X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcBinds.lhs;h=b52ef1ff22e5f6a0ccf9f00a295f9cb5669861b7;hb=6c872fff42025a842e8500ddbb13fdcca60eaf75;hp=d7da495859ec6e0aee012cfe689d568702bf9c06;hpb=c4f3290f3d4c2a5c2e81a97717f7fd06ee180f6d;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcBinds.lhs b/ghc/compiler/typecheck/TcBinds.lhs index d7da495..b52ef1f 100644 --- a/ghc/compiler/typecheck/TcBinds.lhs +++ b/ghc/compiler/typecheck/TcBinds.lhs @@ -1,67 +1,67 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[TcBinds]{TcBinds} \begin{code} module TcBinds ( tcBindsAndThen, tcTopBindsAndThen, - tcPragmaSigs, checkSigTyVars, tcBindWithSigs, - sigCtxt, TcSigInfo(..) ) where + tcSpecSigs, tcBindWithSigs ) where #include "HsVersions.h" -import {-# SOURCE #-} TcGRHSs ( tcGRHSsAndBinds ) +import {-# SOURCE #-} TcMatches ( tcGRHSs, tcMatchesFun ) import {-# SOURCE #-} TcExpr ( tcExpr ) -import HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..), InPat(..), - collectMonoBinders, andMonoBinds - ) -import RnHsSyn ( RenamedHsBinds, RenamedSig(..), - RenamedMonoBinds - ) -import TcHsSyn ( TcHsBinds, TcMonoBinds, - TcIdOcc(..), TcIdBndr, - tcIdType +import HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..), InPat(..), StmtCtxt(..), + collectMonoBinders, andMonoBindList, andMonoBinds ) +import RnHsSyn ( RenamedHsBinds, RenamedSig, RenamedMonoBinds ) +import TcHsSyn ( TcHsBinds, TcMonoBinds, TcId, zonkId, mkHsLet ) import TcMonad -import Inst ( Inst, LIE, emptyLIE, plusLIE, plusLIEs, InstOrigin(..), - newDicts, tyVarsOfInst, instToId, newMethodWithGivenTy, - zonkInst, pprInsts +import Inst ( Inst, LIE, emptyLIE, mkLIE, plusLIE, plusLIEs, InstOrigin(..), + newDicts, tyVarsOfInst, instToId, + getAllFunDepsOfLIE, getIPsOfLIE, zonkFunDeps ) -import TcEnv ( tcExtendLocalValEnv, tcLookupLocalValueOK, - newLocalId, newSpecPragmaId, +import TcEnv ( tcExtendLocalValEnv, + newSpecPragmaId, newLocalId, + tcLookupTyCon, tcGetGlobalTyVars, tcExtendGlobalTyVars ) -import TcMatches ( tcMatchesFun ) -import TcSimplify ( tcSimplify, tcSimplifyAndCheck ) -import TcMonoType ( tcHsType ) +import TcSimplify ( tcSimplify, tcSimplifyAndCheck, tcSimplifyToDicts ) +import TcImprove ( tcImprove ) +import TcMonoType ( tcHsSigType, checkSigTyVars, + TcSigInfo(..), tcTySig, maybeSig, sigCtxt + ) import TcPat ( tcPat ) import TcSimplify ( bindInstsOfLocalFuns ) -import TcType ( TcType, TcThetaType, TcTauType, - TcTyVarSet, TcTyVar, - newTyVarTy, newTcTyVar, tcInstSigType, tcInstSigTcType, - zonkTcType, zonkTcTypes, zonkTcThetaType, zonkTcTyVar +import TcType ( TcType, TcThetaType, + TcTyVar, + newTyVarTy, newTyVar, newTyVarTy_OpenKind, tcInstTcType, + zonkTcType, zonkTcTypes, zonkTcThetaType, zonkTcTyVarToTyVar ) -import Unify ( unifyTauTy, unifyTauTyLists ) - -import Kind ( isUnboxedTypeKind, mkTypeKind, isTypeKind, mkBoxedTypeKind ) -import MkId ( mkUserId ) -import Id ( idType, idName, idInfo, replaceIdInfo ) -import IdInfo ( IdInfo, noIdInfo, setInlinePragInfo, InlinePragInfo(..) ) -import Maybes ( maybeToBool, assocMaybe ) -import Name ( getOccName, getSrcLoc, Name ) -import Type ( mkTyVarTy, mkTyVarTys, isTyVarTy, tyVarsOfTypes, - splitSigmaTy, mkForAllTys, mkFunTys, getTyVar, mkDictTy, - splitRhoTy, mkForAllTy, splitForAllTys +import TcUnify ( unifyTauTy, unifyTauTyLists ) + +import PrelInfo ( main_NAME, ioTyCon_NAME ) + +import Id ( Id, mkVanillaId, setInlinePragma ) +import Var ( idType, idName ) +import IdInfo ( setInlinePragInfo, InlinePragInfo(..) ) +import Name ( Name, getName, getOccName, getSrcLoc ) +import NameSet +import Type ( mkTyVarTy, tyVarsOfTypes, mkTyConApp, + splitSigmaTy, mkForAllTys, mkFunTys, getTyVar, + mkPredTy, splitRhoTy, mkForAllTy, isUnLiftedType, + isUnboxedType, unboxedTypeKind, boxedTypeKind ) -import TyVar ( TyVar, tyVarKind, mkTyVarSet, minusTyVarSet, emptyTyVarSet, - elementOfTyVarSet, unionTyVarSets, tyVarSetToList - ) -import Bag ( bagToList, foldrBag, ) -import Util ( isIn, hasNoDups, assoc ) -import Unique ( Unique ) -import BasicTypes ( TopLevelFlag(..), RecFlag(..) ) +import FunDeps ( tyVarFunDep, oclose ) +import Var ( TyVar, tyVarKind ) +import VarSet +import Bag +import Util ( isIn ) +import Maybes ( maybeToBool ) +import BasicTypes ( TopLevelFlag(..), RecFlag(..), isNotTopLevel ) +import FiniteMap ( listToFM, lookupFM ) import SrcLoc ( SrcLoc ) import Outputable \end{code} @@ -100,84 +100,81 @@ dictionaries, which we resolve at the module level. \begin{code} tcTopBindsAndThen, tcBindsAndThen - :: (RecFlag -> TcMonoBinds s -> this -> that) -- Combinator + :: (RecFlag -> TcMonoBinds -> thing -> thing) -- Combinator -> RenamedHsBinds - -> TcM s (this, LIE s) - -> TcM s (that, LIE s) + -> TcM s (thing, LIE) + -> TcM s (thing, LIE) tcTopBindsAndThen = tc_binds_and_then TopLevel tcBindsAndThen = tc_binds_and_then NotTopLevel -tc_binds_and_then top_lvl combiner binds do_next - = tcBinds top_lvl binds `thenTc` \ (mbinds1, binds_lie, env, ids) -> - tcSetEnv env $ +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 + = do_next - -- Now do whatever happens next, in the augmented envt - do_next `thenTc` \ (thing, thing_lie) -> - - -- Create specialisations of functions bound here - -- Nota Bene: we glom the bindings all together in a single - -- recursive group ("recursive" passed to combiner, below) - -- so that we can do thsi bindInsts thing once for all the bindings - -- and the thing inside. This saves a quadratic-cost algorithm - -- when there's a long sequence of bindings. - bindInstsOfLocalFuns (binds_lie `plusLIE` thing_lie) ids `thenTc` \ (final_lie, mbinds2) -> - - -- All done - let - final_mbinds = mbinds1 `AndMonoBinds` mbinds2 - in - returnTc (combiner Recursive final_mbinds thing, final_lie) +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 -tcBinds :: TopLevelFlag - -> RenamedHsBinds - -> TcM s (TcMonoBinds s, LIE s, TcEnv s, [TcIdBndr s]) - -- The envt is the envt with binders in scope - -- The binders are those bound by this group of bindings - -tcBinds top_lvl EmptyBinds - = tcGetEnv `thenNF_Tc` \ env -> - returnTc (EmptyMonoBinds, emptyLIE, env, []) - - -- Short-cut for the rather common case of an empty bunch of bindings -tcBinds top_lvl (MonoBind EmptyMonoBinds sigs is_rec) - = tcGetEnv `thenNF_Tc` \ env -> - returnTc (EmptyMonoBinds, emptyLIE, env, []) - -tcBinds top_lvl (ThenBinds binds1 binds2) - = tcBinds top_lvl binds1 `thenTc` \ (mbinds1, lie1, env1, ids1) -> - tcSetEnv env1 $ - tcBinds top_lvl binds2 `thenTc` \ (mbinds2, lie2, env2, ids2) -> - returnTc (mbinds1 `AndMonoBinds` mbinds2, lie1 `plusLIE` lie2, env2, ids1++ids2) - -tcBinds top_lvl (MonoBind bind sigs is_rec) - = fixTc (\ ~(prag_info_fn, _) -> - -- This is the usual prag_info fix; the PragmaInfo field of an Id - -- is not inspected till ages later in the compiler, so there - -- should be no black-hole problems here. - - -- TYPECHECK THE SIGNATURES - mapTc tcTySig ty_sigs `thenTc` \ tc_ty_sigs -> +tc_binds_and_then top_lvl combiner (MonoBind bind sigs is_rec) do_next + = -- TYPECHECK THE SIGNATURES + mapTc tcTySig [sig | sig@(Sig name _ _) <- sigs] `thenTc` \ tc_ty_sigs -> - tcBindWithSigs top_lvl binder_names bind - tc_ty_sigs is_rec prag_info_fn `thenTc` \ (poly_binds, poly_lie, poly_ids) -> + tcBindWithSigs top_lvl bind tc_ty_sigs + sigs is_rec `thenTc` \ (poly_binds, poly_lie, poly_ids) -> -- Extend the environment to bind the new polymorphic Ids - tcExtendLocalValEnv binder_names poly_ids $ + tcExtendLocalValEnv [(idName poly_id, poly_id) | poly_id <- poly_ids] $ -- Build bindings and IdInfos corresponding to user pragmas - tcPragmaSigs sigs `thenTc` \ (prag_info_fn, prag_binds, prag_lie) -> - - -- Catch the environment and return - tcGetEnv `thenNF_Tc` \ env -> - returnTc (prag_info_fn, (poly_binds `AndMonoBinds` prag_binds, - poly_lie `plusLIE` prag_lie, - env, poly_ids) - ) ) `thenTc` \ (_, result) -> - returnTc result - where - binder_names = map fst (bagToList (collectMonoBinders bind)) - ty_sigs = [sig | sig@(Sig name _ _) <- sigs] + tcSpecSigs sigs `thenTc` \ (prag_binds, prag_lie) -> + + -- Now do whatever happens next, in the augmented envt + do_next `thenTc` \ (thing, thing_lie) -> + + -- Create specialisations of functions bound here + -- We want to keep non-recursive things non-recursive + -- so that we desugar unboxed bindings correctly + case (top_lvl, is_rec) of + + -- 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 + (TopLevel, _) + -> returnTc (combiner Recursive (poly_binds `andMonoBinds` prag_binds) thing, + thing_lie `plusLIE` prag_lie `plusLIE` poly_lie) + + (NotTopLevel, NonRecursive) + -> bindInstsOfLocalFuns + (thing_lie `plusLIE` prag_lie) + poly_ids `thenTc` \ (thing_lie', lie_binds) -> + + returnTc ( + combiner NonRecursive poly_binds $ + combiner NonRecursive prag_binds $ + combiner 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, + + thing_lie' `plusLIE` poly_lie + ) + + (NotTopLevel, Recursive) + -> bindInstsOfLocalFuns + (thing_lie `plusLIE` poly_lie `plusLIE` prag_lie) + poly_ids `thenTc` \ (final_lie, lie_binds) -> + + returnTc ( + combiner Recursive ( + poly_binds `andMonoBinds` + lie_binds `andMonoBinds` + prag_binds) thing, + final_lie + ) \end{code} An aside. The original version of @tcBindsAndThen@ which lacks a @@ -187,23 +184,23 @@ at a different type to the definition itself. There aren't too many examples of this, which is why I thought it worth preserving! [SLPJ] \begin{pseudocode} -tcBindsAndThen - :: RenamedHsBinds - -> TcM s (thing, LIE s, thing_ty)) - -> TcM s ((TcHsBinds s, thing), LIE s, thing_ty) - -tcBindsAndThen EmptyBinds do_next - = do_next `thenTc` \ (thing, lie, thing_ty) -> - returnTc ((EmptyBinds, thing), lie, thing_ty) - -tcBindsAndThen (ThenBinds binds1 binds2) do_next - = tcBindsAndThen binds1 (tcBindsAndThen binds2 do_next) - `thenTc` \ ((binds1', (binds2', thing')), lie1, thing_ty) -> - - returnTc ((binds1' `ThenBinds` binds2', thing'), lie1, thing_ty) - -tcBindsAndThen (MonoBind bind sigs is_rec) do_next - = tcBindAndThen bind sigs do_next +% tcBindsAndThen +% :: RenamedHsBinds +% -> TcM s (thing, LIE, thing_ty)) +% -> TcM s ((TcHsBinds, thing), LIE, thing_ty) +% +% tcBindsAndThen EmptyBinds do_next +% = do_next `thenTc` \ (thing, lie, thing_ty) -> +% returnTc ((EmptyBinds, thing), lie, thing_ty) +% +% tcBindsAndThen (ThenBinds binds1 binds2) do_next +% = tcBindsAndThen binds1 (tcBindsAndThen binds2 do_next) +% `thenTc` \ ((binds1', (binds2', thing')), lie1, thing_ty) -> +% +% returnTc ((binds1' `ThenBinds` binds2', thing'), lie1, thing_ty) +% +% tcBindsAndThen (MonoBind bind sigs is_rec) do_next +% = tcBindAndThen bind sigs do_next \end{pseudocode} @@ -226,57 +223,62 @@ so all the clever stuff is in here. \begin{code} tcBindWithSigs :: TopLevelFlag - -> [Name] -> RenamedMonoBinds - -> [TcSigInfo s] + -> [TcSigInfo] + -> [RenamedSig] -- Used solely to get INLINE, NOINLINE sigs -> RecFlag - -> (Name -> IdInfo) - -> TcM s (TcMonoBinds s, LIE s, [TcIdBndr s]) + -> TcM s (TcMonoBinds, LIE, [TcId]) -tcBindWithSigs top_lvl binder_names mbind tc_ty_sigs is_rec prag_info_fn +tcBindWithSigs top_lvl mbind tc_ty_sigs inline_sigs is_rec = recoverTc ( -- If typechecking the binds fails, then return with each -- signature-less binder given type (forall a.a), to minimise subsequent -- error messages - newTcTyVar mkBoxedTypeKind `thenNF_Tc` \ alpha_tv -> + newTyVar boxedTypeKind `thenNF_Tc` \ alpha_tv -> let - forall_a_a = mkForAllTy alpha_tv (mkTyVarTy alpha_tv) - poly_ids = map mk_dummy binder_names + forall_a_a = mkForAllTy alpha_tv (mkTyVarTy alpha_tv) + binder_names = map fst (bagToList (collectMonoBinders mbind)) + poly_ids = map mk_dummy binder_names mk_dummy name = case maybeSig tc_ty_sigs name of - Just (TySigInfo _ poly_id _ _ _ _) -> poly_id -- Signature - Nothing -> mkUserId name forall_a_a -- No signature + Just (TySigInfo _ poly_id _ _ _ _ _ _) -> poly_id -- Signature + Nothing -> mkVanillaId name forall_a_a -- No signature in returnTc (EmptyMonoBinds, emptyLIE, poly_ids) ) $ - -- Create a new identifier for each binder, with each being given - -- a fresh unique, and a type-variable type. - -- For "mono_lies" see