X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcBinds.lhs;h=6a66814edc5276a0d70229f82563c7f4aa1b78b8;hb=ca0b7c66f2e8e50f15a03c406408d9e86455f8eb;hp=f0679f3a4d30931e2d7fb4cf72fca7bdf16f82e7;hpb=c2b053f3228a8e32cf4d4909c2e97b338e3ac3c1;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcBinds.lhs b/ghc/compiler/typecheck/TcBinds.lhs index f0679f3..6a66814 100644 --- a/ghc/compiler/typecheck/TcBinds.lhs +++ b/ghc/compiler/typecheck/TcBinds.lhs @@ -4,65 +4,50 @@ \section[TcBinds]{TcBinds} \begin{code} -module TcBinds ( tcBindsAndThen, tcTopBindsAndThen, - 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 HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..), InPat(..), StmtCtxt(..), - collectMonoBinders, andMonoBindList, andMonoBinds +import CmdLineOpts ( DynFlag(Opt_NoMonomorphismRestriction) ) +import HsSyn ( HsExpr(..), HsBind(..), LHsBind, LHsBinds, Sig(..), + LSig, Match(..), HsBindGroup(..), IPBind(..), + collectSigTysFromHsBinds, collectHsBindBinders, ) -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, getFunDepsOfLIE, - zonkFunDeps - ) -import TcEnv ( tcExtendLocalValEnv, - newSpecPragmaId, newLocalId, - tcLookupTyCon, - tcGetGlobalTyVars, tcExtendGlobalTyVars - ) -import TcSimplify ( tcSimplify, tcSimplifyAndCheck, tcSimplifyToDicts ) -import TcImprove ( tcImprove ) -import TcMonoType ( tcHsType, checkSigTyVars, - TcSigInfo(..), tcTySig, maybeSig, sigCtxt +import TcHsSyn ( 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 TcHsType ( tcHsSigType, UserTypeCtxt(..), TcSigInfo(..), + tcTySig, maybeSig, tcAddScopedTyVars ) -import TcPat ( tcPat ) +import TcPat ( tcPat, tcSubPat, tcMonoPatBndr ) import TcSimplify ( bindInstsOfLocalFuns ) -import TcType ( TcType, TcThetaType, - TcTyVar, - newTyVarTy, newTyVar, newTyVarTy_OpenKind, tcInstTcType, - zonkTcType, zonkTcTypes, zonkTcThetaType, 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 PrelInfo ( main_NAME, ioTyCon_NAME ) - -import Id ( Id, mkVanillaId, setInlinePragma ) +import CoreFVs ( idFreeTyVars ) +import Id ( mkLocalId, mkSpecPragmaId, setInlinePragma ) import Var ( idType, idName ) -import IdInfo ( IdInfo, vanillaIdInfo, setInlinePragInfo, InlinePragInfo(..) ) -import Name ( Name, getName, getOccName, getSrcLoc ) +import Name ( Name, getSrcLoc ) import NameSet -import Type ( mkTyVarTy, tyVarsOfTypes, mkTyConApp, - splitSigmaTy, mkForAllTys, mkFunTys, getTyVar, - mkDictTy, splitRhoTy, mkForAllTy, isUnLiftedType, - isUnboxedType, unboxedTypeKind, boxedTypeKind - ) -import FunDeps ( tyVarFunDep, oclose ) -import Var ( TyVar, tyVarKind ) +import Var ( tyVarKind ) import VarSet +import SrcLoc ( Located(..), srcLocSpan, unLoc, noLoc ) import Bag -import Util ( isIn ) -import Maybes ( maybeToBool ) -import BasicTypes ( TopLevelFlag(..), RecFlag(..), isNotTopLevel ) +import Util ( isIn, equalLength ) +import BasicTypes ( TopLevelFlag(..), RecFlag(..), isNonRec, isRec, + isNotTopLevel, isAlwaysActive ) import FiniteMap ( listToFM, lookupFM ) -import SrcLoc ( SrcLoc ) import Outputable \end{code} @@ -99,109 +84,177 @@ At the top-level the LIE is sure to contain nothing but constant dictionaries, which we resolve at the module level. \begin{code} -tcTopBindsAndThen, tcBindsAndThen - :: (RecFlag -> TcMonoBinds -> thing -> thing) -- Combinator - -> RenamedHsBinds - -> TcM s (thing, LIE) - -> TcM s (thing, LIE) +tcTopBinds :: [HsBindGroup Name] -> TcM (LHsBinds TcId, 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 $ + getLclEnv `thenM` \ env -> + returnM (emptyBag, env) + where + -- The top level bindings are flattened into a giant + -- implicitly-mutually-recursive MonoBinds + glue (HsBindGroup binds1 _ _) (binds2, env) = (binds1 `unionBags` binds2, env) + -- Can't have a HsIPBinds at top level -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 +tcBindsAndThen + :: (HsBindGroup TcId -> thing -> thing) -- Combinator + -> [HsBindGroup Name] + -> TcM