X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcBinds.lhs;h=48279327b8d70cda85b81b95a86b20fc653cbd76;hb=778b2c6bdbabf2c9f394f0ca2b76b55a7123aa5f;hp=912a415554664e3b4082b221dd61085a5e599a46;hpb=7d61cb61daa5e433a0cb85b34b7f0c58b2f961ff;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcBinds.lhs b/ghc/compiler/typecheck/TcBinds.lhs index 912a415..4827932 100644 --- a/ghc/compiler/typecheck/TcBinds.lhs +++ b/ghc/compiler/typecheck/TcBinds.lhs @@ -1,50 +1,71 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[TcBinds]{TcBinds} \begin{code} +module TcBinds ( tcBindsAndThen, tcTopBindsAndThen, + tcSpecSigs, tcBindWithSigs ) where + #include "HsVersions.h" -module TcBinds ( tcBindsAndThen, tcPragmaSigs ) where - -import Ubiq - -import HsSyn ( HsBinds(..), Bind(..), Sig(..), MonoBinds(..), - HsExpr, Match, PolyType, InPat, OutPat, - GRHSsAndBinds, ArithSeqInfo, HsLit, Fake, - collectBinders ) -import RnHsSyn ( RenamedHsBinds(..), RenamedBind(..), RenamedSig(..), - RenamedMonoBinds(..) ) -import TcHsSyn ( TcHsBinds(..), TcBind(..), TcMonoBinds(..), - TcIdOcc(..), TcIdBndr(..) ) - -import TcMonad -import GenSpecEtc ( checkSigTyVars, genBinds, TcSigInfo(..) ) -import Inst ( Inst, LIE(..), emptyLIE, plusLIE, InstOrigin(..) ) -import TcEnv ( tcExtendLocalValEnv, tcLookupLocalValueOK, newMonoIds ) -import TcLoop ( tcGRHSsAndBinds ) -import TcMatches ( tcMatchesFun ) -import TcMonoType ( tcPolyType ) +import {-# SOURCE #-} TcMatches ( tcGRHSs, tcMatchesFun ) +import {-# SOURCE #-} TcExpr ( tcExpr ) + +import HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..), InPat(..), StmtCtxt(..), + Match(..), collectMonoBinders, andMonoBindList, andMonoBinds + ) +import RnHsSyn ( RenamedHsBinds, RenamedSig, RenamedMonoBinds ) +import TcHsSyn ( TcHsBinds, TcMonoBinds, TcId, zonkId, mkHsLet ) + +import TcMonad +import Inst ( Inst, LIE, emptyLIE, mkLIE, plusLIE, plusLIEs, InstOrigin(..), + newDicts, tyVarsOfInst, instToId, + getAllFunDepsOfLIE, getIPsOfLIE, zonkFunDeps + ) +import TcEnv ( tcExtendLocalValEnv, + newSpecPragmaId, newLocalId, + tcLookupTyConByKey, + tcGetGlobalTyVars, tcExtendGlobalTyVars + ) +import TcSimplify ( tcSimplify, tcSimplifyAndCheck, tcSimplifyToDicts ) +import TcImprove ( tcImprove ) +import TcMonoType ( tcHsSigType, checkSigTyVars, + TcSigInfo(..), tcTySig, maybeSig, sigCtxt + ) import TcPat ( tcPat ) import TcSimplify ( bindInstsOfLocalFuns ) -import TcType ( newTcTyVar, tcInstType ) -import Unify ( unifyTauTy ) - -import Kind ( mkBoxedTypeKind, mkTypeKind ) -import Id ( GenId, idType, mkUserId ) -import IdInfo ( noIdInfo ) -import Name ( Name ) -- instances -import Maybes ( assocMaybe, catMaybes, Maybe(..) ) -import Outputable ( pprNonOp ) -import PragmaInfo ( PragmaInfo(..) ) -import Pretty -import Type ( mkTyVarTy, mkTyVarTys, isTyVarTy, - mkSigmaTy, splitSigmaTy, - splitRhoTy, mkForAllTy, splitForAllTy ) -import Util ( panic ) +import TcType ( TcType, TcThetaType, + TcTyVar, + newTyVarTy, newTyVar, newTyVarTy_OpenKind, tcInstTcType, + zonkTcType, zonkTcTypes, zonkTcThetaType, zonkTcTyVarToTyVar + ) +import TcUnify ( unifyTauTy, unifyTauTyLists ) + +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 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 Unique ( ioTyConKey, mainKey, hasKey, Uniquable(..) ) +import SrcLoc ( SrcLoc ) +import Outputable \end{code} + %************************************************************************ %* * \subsection{Type-checking bindings} @@ -62,7 +83,7 @@ specialising the things bound. @tcBindsAndThen@ also takes a "combiner" which glues together the bindings and the "thing" to make a new "thing". -The real work is done by @tcBindAndThen@. +The real work is done by @tcBindWithSigsAndThen@. Recursive and non-recursive binds are handled in essentially the same way: because of uniques there are no scoping issues left. The only @@ -77,24 +98,82 @@ 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, thing_ty) - -> TcM