X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcBinds.lhs;h=b5d2cb74770412effb48c8bcfd4579a1aa910a9a;hb=dbaa3bb30eaf9d806357e41435dab32695c47842;hp=a50bc502d023779bd6740f94fc1239d8f293ac3d;hpb=39068cf49bf3553f90ec316569619c310a6be8de;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcBinds.lhs b/ghc/compiler/typecheck/TcBinds.lhs index a50bc50..b5d2cb7 100644 --- a/ghc/compiler/typecheck/TcBinds.lhs +++ b/ghc/compiler/typecheck/TcBinds.lhs @@ -4,58 +4,50 @@ \section[TcBinds]{TcBinds} \begin{code} -module TcBinds ( tcBindsAndThen, tcTopBinds, - tcSpecSigs, tcBindWithSigs ) where +module TcBinds ( tcBindsAndThen, tcTopBinds, tcMonoBinds, tcSpecSigs ) where #include "HsVersions.h" -import {-# SOURCE #-} TcMatches ( tcGRHSs, tcMatchesFun ) -import {-# SOURCE #-} TcExpr ( tcExpr ) +import {-# SOURCE #-} TcMatches ( tcGRHSsPat, tcMatchesFun ) +import {-# SOURCE #-} TcExpr ( tcCheckSigma, tcCheckRho ) -import CmdLineOpts ( opt_NoMonomorphismRestriction ) +import CmdLineOpts ( DynFlag(Opt_NoMonomorphismRestriction) ) import HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..), - Match(..), HsMatchContext(..), - collectMonoBinders, andMonoBinds + Match(..), mkMonoBind, + collectMonoBinders, andMonoBinds, + collectSigTysFromMonoBinds ) import RnHsSyn ( RenamedHsBinds, RenamedSig, RenamedMonoBinds ) -import TcHsSyn ( TcMonoBinds, TcId, zonkId, mkHsLet ) - -import TcMonad -import Inst ( LIE, emptyLIE, mkLIE, plusLIE, InstOrigin(..), - newDicts, instToId - ) -import TcEnv ( tcExtendLocalValEnv, - newSpecPragmaId, newLocalId - ) -import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck, tcSimplifyCheck, tcSimplifyRestricted, tcSimplifyToDicts ) -import TcMonoType ( tcHsSigType, checkSigTyVars, - TcSigInfo(..), tcTySig, maybeSig, sigCtxt +import TcHsSyn ( TcHsBinds, TcMonoBinds, TcId, zonkId, mkHsLet ) + +import TcRnMonad +import Inst ( InstOrigin(..), newDicts, newIPDict, instToId ) +import TcEnv ( tcExtendLocalValEnv, tcExtendLocalValEnv2, newLocalName ) +import TcUnify ( Expected(..), newHole, unifyTauTyLists, checkSigTyVarsWrt, sigCtxt ) +import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck, tcSimplifyRestricted, + tcSimplifyToDicts, tcSimplifyIPs ) +import TcMonoType ( tcHsSigType, UserTypeCtxt(..), TcSigInfo(..), + tcTySig, maybeSig, tcSigPolyId, tcSigMonoId, tcAddScopedTyVars ) -import TcPat ( tcPat ) +import TcPat ( tcPat, tcSubPat, tcMonoPatBndr ) import TcSimplify ( bindInstsOfLocalFuns ) -import TcType ( newTyVarTy, newTyVar, - zonkTcTyVarToTyVar +import TcMType ( newTyVar, newTyVarTy, zonkTcTyVarToTyVar ) +import TcType ( TcTyVar, mkTyVarTy, mkForAllTys, mkFunTys, tyVarsOfType, + mkPredTy, mkForAllTy, isUnLiftedType, + unliftedTypeKind, liftedTypeKind, openTypeKind, eqKind ) -import TcUnify ( unifyTauTy, unifyTauTyLists ) import CoreFVs ( idFreeTyVars ) -import Id ( mkLocalId, setInlinePragma ) +import Id ( mkLocalId, mkSpecPragmaId, setInlinePragma ) import Var ( idType, idName ) -import IdInfo ( InlinePragInfo(..) ) -import Name ( Name, getOccName, getSrcLoc ) +import Name ( Name, getSrcLoc ) import NameSet -import Type ( mkTyVarTy, tyVarsOfTypes, - mkForAllTys, mkFunTys, tyVarsOfType, - mkPredTy, mkForAllTy, isUnLiftedType, - unliftedTypeKind, liftedTypeKind, openTypeKind - ) import Var ( tyVarKind ) import VarSet import Bag -import Util ( isIn ) -import ListSetOps ( minusList ) -import Maybes ( maybeToBool ) -import BasicTypes ( TopLevelFlag(..), RecFlag(..), isNonRec, isNotTopLevel ) +import Util ( isIn, equalLength ) +import BasicTypes ( TopLevelFlag(..), RecFlag(..), isNonRec, isRec, + isNotTopLevel, isAlwaysActive ) import FiniteMap ( listToFM, lookupFM ) import Outputable \end{code} @@ -93,20 +85,29 @@ At the top-level the LIE is sure to contain nothing but constant dictionaries, which we resolve at the module level. \begin{code} -tcTopBinds :: RenamedHsBinds -> TcM ((TcMonoBinds, TcEnv), LIE) +tcTopBinds :: RenamedHsBinds -> TcM (TcMonoBinds, TcLclEnv) + -- Note: returning the TcLclEnv is more than we really + -- want. The bit we care about is the local bindings + -- and the free type variables thereof tcTopBinds