thing + -> TcM thing + +tcBindsAndThen = tc_binds_and_then NotTopLevel + +tc_binds_and_then top_lvl combiner [] do_next = do_next +tc_binds_and_then top_lvl combiner (group : groups) do_next + = tc_bind_and_then top_lvl combiner group $ + tc_binds_and_then top_lvl combiner groups 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_bind_and_then top_lvl combiner (HsIPBinds binds) do_next + = getLIE do_next `thenM` \ (result, expr_lie) -> + mapAndUnzipM (wrapLocSndM tc_ip_bind) binds `thenM` \ (avail_ips, binds') -> -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] $ + -- 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 (HsIPBinds binds') $ + combiner (HsBindGroup dict_binds [] Recursive) result) + where + -- I wonder if we should do these one at at time + -- Consider ?x = 4 + -- ?y = ?x + 1 + tc_ip_bind (IPBind ip expr) + = newTyVarTy openTypeKind `thenM` \ ty -> + newIPDict (IPBindOrigin ip) ip ty `thenM` \ (ip', ip_inst) -> + tcCheckRho expr ty `thenM` \ expr' -> + returnM (ip_inst, (IPBind ip' expr')) + +tc_bind_and_then top_lvl combiner (HsBindGroup binds sigs is_rec) do_next + | isEmptyBag binds + = do_next + | otherwise + = -- 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 (collectSigTysFromHsBinds (bagToList binds)) $ + tcBindWithSigs top_lvl binds sigs is_rec `thenM` \ (poly_binds, poly_ids) -> + + 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 (HsBindGroup + (poly_binds `unionBags` prag_binds) + [] -- no sigs + Recursive) + thing) + + NotTopLevel -- For nested bindings we must do the + -- bindInstsOfLocalFuns thing. We must include + -- the LIE from the RHSs too -- polymorphic recursion! + -> 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 (HsBindGroup + (poly_binds `unionBags` + lie_binds `unionBags` + prag_binds) + [] Recursive) thing + ) + else + returnM ( + combiner (HsBindGroup poly_binds [] NonRecursive) $ + combiner (HsBindGroup prag_binds [] NonRecursive) $ + combiner (HsBindGroup lie_binds [] Recursive) $ + -- NB: the binds returned by tcSimplify and + -- bindInstsOfLocalFuns aren't guaranteed in + -- dependency order (though we could change + -- that); hence the Recursive marker. + thing) + +{- + = -- 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 (collectSigTysFromHsBinds (bagToList binds)) $ + + tcBindWithSigs top_lvl binds sigs is_rec `thenM` \ (poly_binds, 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 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 $ + 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 (HsBindGroup + (poly_binds `unionBags` prag_binds) + [] -- no sigs + Recursive) + 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 (HsBindGroup ( + poly_binds `unionBags` + lie_binds `unionBags` + prag_binds) + [] Recursive) thing + ) + else + returnM ( + combiner (HsBindGroup poly_binds [] NonRecursive) $ + combiner (HsBindGroup prag_binds [] NonRecursive) $ + combiner (HsBindGroup lie_binds [] Recursive) $ -- 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} + 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 -> + + -- Now do whatever happens next, in the augmented envt + do_next `thenM` \ thing -> -An aside. The original version of @tcBindsAndThen@ which lacks a -combiner function, appears below. Though it is perfectly well -behaved, it cannot be typed by Haskell, because the recursive call is -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, 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} + returnM (prag_binds, thing) +\end{code} %************************************************************************ @@ -221,216 +274,171 @@ so all the clever stuff is in here. as the Name in the tc_ty_sig \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 ( +tcBindWithSigs :: TopLevelFlag + -> LHsBinds Name + -> [LSig Name] + -> RecFlag + -> TcM (LHsBinds TcId, [TcId]) + +tcBindWithSigs top_lvl mbind sigs is_rec + = -- TYPECHECK