs = tvs, sig_theta = theta, sig_tau = tau, + sig_loc = loc }) } +\end{code} + +\begin{code} +generalise :: TopLevelFlag -> Bool -> [MonoBindInfo] -> [TcSigInfo] -> [Inst] + -> TcM ([TcTyVar], TcDictBinds, [TcId]) +generalise top_lvl is_unrestricted mono_infos sigs lie_req + | not is_unrestricted -- RESTRICTED CASE + = -- Check signature contexts are empty + do { checkTc (all is_mono_sig sigs) + (restrictedBindCtxtErr bndr_names) -- Now simplify with exactly that set of tyvars -- We have to squash those Methods - tcSimplifyRestricted doc tau_tvs lie_req `thenM` \ (qtvs, binds) -> + ; (qtvs, binds) <- tcSimplifyRestricted doc top_lvl bndr_names + tau_tvs lie_req -- Check that signature type variables are OK - checkSigsTyVars qtvs sigs `thenM` \ final_qtvs -> + ; final_qtvs <- checkSigsTyVars qtvs sigs + + ; return (final_qtvs, binds, []) } - returnM (final_qtvs, binds, []) + | null sigs -- UNRESTRICTED CASE, NO TYPE SIGS + = tcSimplifyInfer doc tau_tvs lie_req - else if null sigs then -- UNRESTRICTED CASE, NO TYPE SIGS - tcSimplifyInfer doc tau_tvs lie_req + | otherwise -- UNRESTRICTED CASE, WITH TYPE SIGS + = do { let sig1 = head sigs + ; sig_lie <- newDictsAtLoc (sig_loc sig1) (sig_theta sig1) + ; let -- The "sig_avails" is the stuff available. We get that from + -- the context of the type signature, BUT ALSO the lie_avail + -- so that polymorphic recursion works right (see comments at end of fn) + local_meths = [mkMethInst sig mono_id | (_, Just sig, mono_id) <- mono_infos] + sig_avails = sig_lie ++ local_meths - else -- UNRESTRICTED CASE, WITH TYPE SIGS - -- CHECKING CASE: Unrestricted group, there are type signatures - -- Check signature contexts are identical - checkSigsCtxts sigs `thenM` \ (sig_avails, sig_dicts) -> - -- Check that the needed dicts can be -- expressed in terms of the signature ones - tcSimplifyInferCheck doc tau_tvs sig_avails lie_req `thenM` \ (forall_tvs, dict_binds) -> + ; (forall_tvs, dict_binds) <- tcSimplifyInferCheck doc tau_tvs sig_avails lie_req -- Check that signature type variables are OK - checkSigsTyVars forall_tvs sigs `thenM` \ final_qtvs -> + ; final_qtvs <- checkSigsTyVars forall_tvs sigs - returnM (final_qtvs, dict_binds, sig_dicts) + ; returnM (final_qtvs, dict_binds, map instToId sig_lie) } where - tysig_names = map (idName . tcSigPolyId) sigs - is_mono_sig (TySigInfo _ _ theta _ _ _ _) = null theta + bndr_names = bndrNames mono_infos + tau_tvs = foldr (unionVarSet . tyVarsOfType . getMonoType) emptyVarSet mono_infos + is_mono_sig sig = null (sig_theta sig) + doc = ptext SLIT("type signature(s) for") <+> pprBinders bndr_names - doc = ptext SLIT("type signature(s) for") <+> pprBinders binder_names - ------------------------ - -- CHECK THAT ALL THE SIGNATURE CONTEXTS ARE UNIFIABLE - -- The type signatures on a mutually-recursive group of definitions - -- must all have the same context (or none). - -- - -- We unify them because, with polymorphic recursion, their types - -- might not otherwise be related. This is a rather subtle issue. - -- ToDo: amplify -checkSigsCtxts sigs@(TySigInfo id1 sig_tvs theta1 _ _ _ src_loc : other_sigs) - = addSrcLoc src_loc $ - mappM_ check_one other_sigs `thenM_` - if null theta1 then - returnM ([], []) -- Non-overloaded type signatures - else - newDicts SignatureOrigin theta1 `thenM` \ sig_dicts -> - let - -- The "sig_avails" is the stuff available. We get that from - -- the context of the type signature, BUT ALSO the