binds = tc_binds_and_then TopLevel glue binds $ - tcGetEnv `thenNF_Tc` \ env -> - returnTc ((EmptyMonoBinds, env), emptyLIE) + getLclEnv `thenM` \ env -> + returnM (EmptyMonoBinds, env) where - glue is_rec binds1 (binds2, thing) = (binds1 `AndMonoBinds` binds2, thing) + -- The top level bindings are flattened into a giant + -- implicitly-mutually-recursive MonoBinds + glue binds1 (binds2, env) = (flatten binds1 `AndMonoBinds` binds2, env) + flatten EmptyBinds = EmptyMonoBinds + flatten (b1 `ThenBinds` b2) = flatten b1 `AndMonoBinds` flatten b2 + flatten (MonoBind b _ _) = b + -- Can't have a IPBinds at top level tcBindsAndThen - :: (RecFlag -> TcMonoBinds -> thing -> thing) -- Combinator + :: (TcHsBinds -> thing -> thing) -- Combinator -> RenamedHsBinds - -> TcM (thing, LIE) - -> TcM (thing, LIE) + -> TcM thing + -> TcM thing tcBindsAndThen = tc_binds_and_then NotTopLevel @@ -120,63 +121,86 @@ tc_binds_and_then top_lvl combiner (ThenBinds b1 b2) do_next tc_binds_and_then top_lvl combiner b2 $ do_next +tc_binds_and_then top_lvl combiner (IPBinds binds is_with) do_next + = getLIE do_next `thenM` \ (result, expr_lie) -> + mapAndUnzipM tc_ip_bind binds `thenM` \ (avail_ips, binds') -> + + -- If the binding binds ?x = E, we must now + -- discharge any ?x constraints in expr_lie + tcSimplifyIPs avail_ips expr_lie `thenM` \ dict_binds -> + + returnM (combiner (IPBinds binds' is_with) $ + combiner (mkMonoBind Recursive dict_binds) result) + where + -- I wonder if we should do these one at at time + -- Consider ?x = 4 + -- ?y = ?x + 1 + tc_ip_bind (ip, expr) + = newTyVarTy openTypeKind `thenM` \ ty -> + getSrcLocM `thenM` \ loc -> + newIPDict (IPBind ip) ip ty `thenM` \ (ip', ip_inst) -> + tcCheckRho expr ty `thenM` \ expr' -> + returnM (ip_inst, (ip', expr')) + 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 -> + = -- BRING ANY SCOPED TYPE VARIABLES INTO SCOPE + -- Notice that they scope over + -- a) the type signatures in the binding group + -- b) the bindings in the group + -- c) the scope of the binding group (the "in" part) + tcAddScopedTyVars (collectSigTysFromMonoBinds bind) $ + + tcBindWithSigs top_lvl bind sigs is_rec `thenM` \ (poly_binds, poly_ids) -> - 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) -> - - -- Create specialisations of functions bound here - -- We want to keep non-recursive things non-recursive - -- so that we desugar unlifted 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 $ + case top_lvl of + TopLevel -- For the top level don't bother will all this + -- bindInstsOfLocalFuns stuff. All the top level + -- things are rec'd together anyway, so it's fine to + -- leave them to the tcSimplifyTop, and quite a bit faster too + -- + -- Subtle (and ugly) point: furthermore at top level we + -- return the TcLclEnv, which contains the LIE var; we + -- don't want to return the wrong one! + -> tc_body poly_ids `thenM` \ (prag_binds, thing) -> + returnM (combiner (mkMonoBind Recursive (poly_binds `andMonoBinds` prag_binds)) + thing) + + NotTopLevel -- For nested bindings we must do teh bindInstsOfLocalFuns thing + -> getLIE (tc_body poly_ids) `thenM` \ ((prag_binds, thing), lie) -> + + -- Create specialisations of functions bound here + bindInstsOfLocalFuns lie poly_ids `thenM` \ lie_binds -> + + -- We want to keep non-recursive things non-recursive + -- so that we desugar unlifted bindings correctly + if isRec is_rec then + returnM ( + combiner (mkMonoBind Recursive ( + poly_binds `andMonoBinds` + lie_binds `andMonoBinds` + prag_binds)) thing + ) + else + returnM ( + combiner (mkMonoBind NonRecursive poly_binds) $ + combiner (mkMonoBind NonRecursive prag_binds) $ + combiner (mkMonoBind Recursive lie_binds) $ -- NB: the binds returned by tcSimplify and bindInstsOfLocalFuns -- aren't guaranteed in dependency order (though we could change -- that); hence the Recursive marker. - thing, - - thing_lie' `plusLIE` poly_lie - ) + thing) + where + tc_body poly_ids -- Type check the pragmas and "thing inside" + = -- Extend the environment to bind the new polymorphic Ids + tcExtendLocalValEnv poly_ids $ + + -- Build bindings and