THE SIGNATURES + recoverM (returnM []) ( + mappM tcTySig [sig | sig@(L _(Sig name _)) <- sigs] + ) `thenM` \ tc_ty_sigs -> + + -- 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 boxedTypeKind `thenNF_Tc` \ alpha_tv -> + newTyVar liftedTypeKind `thenM` \ alpha_tv -> let forall_a_a = mkForAllTy alpha_tv (mkTyVarTy alpha_tv) - binder_names = map fst (bagToList (collectMonoBinders mbind)) + binder_names = collectHsBindBinders 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 + Just sig -> sig_poly_id 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 (emptyBag, poly_ids) + ) $ -- 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 - tcImprove lie_req `thenTc_` - - -- COMPUTE VARIABLES OVER WHICH TO QUANTIFY, namely tyvars_to_gen - -- The tyvars_not_to_gen are free in the environment, and hence - -- candidates for generalisation, but sometimes the monomorphism - -- restriction means we can't generalise them nevertheless - 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 -> + traceTc (ptext SLIT("--------------------------------------------------------")) `thenM_` + traceTc (ptext SLIT("Bindings for") <+> ppr (collectHsBindBinders mbind)) `thenM_` + getLIE (tcMonoBinds mbind tc_ty_sigs is_rec) `thenM` \ ((mbind', bndr_names_w_ids), lie_req) -> 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 + (binder_names, mono_ids) = unzip (bagToList bndr_names_w_ids) + tau_tvs = foldr (unionVarSet . tyVarsOfType . idType) emptyVarSet mono_ids in - -- SIMPLIFY THE LIE - tcExtendGlobalTyVars tyvars_not_to_gen ( - if null real_tyvars_to_gen_list then - -- No polymorphism, 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) - top_lvl 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 -> + -- GENERALISE + -- (it seems a bit crude to have to do getLIE twice, + -- but I can't see a better way just now) + addSrcSpan (srcLocSpan (minimum (map getSrcLoc binder_names))) $ + -- TODO: location wrong + + 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 + -- This commits any unbound kind variables to boxed kind, by unification + -- It's important that the final quanfified type variables + -- are fully zonked, *including boxity*, because they'll be + -- 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. + 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 + 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 - dict_tys = map idType dicts_bound + poly_ids = [poly_id | (_, poly_id, _) <- exports] + dict_tys = map idType zonked_dict_ids + + inlines = mkNameSet [ name + | L _ (InlineSig True (L _ name) _) <- sigs] + -- Any INLINE sig (regardless of phase control) + -- makes the RHS look small - 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 + inline_phases = listToFM [ (name, phase) + | L _ (InlineSig _ (L _ 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 _ _ _ _ _) -> - (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) + Just sig -> (sig_tvs sig, sig_poly_id sig) + 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 -- It's important to build a fully-zonked poly_ty, because -- we'll slurp out its free type variables when extending the -- local environment (tcExtendLocalValEnv); if it's not zonked -- it appears to have free tyvars that aren't actually free -- at all. - - pat_binders :: [Name] - pat_binders = map fst $ bagToList $ collectMonoBinders $ - (justPatBindings mbind EmptyMonoBinds) in - -- CHECK FOR UNBOXED BINDERS IN PATTERN BINDINGS - mapTc (\id -> checkTc (not (idName id `elem` pat_binders - && isUnboxedType (idType id))) - (unboxedPatBindErr id)) zonked_mono_ids - `thenTc_` - - -- BUILD RESULTS - returnTc ( - AbsBinds real_tyvars_to_gen_list - dicts_bound - exports - inlines - (dict_binds `andMonoBinds` mbind'), - lie_free, - [poly_id | (_, poly_id, _) <- exports] - ) - where - 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 + traceTc (text "binding:" <+> ppr ((zonked_dict_ids, dict_binds), + exports, map