s (thing, LIE s, thing_ty) - -tcBindsAndThen combiner EmptyBinds do_next - = do_next `thenTc` \ (thing, lie, thing_ty) -> - returnTc (combiner EmptyBinds thing, lie, thing_ty) - -tcBindsAndThen combiner (SingleBind bind) do_next - = tcBindAndThen combiner bind [] do_next + -> 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) -> -tcBindsAndThen combiner (BindWith bind sigs) do_next - = tcBindAndThen combiner bind sigs do_next + -- Now do whatever happens next, in the augmented envt + do_next `thenTc` \ (thing, thing_lie) -> -tcBindsAndThen combiner (ThenBinds binds1 binds2) do_next - = tcBindsAndThen combiner binds1 (tcBindsAndThen combiner binds2 do_next) + -- Create specialisations of functions bound here + -- We want to keep non-recursive things non-recursive + -- so that we desugar unboxed bindings correctly + case (top_lvl, is_rec) of + + -- For the top level don't bother will all this bindInstsOfLocalFuns stuff + -- All the top level things are rec'd together anyway, so it's fine to + -- leave them to the tcSimplifyTop, and quite a bit faster too + (TopLevel, _) + -> returnTc (combiner Recursive (poly_binds `andMonoBinds` prag_binds) thing, + thing_lie `plusLIE` prag_lie `plusLIE` poly_lie) + + (NotTopLevel, NonRecursive) + -> bindInstsOfLocalFuns + (thing_lie `plusLIE` prag_lie) + poly_ids `thenTc` \ (thing_lie', lie_binds) -> + + returnTc ( + combiner NonRecursive poly_binds $ + combiner NonRecursive prag_binds $ + combiner Recursive lie_binds $ + -- NB: the binds returned by tcSimplify and bindInstsOfLocalFuns + -- aren't guaranteed in dependency order (though we could change + -- that); hence the Recursive marker. + thing, + + thing_lie' `plusLIE` poly_lie + ) + + (NotTopLevel, Recursive) + -> bindInstsOfLocalFuns + (thing_lie `plusLIE` poly_lie `plusLIE` prag_lie) + poly_ids `thenTc` \ (final_lie, lie_binds) -> + + returnTc ( + combiner Recursive ( + poly_binds `andMonoBinds` + lie_binds `andMonoBinds` + prag_binds) thing, + final_lie + ) \end{code} An aside. The original version of @tcBindsAndThen@ which lacks a @@ -104,189 +183,640 @@ 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 (SingleBind bind) do_next - = tcBindAndThen bind [] do_next - -tcBindsAndThen (BindWith bind sigs) do_next - = tcBindAndThen bind sigs do_next - -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 +% :: 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} + %************************************************************************ %* * -\subsection{Bind} +\subsection{tcBindWithSigs} %* * %************************************************************************ -\begin{code} -tcBindAndThen - :: (TcHsBinds s -> thing -> thing) -- Combinator - -> RenamedBind -- The Bind to typecheck - -> [RenamedSig] -- ...and its signatures - -> TcM s (thing, LIE s, thing_ty) -- Thing to type check in - -- augmented envt - -> TcM s (thing, LIE s, thing_ty) -- Results, incl the - -tcBindAndThen combiner bind sigs 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. - - tcBindAndSigs binder_names bind - sigs 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) -> - - -- Now do whatever happens next, in the augmented envt - do_next `thenTc` \ (thing, thing_lie, thing_ty) -> +@tcBindWithSigs@ deals with a single binding group. It does generalisation, +so all the clever stuff is in here. - -- Create specialisations of functions bound here - bindInstsOfLocalFuns (prag_lie `plusLIE` thing_lie) - poly_ids `thenTc` \ (lie2, inst_mbinds) -> +* binder_names and mbind must define the same set of Names - -- All done - let - final_lie = lie2 `plusLIE` poly_lie - final_binds = poly_binds `ThenBinds` - SingleBind (NonRecBind inst_mbinds) `ThenBinds` - prag_binds - in - returnTc (prag_info_fn, (combiner final_binds thing, final_lie, thing_ty)) - ) `thenTc` \ (_, result) -> - returnTc result - where - binder_names = collectBinders bind +* The Names in tc_ty_sigs must be a subset of binder_names +* The Ids in tc_ty_sigs don't necessarily have to have the same name + as the Name in the tc_ty_sig -tcBindAndSigs binder_names bind sigs prag_info_fn +\begin{code} +tcBindWithSigs + :: TopLevelFlag + -> RenamedMonoBinds + -> [TcSigInfo] + -> [RenamedSig] -- Used solely to get INLINE, NOINLINE sigs + -> RecFlag + -> TcM s (TcMonoBinds, LIE, [TcId]) + +tcBindWithSigs top_lvl mbind tc_ty_sigs inline_sigs is_rec = recoverTc ( -- If typechecking the binds fails, then return with each - -- binder given type (forall a.a), to minimise subsequent + -- 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 = [ mkUserId name forall_a_a (prag_info_fn name) - | name <- 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 -> mkVanillaId name forall_a_a -- No signature in - returnTc (EmptyBinds, emptyLIE, poly_ids) + returnTc (EmptyMonoBinds, emptyLIE, poly_ids) ) $ - -- Create a new identifier for each binder, with each being given - -- a type-variable type. - newMonoIds binder_names kind (\ mono_ids -> - tcTySigs sigs `thenTc` \ sig_info -> - tc_bind bind `thenTc` \ (bind', lie) -> - returnTc (mono_ids, bind', lie, sig_info) - ) - `thenTc` \ (mono_ids, bind', lie, sig_info) -> + -- TYPECHECK THE BINDINGS + 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 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 + lie_avail_req = lie_avail `plusLIE` lie_req in + tcImprove lie_avail_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 + 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. + -- + -- Also NB that tcSimplify takes zonked tyvars as its arg, hence we pass + -- real_tyvars_to_gen + in - -- Notice that genBinds gets the old (non-extended) environment - genBinds binder_names mono_ids bind' lie sig_info prag_info_fn + -- SIMPLIFY THE LIE + tcExtendGlobalTyVars tyvars_not_to_gen ( + let ips = getIPsOfLIE lie_avail_req in + if null real_tyvars_to_gen_list && (null ips || not is_unrestricted) then + -- No polymorphism, and no IPs, so no need to simplify context + returnTc (lie_req, EmptyMonoBinds, []) + else + case maybe_sig_theta of + Nothing -> + -- No signatures, so just simplify the lie + -- NB: no signatures => no polymorphic recursion, so no + -- need to use 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)) + + 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 (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) -> + + -- 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. + -- That's why we just use an ASSERT here. + + + -- BUILD THE POLYMORPHIC RESULT IDs + mapNF_Tc zonkId mono_ids `thenNF_Tc` \ zonked_mono_ids -> + let + exports = zipWith mk_export binder_names zonked_mono_ids + dict_tys = map idType dicts_bound + + inlines = mkNameSet [name | InlineSig name _ loc <- inline_sigs] + no_inlines = listToFM ([(name, IMustNotBeINLINEd False phase) | NoInlineSig name phase loc <- inline_sigs] ++ + [(name, IMustNotBeINLINEd True phase) | InlineSig name phase loc <- inline_sigs, maybeToBool phase]) + -- "INLINE n foo" means inline foo, but not until at least phase n + -- "NOINLINE n foo" means don't inline foo until at least phase n, and even + -- then only if it is small enough etc. + -- "NOINLINE foo" means don't inline foo ever, which we signal with a (IMustNotBeINLINEd Nothing) + -- See comments in CoreUnfold.blackListed for the Authorised Version + + mk_export binder_name zonked_mono_id + = (tyvars, + attachNoInlinePrag no_inlines poly_id, + zonked_mono_id) + where + (tyvars, poly_id) = + case maybeSig tc_ty_sigs binder_name of + Just (TySigInfo _ sig_poly_id sig_tyvars _ _ _ _ _) -> + (sig_tyvars, sig_poly_id) + Nothing -> (real_tyvars_to_gen_list, new_poly_id) + + new_poly_id = mkVanillaId binder_name poly_ty + poly_ty = mkForAllTys real_tyvars_to_gen_list + $ mkFunTys dict_tys + $ idType (zonked_mono_id) + -- It's important to build a fully-zonked poly_ty, because + -- we'll slurp out its free type variables when extending the + -- local environment (tcExtendLocalValEnv); if it's not zonked + -- it appears to have free tyvars that aren't actually free + -- at all. + + pat_binders :: [Name] + pat_binders = map fst $ bagToList $ collectMonoBinders $ + (justPatBindings mbind EmptyMonoBinds) + in + -- CHECK FOR UNBOXED BINDERS IN PATTERN BINDINGS + mapTc (\id -> checkTc (not (idName id `elem` pat_binders + && isUnboxedType (idType id))) + (unboxedPatBindErr id)) zonked_mono_ids + `thenTc_` + + -- BUILD RESULTS + returnTc ( + -- pprTrace "binding.." (ppr ((dicts_bound, dict_binds), exports, [idType poly_id | (_, poly_id, _) <- exports])) $ + AbsBinds real_tyvars_to_gen_list + dicts_bound + exports + inlines + (dict_binds `andMonoBinds` mbind'), + lie_free, + [poly_id | (_, poly_id, _) <- exports] + ) where - kind = case bind of - NonRecBind _ -> mkBoxedTypeKind -- Recursive, so no unboxed types - RecBind _ -> mkTypeKind -- Non-recursive, so we permit unboxed types + tysig_names = [name | (TySigInfo name _ _ _ _ _ _ _) <- tc_ty_sigs] + is_unrestricted = isUnRestrictedGroup tysig_names mbind + +justPatBindings bind@(PatMonoBind _ _ _) binds = bind `andMonoBinds` binds +justPatBindings (AndMonoBinds b1 b2) binds = + justPatBindings b1 (justPatBindings b2 binds) +justPatBindings other_bind binds = binds + +attachNoInlinePrag no_inlines bndr + = case lookupFM no_inlines (idName bndr) of + Just prag -> bndr `setInlinePragma` prag + Nothing -> bndr \end{code} -\begin{code} -tc_bind :: RenamedBind -> TcM s (TcBind s, LIE s) +Polymorphic recursion +~~~~~~~~~~~~~~~~~~~~~ +The game plan for polymorphic recursion in the code above is -tc_bind (NonRecBind mono_binds) - = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) -> - returnTc (NonRecBind mono_binds2, lie) + * 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. -tc_bind (RecBind mono_binds) - = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) -> - returnTc (RecBind mono_binds2, lie) -\end{code} +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: -\begin{code} -tcMonoBinds :: RenamedMonoBinds -> TcM s (TcMonoBinds s, LIE s) + 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. -tcMonoBinds EmptyMonoBinds = returnTc (EmptyMonoBinds, emptyLIE) + ff = f Int dEqInt -tcMonoBinds (AndMonoBinds mb1 mb2) - = tcMonoBinds mb1 `thenTc` \ (mb1a, lie1) -> - tcMonoBinds mb2 `thenTc` \ (mb2a, lie2) -> - returnTc (AndMonoBinds mb1a mb2a, lie1 `plusLIE` lie2) + = let f' = f Int dEqInt in \ys. ...f'... -tcMonoBinds bind@(PatMonoBind pat grhss_and_binds locn) - = tcAddSrcLoc locn $ + = let f' = let f' = f Int dEqInt in \ys. ...f'... + in \ys. ...f'... - -- LEFT HAND SIDE - tcPat pat `thenTc` \ (pat2, lie_pat, pat_ty) -> +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. - -- BINDINGS AND GRHSS - tcGRHSsAndBinds grhss_and_binds `thenTc` \ (grhss_and_binds2, lie, grhss_ty) -> - -- Unify the two sides - tcAddErrCtxt (patMonoBindsCtxt bind) $ - unifyTauTy pat_ty grhss_ty `thenTc_` +%************************************************************************ +%* * +\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 +remove from tyvars_to_gen any constrained type variables + +*Don't* simplify dicts at this point, because we aren't going +to generalise over these dicts. By the time we do simplify them +we may well know more. For example (this actually came up) + f :: Array Int Int + f x = array ... xs where xs = [1,2,3,4,5] +We don't want to generate lots of (fromInt Int 1), (fromInt Int 2) +stuff. If we simplify only at the f-binding (not the xs-binding) +we'll know that the literals are all Ints, and we can just produce +Int literals! + +Find all the type variables involved in overloading, the +"constrained_tyvars". These are the ones we *aren't* going to +generalise. We must be careful about doing this: + + (a) If we fail to generalise a tyvar which is not