X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcBinds.lhs;h=1d1e53e182b5b65b5866967fd3b18b822f1e54e3;hb=95581e0c3b2d4d6edd33fdd6e135aa3917072c4c;hp=a50bc502d023779bd6740f94fc1239d8f293ac3d;hpb=39068cf49bf3553f90ec316569619c310a6be8de;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcBinds.lhs b/ghc/compiler/typecheck/TcBinds.lhs index a50bc50..1d1e53e 100644 --- a/ghc/compiler/typecheck/TcBinds.lhs +++ b/ghc/compiler/typecheck/TcBinds.lhs @@ -4,7 +4,7 @@ \section[TcBinds]{TcBinds} \begin{code} -module TcBinds ( tcBindsAndThen, tcTopBinds, +module TcBinds ( tcBindsAndThen, tcTopBinds, tcMonoBinds, tcSpecSigs, tcBindWithSigs ) where #include "HsVersions.h" @@ -12,10 +12,11 @@ module TcBinds ( tcBindsAndThen, tcTopBinds, import {-# SOURCE #-} TcMatches ( tcGRHSs, tcMatchesFun ) import {-# SOURCE #-} TcExpr ( tcExpr ) -import CmdLineOpts ( opt_NoMonomorphismRestriction ) +import CmdLineOpts ( DynFlag(Opt_NoMonomorphismRestriction) ) import HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..), Match(..), HsMatchContext(..), - collectMonoBinders, andMonoBinds + collectMonoBinders, andMonoBinds, + collectSigTysFromMonoBinds ) import RnHsSyn ( RenamedHsBinds, RenamedSig, RenamedMonoBinds ) import TcHsSyn ( TcMonoBinds, TcId, zonkId, mkHsLet ) @@ -24,38 +25,33 @@ import TcMonad import Inst ( LIE, emptyLIE, mkLIE, plusLIE, InstOrigin(..), newDicts, instToId ) -import TcEnv ( tcExtendLocalValEnv, - newSpecPragmaId, newLocalId +import TcEnv ( tcExtendLocalValEnv, tcExtendLocalValEnv2, newLocalName ) +import TcUnify ( unifyTauTyLists, checkSigTyVarsWrt, sigCtxt ) +import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck, tcSimplifyRestricted, tcSimplifyToDicts ) +import TcMonoType ( tcHsSigType, UserTypeCtxt(..), TcSigInfo(..), + tcTySig, maybeSig, tcSigPolyId, tcSigMonoId, tcAddScopedTyVars ) -import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck, tcSimplifyCheck, tcSimplifyRestricted, tcSimplifyToDicts ) -import TcMonoType ( tcHsSigType, checkSigTyVars, - TcSigInfo(..), tcTySig, maybeSig, sigCtxt - ) -import TcPat ( tcPat ) +import TcPat ( tcPat, tcSubPat, tcMonoPatBndr ) import TcSimplify ( bindInstsOfLocalFuns ) -import TcType ( newTyVarTy, newTyVar, - zonkTcTyVarToTyVar +import TcMType ( newTyVar, newTyVarTy, newHoleTyVarTy, + zonkTcTyVarToTyVar, readHoleResult + ) +import TcType ( 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, isNotTopLevel, + isAlwaysActive ) import FiniteMap ( listToFM, lookupFM ) import Outputable \end{code} @@ -121,14 +117,21 @@ tc_binds_and_then top_lvl combiner (ThenBinds b1 b2) do_next do_next tc_binds_and_then top_lvl combiner (MonoBind bind sigs is_rec) do_next - = -- TYPECHECK THE SIGNATURES + = -- 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) $ + + -- 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] $ + tcExtendLocalValEnv poly_ids $ -- Build bindings and IdInfos corresponding to user pragmas tcSpecSigs sigs `thenTc` \ (prag_binds, prag_lie) -> @@ -216,8 +219,8 @@ tcBindWithSigs top_lvl mbind tc_ty_sigs inline_sigs is_rec 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) ) $ @@ -225,10 +228,12 @@ tcBindWithSigs top_lvl mbind tc_ty_sigs inline_sigs is_rec -- TYPECHECK THE BINDINGS tcMonoBinds mbind tc_ty_sigs is_rec `thenTc` \ (mbind', lie_req, binder_names, mono_ids) -> let - tau_tvs = varSetElems (foldr (unionVarSet . tyVarsOfType . idType) emptyVarSet mono_ids) + tau_tvs = foldr (unionVarSet . tyVarsOfType . idType) emptyVarSet mono_ids in -- GENERALISE + tcAddSrcLoc (minimum (map getSrcLoc binder_names)) $ + tcAddErrCtxt (genCtxt binder_names) $ generalise binder_names mbind tau_tvs lie_req tc_ty_sigs `thenTc` \ (tc_tyvars_to_gen, lie_free, dict_binds, dict_ids) -> @@ -250,22 +255,16 @@ tcBindWithSigs top_lvl mbind tc_ty_sigs inline_sigs is_rec 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_` - -- 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 <- inline_sigs] + no_inlines = listToFM [(name, phase) | InlineSig _ name phase _ <- inline_sigs, + not (isAlwaysActive phase)] + -- AlwaysActive is the default, so don't bother with them mk_export binder_name zonked_mono_id = (tyvars, @@ -274,14 +273,14 @@ tcBindWithSigs top_lvl mbind tc_ty_sigs inline_sigs is_rec 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 @@ -290,17 +289,28 @@ 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)) `thenTc_` + + -- 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 `thenTc_` + + returnTc ( + AbsBinds [] [] exports inlines mbind', + lie_req, -- Do not generate even any x=y bindings + poly_ids + ) - -- BUILD RESULTS + else -- The normal case returnTc ( AbsBinds real_tyvars_to_gen zonked_dict_ids exports inlines (dict_binds `andMonoBinds` mbind'), - lie_free, - [poly_id | (_, poly_id, _) <- exports] + lie_free, poly_ids ) attachNoInlinePrag no_inlines bndr @@ -308,8 +318,14 @@ attachNoInlinePrag no_inlines bndr 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 +333,19 @@ 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) `thenTc_` + checkTc (isNonRec is_rec) + (unliftedBindErr "Recursive" mbind) `thenTc_` + checkTc (single_bind mbind) + (unliftedBindErr "Multiple" mbind) `thenTc_` + 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} @@ -411,20 +412,36 @@ 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 + doptsTc Opt_NoMonomorphismRestriction `thenTc` \ 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) `thenTc_` + -- Now simplify with exactly that set of tyvars + -- We have to squash those Methods + tcSimplifyRestricted doc tau_tvs lie_req `thenTc` \ (qtvs, lie_free, binds) -> + + -- Check that signature type variables are OK + checkSigsTyVars sigs `thenTc_` + + returnTc (qtvs, lie_free, 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 empty + checkSigsCtxts sigs `thenTc` \ (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) -> @@ -434,44 +451,9 @@ generalise_help doc tau_tvs lie_req sigs 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) -> - - returnTc (final_forall_tvs, lie_free, binds, []) - 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 @@ -483,8 +465,9 @@ 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) + = tcAddSrcLoc src_loc $ + mapTc_ check_one other_sigs `thenTc_` if null theta1 then returnTc ([], []) -- Non-overloaded type signatures else @@ -498,23 +481,21 @@ checkSigsCtxts sigs@(TySigInfo _ id1 sig_tvs theta1 _ _ _ _ : other_sigs) returnTc (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 _ _ _ _) + = tcAddErrCtxt (sigContextsCtxt id1 id) $ + checkTc (equalLength theta theta1) sigContextsErr `thenTc_` unifyTauTyLists sig1_dict_tys (map mkPredTy theta) checkSigsTyVars sigs = mapTc_ check_one sigs 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) + = tcAddSrcLoc