lie_avail - -- so that polymorphic recursion works right (see comments at end of fn) - sig_avails = sig_dicts ++ sig_meths - in - returnM (sig_avails, map instToId sig_dicts) - where - sig1_dict_tys = map mkPredTy theta1 - sig_meths = concat [insts | TySigInfo _ _ _ _ _ insts _ <- sigs] - - check_one sig@(TySigInfo id _ theta _ _ _ _) - = addErrCtxt (sigContextsCtxt id1 id) $ - checkTc (equalLength theta theta1) sigContextsErr `thenM_` - unifyTauTyLists sig1_dict_tys (map mkPredTy theta) + mkMethInst (TcSigInfo { sig_id = poly_id, sig_tvs = tvs, + sig_theta = theta, sig_tau = tau, sig_loc = loc }) mono_id + = Method mono_id poly_id (mkTyVarTys tvs) theta tau loc checkSigsTyVars :: [TcTyVar] -> [TcSigInfo] -> TcM [TcTyVar] checkSigsTyVars qtvs sigs - = mappM check_one sigs `thenM` \ sig_tvs_s -> - let - -- Sigh. Make sure that all the tyvars in the type sigs - -- appear in the returned ty var list, which is what we are - -- going to generalise over. Reason: we occasionally get - -- silly types like - -- type T a = () -> () - -- f :: T a - -- f () = () - -- Here, 'a' won't appear in qtvs, so we have to add it - - sig_tvs = foldr (unionVarSet . mkVarSet) emptyVarSet sig_tvs_s - all_tvs = mkVarSet qtvs `unionVarSet` sig_tvs - in - returnM (varSetElems all_tvs) + = do { gbl_tvs <- tcGetGlobalTyVars + ; sig_tvs_s <- mappM (check_sig gbl_tvs) sigs + + ; let -- Sigh. Make sure that all the tyvars in the type sigs + -- appear in the returned ty var list, which is what we are + -- going to generalise over. Reason: we occasionally get + -- silly types like + -- type T a = () -> () + -- f :: T a + -- f () = () + -- Here, 'a' won't appear in qtvs, so we have to add it + sig_tvs = foldl extendVarSetList emptyVarSet sig_tvs_s + all_tvs = varSetElems (extendVarSetList sig_tvs qtvs) + ; returnM all_tvs } where - check_one (TySigInfo id sig_tyvars sig_theta sig_tau _ _ src_loc) - = addSrcLoc src_loc $ - addErrCtxt (ptext SLIT("When checking the type signature for") - <+> quotes (ppr id)) $ - addErrCtxtM (sigCtxt id sig_tyvars sig_theta sig_tau) $ - checkSigTyVarsWrt (idFreeTyVars id) sig_tyvars -\end{code} + check_sig gbl_tvs (TcSigInfo {sig_id = id, sig_tvs = tvs, + sig_theta = theta, sig_tau = tau}) + = addErrCtxt (ptext SLIT("In the type signature for") <+> quotes (ppr id)) $ + addErrCtxtM (sigCtxt id tvs theta tau) $ + do { tvs' <- checkDistinctTyVars tvs + ; ifM (any (`elemVarSet` gbl_tvs) tvs') + (bleatEscapedTvs gbl_tvs tvs tvs') + ; return tvs' } + +checkDistinctTyVars :: [TcTyVar] -> TcM [TcTyVar] +-- (checkDistinctTyVars tvs) checks that the tvs from one type signature +-- are still all type variables, and all distinct from each other. +-- It returns a zonked set of type variables. +-- For example, if the type sig is +-- f :: forall a b. a -> b -> b +-- we want to check that 'a' and 'b' haven't +-- (a) been unified with a non-tyvar type +-- (b) been unified with each other (all distinct) + +checkDistinctTyVars sig_tvs + = do { zonked_tvs <- mapM zonk_one sig_tvs + ; foldlM check_dup emptyVarEnv (sig_tvs `zip` zonked_tvs) + ; return zonked_tvs } + where + zonk_one sig_tv = do { ty <- zonkTcTyVar sig_tv + ; return (tcGetTyVar "checkDistinctTyVars" ty) } + -- 'ty' is bound to be a type variable, because SigSkolTvs + -- can only be unified with type variables + + check_dup :: TyVarEnv TcTyVar -> (TcTyVar, TcTyVar) -> TcM (TyVarEnv TcTyVar) + -- The TyVarEnv maps each zonked type variable back to its + -- corresponding user-written signature type variable + check_dup acc (sig_tv, zonked_tv) + = case lookupVarEnv acc zonked_tv of + Just sig_tv' -> bomb_out sig_tv sig_tv' + + Nothing -> return (extendVarEnv acc zonked_tv sig_tv) + + bomb_out sig_tv1 sig_tv2 + = failWithTc (ptext SLIT("Quantified type variable") <+> quotes (ppr tidy_tv1) + <+> ptext SLIT("is unified with another quantified type variable") + <+> ppr tidy_tv2) + where + (env1, tidy_tv1) = tidyOpenTyVar emptyTidyEnv sig_tv1 + (_env2, tidy_tv2) = tidyOpenTyVar env1 sig_tv2 +\end{code} + @getTyVarsToGen@ decides what type variables to generalise over. @@ -590,160 +765,25 @@ constrained tyvars. We don't use any of the results, except to find which tyvars are constrained. \begin{code} -isUnRestrictedGroup :: [Name] -- Signatures given for these - -> RenamedMonoBinds - -> Bool +isUnRestrictedGroup :: LHsBinds Name -> [TcSigInfo] -> TcM Bool +isUnRestrictedGroup binds sigs + = do { mono_restriction <- doptM Opt_MonomorphismRestriction + ; return (not mono_restriction || all_unrestricted) } + where + all_unrestricted = all (unrestricted . unLoc) (bagToList binds) + tysig_names = map (idName . sig_id) sigs + + unrestricted (PatBind other _ _) = False + unrestricted (VarBind v _) = v `is_elem` tysig_names + unrestricted (FunBind v _ matches) = unrestricted_match matches + || unLoc v `is_elem` tysig_names + + unrestricted_match (MatchGroup (L _ (Match [] _ _) : _) _) = False + -- No args => like a pattern binding + unrestricted_match other = True + -- Some args => a function binding is_elem v vs = isIn "isUnResMono" v vs - -isUnRestrictedGroup sigs (PatMonoBind other _ _) = False -isUnRestrictedGroup sigs (VarMonoBind v _) = v `is_elem` sigs -isUnRestrictedGroup sigs (FunMonoBind v _ matches _) = isUnRestrictedMatch matches || - v `is_elem` sigs -isUnRestrictedGroup sigs (AndMonoBinds mb1 mb2) = isUnRestrictedGroup sigs mb1 && - isUnRestrictedGroup sigs mb2 -isUnRestrictedGroup sigs EmptyMonoBinds = True - -isUnRestrictedMatch (Match [] _ _ : _) = False -- No args => like a pattern binding -isUnRestrictedMatch other = True -- Some args => a function binding -\end{code} - - -%************************************************************************ -%* * -\subsection{tcMonoBind} -%* * -%************************************************************************ - -@tcMonoBinds@ deals with a single @MonoBind@. -The signatures have been dealt with already. - -\begin{code} -tcMonoBinds :: RenamedMonoBinds - -> [TcSigInfo] - -> RecFlag - -> TcM (TcMonoBinds, - [Name], -- Bound names - [TcId]) -- Corresponding monomorphic bound things - -tcMonoBinds mbinds tc_ty_sigs is_rec - = tc_mb_pats mbinds `thenM` \ (complete_it, tvs, ids, lie_avail) -> - let - id_list = bagToList ids - (names, mono_ids) = unzip id_list - - -- This last defn is the key one: - -- extend the val envt with bindings for the - -- things bound in this group, overriding the monomorphic - -- ids with the polymorphic ones from the pattern - extra_val_env = case is_rec of - Recursive -> map mk_bind id_list - NonRecursive -> [] - in - -- Don't know how to deal with pattern-bound existentials yet - checkTc (isEmptyBag tvs && null lie_avail) - (existentialExplode mbinds) `thenM_` - - -- *Before* checking the RHSs, but *after* checking *all* the patterns, - -- extend the envt with bindings for all the bound ids; - -- and *then* override with the polymorphic Ids from the signatures - -- That