actually + constrained, then it will never, ever get bound, and lands + up printed out in interface files! Notorious example: + instance Eq a => Eq (Foo a b) where .. + Here, b is not constrained, even though it looks as if it is. + Another, more common, example is when there's a Method inst in + the LIE, whose type might very well involve non-overloaded + type variables. + + (b) On the other hand, we mustn't generalise tyvars which are constrained, + because we are going to pass on out the unmodified LIE, with those + tyvars in it. They won't be in scope if we've generalised them. + +So we are careful, and do a complete simplification just to find the +constrained tyvars. We don't use any of the results, except to +find which tyvars are constrained. + +\begin{code} +getTyVarsToGen is_unrestricted mono_id_tys lie + = tcGetGlobalTyVars `thenNF_Tc` \ free_tyvars -> + zonkTcTypes mono_id_tys `thenNF_Tc` \ zonked_mono_id_tys -> + let + body_tyvars = tyVarsOfTypes zonked_mono_id_tys `minusVarSet` free_tyvars + fds = getAllFunDepsOfLIE lie + in + if is_unrestricted + then + -- We need to augment the type variables that appear explicitly in + -- the type by those that are determined by the functional dependencies. + -- e.g. suppose our type is C a b => a -> a + -- with the fun-dep a->b + -- Then we should generalise over b too; otherwise it will be + -- reported as ambiguous. + zonkFunDeps fds `thenNF_Tc` \ fds' -> + let tvFundep = tyVarFunDep fds' + extended_tyvars = oclose tvFundep body_tyvars + in + returnNF_Tc (emptyVarSet, extended_tyvars) + else + -- 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 (unionVarSet . tyVarsOfInst) emptyVarSet constrained_dicts + reduced_tyvars_to_gen = body_tyvars `minusVarSet` constrained_tyvars + in + returnTc (constrained_tyvars, reduced_tyvars_to_gen) +\end{code} - -- RETURN - returnTc (PatMonoBind pat2 grhss_and_binds2 locn, - plusLIE lie_pat lie) -tcMonoBinds (FunMonoBind name matches locn) - = tcAddSrcLoc locn $ - tcLookupLocalValueOK "tcMonoBinds" name `thenNF_Tc` \ id -> - tcMatchesFun name (idType id) matches `thenTc` \ (matches', lie) -> - returnTc (FunMonoBind (TcId id) matches' locn, lie) +\begin{code} +isUnRestrictedGroup :: [Name] -- Signatures given for these + -> RenamedMonoBinds + -> Bool + +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 || + 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 \end{code} + %************************************************************************ %* * -\subsection{Signatures} +\subsection{tcMonoBind} %* * %************************************************************************ -@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. +@tcMonoBinds@ deals with a single @MonoBind@. +The signatures have been dealt with already. \begin{code} -tcTySigs :: [RenamedSig] -> TcM s [TcSigInfo s] +tcMonoBinds :: RenamedMonoBinds + -> [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 + + complete_it extra_val_env `thenTc` \ (mbinds', lie_req_rhss) -> + + 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 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 -tcTySigs (Sig v ty _ src_loc : other_sigs) - = tcAddSrcLoc src_loc ( - tcPolyType ty `thenTc` \ sigma_ty -> - tcInstType [] sigma_ty `thenNF_Tc` \ sigma_ty' -> + 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 - (tyvars', theta', tau') = splitSigmaTy sigma_ty' + 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) + = new_lhs_ty `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 $ + new_lhs_ty `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) - tcLookupLocalValueOK "tcSig1" v `thenNF_Tc` \ val -> - unifyTauTy (idType val) tau' `thenTc_` + -- Figure out the appropriate kind for the pattern, + -- and generate a suitable type variable + new_lhs_ty = case is_rec of + Recursive -> newTyVarTy boxedTypeKind -- Recursive, so no unboxed types + NonRecursive -> newTyVarTy_OpenKind -- Non-recursive, so