comments about polymorphic recursion at the - -- end of the function. - mapAndUnzipNF_Tc mk_mono_id binder_names `thenNF_Tc` \ (mono_lies, mono_ids) -> - let - mono_lie = plusLIEs mono_lies - mono_id_tys = map idType mono_ids - in - -- TYPECHECK THE BINDINGS - tcMonoBinds mbind binder_names mono_ids tc_ty_sigs `thenTc` \ (mbind', lie) -> + tcMonoBinds mbind tc_ty_sigs is_rec `thenTc` \ (mbind', lie_req, binder_names, mono_ids) -> -- CHECK THAT THE SIGNATURES MATCH -- (must do this before getTyVarsToGen) - checkSigMatch tc_ty_sigs `thenTc` \ sig_theta -> - + checkSigMatch top_lvl binder_names mono_ids tc_ty_sigs `thenTc` \ maybe_sig_theta -> + + -- IMPROVE the LIE + -- Force any unifications dictated by functional dependencies. + -- Because unification may happen, it's important that this step + -- come before: + -- - computing vars over which to quantify + -- - zonking the generalized type vars + tcImprove lie_req `thenTc_` + -- COMPUTE VARIABLES OVER WHICH TO QUANTIFY, namely tyvars_to_gen -- The tyvars_not_to_gen are free in the environment, and hence -- candidates for generalisation, but sometimes the monomorphism -- restriction means we can't generalise them nevertheless - getTyVarsToGen is_unrestricted mono_id_tys lie `thenTc` \ (tyvars_not_to_gen, tyvars_to_gen) -> - - -- DEAL WITH TYPE VARIABLE KINDS - -- **** This step can do unification => keep other zonking after this **** - mapTc defaultUncommittedTyVar (tyVarSetToList tyvars_to_gen) `thenTc` \ real_tyvars_to_gen_list -> let - real_tyvars_to_gen = mkTyVarSet real_tyvars_to_gen_list + mono_id_tys = map idType mono_ids + in + getTyVarsToGen is_unrestricted mono_id_tys lie_req `thenNF_Tc` \ (tyvars_not_to_gen, tyvars_to_gen) -> + + -- Finally, zonk the generalised type variables to real TyVars + -- This commits any unbound kind variables to boxed kind + -- I'm a little worried that such a kind variable might be + -- free in the environment, but I don't think it's possible for + -- this to happen when the type variable is not free in the envt + -- (which it isn't). SLPJ Nov 98 + mapTc zonkTcTyVarToTyVar (varSetElems tyvars_to_gen) `thenTc` \ real_tyvars_to_gen_list -> + let + real_tyvars_to_gen = mkVarSet real_tyvars_to_gen_list -- It's important that the final list -- (real_tyvars_to_gen and real_tyvars_to_gen_list) is fully -- zonked, *including boxity*, because they'll be included in the forall types of @@ -287,16 +289,26 @@ tcBindWithSigs top_lvl binder_names mbind tc_ty_sigs is_rec prag_info_fn in -- SIMPLIFY THE LIE - tcExtendGlobalTyVars (tyVarSetToList tyvars_not_to_gen) ( - if null tc_ty_sigs then + tcExtendGlobalTyVars tyvars_not_to_gen ( + let ips = getIPsOfLIE lie_req in + if null real_tyvars_to_gen_list && (null ips || not is_unrestricted) then + -- No polymorphism, and no IPs, so no need to simplify context + returnTc (lie_req, EmptyMonoBinds, []) + else + case maybe_sig_theta of + Nothing -> -- No signatures, so just simplify the lie -- NB: no signatures => no polymorphic recursion, so no - -- need to use mono_lies (which will be empty anyway) + -- need to use lie_avail (which will be empty anyway) tcSimplify (text "tcBinds1" <+> ppr binder_names) - top_lvl real_tyvars_to_gen lie `thenTc` \ (lie_free, dict_binds, lie_bound) -> + real_tyvars_to_gen lie_req `thenTc` \ (lie_free, dict_binds, lie_bound) -> returnTc (lie_free, dict_binds, map instToId (bagToList lie_bound)) - else + Just (sig_theta, lie_avail) -> + -- There are signatures, and their context is sig_theta + -- Furthermore, lie_avail is an LIE containing the 'method insts' + -- for the things bound here + zonkTcThetaType sig_theta `thenNF_Tc` \ sig_theta' -> newDicts SignatureOrigin sig_theta' `thenNF_Tc` \ (dicts_sig, dict_ids) -> -- It's important that sig_theta is zonked, because @@ -306,94 +318,119 @@ tcBindWithSigs top_lvl binder_names mbind tc_ty_sigs is_rec prag_info_fn let -- The "givens" is the stuff available. We get that from - -- the context of the type signature, BUT ALSO the mono_lie + -- the context of the type signature, BUT ALSO the lie_avail -- so that polymorphic recursion works right (see comments at end of fn) - givens = dicts_sig `plusLIE` mono_lie + givens = dicts_sig `plusLIE` lie_avail in -- Check that the needed dicts can be expressed in -- terms of the signature ones tcAddErrCtxt (bindSigsCtxt tysig_names) $ tcSimplifyAndCheck - (ptext SLIT("type signature for") <+> - hsep (punctuate comma (map (quotes . ppr) binder_names))) - real_tyvars_to_gen givens lie `thenTc` \ (lie_free, dict_binds) -> + (ptext SLIT("type signature for") <+> pprQuotedList binder_names) + real_tyvars_to_gen givens lie_req `thenTc` \ (lie_free, dict_binds) -> returnTc (lie_free, dict_binds, dict_ids) ) `thenTc` \ (lie_free, dict_binds, dicts_bound) -> - ASSERT( not (any (isUnboxedTypeKind . tyVarKind) real_tyvars_to_gen_list) ) + -- GET THE FINAL MONO_ID_TYS + zonkTcTypes mono_id_tys `thenNF_Tc` \ zonked_mono_id_types -> + + + -- CHECK FOR BOGUS UNPOINTED BINDINGS + (if any isUnLiftedType zonked_mono_id_types then + -- Unlifted bindings must be non-recursive, + -- not top level, and non-polymorphic + checkTc (isNotTopLevel top_lvl) + (unliftedBindErr "Top-level" mbind) `thenTc_` + checkTc (case is_rec of {Recursive -> False; NonRecursive -> True}) + (unliftedBindErr "Recursive" mbind) `thenTc_` + checkTc (null real_tyvars_to_gen_list) + (unliftedBindErr "Polymorphic" mbind) + else + returnTc () + ) `thenTc_` + + ASSERT( not (any ((== unboxedTypeKind) . tyVarKind) real_tyvars_to_gen_list) ) -- 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. + -- 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. + -- BUILD THE POLYMORPHIC RESULT IDs - zonkTcTypes mono_id_tys `thenNF_Tc` \ zonked_mono_id_types -> + mapNF_Tc zonkId mono_ids `thenNF_Tc` \ zonked_mono_ids -> let - exports = zipWith3 mk_export binder_names mono_ids zonked_mono_id_types - dict_tys = map tcIdType dicts_bound - - mk_export binder_name mono_id zonked_mono_id_ty - = (tyvars, TcId (replaceIdInfo poly_id (prag_info_fn binder_name)), TcId mono_id) + exports = zipWith