X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcBinds.lhs;h=b252acae08e0f1d29c4db1f7408080ee0bfbbeca;hb=6f122ef3930b51bca54bb96858fe9b8f1d85c461;hp=d8f3a6c2fe3e025791e9b2967395bfa8eb189412;hpb=5a26fb46a911300126e5980c17d4aaa197896197;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcBinds.lhs b/ghc/compiler/typecheck/TcBinds.lhs index d8f3a6c..b252aca 100644 --- a/ghc/compiler/typecheck/TcBinds.lhs +++ b/ghc/compiler/typecheck/TcBinds.lhs @@ -1,71 +1,69 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[TcBinds]{TcBinds} \begin{code} -#include "HsVersions.h" +module TcBinds ( tcBindsAndThen, tcTopBindsAndThen, + tcSpecSigs, tcBindWithSigs ) where -module TcBinds ( tcBindsAndThen, tcPragmaSigs, checkSigTyVars, tcBindWithSigs, TcSigInfo(..) ) where +#include "HsVersions.h" -IMP_Ubiq() +import {-# SOURCE #-} TcMatches ( tcGRHSs, tcMatchesFun ) +import {-# SOURCE #-} TcExpr ( tcExpr ) -import HsSyn ( HsBinds(..), Sig(..), MonoBinds(..), - Match, HsType, InPat(..), OutPat(..), HsExpr(..), - SYN_IE(RecFlag), nonRecursive, - GRHSsAndBinds, ArithSeqInfo, HsLit, Fake, Stmt, DoOrListComp, Fixity, - collectMonoBinders ) -import RnHsSyn ( SYN_IE(RenamedHsBinds), RenamedSig(..), - SYN_IE(RenamedMonoBinds) - ) -import TcHsSyn ( SYN_IE(TcHsBinds), SYN_IE(TcMonoBinds), - TcIdOcc(..), SYN_IE(TcIdBndr), SYN_IE(TcExpr), - 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, SYN_IE(LIE), emptyLIE, plusLIE, InstOrigin(..), - newDicts, tyVarsOfInst, instToId +import Inst ( Inst, LIE, emptyLIE, mkLIE, plusLIE, plusLIEs, InstOrigin(..), + newDicts, tyVarsOfInst, instToId, + getAllFunDepsOfLIE, getIPsOfLIE, zonkFunDeps ) -import TcEnv ( tcExtendLocalValEnv, tcLookupLocalValueOK, newMonoIds, +import TcEnv ( tcExtendLocalValEnv, + newSpecPragmaId, newLocalId, + tcLookupTyCon, tcGetGlobalTyVars, tcExtendGlobalTyVars ) -import SpecEnv ( SpecEnv ) -IMPORT_DELOOPER(TcLoop) ( tcGRHSsAndBinds ) -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 ( SYN_IE(TcType), SYN_IE(TcThetaType), SYN_IE(TcTauType), - SYN_IE(TcTyVarSet), SYN_IE(TcTyVar), - newTyVarTy, zonkTcType, zonkTcTyVar, zonkTcTyVars, - newTcTyVar, tcInstSigType, newTyVarTys +import TcType ( TcType, TcThetaType, + TcTyVar, + newTyVarTy, newTyVar, newTyVarTy_OpenKind, tcInstTcType, + zonkTcType, zonkTcTypes, zonkTcThetaType, zonkTcTyVarToTyVar + ) +import TcUnify ( unifyTauTy, unifyTauTyLists ) + +import PrelInfo ( main_NAME, ioTyCon_NAME ) + +import Id ( Id, mkVanillaId, setInlinePragma, idFreeTyVars ) +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 Unify ( unifyTauTy, unifyTauTyLists ) - -import Kind ( isUnboxedTypeKind, mkTypeKind, isTypeKind, mkBoxedTypeKind ) -import Id ( GenId, idType, mkUserLocal, mkUserId ) -import IdInfo ( noIdInfo ) -import Maybes ( maybeToBool, assocMaybe, catMaybes ) -import Name ( getOccName, getSrcLoc, Name ) -import PragmaInfo ( PragmaInfo(..) ) -import Pretty -import Type ( mkTyVarTy, mkTyVarTys, isTyVarTy, tyVarsOfTypes, eqSimpleTheta, - mkSigmaTy, splitSigmaTy, mkForAllTys, mkFunTys, getTyVar, mkDictTy, - splitRhoTy, mkForAllTy, splitForAllTy ) -import TyVar ( GenTyVar, SYN_IE(TyVar), tyVarKind, minusTyVarSet, emptyTyVarSet, - elementOfTyVarSet, unionTyVarSets, tyVarSetToList ) -import Bag ( bagToList, foldrBag, isEmptyBag ) -import Util ( isIn, zipEqual, zipWithEqual, zipWith3Equal, hasNoDups, assoc, - assertPanic, panic, pprTrace ) -import PprType ( GenClass, GenType, GenTyVar ) -import Unique ( Unique ) +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 --( interppSP, interpp'SP ) - - +import