IdInfos corresponding to user pragmas + tcSpecSigs sigs `thenM` \ prag_binds -> - (NotTopLevel, Recursive) - -> bindInstsOfLocalFuns - (thing_lie `plusLIE` poly_lie `plusLIE` prag_lie) - poly_ids `thenTc` \ (final_lie, lie_binds) -> + -- Now do whatever happens next, in the augmented envt + do_next `thenM` \ thing -> - returnTc ( - combiner Recursive ( - poly_binds `andMonoBinds` - lie_binds `andMonoBinds` - prag_binds) thing, - final_lie - ) + returnM (prag_binds, thing) \end{code} @@ -200,37 +224,48 @@ so all the clever stuff is in here. tcBindWithSigs :: TopLevelFlag -> RenamedMonoBinds - -> [TcSigInfo] -> [RenamedSig] -- Used solely to get INLINE, NOINLINE sigs -> RecFlag - -> TcM (TcMonoBinds, LIE, [TcId]) + -> TcM (TcMonoBinds, [TcId]) + +tcBindWithSigs top_lvl mbind sigs is_rec + = -- TYPECHECK THE SIGNATURES + recoverM (returnM []) ( + mappM tcTySig [sig | sig@(Sig name _ _) <- sigs] + ) `thenM` \ tc_ty_sigs -> -tcBindWithSigs top_lvl mbind tc_ty_sigs inline_sigs is_rec - = recoverTc ( + -- SET UP THE MAIN RECOVERY; take advantage of any type sigs + recoverM ( -- If typechecking the binds fails, then return with each -- signature-less binder given type (forall a.a), to minimise subsequent -- error messages - newTyVar liftedTypeKind `thenNF_Tc` \ alpha_tv -> + newTyVar liftedTypeKind `thenM` \ alpha_tv -> let forall_a_a = mkForAllTy alpha_tv (mkTyVarTy alpha_tv) binder_names = collectMonoBinders mbind poly_ids = map mk_dummy binder_names mk_dummy name = case maybeSig tc_ty_sigs name of - Just (TySigInfo _ poly_id _ _ _ _ _ _) -> poly_id -- Signature - Nothing -> mkLocalId name forall_a_a -- No signature + Just sig -> tcSigPolyId sig -- Signature + Nothing -> mkLocalId name forall_a_a -- No signature in - returnTc (EmptyMonoBinds, emptyLIE, poly_ids) + traceTc (text "tcBindsWithSigs: error recovery" <+> ppr binder_names) `thenM_` + returnM (EmptyMonoBinds, poly_ids) ) $ -- TYPECHECK THE BINDINGS - tcMonoBinds mbind tc_ty_sigs is_rec `thenTc` \ (mbind', lie_req, binder_names, mono_ids) -> + getLIE (tcMonoBinds mbind tc_ty_sigs is_rec) `thenM` \ ((mbind', bndr_names_w_ids), lie_req) -> let - tau_tvs = varSetElems (foldr (unionVarSet . tyVarsOfType . idType) emptyVarSet mono_ids) + (binder_names, mono_ids) = unzip (bagToList bndr_names_w_ids) + tau_tvs = foldr (unionVarSet . tyVarsOfType . idType) emptyVarSet mono_ids in -- GENERALISE - generalise binder_names mbind tau_tvs lie_req tc_ty_sigs - `thenTc` \ (tc_tyvars_to_gen, lie_free, dict_binds, dict_ids) -> + -- (it seems a bit crude to have to do getLIE twice, + -- but I can't see a better way just now) + addSrcLoc (minimum (map getSrcLoc binder_names)) $ + addErrCtxt (genCtxt binder_names) $ + getLIE (generalise binder_names mbind tau_tvs lie_req tc_ty_sigs) + `thenM` \ ((tc_tyvars_to_gen, dict_binds, dict_ids), lie_free) -> -- ZONK THE GENERALISED TYPE VARIABLES TO REAL TyVars @@ -240,48 +275,45 @@ tcBindWithSigs top_lvl mbind tc_ty_sigs inline_sigs is_rec -- included in the forall types of the polymorphic Ids. -- At calls of these Ids we'll instantiate fresh type variables from -- them, and we use their boxity then. - mapNF_Tc zonkTcTyVarToTyVar tc_tyvars_to_gen `thenNF_Tc` \ real_tyvars_to_gen -> + mappM zonkTcTyVarToTyVar tc_tyvars_to_gen `thenM` \ real_tyvars_to_gen -> -- ZONK THE Ids -- It's important that the dict Ids are zonked, including the boxity set -- in the previous step, because they are later used to form the type of -- the polymorphic thing, and forall-types must be zonked so far as -- their bound variables are concerned - mapNF_Tc zonkId dict_ids `thenNF_Tc` \ zonked_dict_ids -> - mapNF_Tc zonkId mono_ids `thenNF_Tc` \ zonked_mono_ids -> - - -- CHECK FOR BOGUS UNLIFTED BINDINGS - checkUnliftedBinds top_lvl is_rec real_tyvars_to_gen mbind zonked_mono_ids `thenTc_` + mappM zonkId dict_ids `thenM` \ zonked_dict_ids -> + mappM zonkId mono_ids `thenM` \ zonked_mono_ids -> -- BUILD THE POLYMORPHIC RESULT IDs let exports = zipWith mk_export binder_names zonked_mono_ids + poly_ids = [poly_id | (_, poly_id, _) <- exports] dict_tys = map idType zonked_dict_ids - 