mk_export binder_names zonked_mono_ids + dict_tys = map idType dicts_bound + + inlines = mkNameSet [name | InlineSig name _ loc <- inline_sigs] + no_inlines = listToFM ([(name, IMustNotBeINLINEd False phase) | NoInlineSig name phase loc <- inline_sigs] ++ + [(name, IMustNotBeINLINEd True phase) | InlineSig name phase loc <- inline_sigs, maybeToBool phase]) + -- "INLINE n foo" means inline foo, but not until at least phase n + -- "NOINLINE n foo" means don't inline foo until at least phase n, and even + -- then only if it is small enough etc. + -- "NOINLINE foo" means don't inline foo ever, which we signal with a (IMustNotBeINLINEd Nothing) + -- See comments in CoreUnfold.blackListed for the Authorised Version + + mk_export binder_name zonked_mono_id + = (tyvars, + attachNoInlinePrag no_inlines poly_id, + zonked_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_list, new_poly_id) - - new_poly_id = mkUserId binder_name poly_ty - poly_ty = mkForAllTys real_tyvars_to_gen_list $ mkFunTys dict_tys $ zonked_mono_id_ty - -- 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. + (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_list, new_poly_id) + + new_poly_id = mkVanillaId binder_name poly_ty + poly_ty = mkForAllTys real_tyvars_to_gen_list + $ 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. + + pat_binders :: [Name] + pat_binders = map fst $ bagToList $ collectMonoBinders $ + (justPatBindings mbind EmptyMonoBinds) in + -- CHECK FOR UNBOXED BINDERS IN PATTERN BINDINGS + mapTc (\id -> checkTc (not (idName id `elem` pat_binders + && isUnboxedType (idType id))) + (unboxedPatBindErr id)) zonked_mono_ids + `thenTc_` -- BUILD RESULTS returnTc ( + -- pprTrace "binding.." (ppr ((dicts_bound, dict_binds), exports, [idType poly_id | (_, poly_id, _) <- exports])) $ AbsBinds real_tyvars_to_gen_list dicts_bound exports - (dict_binds `AndMonoBinds` mbind'), + inlines + (dict_binds `andMonoBinds` mbind'), lie_free, - [poly_id | (_, TcId poly_id, _) <- exports] + [poly_id | (_, poly_id, _) <- exports] ) where - no_of_binders = length binder_names - - mk_mono_id binder_name - | theres_a_signature -- There's a signature; and it's overloaded, - && not (null sig_theta) -- so make a Method - = tcAddSrcLoc sig_loc $ - newMethodWithGivenTy SignatureOrigin - (TcId poly_id) (mkTyVarTys sig_tyvars) - sig_theta sig_tau `thenNF_Tc` \ (mono_lie, TcId mono_id) -> - -- A bit turgid to have to strip the TcId - returnNF_Tc (mono_lie, mono_id) - - | otherwise -- No signature or not overloaded; - = tcAddSrcLoc (getSrcLoc binder_name) $ - (if theres_a_signature then - returnNF_Tc sig_tau -- Non-overloaded signature; use its type - else - newTyVarTy kind -- No signature; use a new type variable - ) `thenNF_Tc` \ mono_id_ty -> - - newLocalId (getOccName binder_name) mono_id_ty `thenNF_Tc` \ mono_id -> - returnNF_Tc (emptyLIE, mono_id) - where - maybe_sig = maybeSig tc_ty_sigs binder_name - theres_a_signature = maybeToBool maybe_sig - Just (TySigInfo name poly_id sig_tyvars sig_theta sig_tau sig_loc) = maybe_sig - - tysig_names = [name | (TySigInfo name _ _ _ _ _) <- tc_ty_sigs] + tysig_names = [name | (TySigInfo name _ _ _ _ _ _ _) <- tc_ty_sigs] is_unrestricted = isUnRestrictedGroup tysig_names mbind - kind = case is_rec of - Recursive -> mkBoxedTypeKind -- Recursive, so no unboxed types - NonRecursive -> mkTypeKind -- Non-recursive, so we permit unboxed types +justPatBindings bind@(PatMonoBind _ _ _) binds = bind `andMonoBinds` binds +justPatBindings (AndMonoBinds b1 b2) binds = + justPatBindings b1 (justPatBindings b2 binds) +justPatBindings other_bind binds = binds + +attachNoInlinePrag no_inlines bndr + = case lookupFM no_inlines (idName bndr) of + Just prag -> bndr `setInlinePragma` prag + Nothing -> bndr \end{code} Polymorphic recursion @@ -418,22 +455,37 @@ If we don't take care, after typechecking we get Notice the the stupid construction of (f a d), which is of course identical to the function we're executing. In this case, the -polymorphic recursion ins't being used (but that's a very common case). +polymorphic recursion isn't being used (but that's a very common case). +We'd prefer -This can lead to a massive space leak, from the following top-level defn: + f = /\a -> \d::Eq a -> letrec + fm = \ys:[a] -> ...fm... + in + fm + +This can lead to a massive space leak, from the following top-level defn +(post-typechecking) ff :: [Int] -> [Int] - ff = f dEqInt + ff = f Int dEqInt Now (f dEqInt) evaluates to a lambda that has f' as a free variable; but f' is another thunk which evaluates to the same thing... and you end up with a chain of identical values all hung onto by the CAF ff. + ff = f Int dEqInt + + = let f' = f Int dEqInt in \ys. ...f'... + + = let f' = let f' = f Int dEqInt in \ys. ...f'... + in \ys. ...f'... + +Etc. Solution: when typechecking the RHSs we always have in hand the *monomorphic* Ids for each binding. So we just need to make sure that if (Method f a d) shows up in the constraints emerging from (...f...) we just use the monomorphic Id. We achieve this by adding monomorphic Ids -to the "givens" when simplifying constraints. Thats' what the "mono_lies" +to the "givens" when simplifying constraints. That's what the "lies_avail" is doing. @@ -443,7 +495,7 @@ is doing. %* * %************************************************************************ -@getTyVarsToGen@ decides what type variables generalise over. +@getTyVarsToGen@ decides what type variables to generalise over. For a "restricted group" -- see the monomorphism restriction for a definition -- we bind no dictionaries, and @@ -485,17 +537,27 @@ getTyVarsToGen is_unrestricted mono_id_tys lie = tcGetGlobalTyVars `thenNF_Tc` \ free_tyvars -> zonkTcTypes mono_id_tys `thenNF_Tc` \ zonked_mono_id_tys -> let - tyvars_to_gen = tyVarsOfTypes zonked_mono_id_tys `minusTyVarSet` free_tyvars + body_tyvars = tyVarsOfTypes zonked_mono_id_tys `minusVarSet` free_tyvars in if is_unrestricted then - returnTc (emptyTyVarSet, tyvars_to_gen) + let fds = getAllFunDepsOfLIE lie in + zonkFunDeps fds `thenNF_Tc` \ fds' -> + let