idType poly_ids)) `thenM_` -attachNoInlinePrag no_inlines bndr - = case lookupFM no_inlines (idName bndr) of + -- 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 ( + unitBag $ noLoc $ + AbsBinds [] [] exports inlines mbind', + -- Do not generate even any x=y bindings + poly_ids + ) + + else -- The normal case + extendLIEs lie_free `thenM_` + returnM ( + unitBag $ noLoc $ + AbsBinds real_tyvars_to_gen + zonked_dict_ids + exports + inlines + (dict_binds `unionBags` mbind'), + poly_ids + ) + +attachInlinePhase inline_phases bndr + = case lookupFM inline_phases (idName bndr) of Just prag -> bndr `setInlinePragma` prag Nothing -> bndr + +-- 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 + -- 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. + + checkTc (isNotTopLevel top_lvl) + (unliftedBindErr "Top-level" mbind) `thenM_` + checkTc (isNonRec is_rec) + (unliftedBindErr "Recursive" mbind) `thenM_` + checkTc (isSingletonBag mbind) + (unliftedBindErr "Multiple" mbind) `thenM_` + checkTc (null real_tyvars_to_gen) + (unliftedBindErr "Polymorphic" mbind) \end{code} + Polymorphic recursion ~~~~~~~~~~~~~~~~~~~~~ The game plan for polymorphic recursion in the code above is @@ -493,6 +501,109 @@ is doing. %* * %************************************************************************ +\begin{code} +generalise binder_names mbind tau_tvs lie_req sigs = + + -- check for -fno-monomorphism-restriction + doptM Opt_NoMonomorphismRestriction `thenM` \ no_MR -> + let is_unrestricted | no_MR = True + | otherwise = isUnRestrictedGroup tysig_names mbind + in + + 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 `thenM` \ (forall_tvs, dict_binds) -> + + -- Check that signature type variables are OK + checkSigsTyVars forall_tvs sigs `thenM` \ final_qtvs -> + + returnM (final_qtvs, dict_binds, sig_dicts) + + where + tysig_names = map (idName . sig_poly_id) sigs + is_mono_sig sig = null (sig_theta sig) + + doc = ptext SLIT("type signature(s) for") <+> pprBinders binder_names + +----------------------- + -- 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 +checkSigsCtxts sigs@(TySigInfo { sig_poly_id = id1, sig_tvs = sig_tvs, sig_theta = theta1, sig_loc = span} + : other_sigs) + = addSrcSpan span $ + mappM_ check_one other_sigs `thenM_` + if null theta1 then + returnM ([], []) -- Non-overloaded type signatures + else + 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 + returnM (sig_avails, map instToId sig_dicts) + where + sig1_dict_tys = map mkPredTy theta1 + sig_meths = concatMap sig_insts sigs + + check_one (TySigInfo {sig_poly_id = id, sig_theta = theta}) + = addErrCtxt (sigContextsCtxt id1 id) $ + checkTc (equalLength theta theta1) sigContextsErr `thenM_` + unifyTauTyLists sig1_dict_tys (map mkPredTy theta) + +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 = foldl extendVarSetList emptyVarSet sig_tvs_s + all_tvs = extendVarSetList sig_tvs qtvs + in + returnM (varSetElems all_tvs) + where + check_one (TySigInfo {sig_poly_id = id, sig_tvs = tvs, sig_theta = theta, sig_tau = tau}) + = addErrCtxt (ptext SLIT("In the type signature for") + <+> quotes (ppr id)) $ + addErrCtxtM (sigCtxt id tvs theta tau) $ + checkSigTyVarsWrt (idFreeTyVars id) tvs +\end{code} + @getTyVarsToGen@ decides what type variables to generalise over. For a "restricted group" -- see the monomorphism restriction @@ -521,6 +632,8 @@ generalise. We must be careful about doing this: Another, more common, example is when there's a Method inst in the LIE, whose type might very well involve non-overloaded type variables. + [NOTE: Jan 2001: I don't understand the problem here so I'm doing + the simple thing instead] (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 @@ -531,50 +644,22 @@ 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 - in - if is_unrestricted - then - let fds = concatMap snd (getFunDepsOfLIE lie) in - zonkFunDeps