is the whole point of the "complete_it" stuff. - -- - -- There's a further wrinkle: we have to delay extending the environment - -- until after we've dealt with any pattern-bound signature type variables - -- Consider f (x::a) = ...f... - -- We're going to check that a isn't unified with anything in the envt, - -- so f itself had better not be! So we pass the envt binding f into - -- complete_it, which extends the actual envt in TcMatches.tcMatch, after - -- dealing with the signature tyvars - - complete_it extra_val_env `thenM` \ mbinds' -> - - returnM (mbinds', names, mono_ids) - where - - mk_bind (name, mono_id) = case maybeSig tc_ty_sigs name of - Nothing -> (name, mono_id) - Just sig -> (idName poly_id, poly_id) - where - poly_id = tcSigPolyId sig - - tc_mb_pats EmptyMonoBinds - = returnM (\ xve -> returnM EmptyMonoBinds, emptyBag, emptyBag, []) - - tc_mb_pats (AndMonoBinds mb1 mb2) - = tc_mb_pats mb1 `thenM` \ (complete_it1, tvs1, ids1, lie_avail1) -> - tc_mb_pats mb2 `thenM` \ (complete_it2, tvs2, ids2, lie_avail2) -> - let - complete_it xve = complete_it1 xve `thenM` \ mb1' -> - complete_it2 xve `thenM` \ mb2' -> - returnM (AndMonoBinds mb1' mb2') - in - returnM (complete_it, - tvs1 `unionBags` tvs2, - ids1 `unionBags` ids2, - lie_avail1 ++ lie_avail2) - - tc_mb_pats (FunMonoBind name inf matches locn) - = (case maybeSig tc_ty_sigs name of - Just sig -> returnM (tcSigMonoId sig) - Nothing -> newLocalName name `thenM` \ bndr_name -> - newTyVarTy openTypeKind `thenM` \ bndr_ty -> - -- NB: not a 'hole' tyvar; since there is no type - -- signature, we revert to ordinary H-M typechecking - -- which means the variable gets an inferred tau-type - returnM (mkLocalId bndr_name bndr_ty) - ) `thenM` \ bndr_id -> - let - bndr_ty = idType bndr_id - complete_it xve = addSrcLoc locn $ - tcMatchesFun xve name bndr_ty matches `thenM` \ matches' -> - returnM (FunMonoBind bndr_id inf matches' locn) - in - returnM (complete_it, emptyBag, unitBag (name, bndr_id), []) - - tc_mb_pats bind@(PatMonoBind pat grhss locn) - = addSrcLoc locn $ - newHoleTyVarTy `thenM` \ pat_ty -> - - -- Now typecheck the pattern - -- We do now support binding fresh (not-already-in-scope) scoped - -- type variables in the pattern of a pattern binding. - -- For example, this is now legal: - -- (x::a, y::b) = e - -- The type variables are brought into scope in tc_binds_and_then, - -- so we don't have to do anything here. - - tcPat tc_pat_bndr pat pat_ty `thenM` \ (pat', tvs, ids, lie_avail) -> - readHoleResult pat_ty `thenM` \ pat_ty' -> - let - complete_it xve = addSrcLoc locn $ - addErrCtxt (patMonoBindsCtxt bind) $ - tcExtendLocalValEnv2 xve $ - tcGRHSs PatBindRhs grhss pat_ty' `thenM` \ grhss' -> - returnM (PatMonoBind pat' grhss' locn) - in - returnM (complete_it, tvs, ids, lie_avail) - - -- tc_pat_bndr is used when dealing with a LHS binder in a pattern. - -- If there was a type sig for that Id, we want to make it much - -- as if that type signature had been on the binder as a SigPatIn. - -- We check for a type signature; if there is one, we use the mono_id - -- from the signature. This is how we make sure the tau part of the - -- signature actually matches the type of the LHS; then tc_mb_pats - -- ensures the LHS and RHS have the same type - - tc_pat_bndr name pat_ty - = case maybeSig tc_ty_sigs name of - Nothing - -> newLocalName name `thenM` \ bndr_name -> - tcMonoPatBndr bndr_name pat_ty - - Just sig -> addSrcLoc (getSrcLoc