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 + inlines = mkNameSet [name | InlineSig True name _ loc <- sigs] + -- Any INLINE sig (regardless of phase control) + -- makes the RHS look small + inline_phases = listToFM [(name, phase) | InlineSig _ name phase _ <- sigs, + not (isAlwaysActive phase)] + -- Set the IdInfo field to control the inline phase + -- AlwaysActive is the default, so don't bother with them mk_export binder_name zonked_mono_id = (tyvars, - attachNoInlinePrag no_inlines poly_id, + attachInlinePhase inline_phases poly_id, zonked_mono_id) where (tyvars, poly_id) = case maybeSig tc_ty_sigs binder_name of - Just (TySigInfo _ sig_poly_id sig_tyvars _ _ _ _ _) -> + Just (TySigInfo sig_poly_id sig_tyvars _ _ _ _ _) -> (sig_tyvars, sig_poly_id) Nothing -> (real_tyvars_to_gen, new_poly_id) new_poly_id = mkLocalId binder_name poly_ty poly_ty = mkForAllTys real_tyvars_to_gen - $ mkFunTys dict_tys - $ idType zonked_mono_id + $ 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 @@ -290,26 +322,45 @@ tcBindWithSigs top_lvl mbind tc_ty_sigs inline_sigs is_rec in traceTc (text "binding:" <+> ppr ((zonked_dict_ids, dict_binds), - exports, [idType poly_id | (_, poly_id, _) <- exports])) `thenTc_` + exports, map idType poly_ids)) `thenM_` - -- BUILD RESULTS - returnTc ( + -- Check for an unlifted, non-overloaded group + -- In that case we must make extra checks + if any (isUnLiftedType . idType) zonked_mono_ids && null zonked_dict_ids + then -- Some bindings are unlifted + checkUnliftedBinds top_lvl is_rec real_tyvars_to_gen mbind `thenM_` + + extendLIEs lie_req `thenM_` + returnM ( + AbsBinds [] [] exports inlines mbind', + -- Do not generate even any x=y bindings + poly_ids + ) + + else -- The normal case + extendLIEs lie_free `thenM_` + returnM ( AbsBinds real_tyvars_to_gen zonked_dict_ids exports inlines (dict_binds `andMonoBinds` mbind'), - lie_free, - [poly_id | (_, poly_id, _) <- exports] + poly_ids ) -attachNoInlinePrag no_inlines bndr - = case lookupFM no_inlines (idName bndr) of +attachInlinePhase inline_phases bndr + = case lookupFM inline_phases (idName bndr) of Just prag -> bndr `setInlinePragma` prag Nothing -> bndr -checkUnliftedBinds top_lvl is_rec real_tyvars_to_gen mbind zonked_mono_ids - = ASSERT( not (any ((== unliftedTypeKind) . tyVarKind) real_tyvars_to_gen) ) +-- Check that non-overloaded unlifted bindings are +-- a) non-recursive, +-- b) not top level, +-- c) non-polymorphic +-- d) not a multiple-binding group (more or less implied by (a)) + +checkUnliftedBinds top_lvl is_rec real_tyvars_to_gen mbind + = ASSERT( not (any ((eqKind unliftedTypeKind) . tyVarKind) real_tyvars_to_gen) ) -- The instCantBeGeneralised stuff in tcSimplify should have -- already raised an error if we're trying to generalise an -- unboxed tyvar (NB: unboxed tyvars are always introduced @@ -317,34 +368,19 @@ checkUnliftedBinds top_lvl is_rec real_tyvars_to_gen mbind zonked_mono_ids -- because we have more precise origin information. -- That's why we just use an ASSERT here. - -- Check that pattern-bound variables are not unlifted - (if or [ (idName id `elem` pat_binders) && isUnLiftedType (idType id) - | id <- zonked_mono_ids ] then - addErrTc (unliftedBindErr "Pattern" mbind) - else - returnTc () - ) `thenTc_` - - -- Unlifted bindings must be non-recursive, - -- not top level, non-polymorphic, and not pattern bound - if any (isUnLiftedType . idType) zonked_mono_ids then - checkTc (isNotTopLevel top_lvl) - (unliftedBindErr "Top-level" mbind) `thenTc_` - checkTc (isNonRec is_rec) - (unliftedBindErr "Recursive" mbind) `thenTc_` - checkTc (null real_tyvars_to_gen) - (unliftedBindErr "Polymorphic" mbind) - else - returnTc () + checkTc (isNotTopLevel top_lvl) + (unliftedBindErr "Top-level" mbind) `thenM_` + checkTc (isNonRec is_rec) + (unliftedBindErr "Recursive" mbind) `thenM_` + checkTc (single_bind mbind) + (unliftedBindErr "Multiple" mbind) `thenM_` + checkTc (null real_tyvars_to_gen) + (unliftedBindErr "Polymorphic" mbind) where - pat_binders :: [Name] - pat_binders = collectMonoBinders (justPatBindings mbind EmptyMonoBinds) - - justPatBindings bind@(PatMonoBind _ _ _) binds = bind `andMonoBinds` binds - justPatBindings (AndMonoBinds b1 b2) binds = - justPatBindings b1 (justPatBindings b2 binds) - justPatBindings other_bind binds = binds + single_bind (PatMonoBind _ _ _) = True + single_bind (FunMonoBind _ _ _ _) = True + single_bind other = False \end{code} @@ -411,67 +447,48 @@ is doing. %************************************************************************ \begin{code} -generalise_help doc tau_tvs lie_req sigs +generalise binder_names mbind tau_tvs lie_req sigs = ------------------------ - | null sigs - = -- INFERENCE CASE: Unrestricted group, no type signatures - tcSimplifyInfer doc - tau_tvs lie_req + -- check for -fno-monomorphism-restriction + doptM Opt_NoMonomorphismRestriction `thenM` \ no_MR -> + let is_unrestricted | no_MR = True + | otherwise = isUnRestrictedGroup tysig_names mbind + in ------------------------ - | otherwise - = -- CHECKING CASE: Unrestricted group, there are type signatures - -- Check signature contexts are empty - checkSigsCtxts sigs `thenTc` \ (sig_avails, sig_dicts) -> + if not is_unrestricted then -- RESTRICTED CASE + -- Check signature contexts are empty + checkTc (all is_mono_sig sigs) + (restrictedBindCtxtErr binder_names) `thenM_` + -- Now simplify with exactly that set of tyvars + -- We have to squash those Methods + tcSimplifyRestricted doc tau_tvs lie_req `thenM` \ (qtvs, binds) -> + + -- Check that signature type variables are OK + checkSigsTyVars qtvs sigs `thenM` \ final_qtvs -> + + returnM (final_qtvs, binds, []) + + else if null sigs then -- UNRESTRICTED CASE, NO TYPE SIGS + tcSimplifyInfer doc tau_tvs lie_req + + else -- UNRESTRICTED CASE, WITH TYPE SIGS + -- CHECKING CASE: Unrestricted group, there are type signatures + -- Check signature contexts are identical + checkSigsCtxts sigs `thenM` \ (sig_avails, sig_dicts) -> + -- Check that the needed dicts can be -- expressed in terms of the signature ones - tcSimplifyInferCheck doc tau_tvs sig_avails lie_req `thenTc` \ (forall_tvs, lie_free, dict_binds) -> + tcSimplifyInferCheck doc tau_tvs sig_avails lie_req `thenM` \ (forall_tvs, dict_binds) -> -- Check that signature type variables are OK - checkSigsTyVars sigs `thenTc_` - - returnTc (forall_tvs, lie_free, dict_binds, sig_dicts) - -generalise binder_names mbind tau_tvs lie_req sigs - | is_unrestricted -- UNRESTRICTED CASE - = generalise_help doc tau_tvs lie_req sigs - - | otherwise -- RESTRICTED CASE - = -- Do a simplification to decide what type variables - -- are constrained. We can't just take the free vars - -- of lie_req because that'll have methods that may - -- incidentally mention entirely unconstrained variables - -- e.g. a call to f :: Eq a => a -> b -> b - -- Here, b is unconstrained. A good example would be - -- foo = f (3::Int) - -- We want to infer the polymorphic type - -- foo :: forall b. b -> b - generalise_help doc tau_tvs lie_req sigs `thenTc` \ (forall_tvs, lie_free, dict_binds, dict_ids) -> - - -- Check signature contexts are empty - checkTc (null sigs || null dict_ids) - (restrictedBindCtxtErr binder_names) `thenTc_` - - -- Identify constrained tyvars - let - constrained_tvs = varSetElems (tyVarsOfTypes (map idType dict_ids)) - -- The dict_ids are fully zonked - final_forall_tvs = forall_tvs `minusList` constrained_tvs - in - - -- Now simplify with exactly that set of tyvars - -- We have to squash those Methods - tcSimplifyRestricted doc final_forall_tvs [] lie_req `thenTc` \ (lie_free, binds) -> + checkSigsTyVars forall_tvs sigs `thenM` \ final_qtvs -> - returnTc (final_forall_tvs, lie_free, binds, []) + returnM (final_qtvs, dict_binds, sig_dicts) where - is_unrestricted | opt_NoMonomorphismRestriction = True - | otherwise = isUnRestrictedGroup tysig_names mbind - - tysig_names = [name | (TySigInfo name _ _ _ _ _ _ _) <- sigs] + tysig_names = map (idName . tcSigPolyId) sigs + is_mono_sig (TySigInfo _ _ theta _ _ _ _) = null theta doc = ptext SLIT("type signature(s) for") <+> pprBinders binder_names @@ -483,38 +500,53 @@ generalise binder_names mbind tau_tvs lie_req sigs -- We unify them because, with polymorphic recursion, their types -- might not otherwise be related. This is a rather subtle issue. -- ToDo: amplify -checkSigsCtxts sigs@(TySigInfo _ id1 sig_tvs theta1 _ _ _ _ : other_sigs) - = mapTc_ check_one other_sigs `thenTc_` +checkSigsCtxts sigs@(TySigInfo id1 sig_tvs theta1 _ _ _ src_loc : other_sigs) + = addSrcLoc src_loc $ + mappM_ check_one other_sigs `thenM_` if null theta1 then - returnTc ([], []) -- Non-overloaded type signatures + returnM ([], []) -- Non-overloaded type signatures else - newDicts SignatureOrigin theta1 `thenNF_Tc` \ sig_dicts -> + newDicts SignatureOrigin theta1 `thenM` \ sig_dicts -> let -- The "sig_avails" is the stuff available. We get that from -- the context of the type signature, BUT ALSO the lie_avail -- so that polymorphic recursion works right (see comments at end of fn) sig_avails = sig_dicts ++ sig_meths in - returnTc (sig_avails, map instToId sig_dicts) + returnM (sig_avails, map instToId sig_dicts) where sig1_dict_tys = map mkPredTy theta1 - n_sig1_theta = length theta1 - sig_meths = concat [insts | TySigInfo _ _ _ _ _ _ insts _ <- sigs] + sig_meths = concat [insts | TySigInfo _ _ _ _ _ insts _ <- sigs] - check_one sig@(TySigInfo _ id _ theta _ _ _ src_loc) - = tcAddSrcLoc src_loc $ - tcAddErrCtxt (sigContextsCtxt id1 id) $ - checkTc (length theta == n_sig1_theta) sigContextsErr `thenTc_` + check_one sig@(TySigInfo id _ theta _ _ _ _) + = addErrCtxt (sigContextsCtxt id1 id) $ + checkTc (equalLength theta theta1) sigContextsErr `thenM_` unifyTauTyLists sig1_dict_tys (map mkPredTy theta) -checkSigsTyVars sigs = mapTc_ check_one sigs +checkSigsTyVars :: [TcTyVar] -> [TcSigInfo] -> TcM [TcTyVar] +checkSigsTyVars qtvs sigs + = mappM check_one sigs `thenM` \ sig_tvs_s -> + let + -- Sigh. Make sure that all the tyvars in the type sigs + -- appear in the returned ty var list, which is what we are + -- going to generalise over. Reason: we occasionally get + -- silly types like + -- type T a = () -> () + -- f :: T a + -- f () = () + -- Here, 'a' won't appear in qtvs, so we have to add it + + sig_tvs = foldr (unionVarSet . mkVarSet) emptyVarSet sig_tvs_s + all_tvs = mkVarSet qtvs `unionVarSet` sig_tvs + in + returnM (varSetElems all_tvs) where - check_one (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) - - sig_msg id = ptext SLIT("When checking the type signature for") <+> quotes (ppr id) + check_one (TySigInfo id sig_tyvars sig_theta sig_tau _ _ src_loc) + = addSrcLoc src_loc $ + addErrCtxt (ptext SLIT("When checking the type signature for") + <+> quotes (ppr id)) $ + addErrCtxtM (sigCtxt id sig_tyvars sig_theta sig_tau) $ + checkSigTyVarsWrt (idFreeTyVars id) sig_tyvars \end{code} @getTyVarsToGen@ decides what type variables to generalise over. @@ -565,14 +597,14 @@ is_elem v vs = isIn "isUnResMono" v vs isUnRestrictedGroup sigs (PatMonoBind other _ _) = False isUnRestrictedGroup sigs (VarMonoBind v _) = v `is_elem` sigs -isUnRestrictedGroup sigs (FunMonoBind v _ matches _) = any isUnRestrictedMatch matches || +isUnRestrictedGroup sigs (FunMonoBind v _ matches _) = isUnRestrictedMatch matches || v `is_elem` sigs isUnRestrictedGroup sigs (AndMonoBinds mb1 mb2) = isUnRestrictedGroup sigs mb1 && isUnRestrictedGroup sigs mb2 isUnRestrictedGroup sigs EmptyMonoBinds = True -isUnRestrictedMatch (Match _ [] Nothing _) = False -- No args, no signature -isUnRestrictedMatch other = True -- Some args or a signature +isUnRestrictedMatch (Match [] _ _ : _) = False -- No args => like a pattern binding +isUnRestrictedMatch other = True -- Some args => a function binding \end{code} @@ -587,126 +619,129 @@ The signatures have been dealt with already. \begin{code} tcMonoBinds :: RenamedMonoBinds - -> [TcSigInfo] - -> RecFlag + -> [TcSigInfo] -> RecFlag -> TcM (TcMonoBinds, - LIE, -- LIE required - [Name], -- Bound names - [TcId]) -- Corresponding monomorphic bound things + Bag (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 - 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 - - complete_it extra_val_env `thenTc` \ (mbinds', lie_req_rhss) -> - - returnTc (mbinds', lie_req_pat `plusLIE` lie_req_rhss, names, mono_ids) + -- Three stages: + -- 