tvFundep = tyVarFunDep fds' + extended_tyvars = oclose tvFundep body_tyvars in + -- pprTrace "gTVTG" (ppr (lie, body_tyvars, extended_tyvars)) $ + returnNF_Tc (emptyVarSet, extended_tyvars) else - tcSimplify (text "getTVG") NotTopLevel tyvars_to_gen lie `thenTc` \ (_, _, constrained_dicts) -> + -- This recover and discard-errs is to avoid duplicate error + -- messages; this, after all, is an "extra" call to tcSimplify + recoverNF_Tc (returnNF_Tc (emptyVarSet, body_tyvars)) $ + discardErrsTc $ + + tcSimplify (text "getTVG") body_tyvars lie `thenTc` \ (_, _, constrained_dicts) -> let -- ASSERT: dicts_sig is already zonked! - constrained_tyvars = foldrBag (unionTyVarSets . tyVarsOfInst) emptyTyVarSet constrained_dicts - reduced_tyvars_to_gen = tyvars_to_gen `minusTyVarSet` constrained_tyvars + constrained_tyvars = foldrBag (unionVarSet . tyVarsOfInst) emptyVarSet constrained_dicts + reduced_tyvars_to_gen = body_tyvars `minusVarSet` constrained_tyvars in returnTc (constrained_tyvars, reduced_tyvars_to_gen) \end{code} @@ -509,7 +571,7 @@ isUnRestrictedGroup :: [Name] -- Signatures given for these is_elem v vs = isIn "isUnResMono" v vs isUnRestrictedGroup sigs (PatMonoBind (VarPatIn v) _ _) = v `is_elem` sigs -isUnRestrictedGroup sigs (PatMonoBind other _ _) = False +isUnRestrictedGroup sigs (PatMonoBind other _ _) = False isUnRestrictedGroup sigs (VarMonoBind v _) = v `is_elem` sigs isUnRestrictedGroup sigs (FunMonoBind _ _ _ _) = True isUnRestrictedGroup sigs (AndMonoBinds mb1 mb2) = isUnRestrictedGroup sigs mb1 && @@ -517,20 +579,6 @@ isUnRestrictedGroup sigs (AndMonoBinds mb1 mb2) = isUnRestrictedGroup sigs mb1 isUnRestrictedGroup sigs EmptyMonoBinds = True \end{code} -@defaultUncommittedTyVar@ checks for generalisation over unboxed -types, and defaults any TypeKind TyVars to BoxedTypeKind. - -\begin{code} -defaultUncommittedTyVar tyvar - | isTypeKind (tyVarKind tyvar) - = newTcTyVar mkBoxedTypeKind `thenNF_Tc` \ boxed_tyvar -> - unifyTauTy (mkTyVarTy boxed_tyvar) (mkTyVarTy tyvar) `thenTc_` - returnTc boxed_tyvar - - | otherwise - = returnTc tyvar -\end{code} - %************************************************************************ %* * @@ -543,47 +591,122 @@ The signatures have been dealt with already. \begin{code} tcMonoBinds :: RenamedMonoBinds - -> [Name] -> [TcIdBndr s] - -> [TcSigInfo s] - -> TcM s (TcMonoBinds s, LIE s) + -> [TcSigInfo] + -> RecFlag + -> TcM s (TcMonoBinds, + LIE, -- LIE required + [Name], -- Bound names + [TcId]) -- Corresponding monomorphic bound things + +tcMonoBinds mbinds tc_ty_sigs is_rec + = tc_mb_pats mbinds `thenTc` \ (complete_it, lie_req_pat, tvs, ids, lie_avail) -> + let + tv_list = bagToList tvs + 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 && isEmptyBag lie_avail) + (existentialExplode mbinds) `thenTc_` + + -- *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 -tcMonoBinds mbind binder_names mono_ids tc_ty_sigs - = tcExtendLocalValEnv binder_names mono_ids ( - tc_mono_binds mbind - ) + complete_it extra_val_env `thenTc` \ (mbinds', lie_req_rhss) -> + + returnTc (mbinds', lie_req_pat `plusLIE` lie_req_rhss, names, mono_ids) where - sig_names = [name | (TySigInfo name _ _ _ _ _) <- tc_ty_sigs] - sig_ids = [id | (TySigInfo _ id _ _ _ _) <- tc_ty_sigs] - - tc_mono_binds EmptyMonoBinds = returnTc (EmptyMonoBinds, emptyLIE) - - tc_mono_binds (AndMonoBinds mb1 mb2) - = tc_mono_binds mb1 `thenTc` \ (mb1a, lie1) -> - tc_mono_binds mb2 `thenTc` \ (mb2a, lie2) -> - returnTc (AndMonoBinds mb1a mb2a, lie1 `plusLIE` lie2) - - tc_mono_binds (FunMonoBind name inf matches locn) - = tcAddSrcLoc locn $ - tcLookupLocalValueOK "tc_mono_binds" name `thenNF_Tc` \ id -> - - -- Before checking the RHS, extend the envt with - -- bindings for the *polymorphic* Ids from any type signatures - tcExtendLocalValEnv sig_names sig_ids $ - tcMatchesFun name (idType id) matches `thenTc` \ (matches', lie) -> - - returnTc (FunMonoBind (TcId id) inf matches' locn, lie) - - tc_mono_binds bind@(PatMonoBind pat grhss_and_binds locn) - = tcAddSrcLoc locn $ - tcAddErrCtxt (patMonoBindsCtxt bind) $ - tcPat pat `thenTc` \ (pat2, lie_pat, pat_ty) -> - - -- Before checking the RHS, but after the pattern, extend the envt with - -- bindings for the *polymorphic* Ids from any type signatures - tcExtendLocalValEnv sig_names sig_ids $ - tcGRHSsAndBinds pat_ty grhss_and_binds `thenTc` \ (grhss_and_binds2, lie) -> - returnTc (PatMonoBind pat2 grhss_and_binds2 locn, - plusLIE lie_pat lie) + + -- This function is used when dealing with a LHS binder; we make a monomorphic + -- version of the Id. We check for type signatures + tc_pat_bndr name pat_ty + = case maybeSig tc_ty_sigs name of + Nothing + -> newLocalId (getOccName name) pat_ty (getSrcLoc name) + + Just (TySigInfo _ _ _ _ _ mono_id _ _) + -> tcAddSrcLoc (getSrcLoc name) $ + unifyTauTy (idType mono_id) pat_ty `thenTc_` + returnTc mono_id + + mk_bind (name, mono_id) = case maybeSig tc_ty_sigs name of + Nothing -> (name, mono_id) + Just (TySigInfo name poly_id _ _ _ _ _ _) -> (name, poly_id) + + tc_mb_pats EmptyMonoBinds + = returnTc (\ xve -> returnTc (EmptyMonoBinds, emptyLIE), emptyLIE, emptyBag, emptyBag, emptyLIE) + + tc_mb_pats (AndMonoBinds mb1 mb2) + = tc_mb_pats mb1 `thenTc` \ (complete_it1, lie_req1, tvs1, ids1, lie_avail1) -> + tc_mb_pats mb2 `thenTc` \ (complete_it2, lie_req2, tvs2, ids2, lie_avail2) -> + let + complete_it xve = complete_it1 xve `thenTc` \ (mb1', lie1) -> + complete_it2 xve `thenTc` \ (mb2', lie2) -> + returnTc (AndMonoBinds mb1' mb2', lie1 `plusLIE` lie2) + in + returnTc (complete_it, + lie_req1 `plusLIE` lie_req2, + tvs1 `unionBags` tvs2, + ids1 `unionBags` ids2, + lie_avail1 `plusLIE` lie_avail2) + + tc_mb_pats (FunMonoBind name inf matches locn) + = newTyVarTy boxedTypeKind `thenNF_Tc` \ bndr_ty -> + tc_pat_bndr name bndr_ty `thenTc` \ bndr_id -> + let + complete_it xve = tcAddSrcLoc locn $ + tcMatchesFun xve name bndr_ty matches `thenTc` \ (matches', lie) -> + returnTc (FunMonoBind bndr_id inf matches' locn, lie) + in + returnTc (complete_it, emptyLIE, emptyBag, unitBag (name, bndr_id), emptyLIE) + + tc_mb_pats bind@(PatMonoBind pat grhss locn) + = tcAddSrcLoc locn $ + + -- Figure out the appropriate kind for the pattern, + -- and generate a suitable type variable + (case is_rec of + Recursive -> newTyVarTy boxedTypeKind -- Recursive, so no unboxed types + NonRecursive -> newTyVarTy_OpenKind -- Non-recursive, so we permit unboxed types + ) `thenNF_Tc` \ pat_ty -> + + -- Now typecheck the pattern + -- We don't support binding fresh type variables in the + -- pattern of a pattern binding. For example, this is illegal: + -- (x::a, y::b) = e + -- whereas this is ok + -- (x::Int, y::Bool) = e + -- + -- We don't check explicitly for this problem. Instead, we simply + -- type check the pattern with tcPat. If the pattern mentions any + -- fresh tyvars we simply get an out-of-scope type variable error + tcPat tc_pat_bndr pat pat_ty `thenTc` \ (pat', lie_req, tvs, ids, lie_avail) -> + let + complete_it xve = tcAddSrcLoc locn $ + tcAddErrCtxt (patMonoBindsCtxt bind) $ + tcExtendLocalValEnv xve $ + tcGRHSs grhss pat_ty PatBindRhs `thenTc` \ (grhss', lie) -> + returnTc (PatMonoBind pat' grhss' locn, lie) + in + returnTc (complete_it, lie_req, tvs, ids, lie_avail) \end{code} %************************************************************************ @@ -592,65 +715,6 @@ tcMonoBinds mbind binder_names mono_ids tc_ty_sigs %* * %************************************************************************ -@tcSigs@ checks the signatures for validity, and returns a list of -{\em freshly-instantiated} signatures. That is, the types are already -split up, and have fresh type variables installed. All non-type-signature -"RenamedSigs" are ignored. - -The @TcSigInfo@ contains @TcTypes@ because they are unified with -the variable's type, and after that checked to see whether they've -been instantiated. - -\begin{code} -data TcSigInfo s - = TySigInfo - Name -- N, the Name in corresponding binding - (TcIdBndr s) -- *Polymorphic* binder for this value... - -- Usually has name = N, but doesn't have to. - [TcTyVar s] - (TcThetaType s) - (TcTauType s) - SrcLoc - - -maybeSig :: [TcSigInfo s] -> Name -> Maybe (TcSigInfo s) - -- Search for a particular signature -maybeSig [] name = Nothing -maybeSig (sig@(TySigInfo sig_name _ _ _ _ _) : sigs) name - | name == sig_name = Just sig - | otherwise = maybeSig sigs name -\end{code} - - -\begin{code} -tcTySig :: RenamedSig - -> TcM s (TcSigInfo s) - -tcTySig (Sig v ty src_loc) - = tcAddSrcLoc src_loc $ - tcHsType ty `thenTc` \ sigma_ty -> - - -- Convert from Type to TcType - tcInstSigType sigma_ty `thenNF_Tc` \ sigma_tc_ty -> - let - poly_id = mkUserId v sigma_tc_ty - in - -- Instantiate this type - -- It's important to do this even though in the error-free case - -- we could just split the sigma_tc_ty (since the tyvars don't - -- unified with anything). But in the case of an error, when - -- the tyvars *do* get unified with something, we want to carry on - -- typechecking the rest of the program with the function bound - -- to a pristine type, namely sigma_tc_ty - tcInstSigTcType sigma_tc_ty `thenNF_Tc` \ (tyvars, rho) -> - let - (theta, tau) = splitRhoTy rho - -- This splitSigmaTy tries hard to make sure that tau' is a type synonym - -- wherever possible, which can improve interface files. - in - returnTc (TySigInfo v poly_id tyvars theta tau src_loc) -\end{code} - @checkSigMatch@ does the next step in checking signature matching. The tau-type part has already been unified. What we do here is to check that this unification has not over-constrained the (polymorphic) @@ -660,13 +724,53 @@ The error message here is somewhat unsatisfactory, but it'll do for now (ToDo). \begin{code} -checkSigMatch [] - = returnTc (error "checkSigMatch") +checkSigMatch top_lvl binder_names mono_ids sigs + | main_bound_here + = -- First unify the main_id with IO t, for any old t + tcSetErrCtxt mainTyCheckCtxt ( + tcLookupTyCon ioTyCon_NAME `thenTc` \ ioTyCon -> + newTyVarTy boxedTypeKind `thenNF_Tc` \ t_tv -> + unifyTauTy ((mkTyConApp ioTyCon [t_tv])) + (idType main_mono_id) + ) `thenTc_` + + -- Now check the signatures + -- Must do this after the unification with IO t, + -- in case of a silly signature like + -- main :: forall a. a + -- The unification to IO t will bind the type variable 'a', + -- which is just waht check_one_sig looks for + mapTc check_one_sig sigs `thenTc_` + mapTc check_main_ctxt sigs `thenTc_` + + returnTc (Just ([], emptyLIE)) + + | not (null sigs) + = mapTc check_one_sig sigs `thenTc_` + mapTc check_one_ctxt all_sigs_but_first `thenTc_` + returnTc (Just (theta1, sig_lie)) + + | otherwise + = returnTc Nothing -- No constraints from type sigs + + where + (TySigInfo _ id1 _ theta1 _ _ _ _ : all_sigs_but_first) = sigs + + sig1_dict_tys = mk_dict_tys theta1 + n_sig1_dict_tys = length sig1_dict_tys + sig_lie = mkLIE [inst | TySigInfo _ _ _ _ _ _ inst _ <- sigs] -checkSigMatch tc_ty_sigs@( sig1@(TySigInfo _ id1 _ theta1 _ _) : all_sigs_but_first ) - = -- CHECK THAT THE SIGNATURE TYVARS AND TAU_TYPES ARE OK + maybe_main = find_main top_lvl binder_names mono_ids + main_bound_here = maybeToBool maybe_main + Just main_mono_id = maybe_main + + -- CHECK THAT THE SIGNATURE TYVARS AND TAU_TYPES ARE OK -- Doesn't affect substitution - mapTc check_one_sig tc_ty_sigs `thenTc_` + check_one_sig (TySigInfo _ id sig_tyvars _ sig_tau _ _ src_loc) + = tcAddSrcLoc src_loc $ + tcAddErrCtxtM (sigCtxt (sig_msg id) (idType id)) $ + checkSigTyVars sig_tyvars + -- CHECK THAT ALL THE SIGNATURE CONTEXTS ARE UNIFIABLE -- The type signatures on a mutually-recursive group of definitions @@ -675,14 +779,7 @@ checkSigMatch tc_ty_sigs@( sig1@(TySigInfo _ id1 _ theta1 _ _) : all_sigs_but_fi -- We unify them because, with polymorphic recursion, their types -- might not otherwise be related. This is a rather subtle issue. -- ToDo: amplify - mapTc check_one_cxt all_sigs_but_first `thenTc_` - - returnTc theta1 - where - sig1_dict_tys = mk_dict_tys theta1 - n_sig1_dict_tys = length sig1_dict_tys - - check_one_cxt sig@(TySigInfo _ id _ theta _ src_loc) + check_one_ctxt sig@(TySigInfo _ id _ theta _ _ _ src_loc) = tcAddSrcLoc src_loc $ tcAddErrCtxt (sigContextsCtxt id1 id) $ checkTc (length this_sig_dict_tys == n_sig1_dict_tys) @@ -691,91 +788,23 @@ checkSigMatch tc_ty_sigs@( sig1@(TySigInfo _ id1 _ theta1 _ _) : all_sigs_but_fi where this_sig_dict_tys = mk_dict_tys theta - check_one_sig (TySigInfo name id sig_tyvars _ sig_tau src_loc) - = tcAddSrcLoc src_loc $ - tcAddErrCtxt (sigCtxt id) $ - checkSigTyVars sig_tyvars sig_tau - - mk_dict_tys theta = [mkDictTy c ts | (c,ts) <- theta] -\end{code} - - -@checkSigTyVars@ is used after the type in a type signature has been unified with -the actual type found. It then checks that the type variables of the type signature -are - (a) still all type variables - eg matching signature [a] against inferred type [(p,q)] - [then a will be unified to a non-type variable] - - (b) still all distinct - eg matching signature [(a,b)] against inferred type [(p,p)] - [then a and b will be unified together] - - (c) not mentioned in the environment - eg the signature for f in this: - - g x = ... where - f :: a->[a] - f y = [x,y] - - Here, f is forced to be monorphic by the free occurence of x. - -Before doing this, the substitution is applied to the signature type variable. - -We used to have the notion of a "DontBind" type variable, which would -only be bound to itself or nothing. Then points (a) and (b) were -self-checking. But it gave rise to bogus consequential error messages. -For example: - - f = (*) -- Monomorphic + -- CHECK THAT FOR A GROUP INVOLVING Main.main, all + -- the signature contexts are empty (what a bore) + check_main_ctxt sig@(TySigInfo _ id _ theta _ _ _ src_loc) + = tcAddSrcLoc src_loc $ + checkTc (null theta) (mainContextsErr id) - g :: Num a => a -> a - g x = f x x + mk_dict_tys theta = map mkPredTy theta -Here, we get a complaint when checking the type signature for g, -that g isn't polymorphic enough; but then we get another one when -dealing with the (Num x) context arising from f's definition; -we try to unify x with Int (to default it), but find that x has already -been unified with the DontBind variable "a" from g's signature. -This is really a problem with side-effecting unification; we'd like to -undo g's effects when its type signature fails, but unification is done -by side effect, so we can't (easily). + sig_msg id tidy_ty = sep [ptext SLIT("When checking the type signature"), + nest 4 (ppr id <+> dcolon <+> ppr tidy_ty)] -So we revert to ordinary type variables for signatures, and try to -give a helpful message in checkSigTyVars. - -\begin{code} -checkSigTyVars :: [TcTyVar s] -- The original signature type variables - -> TcType s -- signature type (for err msg) - -> TcM s [TcTyVar s] -- Zonked signature type variables - -checkSigTyVars sig_tyvars sig_tau - = mapNF_Tc zonkTcTyVar sig_tyvars `thenNF_Tc` \ sig_tys -> - let - sig_tyvars' = map (getTyVar "checkSigTyVars") sig_tys - in - - -- Check points (a) and (b) - checkTcM (all isTyVarTy sig_tys && hasNoDups sig_tyvars') - (zonkTcType sig_tau `thenNF_Tc` \ sig_tau' -> - failWithTc (badMatchErr sig_tau sig_tau') - ) `thenTc_` - - -- Check point (c) - -- We want to report errors in terms of the original signature tyvars, - -- ie sig_tyvars, NOT sig_tyvars'. sig_tyvars' correspond - -- 1-1 with sig_tyvars, so we can just map back. - tcGetGlobalTyVars `thenNF_Tc` \ globals -> - let - mono_tyvars' = [sig_tv' | sig_tv' <- sig_tyvars', - sig_tv' `elementOfTyVarSet` globals] - - mono_tyvars = map (assoc "checkSigTyVars" (sig_tyvars' `zip` sig_tyvars)) mono_tyvars' - in - checkTcM (null mono_tyvars') - (failWithTc (notAsPolyAsSigErr sig_tau mono_tyvars)) `thenTc_` - - returnTc sig_tyvars' + -- Search for Main.main in the binder_names, return corresponding mono_id + find_main NotTopLevel binder_names mono_ids = Nothing + find_main TopLevel binder_names mono_ids = go binder_names mono_ids + go [] [] = Nothing + go (n:ns) (m:ms) | n == main_NAME = Just m + | otherwise = go ns ms \end{code} @@ -785,28 +814,13 @@ checkSigTyVars sig_tyvars sig_tau %* * %************************************************************************ - -@tcPragmaSigs@ munches up the "signatures" that arise through *user* +@tcSpecSigs@ munches up the specialisation "signatures" that arise through *user* pragmas. It is convenient for them to appear in the @[RenamedSig]@ part of a binding because then the same machinery can be used for moving them into place as is done for type signatures. -\begin{code} -tcPragmaSigs :: [RenamedSig] -- The pragma signatures - -> TcM s (Name -> IdInfo, -- Maps name to the appropriate IdInfo - TcMonoBinds s, - LIE s) +They look like this: -tcPragmaSigs sigs - = mapAndUnzip3Tc tcPragmaSig sigs `thenTc` \ (maybe_info_modifiers, binds, lies) -> - let - prag_fn name = foldr ($) noIdInfo [f | Just (n,f) <- maybe_info_modifiers, n==name] - in - returnTc (prag_fn, andMonoBinds binds, plusLIEs lies) -\end{code} - -The interesting case is for SPECIALISE pragmas. There are two forms. -Here's the first form: \begin{verbatim} f :: Ord a => [a] -> b -> b {-# SPECIALIZE f :: [Int] -> b -> b #-} @@ -829,86 +843,41 @@ specialiser will subsequently discover that there's a call of @f@ at Int, and will create a specialisation for @f@. After that, the binding for @f*@ can be discarded. -The second form is this: -\begin{verbatim} - f :: Ord a => [a] -> b -> b - {-# SPECIALIZE f :: [Int] -> b -> b = g #-} -\end{verbatim} - -Here @g@ is specified as a function that implements the specialised -version of @f@. Suppose that g has type (a->b->b); that is, g's type -is more general than that required. For this we generate -\begin{verbatim} - f@Int = /\b -> g Int b - f* = f@Int -\end{verbatim} - -Here @f@@Int@ is a SpecId, the specialised version of @f@. It inherits -f's export status etc. @f*@ is a SpecPragmaId, as before, which just serves -to prevent @f@@Int@ from being discarded prematurely. After specialisation, -if @f@@Int@ is going to be used at all it will be used explicitly, so the simplifier can -discard the