src_loc $ + tcAddErrCtxt (ptext SLIT("When checking the type signature for") + <+> quotes (ppr id)) $ + tcAddErrCtxtM (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 +546,14 @@ 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} @@ -630,26 +611,11 @@ tcMonoBinds mbinds tc_ty_sigs is_rec returnTc (mbinds', lie_req_pat `plusLIE` lie_req_rhss, names, mono_ids) 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) + Nothing -> (name, mono_id) + Just sig -> (idName poly_id, poly_id) + where + poly_id = tcSigPolyId sig tc_mb_pats EmptyMonoBinds = returnTc (\ xve -> returnTc (EmptyMonoBinds, emptyLIE), emptyLIE, emptyBag, emptyBag, emptyLIE) @@ -669,44 +635,65 @@ tcMonoBinds mbinds tc_ty_sigs is_rec lie_avail1 `plusLIE` lie_avail2) tc_mb_pats (FunMonoBind name inf matches locn) - = newTyVarTy kind `thenNF_Tc` \ bndr_ty -> - tc_pat_bndr name bndr_ty `thenTc` \ bndr_id -> + = (case maybeSig tc_ty_sigs name of + Just sig -> returnNF_Tc (tcSigMonoId sig) + Nothing -> newLocalName name `thenNF_Tc` \ bndr_name -> + newTyVarTy openTypeKind `thenNF_Tc` \ bndr_ty -> + -- NB: not a 'hole' tyvar; since there is no type + -- signature, we revert to ordinary H-M typechecking + -- which means the variable gets an inferred tau-type + returnNF_Tc (mkLocalId bndr_name bndr_ty) + ) `thenNF_Tc` \ bndr_id -> let + bndr_ty = idType bndr_id complete_it xve = tcAddSrcLoc locn $ - tcMatchesFun xve name bndr_ty matches `thenTc` \ (matches', lie) -> + 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 $ - newTyVarTy kind `thenNF_Tc` \ pat_ty -> + newHoleTyVarTy `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: + -- 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 + -- The type variables are brought into scope in tc_binds_and_then, + -- so we don't have to do anything here. + tcPat tc_pat_bndr pat pat_ty `thenTc` \ (pat', lie_req, tvs, ids, lie_avail) -> + readHoleResult pat_ty `thenTc` \ pat_ty' -> let complete_it xve = tcAddSrcLoc locn $ tcAddErrCtxt (patMonoBindsCtxt bind) $ - tcExtendLocalValEnv xve $ - tcGRHSs grhss pat_ty PatBindRhs `thenTc` \ (grhss', lie) -> + tcExtendLocalValEnv2 xve $ + tcGRHSs PatBindRhs grhss pat_ty' `thenTc` \ (grhss', lie) -> returnTc (PatMonoBind pat' grhss' locn, lie) in returnTc (complete_it, lie_req, tvs, ids, lie_avail) - -- 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 `thenNF_Tc` \ bndr_name -> + tcMonoPatBndr bndr_name pat_ty + + Just sig -> tcAddSrcLoc (getSrcLoc name) $ + tcSubPat (idType mono_id) pat_ty `thenTc` \ (co_fn, lie) -> + returnTc (co_fn, lie, mono_id) + where + mono_id = tcSigMonoId sig \end{code} @@ -759,7 +746,7 @@ tcSpecSigs (SpecSig name poly_ty src_loc : sigs) tcAddErrCtxt (valSpecSigCtxt name poly_ty) $ -- Get and instantiate its alleged specialised type - tcHsSigType poly_ty `thenTc` \ sig_ty -> + tcHsSigType (FunSigCtxt name) 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 @@ -771,11 +758,15 @@ tcSpecSigs (SpecSig name poly_ty src_loc : sigs) -- 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 `thenNF_Tc` \ 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), + returnTc (binds_rest `andMonoBinds` spec_bind, lie_rest `plusLIE` mkLIE spec_dicts) tcSpecSigs (other_sig : sigs) = tcSpecSigs sigs @@ -803,9 +794,10 @@ 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 +817,11 @@ 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}