we permit unboxed types +\end{code} - returnTc (TySigInfo val tyvars' theta' tau' src_loc) - ) `thenTc` \ sig_info1 -> +%************************************************************************ +%* * +\subsection{Signatures} +%* * +%************************************************************************ + +@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) +type variables of the original signature type. - tcTySigs other_sigs `thenTc` \ sig_infos -> - returnTc (sig_info1 : sig_infos) +The error message here is somewhat unsatisfactory, but it'll do for +now (ToDo). + +\begin{code} +checkSigMatch :: TopLevelFlag -> [Name] -> [TcId] -> [TcSigInfo] -> TcM s (Maybe (TcThetaType, LIE)) +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 ( + tcLookupTyConByKey ioTyConKey `thenTc` \ ioTyCon -> + newTyVarTy boxedTypeKind `thenNF_Tc` \ t_tv -> + unifyTauTy ((mkTyConApp ioTyCon [t_tv])) + (idType main_mono_id) + ) `thenTc_` + + -- Now check the signatures + -- Must do this after the unification with IO t, + -- in case of a silly signature like + -- main :: forall a. a + -- The unification to IO t will bind the type variable 'a', + -- which is just waht check_one_sig looks for + mapTc check_one_sig sigs `thenTc_` + mapTc check_main_ctxt sigs `thenTc_` + + returnTc (Just ([], emptyLIE)) + + | not (null sigs) + = mapTc check_one_sig sigs `thenTc_` + mapTc check_one_ctxt all_sigs_but_first `thenTc_` + returnTc (Just (theta1, sig_lie)) + + | otherwise + = returnTc Nothing -- No constraints from type sigs -tcTySigs (other : sigs) = tcTySigs sigs -tcTySigs [] = returnTc [] + where + (TySigInfo _ id1 _ theta1 _ _ _ _ : all_sigs_but_first) = sigs + + sig1_dict_tys = mk_dict_tys theta1 + n_sig1_dict_tys = length sig1_dict_tys + sig_lie = mkLIE (concat [insts | TySigInfo _ _ _ _ _ _ insts _ <- sigs]) + + 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) + + + -- 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 `hasKey` mainKey = Just m + | otherwise = go ns ms \end{code} @@ -296,45 +826,13 @@ tcTySigs [] = returnTc [] %* * %************************************************************************ - -@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) - -tcPragmaSigs sigs = returnTc ( \name -> NoPragmaInfo, EmptyBinds, emptyLIE ) - -{- -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 +They look like this: -\begin{code} -tcPragmaSig (DeforestSig name loc) - = returnTc ((name, addInfo DoDeforest),EmptyBinds,emptyLIE) -tcPragmaSig (InlineSig name loc) - = returnTc ((name, addInfo_UF (iWantToBeINLINEd UnfoldAlways)), EmptyBinds, emptyLIE) -tcPragmaSig (MagicUnfoldingSig name string loc) - = returnTc ((name, addInfo_UF (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 #-} @@ -357,151 +855,111 @@ 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} +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::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} +\begin{code} +tcSpecSigs :: [RenamedSig] -> TcM s (TcMonoBinds, LIE) +tcSpecSigs (SpecSig name poly_ty src_loc : sigs) + = -- SPECIALISE f :: forall b. theta => tau = g + tcAddSrcLoc src_loc $ + tcAddErrCtxt (valSpecSigCtxt name poly_ty) $ -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. + -- Get and instantiate its alleged specialised type + tcHsSigType poly_ty `thenTc` \ sig_ty -> -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. + -- 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) -> -\begin{code} -tcPragmaSig (SpecSig name poly_ty maybe_spec_name src_loc) - = tcAddSrcLoc src_loc $ - tcAddErrCtxt (valSpecSigCtxt name spec_ty) $ + -- Squeeze out any Methods (see comments with tcSimplifyToDicts) + tcSimplifyToDicts spec_lie `thenTc` \ (spec_lie1, spec_binds) -> - -- Get and instantiate its alleged specialised type - tcPolyType poly_ty `thenTc` \ sig_sigma -> - tcInstType [] sig_sigma `thenNF_Tc` \ sig_ty -> - let - (sig_tyvars, sig_theta, sig_tau) = splitSigmaTy