f* binding. - -Actually, there is really only point in giving a SPECIALISE pragma on exported things, -and the simplifer won't discard SpecIds for exporte things anyway, so maybe this is -a bit of overkill. +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:: TcM s (Maybe (Name, IdInfo -> IdInfo), TcMonoBinds s, LIE s) -tcPragmaSig (Sig _ _ _) = returnTc (Nothing, EmptyMonoBinds, emptyLIE) -tcPragmaSig (SpecInstSig _ _) = returnTc (Nothing, EmptyMonoBinds, emptyLIE) - -tcPragmaSig (InlineSig name loc) - = returnTc (Just (name, setInlinePragInfo IWantToBeINLINEd), EmptyMonoBinds, emptyLIE) - -tcPragmaSig (SpecSig name poly_ty maybe_spec_name src_loc) +tcSpecSigs :: [RenamedSig] -> TcM s (TcMonoBinds, LIE) +tcSpecSigs (SpecSig name poly_ty src_loc : sigs) = -- SPECIALISE f :: forall b. theta => tau = g tcAddSrcLoc src_loc $ tcAddErrCtxt (valSpecSigCtxt name poly_ty) $ -- Get and instantiate its alleged specialised type - tcHsType poly_ty `thenTc` \ sig_sigma -> - tcInstSigType sig_sigma `thenNF_Tc` \ sig_ty -> + tcHsSigType poly_ty `thenTc` \ sig_ty -> -- Check that f has a more general type, and build a RHS for -- the spec-pragma-id at the same time tcExpr (HsVar name) sig_ty `thenTc` \ (spec_expr, spec_lie) -> - case maybe_spec_name of - Nothing -> -- Just specialise "f" by building a SpecPragmaId binding - -- It is the thing that makes sure we don't prematurely - -- dead-code-eliminate the binding we are really interested in. - newSpecPragmaId name sig_ty `thenNF_Tc` \ spec_id -> - returnTc (Nothing, VarMonoBind (TcId spec_id) spec_expr, spec_lie) - - Just g_name -> -- Don't create a SpecPragmaId. Instead add some suitable IdIfo - - panic "Can't handle SPECIALISE with a '= g' part" - - {- Not yet. Because we're still in the TcType world we - can't really add to the SpecEnv of the Id. Instead we have to - record the information in a different sort of Sig, and add it to - the IdInfo after zonking. - - For now we just leave out this case - - -- Get the type of f, and find out what types - -- f has to be instantiated at to give the signature type - tcLookupLocalValueOK "tcPragmaSig" name `thenNF_Tc` \ f_id -> - tcInstSigTcType (idType f_id) `thenNF_Tc` \ (f_tyvars, f_rho) -> - - let - (sig_tyvars, sig_theta, sig_tau) = splitSigmaTy sig_ty - (f_theta, f_tau) = splitRhoTy f_rho - sig_tyvar_set = mkTyVarSet sig_tyvars - in - unifyTauTy sig_tau f_tau `thenTc_` - - tcPolyExpr str (HsVar g_name) (mkSigmaTy sig_tyvars f_theta sig_tau) `thenTc` \ (_, _, - -} - -tcPragmaSig other = pprTrace "tcPragmaSig: ignoring" (ppr other) $ - returnTc (Nothing, EmptyMonoBinds, emptyLIE) + -- Squeeze out any Methods (see comments with tcSimplifyToDicts) + tcSimplifyToDicts spec_lie `thenTc` \ (spec_lie1, spec_binds) -> + + -- Just specialise "f" by building a SpecPragmaId binding + -- It is the thing that makes sure we don't prematurely + -- dead-code-eliminate the binding we are really interested in. + newSpecPragmaId name sig_ty `thenNF_Tc` \ spec_id -> + + -- Do the rest and combine + tcSpecSigs sigs `thenTc` \ (binds_rest, lie_rest) -> + returnTc (binds_rest `andMonoBinds` VarMonoBind spec_id (mkHsLet spec_binds spec_expr), + lie_rest `plusLIE` spec_lie1) + +tcSpecSigs (other_sig : sigs) = tcSpecSigs sigs +tcSpecSigs [] = returnTc (EmptyMonoBinds, emptyLIE) \end{code} @@ -926,7 +895,7 @@ patMonoBindsCtxt bind ----------------------------------------------- valSpecSigCtxt v ty = sep [ptext SLIT("In a SPECIALIZE pragma for a value:"), - nest 4 (ppr v <+> ptext SLIT(" ::") <+> ppr ty)] + nest 4 (ppr v <+> dcolon <+> ppr ty)] ----------------------------------------------- notAsPolyAsSigErr sig_tau mono_tyvars @@ -944,42 +913,41 @@ badMatchErr sig_ty inferred_ty ]) ----------------------------------------------- -sigCtxt id - = sep [ptext SLIT("When checking the type signature for"), quotes (ppr id)] +unboxedPatBindErr id + = ptext SLIT("variable in a lazy pattern binding has unboxed type: ") + <+> quotes (ppr id) +----------------------------------------------- bindSigsCtxt ids = ptext SLIT("When checking the type signature(s) for") <+> pprQuotedList ids ----------------------------------------------- sigContextsErr = ptext SLIT("Mismatched contexts") + sigContextsCtxt s1 s2 = hang (hsep [ptext SLIT("When matching the contexts of the signatures for"), quotes (ppr s1), ptext SLIT("and"), quotes (ppr s2)]) 4 (ptext SLIT("(the signature contexts in a mutually recursive group should all be identical)")) +mainContextsErr id + | getName id == main_NAME = ptext SLIT("Main.main cannot be overloaded") + | otherwise + = quotes (ppr id) <+> ptext SLIT("cannot be overloaded") <> char ',' <> -- sigh; workaround for cpp's inability to deal + ptext SLIT("because it is mutually recursive with Main.main") -- with commas inside SLIT strings. + +mainTyCheckCtxt + = hsep [ptext SLIT("When checking that"), quotes (ppr main_NAME), + ptext SLIT("has the required type")] + ----------------------------------------------- -specGroundnessCtxt - = panic "specGroundnessCtxt" - --------------------------------------------- -specContextGroundnessCtxt -- err_ctxt dicts - = panic "specContextGroundnessCtxt" -{- - = hang ( - sep [hsep [ptext SLIT("In the SPECIALIZE pragma for"), ppr name], - hcat [ptext SLIT(" specialised to the type"), ppr spec_ty], - pp_spec_id, - ptext SLIT("... not all overloaded type variables were instantiated"), - ptext SLIT("to ground types:")]) - 4 (vcat [hsep [ppr c, ppr t] - | (c,t) <- map getDictClassAndType dicts]) - where - (name, spec_ty, locn, pp_spec_id) - = case err_ctxt of - ValSpecSigCtxt n ty loc -> (n, ty, loc, \ x -> empty) - ValSpecSpecIdCtxt n ty spec loc -> - (n, ty, loc, - hsep [ptext SLIT("... type of explicit id"), ppr spec]) --} +unliftedBindErr flavour mbind + = hang (text flavour <+> ptext SLIT("bindings for unlifted types aren't allowed")) + 4 (ppr mbind) + +existentialExplode mbinds + = hang (vcat [text "My brain just exploded.", + text "I can't handle pattern bindings for existentially-quantified constructors.", + text "In the binding group"]) + 4 (ppr mbinds) \end{code}