name) $ - tcSubPat (idType mono_id) pat_ty `thenM` \ co_fn -> - returnM (co_fn, mono_id) - where - mono_id = tcSigMonoId sig \end{code} @@ -786,13 +826,13 @@ We used to have a form {-# SPECIALISE f :: = g #-} which promised that g implemented f at , but we do that with a RULE now: - {-# SPECIALISE (f::) = g #-} \begin{code} -tcSpecSigs :: [RenamedSig] -> TcM TcMonoBinds -tcSpecSigs (SpecSig name poly_ty src_loc : sigs) +tcSpecSigs :: [LSig Name] -> TcM (LHsBinds TcId) +tcSpecSigs (L loc (SpecSig (L nm_loc name) poly_ty) : sigs) = -- SPECIALISE f :: forall b. theta => tau = g - addSrcLoc src_loc $ + setSrcSpan loc $ addErrCtxt (valSpecSigCtxt name poly_ty) $ -- Get and instantiate its alleged specialised type @@ -800,7 +840,7 @@ tcSpecSigs (SpecSig name poly_ty src_loc : sigs) -- Check that f has a more general type, and build a RHS for -- the spec-pragma-id at the same time - getLIE (tcExpr (HsVar name) sig_ty) `thenM` \ (spec_expr, spec_lie) -> + getLIE (tcCheckSigma (L nm_loc (HsVar name)) sig_ty) `thenM` \ (spec_expr, spec_lie) -> -- Squeeze out any Methods (see comments with tcSimplifyToDicts) tcSimplifyToDicts spec_lie `thenM` \ spec_binds -> @@ -810,19 +850,18 @@ tcSpecSigs (SpecSig name poly_ty src_loc : sigs) -- dead-code-eliminate the binding we are really interested in. newLocalName name `thenM` \ spec_name -> let - spec_bind = VarMonoBind (mkSpecPragmaId spec_name sig_ty) + spec_bind = VarBind (mkSpecPragmaId spec_name sig_ty) (mkHsLet spec_binds spec_expr) in -- Do the rest and combine tcSpecSigs sigs `thenM` \ binds_rest -> - returnM (binds_rest `andMonoBinds` spec_bind) + returnM (binds_rest `snocBag` L loc spec_bind) tcSpecSigs (other_sig : sigs) = tcSpecSigs sigs -tcSpecSigs [] = returnM EmptyMonoBinds +tcSpecSigs [] = returnM emptyLHsBinds \end{code} - %************************************************************************ %* * \subsection[TcBinds-errors]{Error contexts and messages} @@ -831,8 +870,10 @@ tcSpecSigs [] = returnM EmptyMonoBinds \begin{code} -patMonoBindsCtxt bind - = hang (ptext SLIT("In a pattern binding:")) 4 (ppr bind) +-- This one is called on LHS, when pat and grhss are both Name +-- and on RHS, when pat is TcId and grhss is still Name +patMonoBindsCtxt pat grhss + = hang (ptext SLIT("In a pattern binding:")) 4 (pprPatBind pat grhss) ----------------------------------------------- valSpecSigCtxt v ty @@ -840,13 +881,15 @@ valSpecSigCtxt v ty nest 4 (ppr v <+> dcolon <+> ppr ty)] ----------------------------------------------- -sigContextsErr = ptext SLIT("Mismatched contexts") - -sigContextsCtxt s1 s2 +sigContextsCtxt sig1 sig2 = vcat [ptext SLIT("When matching the contexts of the signatures for"), - nest 2 (vcat [ppr s1 <+> dcolon <+> ppr (idType s1), - ppr s2 <+> dcolon <+> ppr (idType s2)]), + nest 2 (vcat [ppr id1 <+> dcolon <+> ppr (idType id1), + ppr id2 <+> dcolon <+> ppr (idType id2)]), ptext SLIT("The signature contexts in a mutually recursive group should all be identical")] + where + id1 = sig_id sig1 + id2 = sig_id sig2 + ----------------------------------------------- unliftedBindErr flavour mbind @@ -868,9 +911,4 @@ restrictedBindCtxtErr binder_names genCtxt binder_names = ptext SLIT("When generalising the type(s) for") <+> pprBinders binder_names - --- Used in error messages --- Use quotes for a single one; they look a bit "busy" for several -pprBinders [bndr] = quotes (ppr bndr) -pprBinders bndrs = pprWithCommas ppr bndrs \end{code}