1. Check the patterns, building up an environment binding + -- the variables in this group (in the recursive case) + -- 2. Extend the environment + -- 3. Check the RHSs + = tc_mb_pats mbinds `thenM` \ (complete_it, xve) -> + tcExtendLocalValEnv2 (bagToList xve) complete_it where - - -- This function is used when dealing with a LHS binder; - -- we make a monomorphic version of the Id. - -- We check for a type signature; if there is one, we use the mono_id - -- from the signature. This is how we make sure the tau part of the - -- signature actually maatches the type of the LHS; then tc_mb_pats - -- ensures the LHS and RHS have the same type - - tc_pat_bndr name pat_ty - = case maybeSig tc_ty_sigs name of - Nothing - -> 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 EmptyMonoBinds + = returnM (returnM (EmptyMonoBinds, emptyBag), emptyBag) 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) -> + = tc_mb_pats mb1 `thenM` \ (complete_it1, xve1) -> + tc_mb_pats mb2 `thenM` \ (complete_it2, xve2) -> let - complete_it xve = complete_it1 xve `thenTc` \ (mb1', lie1) -> - complete_it2 xve `thenTc` \ (mb2', lie2) -> - returnTc (AndMonoBinds mb1' mb2', lie1 `plusLIE` lie2) + complete_it = complete_it1 `thenM` \ (mb1', bs1) -> + complete_it2 `thenM` \ (mb2', bs2) -> + returnM (AndMonoBinds mb1' mb2', bs1 `unionBags` bs2) in - returnTc (complete_it, - lie_req1 `plusLIE` lie_req2, - tvs1 `unionBags` tvs2, - ids1 `unionBags` ids2, - lie_avail1 `plusLIE` lie_avail2) + returnM (complete_it, xve1 `unionBags` xve2) tc_mb_pats (FunMonoBind name inf matches locn) - = newTyVarTy kind `thenNF_Tc` \ bndr_ty -> - tc_pat_bndr name bndr_ty `thenTc` \ bndr_id -> + -- Three cases: + -- a) Type sig supplied + -- b) No type sig and recursive + -- c) No type sig and non-recursive + + | Just sig <- maybeSig tc_ty_sigs name + = let -- (a) There is a type signature + -- Use it for the environment extension, and check + -- the RHS has the appropriate type (with outer for-alls stripped off) + mono_id = tcSigMonoId sig + mono_ty = idType mono_id + complete_it = addSrcLoc locn $ + tcMatchesFun name matches (Check mono_ty) `thenM` \ matches' -> + returnM (FunMonoBind mono_id inf matches' locn, + unitBag (name, mono_id)) + in + returnM (complete_it, if isRec is_rec then unitBag (name,tcSigPolyId sig) + else emptyBag) + + | isRec is_rec + = -- (b) No type signature, and recursive + -- So we must use an ordinary H-M type variable + -- which means the variable gets an inferred tau-type + newLocalName name `thenM` \ mono_name -> + newTyVarTy openTypeKind `thenM` \ mono_ty -> let - complete_it xve = tcAddSrcLoc locn $ - tcMatchesFun xve name bndr_ty matches `thenTc` \ (matches', lie) -> - returnTc (FunMonoBind bndr_id inf matches' locn, lie) + mono_id = mkLocalId mono_name mono_ty + complete_it = addSrcLoc locn $ + tcMatchesFun name matches (Check mono_ty) `thenM` \ matches' -> + returnM (FunMonoBind mono_id inf matches' locn, + unitBag (name, mono_id)) in - returnTc (complete_it, emptyLIE, emptyBag, unitBag (name, bndr_id), emptyLIE) - + returnM (complete_it, unitBag (name, mono_id)) + + | otherwise -- (c) No type signature, and non-recursive + = let -- So we can use a 'hole' type to infer a higher-rank type + complete_it + = addSrcLoc locn $ + newHole `thenM` \ hole -> + tcMatchesFun name matches (Infer hole) `thenM` \ matches' -> + readMutVar hole `thenM` \ fun_ty -> + newLocalName name `thenM` \ mono_name -> + let + mono_id = mkLocalId mono_name fun_ty + in + returnM (FunMonoBind mono_id inf matches' locn, + unitBag (name, mono_id)) + in + returnM (complete_it, emptyBag) + tc_mb_pats bind@(PatMonoBind pat grhss locn) - = tcAddSrcLoc locn $ - newTyVarTy kind `thenNF_Tc` \ pat_ty -> + = addSrcLoc locn $ -- Now typecheck the pattern - -- We don't support binding fresh type variables in the - -- pattern of a pattern binding. For example, this is illegal: + -- We do now support binding fresh (not-already-in-scope) scoped + -- type variables in the pattern of a pattern binding. + -- For example, this is now legal: -- (x::a, y::b) = e - -- 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) -> + -- The