fds `thenNF_Tc` \ fds' -> - let tvFundep = tyVarFunDep fds' - extended_tyvars = oclose tvFundep body_tyvars in - -- pprTrace "gTVTG" (ppr (lie, body_tyvars, extended_tyvars)) $ - returnNF_Tc (emptyVarSet, extended_tyvars) - else - -- 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") NotTopLevel 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} - - -\begin{code} isUnRestrictedGroup :: [Name] -- Signatures given for these - -> RenamedMonoBinds + -> LHsBinds Name -> Bool +isUnRestrictedGroup sigs binds = all (unrestricted . unLoc) (bagToList binds) + where + unrestricted (PatBind other _) = False + unrestricted (VarBind v _) = v `is_elem` sigs + unrestricted (FunBind v _ matches) = unrestricted_match matches + || unLoc v `is_elem` sigs + + unrestricted_match (L _ (Match [] _ _) : _) = False + -- No args => like a pattern binding + unrestricted_match other = True + -- Some args => a function binding is_elem v vs = isIn "isUnResMono" v vs - -isUnRestrictedGroup sigs (PatMonoBind (VarPatIn v) _ _) = v `is_elem` sigs -isUnRestrictedGroup sigs (PatMonoBind other _ _) = False -isUnRestrictedGroup sigs (VarMonoBind v _) = v `is_elem` sigs -isUnRestrictedGroup sigs (FunMonoBind _ _ _ _) = True -isUnRestrictedGroup sigs (AndMonoBinds mb1 mb2) = isUnRestrictedGroup sigs mb1 && - isUnRestrictedGroup sigs mb2 -isUnRestrictedGroup sigs EmptyMonoBinds = True \end{code} @@ -588,221 +673,140 @@ isUnRestrictedGroup sigs EmptyMonoBinds = True The signatures have been dealt with already. \begin{code} -tcMonoBinds :: RenamedMonoBinds - -> [TcSigInfo] - -> RecFlag - -> TcM s (TcMonoBinds, - LIE, -- LIE required - [Name], -- Bound names - [TcId]) -- Corresponding monomorphic bound things +tcMonoBinds :: LHsBinds Name + -> [TcSigInfo] -> RecFlag + -> TcM (LHsBinds TcId, + 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) -> + -- 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 + = mapBagM tc_lbind_pats mbinds `thenM` \ bag_of_pairs -> 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 -> [] + (complete_it, xve) + = foldrBag combine + (returnM (emptyBag, emptyBag), emptyBag) + bag_of_pairs + combine (complete_it1, xve1) (complete_it2, xve2) + = (complete_it, xve1 `unionBags` xve2) + where + complete_it = complete_it1 `thenM` \ (b1, bs1) -> + complete_it2 `thenM` \ (b2, bs2) -> + returnM (b1 `consBag` b2, bs1 `unionBags` bs2) 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) + 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 type signatures - tc_pat_bndr name pat_ty - = case maybeSig tc_ty_sigs name of - Nothing - -> newLocalId (getOccName name) pat_ty (getSrcLoc name) - - Just (TySigInfo _ _ _ _ _ mono_id _ _) - -> tcAddSrcLoc (getSrcLoc name) $ - unifyTauTy (idType mono_id) pat_ty `thenTc_` - returnTc mono_id - - mk_bind (name, mono_id) = case maybeSig tc_ty_sigs name of - Nothing -> (name, mono_id) - Just (TySigInfo name poly_id _ _ _ _ _ _) -> (name, poly_id) - - tc_mb_pats EmptyMonoBinds - = returnTc (\ xve -> returnTc (EmptyMonoBinds, emptyLIE), emptyLIE, emptyBag, emptyBag, emptyLIE) - - tc_mb_pats (AndMonoBinds mb1 mb2) - = tc_mb_pats mb1 `thenTc` \ (complete_it1, lie_req1, tvs1, ids1, lie_avail1) -> - tc_mb_pats mb2 `thenTc` \ (complete_it2, lie_req2, tvs2, ids2, lie_avail2) -> - let - complete_it xve = complete_it1 xve `thenTc` \ (mb1', lie1) -> - complete_it2 xve `thenTc` \ (mb2', lie2) -> - returnTc (AndMonoBinds mb1' mb2', lie1 `plusLIE` lie2) + tc_lbind_pats :: LHsBind Name + -> TcM (TcM (LHsBind TcId, Bag (Name,TcId)), -- Completer + Bag (Name,TcId)) + -- wrapper for tc_bind_pats to deal with the location stuff + tc_lbind_pats (L loc bind) + = addSrcSpan loc $ do + (tc, bag) <- tc_bind_pats bind + return (wrap tc, bag) + where + wrap tc = addSrcSpan loc $ do + (bind, stuff) <- tc + return (L loc bind, stuff) + + + tc_bind_pats :: HsBind Name + -> TcM (TcM (HsBind TcId, Bag (Name,TcId)), -- Completer + Bag (Name,TcId)) + tc_bind_pats (FunBind (L nm_loc name) inf matches) + -- 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 = sig_mono_id sig + mono_ty = idType mono_id + complete_it = tcMatchesFun name matches (Check mono_ty) `thenM` \ matches' -> + returnM (FunBind (L nm_loc mono_id) inf matches', + unitBag (name, mono_id)) in - returnTc (complete_it, - lie_req1 `plusLIE` lie_req2, - tvs1 `unionBags` tvs2, - ids1 `unionBags` ids2, - lie_avail1 `plusLIE` lie_avail2) - - tc_mb_pats (FunMonoBind name inf matches locn) - = newTyVarTy boxedTypeKind `thenNF_Tc` \ bndr_ty -> - tc_pat_bndr name bndr_ty `thenTc` \ bndr_id -> + returnM (complete_it, if isRec is_rec then unitBag (name, sig_poly_id 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 = tcMatchesFun name matches (Check mono_ty) `thenM` \ matches' -> + returnM (FunBind (L nm_loc mono_id) inf matches', + unitBag (name, mono_id)) in - returnTc (complete_it, emptyLIE, emptyBag, unitBag (name, bndr_id), emptyLIE) - - tc_mb_pats bind@(PatMonoBind pat grhss locn) - = tcAddSrcLoc locn $ + 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 + = 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 (FunBind (L nm_loc mono_id) inf matches', + unitBag (name, mono_id)) + in + returnM (complete_it, emptyBag) + + tc_bind_pats bind@(PatBind pat grhss) + = -- Now typecheck the pattern + -- 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 + -- 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 -> - -- Figure out the appropriate kind for the pattern, - -- and generate a suitable type variable - (case is_rec of - Recursive -> newTyVarTy boxedTypeKind -- Recursive, so no unboxed types - NonRecursive -> newTyVarTy_OpenKind -- Non-recursive, so we permit unboxed types - ) `thenNF_Tc` \ pat_ty -> + -- Don't know how to deal with pattern-bound existentials yet + checkTc (isEmptyBag tvs && null lie_avail) + (existentialExplode bind) `thenM_` - -- 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) + complete_it = addErrCtxt (patMonoBindsCtxt bind) $ + tcGRHSsPat grhss (Check pat_ty) `thenM` \ grhss' -> + returnM (PatBind pat' grhss', ids) in - returnTc (complete_it, lie_req, tvs, ids, lie_avail) -\end{code} - -%************************************************************************ -%* * -\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. - -The error message here is somewhat unsatisfactory, but it'll do for -now (ToDo). - -\begin{code} -checkSigMatch top_lvl binder_names mono_ids sigs - | main_bound_here - = -- First unify the main_id with IO t, for any old t - tcSetErrCtxt mainTyCheckCtxt ( - tcLookupTyCon ioTyCon_NAME `thenTc` \ ioTyCon -> - newTyVarTy boxedTypeKind `thenNF_Tc` \ t_tv -> - unifyTauTy ((mkTyConApp ioTyCon [t_tv])) - (idType main_mono_id) - ) `thenTc_` - - -- Now check the signatures - -- Must do this after the unification with IO t, - -- in case of a silly signature like - -- main :: forall a. a - -- The unification to IO t will bind the type variable 'a', - -- which is just waht check_one_sig looks for - mapTc check_one_sig sigs `thenTc_` - mapTc check_main_ctxt sigs `thenTc_` - - returnTc (Just ([], emptyLIE)) - - | not (null sigs) - = mapTc check_one_sig sigs `thenTc_` - mapTc check_one_ctxt all_sigs_but_first `thenTc_` - returnTc (Just (theta1, sig_lie)) - - | otherwise - = returnTc Nothing -- No constraints from type sigs - - where - (TySigInfo _ id1 _ theta1 _ _ _ _ : all_sigs_but_first) = sigs - - sig1_dict_tys = mk_dict_tys theta1 - n_sig1_dict_tys = length sig1_dict_tys - sig_lie = mkLIE [inst | TySigInfo _ _ _ _ _ _ inst _ <- sigs] - - 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_tau _ _ src_loc) - = tcAddSrcLoc src_loc $ - tcAddErrCtxtM (sigCtxt (sig_msg id) (idType id)) $ - checkSigTyVars sig_tyvars - - - -- CHECK THAT ALL THE SIGNATURE CONTEXTS ARE UNIFIABLE - -- The type signatures on a mutually-recursive group of definitions - -- 