sig_ty - origin = ValSpecOrigin name - in + -- 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 the SPECIALIZE pragma had an empty context - checkTc (null sig_theta) - (panic "SPECIALIZE non-empty context (ToDo: msg)") `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) - -- Get and instantiate the type of the id mentioned - tcLookupLocalValueOK "tcPragmaSig" name `thenNF_Tc` \ main_id -> - tcInstType [] (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 +tcSpecSigs (other_sig : sigs) = tcSpecSigs sigs +tcSpecSigs [] = returnTc (EmptyMonoBinds, emptyLIE) +\end{code} - -- 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) -> - 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) +%************************************************************************ +%* * +\subsection[TcBinds-errors]{Error contexts and messages} +%* * +%************************************************************************ - Just spec_name -> -- Use spec_name as the specialisation value ... - -- Type check a simple occurrence of the specialised Id - tcId spec_name `thenTc` \ (spec_body, spec_lie, spec_tau) -> +\begin{code} +patMonoBindsCtxt bind + = hang (ptext SLIT("In a pattern binding:")) 4 (ppr bind) - -- 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_` +----------------------------------------------- +valSpecSigCtxt v ty + = sep [ptext SLIT("In a SPECIALIZE pragma for a value:"), + nest 4 (ppr v <+> dcolon <+> ppr ty)] - -- Make a local SpecId to bind to applied spec_id - newSpecId main_id main_arg_tys sig_ty `thenNF_Tc` \ local_spec_id -> +----------------------------------------------- +notAsPolyAsSigErr sig_tau mono_tyvars + = hang (ptext SLIT("A type signature is more polymorphic than the inferred type")) + 4 (vcat [text "Can't for-all the type variable(s)" <+> + pprQuotedList mono_tyvars, + text "in the type" <+> quotes (ppr sig_tau) + ]) - 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, addInfo spec_info), spec_binds, spec_lie) --} -\end{code} +----------------------------------------------- +badMatchErr sig_ty inferred_ty + = hang (ptext SLIT("Type signature doesn't match inferred type")) + 4 (vcat [hang (ptext SLIT("Signature:")) 4 (ppr sig_ty), + hang (ptext SLIT("Inferred :")) 4 (ppr inferred_ty) + ]) +----------------------------------------------- +unboxedPatBindErr id + = ptext SLIT("variable in a lazy pattern binding has unboxed type: ") + <+> quotes (ppr id) -Error contexts and messages -~~~~~~~~~~~~~~~~~~~~~~~~~~~ -\begin{code} -patMonoBindsCtxt bind sty - = ppHang (ppPStr SLIT("In a pattern binding:")) 4 (ppr sty bind) - --------------------------------------------- -specContextGroundnessCtxt -- err_ctxt dicts sty - = panic "specContextGroundnessCtxt" -{- - = ppHang ( - ppSep [ppBesides [ppStr "In the SPECIALIZE pragma for `", ppr sty name, ppStr "'"], - ppBesides [ppStr " specialised to the type `", ppr sty spec_ty, ppStr "'"], - pp_spec_id sty, - ppStr "... not all overloaded type variables were instantiated", - ppStr "to ground types:"]) - 4 (ppAboves [ppCat [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 -> ppNil) - ValSpecSpecIdCtxt n ty spec loc -> - (n, ty, loc, - \ sty -> ppBesides [ppStr "... type of explicit id `", ppr sty spec, ppStr "'"]) --} +----------------------------------------------- +bindSigsCtxt ids + = ptext SLIT("When checking the type signature(s) for") <+> pprQuotedList ids ----------------------------------------------- -specGroundnessCtxt - = panic "specGroundnessCtxt" +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)")) -valSpecSigCtxt v ty sty - = ppHang (ppPStr SLIT("In a SPECIALIZE pragma for a value:")) - 4 (ppSep [ppBeside (pprNonOp sty v) (ppPStr SLIT(" ::")), - ppr sty ty]) -\end{code} +mainContextsErr id + | id `hasKey` mainKey = 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 (ptext SLIT("main")), + 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}