Outputable \end{code} @@ -101,58 +99,82 @@ At the top-level the LIE is sure to contain nothing but constant dictionaries, which we resolve at the module level. \begin{code} -tcBindsAndThen - :: (TcHsBinds s -> thing -> thing) -- Combinator +tcTopBindsAndThen, tcBindsAndThen + :: (RecFlag -> TcMonoBinds -> thing -> thing) -- Combinator -> RenamedHsBinds - -> TcM s (thing, LIE s) - -> TcM s (thing, LIE s) - -tcBindsAndThen combiner EmptyBinds do_next - = do_next `thenTc` \ (thing, lie) -> - returnTc (combiner EmptyBinds thing, lie) - -tcBindsAndThen combiner (ThenBinds binds1 binds2) do_next - = tcBindsAndThen combiner binds1 (tcBindsAndThen combiner binds2 do_next) - -tcBindsAndThen combiner (MonoBind bind sigs is_rec) do_next - = 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 prag_info_fn) ty_sigs `thenTc` \ tc_ty_sigs -> - - tcBindWithSigs binder_names bind - tc_ty_sigs is_rec prag_info_fn `thenTc` \ (poly_binds, poly_lie, poly_ids) -> - - -- Extend the environment to bind the new polymorphic Ids - tcExtendLocalValEnv binder_names poly_ids $ - - -- Build bindings and IdInfos corresponding to user pragmas - tcPragmaSigs sigs `thenTc` \ (prag_info_fn, prag_binds, prag_lie) -> + -> 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 EmptyBinds do_next + = do_next +tc_binds_and_then top_lvl combiner (MonoBind EmptyMonoBinds sigs is_rec) do_next + = 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 (MonoBind bind sigs is_rec) do_next + = -- TYPECHECK THE SIGNATURES + mapTc tcTySig [sig | sig@(Sig name _ _) <- sigs] `thenTc` \ tc_ty_sigs -> + + 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 [(idName poly_id, poly_id) | poly_id <- poly_ids] $ + + -- Build bindings and IdInfos corresponding to user pragmas + tcSpecSigs sigs `thenTc` \ (prag_binds, prag_lie) -> -- Now do whatever happens next, in the augmented envt - do_next `thenTc` \ (thing, thing_lie) -> + do_next `thenTc` \ (thing, thing_lie) -> -- Create specialisations of functions bound here - bindInstsOfLocalFuns (prag_lie `plusLIE` thing_lie) - poly_ids `thenTc` \ (lie2, inst_mbinds) -> - - -- All done - let - final_lie = lie2 `plusLIE` poly_lie - final_binds = MonoBind poly_binds [] is_rec `ThenBinds` - MonoBind inst_mbinds [] nonRecursive `ThenBinds` - prag_binds - in - returnTc (prag_info_fn, (combiner final_binds thing, final_lie)) - ) `thenTc` \ (_, result) -> - returnTc result - where - binder_names = map fst (bagToList (collectMonoBinders bind)) - ty_sigs = [sig | sig@(Sig name _ _) <- sigs] - + -- 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 @@ -162,23 +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} @@ -200,139 +222,283 @@ so all the clever stuff is in here. \begin{code} tcBindWithSigs - :: [Name] + :: TopLevelFlag -> RenamedMonoBinds - -> [TcSigInfo s] + -> [TcSigInfo] + -> [RenamedSig] -- Used solely to get INLINE, NOINLINE sigs -> RecFlag - -> (Name -> PragmaInfo) - -> TcM s (TcMonoBinds s, LIE s, [TcIdBndr s]) + -> TcM s (TcMonoBinds, LIE, [TcId]) -tcBindWithSigs 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 NoPragmaInfo -- 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. - tcGetUniques no_of_binders `thenNF_Tc` \ uniqs -> - mapNF_Tc mk_mono_id_ty binder_names `thenNF_Tc` \ mono_id_tys -> - let - mono_id_tyvars = tyVarsOfTypes mono_id_tys - mono_ids = zipWith3Equal "tcBindAndSigs" mk_id binder_names uniqs mono_id_tys - mk_id name uniq ty = mkUserLocal (getOccName name) uniq ty (getSrcLoc name) - 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 + let lie_avail = case maybe_sig_theta of + Nothing -> emptyLIE + Just (_, la) -> la in + tcImprove (lie_avail `plusLIE` 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_tyvars lie `thenTc` \ (tyvars_not_to_gen, tyvars_to_gen) -> - - -- DEAL WITH TYPE VARIABLE KINDS - mapTc defaultUncommittedTyVar (tyVarSetToList tyvars_to_gen) `thenTc` \ tyvars_to_gen_list -> - -- It's important that the final list (tyvars_to_gen_list) is fully + let + 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 -- the polymorphic Ids, and instances of these Ids will be generated from them. - -- - -- This step can do unification => keep other zonking after this + -- + -- Also NB that tcSimplify takes zonked tyvars as its arg, hence we pass + -- real_tyvars_to_gen + in -- SIMPLIFY THE LIE tcExtendGlobalTyVars tyvars_not_to_gen ( - if null tc_ty_sigs then + 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 - tcSimplify tyvars_to_gen lie `thenTc` \ (lie_free, dict_binds, lie_bound) -> + -- NB: no signatures => no polymorphic recursion, so no + -- need to use lie_avail (which will be empty anyway) + tcSimplify (text "tcBinds1" <+> ppr binder_names) + real_tyvars_to_gen lie_req `thenTc` \ (lie_free, dict_binds, lie_bound) -> returnTc (lie_free, dict_binds, map instToId (bagToList lie_bound)) - else - zonk_theta sig_theta `thenNF_Tc` \ sig_theta' -> + 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 -- dict_id is later used to form the type of the polymorphic thing, -- and forall-types must be zonked so far as their bound variables -- are concerned + let + -- The "givens" 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) + givens = dicts_sig `plusLIE` lie_avail + in + -- Check that the needed dicts can be expressed in -- terms of the signature ones - tcAddErrCtxt (sigsCtxt tysig_names) $ - tcSimplifyAndCheck tyvars_to_gen dicts_sig lie `thenTc` \ (lie_free, dict_binds) -> + tcAddErrCtxt (bindSigsCtxt tysig_names) $ + tcSimplifyAndCheck + (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) 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 - mapNF_Tc zonkTcType 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 - | maybeToBool maybe_sig = (sig_tyvars, TcId sig_poly_id, TcId mono_id) - | otherwise = (tyvars_to_gen_list, TcId poly_id, 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 - maybe_sig = maybeSig tc_ty_sigs binder_name - Just (TySigInfo _ sig_poly_id sig_tyvars _ _ _) = maybe_sig - poly_id = mkUserId binder_name poly_ty (prag_info_fn binder_name) - poly_ty = mkForAllTys 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 ( - AbsBinds tyvars_to_gen_list + -- 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_ty binder_name = case maybeSig tc_ty_sigs binder_name of - Just (TySigInfo name _ _ _ tau_ty _) -> returnNF_Tc tau_ty -- There's a signature - otherwise -> newTyVarTy kind -- No signature - - tysig_names = [name | (TySigInfo name _ _ _ _ _) <- tc_ty_sigs] + tysig_names = [name | (TySigInfo name _ _ _ _ _ _ _) <- tc_ty_sigs] is_unrestricted = isUnRestrictedGroup tysig_names mbind - kind | is_rec = mkBoxedTypeKind -- Recursive, so no unboxed types - | otherwise = 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 -zonk_theta theta = mapNF_Tc zonk theta - where - zonk (c,t) = zonkTcType t `thenNF_Tc` \ t' -> - returnNF_Tc (c,t') +attachNoInlinePrag no_inlines bndr + = case lookupFM no_inlines (idName bndr) of + Just prag -> bndr `setInlinePragma` prag + Nothing -> bndr \end{code} -@getImplicitStuffToGen@ decides what type variables generalise over. +Polymorphic recursion +~~~~~~~~~~~~~~~~~~~~~ +The game plan for polymorphic recursion in the code above is + + * Bind any variable for which we have a type signature + to an Id with a polymorphic type. Then when type-checking + the RHSs we'll make a full polymorphic call. + +This fine, but if you aren't a bit careful you end up with a horrendous +amount of partial application and (worse) a huge space leak. For example: + + f :: Eq a => [a] -> [a] + f xs = ...f... + +If we don't take care, after typechecking we get + + f = /\a -> \d::Eq a -> let f' = f a d + in + \ys:[a] -> ...f'... + +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 isn't being used (but that's a very common case). +We'd prefer + + 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 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. That's what the "lies_avail" +is doing. + + +%************************************************************************ +%* * +\subsection{getTyVarsToGen} +%* * +%************************************************************************ + +@getTyVarsToGen@ decides what type variables to generalise over. For a "restricted group" -- see the monomorphism restriction for a definition -- we bind no dictionaries, and @@ -370,21 +536,31 @@ constrained tyvars. We don't use any of the results, except to find which tyvars are constrained. \begin{code} -getTyVarsToGen is_unrestricted mono_tyvars lie - = tcGetGlobalTyVars `thenNF_Tc` \ free_tyvars -> - zonkTcTyVars mono_tyvars `thenNF_Tc` \ mentioned_tyvars -> +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 = mentioned_tyvars `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 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} @@ -398,7 +574,7 @@ 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 && @@ -406,20 +582,6 @@ 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} - %************************************************************************ %* * @@ -432,45 +594,122 @@ 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 $ - tcPat pat `thenTc` \ (pat2, lie_pat, pat_ty) -> - tcExtendLocalValEnv sig_names sig_ids $ - tcGRHSsAndBinds grhss_and_binds `thenTc` \ (grhss_and_binds2, lie, grhss_ty) -> - tcAddErrCtxt (patMonoBindsCtxt bind) $ - unifyTauTy pat_ty grhss_ty `thenTc_` - 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} %************************************************************************ @@ -479,50 +718,6 @@ 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 - (TcIdBndr s) -- *Polymorphic* binder for this value... - [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 :: (Name -> PragmaInfo) - -> RenamedSig - -> TcM s (TcSigInfo s) - -tcTySig prag_info_fn (Sig v ty src_loc) - = tcAddSrcLoc src_loc $ - tcHsType ty `thenTc` \ sigma_ty -> - tcInstSigType sigma_ty `thenNF_Tc` \ sigma_ty' -> - let - poly_id = mkUserId v sigma_ty' (prag_info_fn v) - (tyvars', theta', tau') = splitSigmaTy sigma_ty' - -- 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) @@ -532,90 +727,86 @@ 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)) -checkSigMatch tc_ty_sigs - = -- 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 - tcAddErrCtxt (sigContextsCtxt tc_ty_sigs) ( - mapTc (unifyTauTyLists dict_tys1) dict_tys_s - ) `thenTc_` - - -- CHECK THAT THE SIGNATURE TYVARS AND TAU_TYPES ARE OK - -- Doesn't affect substitution - mapTc check_one_sig tc_ty_sigs `thenTc_` + | otherwise + = returnTc Nothing -- No constraints from type sigs - returnTc theta1 where - (theta1:thetas) = [theta | TySigInfo _ _ _ theta _ _ <- tc_ty_sigs] - (dict_tys1 : dict_tys_s) = map mk_dict_tys (theta1 : thetas) - mk_dict_tys theta = [mkDictTy c t | (c,t) <- theta] - - check_one_sig (TySigInfo name id sig_tyvars _ sig_tau src_loc) - = tcAddSrcLoc src_loc $ - tcAddErrCtxt (sigCtxt id) $ - checkSigTyVars sig_tyvars sig_tau -\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] - -BUT ACTUALLY THESE FIRST TWO ARE FORCED BY USING DontBind TYVARS - - (c) not mentioned in the environment - eg the signature for f in this: + (TySigInfo _ id1 _ theta1 _ _ _ _ : all_sigs_but_first) = sigs - g x = ... where - f :: a->[a] - f y = [x,y] + sig1_dict_tys = mk_dict_tys theta1 + n_sig1_dict_tys = length sig1_dict_tys + sig_lie = mkLIE [inst | TySigInfo _ _ _ _ _ _ inst _ <- sigs] - 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. + 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 + check_one_sig (TySigInfo _ id sig_tyvars sig_theta sig_tau _ _ src_loc) + = tcAddSrcLoc src_loc $ + tcAddErrCtxtM (sigCtxt (sig_msg id) sig_tyvars sig_theta sig_tau) $ + checkSigTyVars sig_tyvars (idFreeTyVars id) -\begin{code} -checkSigTyVars :: [TcTyVar s] -- The original signature type variables - -> TcType s -- signature type (for err msg) - -> TcM s () -checkSigTyVars sig_tyvars sig_tau - = tcGetGlobalTyVars `thenNF_Tc` \ globals -> - let - mono_tyvars = filter (`elementOfTyVarSet` globals) sig_tyvars - in - -- TEMPORARY FIX - -- Until the final Bind-handling stuff is in, several type signatures in the same - -- bindings group can cause the signature type variable from the different - -- signatures to be unified. So we still need to zonk and check point (b). - -- Remove when activating the new binding code - mapNF_Tc zonkTcTyVar sig_tyvars `thenNF_Tc` \ sig_tys -> - checkTcM (hasNoDups (map (getTyVar "checkSigTyVars") sig_tys)) - (zonkTcType sig_tau `thenNF_Tc` \ sig_tau' -> - failTc (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_tys and sig_tyvars' correspond - -- 1-1 with sig_tyvars, so we can just map back. - checkTc (null mono_tyvars) - (notAsPolyAsSigErr sig_tau mono_tyvars) + -- 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 + 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) + sigContextsErr `thenTc_` + unifyTauTyLists sig1_dict_tys this_sig_dict_tys + where + this_sig_dict_tys = mk_dict_tys theta + + -- 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) + + mk_dict_tys theta = map mkPredTy theta + + sig_msg id = ptext SLIT("When checking the type signature for") <+> quotes (ppr id) + + -- 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} @@ -625,53 +816,13 @@ 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 -> PragmaInfo, -- Maps name to the appropriate PragmaInfo - TcHsBinds s, - LIE s) +They look like this: --- For now we just deal with INLINE pragmas -tcPragmaSigs sigs = returnTc (prag_fn, EmptyBinds, emptyLIE ) - where - prag_fn name | any has_inline sigs = IWantToBeINLINEd - | otherwise = NoPragmaInfo - where - has_inline (InlineSig n _) = (n == name) - has_inline other = False - - -{- -tcPragmaSigs sigs - = mapAndUnzip3Tc tcPragmaSig sigs `thenTc` \ (names_w_id_infos, binds, lies) -> - let - name_to_info name = foldr ($) noIdInfo - [info_fn | (n,info_fn) <- names_w_id_infos, n==name] - in - returnTc (name_to_info, - foldr ThenBinds EmptyBinds binds, - foldr plusLIE emptyLIE lies) -\end{code} - -Here are the easy cases for tcPragmaSigs - -\begin{code} -tcPragmaSig (DeforestSig name loc) - = returnTc ((name, addDeforestInfo DoDeforest),EmptyBinds,emptyLIE) -tcPragmaSig (InlineSig name loc) - = returnTc ((name, addUnfoldInfo (iWantToBeINLINEd UnfoldAlways)), EmptyBinds, emptyLIE) -tcPragmaSig (MagicUnfoldingSig name string loc) - = returnTc ((name, addUnfoldInfo (mkMagicUnfolding string)), EmptyBinds, emptyLIE) -\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 #-} @@ -694,113 +845,41 @@ 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 (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 -> - let - (sig_tyvars, sig_theta, sig_tau) = splitSigmaTy sig_ty - origin = ValSpecOrigin name - in - - -- Check that the SPECIALIZE pragma had an empty context - checkTc (null sig_theta) - (panic "SPECIALIZE non-empty context (ToDo: msg)") `thenTc_` - - -- Get and instantiate the type of the id mentioned - tcLookupLocalValueOK "tcPragmaSig" name `thenNF_Tc` \ main_id -> - tcInstSigType [] (idType main_id) `thenNF_Tc` \ main_ty -> - let - (main_tyvars, main_rho) = splitForAllTy main_ty - (main_theta,main_tau) = splitRhoTy main_rho - main_arg_tys = mkTyVarTys main_tyvars - in + tcHsSigType poly_ty `thenTc` \ sig_ty -> - -- Check that the specialised type is indeed an instance of - -- the type of the main function. - unifyTauTy sig_tau main_tau `thenTc_` - checkSigTyVars sig_tyvars sig_tau `thenTc_` - - -- Check that the type variables of the polymorphic function are - -- either left polymorphic, or instantiate to ground type. - -- Also check that the overloaded type variables are instantiated to - -- ground type; or equivalently that all dictionaries have ground type - mapTc zonkTcType main_arg_tys `thenNF_Tc` \ main_arg_tys' -> - zonkTcThetaType main_theta `thenNF_Tc` \ main_theta' -> - tcAddErrCtxt (specGroundnessCtxt main_arg_tys') - (checkTc (all isGroundOrTyVarTy main_arg_tys')) `thenTc_` - tcAddErrCtxt (specContextGroundnessCtxt main_theta') - (checkTc (and [isGroundTy ty | (_,ty) <- theta'])) `thenTc_` - - -- Build the SpecPragmaId; 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_pragma_id -> - - -- Build a suitable binding; depending on whether we were given - -- a value (Maybe Name) to be used as the specialisation. - case using of - Nothing -> -- No implementation function specified - - -- Make a Method inst for the occurrence of the overloaded function - newMethodWithGivenTy (OccurrenceOf name) - (TcId main_id) main_arg_tys main_rho `thenNF_Tc` \ (lie, meth_id) -> + -- 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) -> - let - pseudo_bind = VarMonoBind spec_pragma_id pseudo_rhs - pseudo_rhs = mkHsTyLam sig_tyvars (HsVar (TcId meth_id)) - in - returnTc (pseudo_bind, lie, \ info -> info) - - Just spec_name -> -- Use spec_name as the specialisation value ... + -- Squeeze out any Methods (see comments with tcSimplifyToDicts) + tcSimplifyToDicts spec_lie `thenTc` \ (spec_lie1, spec_binds) -> - -- Type check a simple occurrence of the specialised Id - tcId spec_name `thenTc` \ (spec_body, spec_lie, spec_tau) -> + -- 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 -> - -- Check that it has the correct type, and doesn't constrain the - -- signature variables at all - unifyTauTy sig_tau spec_tau `thenTc_` - checkSigTyVars sig_tyvars sig_tau `thenTc_` + -- 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) - -- Make a local SpecId to bind to applied spec_id - newSpecId main_id main_arg_tys sig_ty `thenNF_Tc` \ local_spec_id -> - - let - spec_rhs = mkHsTyLam sig_tyvars spec_body - spec_binds = VarMonoBind local_spec_id spec_rhs - `AndMonoBinds` - VarMonoBind spec_pragma_id (HsVar (TcId local_spec_id)) - spec_info = SpecInfo spec_tys (length main_theta) local_spec_id - in - returnTc ((name, addSpecInfo spec_info), spec_binds, spec_lie) --} +tcSpecSigs (other_sig : sigs) = tcSpecSigs sigs +tcSpecSigs [] = returnTc (EmptyMonoBinds, emptyLIE) \end{code} @@ -812,77 +891,65 @@ tcPragmaSig (SpecSig name poly_ty maybe_spec_name src_loc) \begin{code} -patMonoBindsCtxt bind sty - = hang (ptext SLIT("In a pattern binding:")) 4 (ppr sty bind) +patMonoBindsCtxt bind + = hang (ptext SLIT("In a pattern binding:")) 4 (ppr bind) ----------------------------------------------- -valSpecSigCtxt v ty sty - = hang (ptext SLIT("In a SPECIALIZE pragma for a value:")) - 4 (sep [(<>) (ppr sty v) (ptext SLIT(" ::")), - ppr sty ty]) - - +valSpecSigCtxt v ty + = sep [ptext SLIT("In a SPECIALIZE pragma for a value:"), + nest 4 (ppr v <+> dcolon <+> ppr ty)] ----------------------------------------------- -notAsPolyAsSigErr sig_tau mono_tyvars sty +notAsPolyAsSigErr sig_tau mono_tyvars = hang (ptext SLIT("A type signature is more polymorphic than the inferred type")) - 4 (vcat [text "Some type variables in the inferred type can't be forall'd, namely:", - interpp'SP sty mono_tyvars, - ptext SLIT("Possible cause: the RHS mentions something subject to the monomorphism restriction") - ]) + 4 (vcat [text "Can't for-all the type variable(s)" <+> + pprQuotedList mono_tyvars, + text "in the type" <+> quotes (ppr sig_tau) + ]) ----------------------------------------------- -badMatchErr sig_ty inferred_ty sty +badMatchErr sig_ty inferred_ty = hang (ptext SLIT("Type signature doesn't match inferred type")) - 4 (vcat [hang (ptext SLIT("Signature:")) 4 (ppr sty sig_ty), - hang (ptext SLIT("Inferred :")) 4 (ppr sty inferred_ty) + 4 (vcat [hang (ptext SLIT("Signature:")) 4 (ppr sig_ty), + hang (ptext SLIT("Inferred :")) 4 (ppr inferred_ty) ]) ----------------------------------------------- -sigCtxt id sty - = sep [ptext SLIT("When checking signature for"), ppr sty id] -sigsCtxt ids sty - = sep [ptext SLIT("When checking signature(s) for:"), interpp'SP sty ids] +unboxedPatBindErr id + = ptext SLIT("variable in a lazy pattern binding has unboxed type: ") + <+> quotes (ppr id) ----------------------------------------------- -sigContextsCtxt ty_sigs sty - = hang (ptext SLIT("When matching the contexts of the signatures of a recursive group")) - 4 (vcat (map ppr_tc_ty_sig ty_sigs)) - where - ppr_tc_ty_sig (TySigInfo val _ tyvars theta tau_ty _) - = hang ((<>) (ppr sty val) (ptext SLIT(" :: "))) - 4 (if null theta - then empty - else hcat [parens (hsep (punctuate comma (map (ppr_inst sty) theta))), - text " => ..."]) - ppr_inst sty (clas, ty) = hsep [ppr sty clas, ppr sty ty] +bindSigsCtxt ids + = ptext SLIT("When checking the type signature(s) for") <+> pprQuotedList ids ----------------------------------------------- -specGroundnessCtxt - = panic "specGroundnessCtxt" - --------------------------------------------- -specContextGroundnessCtxt -- err_ctxt dicts sty - = panic "specContextGroundnessCtxt" -{- - = hang ( - sep [hsep [ptext SLIT("In the SPECIALIZE pragma for"), ppr sty name], - hcat [ptext SLIT(" specialised to the type"), ppr sty spec_ty], - pp_spec_id sty, - ptext SLIT("... not all overloaded type variables were instantiated"), - ptext SLIT("to ground types:")]) - 4 (vcat [hsep [ppr sty c, ppr sty 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, - \ sty -> hsep [ptext SLIT("... type of explicit id"), ppr sty spec]) --} -\end{code} +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")] +----------------------------------------------- +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}