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 = [mkDictTy c ts | (c,ts) <- theta] - - sig_msg id tidy_ty = sep [ptext SLIT("When checking the type signature"), - nest 4 (ppr id <+> dcolon <+> ppr tidy_ty)] - - -- Search for Main.main in the binder_names, return corresponding mono_id - find_main NotTopLevel binder_names mono_ids = Nothing - find_main TopLevel binder_names mono_ids = go binder_names mono_ids - go [] [] = Nothing - go (n:ns) (m:ms) | n == main_NAME = Just m - | otherwise = go ns ms + returnM (complete_it, if isRec is_rec then ids else emptyBag) + + -- 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_bind_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 -> addSrcSpan (srcLocSpan (getSrcLoc name)) $ + -- TODO: location wrong + tcSubPat (idType mono_id) pat_ty `thenM` \ co_fn -> + returnM (co_fn, mono_id) + where + mono_id = sig_mono_id sig \end{code} @@ -848,37 +852,39 @@ a RULE now: {-# SPECIALISE (f:: TcM s (TcMonoBinds, LIE) -tcSpecSigs (SpecSig name poly_ty src_loc : sigs) +tcSpecSigs :: [LSig Name] -> TcM (LHsBinds TcId) +tcSpecSigs (L loc (SpecSig (L nm_loc name) poly_ty) : sigs) = -- SPECIALISE f :: forall b. theta => tau = g - tcAddSrcLoc src_loc $ - tcAddErrCtxt (valSpecSigCtxt name poly_ty) $ + addSrcSpan loc $ + addErrCtxt (valSpecSigCtxt name poly_ty) $ -- Get and instantiate its alleged specialised type - tcHsType 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 (L nm_loc (HsVar name)) sig_ty) `thenM` \ (spec_expr, spec_lie) -> -- Squeeze out any Methods (see comments with tcSimplifyToDicts) - tcSimplifyToDicts spec_lie `thenTc` \ (spec_lie1, 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 = VarBind (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` spec_lie1) + tcSpecSigs sigs `thenM` \ binds_rest -> + returnM (binds_rest `snocBag` L loc spec_bind) tcSpecSigs (other_sig : sigs) = tcSpecSigs sigs -tcSpecSigs [] = returnTc (EmptyMonoBinds, emptyLIE) +tcSpecSigs [] = returnM emptyBag \end{code} - %************************************************************************ %* * \subsection[TcBinds-errors]{Error contexts and messages} @@ -896,56 +902,37 @@ valSpecSigCtxt v ty nest 4 (ppr v <+> dcolon <+> ppr ty)] ----------------------------------------------- -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) - ]) - ------------------------------------------------ -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) - ------------------------------------------------ -bindSigsCtxt ids - = ptext SLIT("When checking the type signature(s) for") <+> pprQuotedList ids - ------------------------------------------------ -sigContextsErr - = ptext SLIT("Mismatched contexts") +sigContextsErr = ptext SLIT("Mismatched contexts") sigContextsCtxt s1 s2 - = hang (hsep [ptext SLIT("When matching the contexts of the signatures for"), - quotes (ppr s1), ptext SLIT("and"), quotes (ppr s2)]) - 4 (ptext SLIT("(the signature contexts in a mutually recursive group should all be identical)")) - -mainContextsErr id - | getName id == main_NAME = ptext SLIT("Main.main cannot be overloaded") - | otherwise - = quotes (ppr id) <+> ptext SLIT("cannot be overloaded") <> char ',' <> -- sigh; workaround for cpp's inability to deal - ptext SLIT("because it is mutually recursive with Main.main") -- with commas inside SLIT strings. - -mainTyCheckCtxt - = hsep [ptext SLIT("When checking that"), quotes (ppr main_NAME), - ptext SLIT("has the required type")] + = 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 - = hang (text flavour <+> ptext SLIT("bindings for unlifted types aren't allowed")) + = 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) + +----------------------------------------------- +restrictedBindCtxtErr binder_names + = hang (ptext SLIT("Illegal overloaded type signature(s)")) + 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 +-- 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}