type variables are brought into scope in tc_binds_and_then, + -- so we don't have to do anything here. + + newHole `thenM` \ hole -> + tcPat tc_pat_bndr pat (Infer hole) `thenM` \ (pat', tvs, ids, lie_avail) -> + readMutVar hole `thenM` \ pat_ty -> + + -- Don't know how to deal with pattern-bound existentials yet + checkTc (isEmptyBag tvs && null lie_avail) + (existentialExplode bind) `thenM_` + 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) + complete_it = addSrcLoc locn $ + addErrCtxt (patMonoBindsCtxt bind) $ + tcGRHSsPat grhss (Check pat_ty) `thenM` \ grhss' -> + returnM (PatMonoBind pat' grhss' locn, ids) in - returnTc (complete_it, lie_req, tvs, ids, lie_avail) + returnM (complete_it, if isRec is_rec then ids else emptyBag) - -- Figure out the appropriate kind for the pattern, - -- and generate a suitable type variable - kind = case is_rec of - Recursive -> liftedTypeKind -- Recursive, so no unlifted types - NonRecursive -> openTypeKind -- Non-recursive, so we permit unlifted types + -- tc_pat_bndr is used when dealing with a LHS binder in a pattern. + -- If there was a type sig for that Id, we want to make it much + -- as if that type signature had been on the binder as a SigPatIn. + -- We check for a type signature; if there is one, we use the mono_id + -- from the signature. This is how we make sure the tau part of the + -- signature actually matches the type of the LHS; then tc_mb_pats + -- ensures the LHS and RHS have the same type + + tc_pat_bndr name pat_ty + = case maybeSig tc_ty_sigs name of + Nothing -> newLocalName name `thenM` \ bndr_name -> + tcMonoPatBndr bndr_name pat_ty + + Just sig -> addSrcLoc (getSrcLoc name) $ + tcSubPat (idType mono_id) pat_ty `thenM` \ co_fn -> + returnM (co_fn, mono_id) + where + mono_id = tcSigMonoId sig \end{code} @@ -752,34 +787,37 @@ a RULE now: {-# SPECIALISE (f:: TcM (TcMonoBinds, LIE) +tcSpecSigs :: [RenamedSig] -> TcM TcMonoBinds tcSpecSigs (SpecSig name poly_ty src_loc : sigs) = -- SPECIALISE f :: forall b. theta => tau = g - tcAddSrcLoc src_loc $ - tcAddErrCtxt (valSpecSigCtxt name poly_ty) $ + addSrcLoc src_loc $ + addErrCtxt (valSpecSigCtxt name poly_ty) $ -- Get and instantiate its alleged specialised type - tcHsSigType poly_ty `thenTc` \ sig_ty -> + tcHsSigType (FunSigCtxt name) poly_ty `thenM` \ 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) -> + getLIE (tcCheckSigma (HsVar name) sig_ty) `thenM` \ (spec_expr, spec_lie) -> -- Squeeze out any Methods (see comments with tcSimplifyToDicts) - tcSimplifyToDicts spec_lie `thenTc` \ (spec_dicts, spec_binds) -> + tcSimplifyToDicts spec_lie `thenM` \ 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 -> + newLocalName name `thenM` \ spec_name -> + let + spec_bind = VarMonoBind (mkSpecPragmaId spec_name sig_ty) + (mkHsLet spec_binds spec_expr) + in -- 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` mkLIE spec_dicts) + tcSpecSigs sigs `thenM` \ binds_rest -> + returnM (binds_rest `andMonoBinds` spec_bind) tcSpecSigs (other_sig : sigs) = tcSpecSigs sigs -tcSpecSigs [] = returnTc (EmptyMonoBinds, emptyLIE) +tcSpecSigs [] = returnM EmptyMonoBinds \end{code} @@ -803,9 +841,10 @@ valSpecSigCtxt v ty 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)")) + = vcat [ptext SLIT("When matching the contexts of the signatures for"), + nest 2 (vcat [ppr s1 <+> dcolon <+> ppr (idType s1), + ppr s2 <+> dcolon <+> ppr (idType s2)]), + ptext SLIT("The signature contexts in a mutually recursive group should all be identical")] ----------------------------------------------- unliftedBindErr flavour mbind @@ -825,6 +864,11 @@ restrictedBindCtxtErr binder_names 4 (vcat [ptext SLIT("in a binding group for") <+> pprBinders binder_names, ptext SLIT("that falls under the monomorphism restriction")]) +genCtxt binder_names + = ptext SLIT("When generalising the type(s) for") <+> pprBinders binder_names + -- Used in error messages -pprBinders bndrs = pprWithCommas ppr bndrs +-- Use quotes for a single one; they look a bit "busy" for several +pprBinders [bndr] = quotes (ppr bndr) +pprBinders bndrs = pprWithCommas ppr bndrs \end{code}