X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcBinds.lhs;h=5bd9cae2b8644ef751a63b3728b333daabbe4b95;hb=ebf2c80221ccf11aeb7a0a2be27bfc72529855a5;hp=912a415554664e3b4082b221dd61085a5e599a46;hpb=7d61cb61daa5e433a0cb85b34b7f0c58b2f961ff;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcBinds.lhs b/ghc/compiler/typecheck/TcBinds.lhs index 912a415..5bd9cae 100644 --- a/ghc/compiler/typecheck/TcBinds.lhs +++ b/ghc/compiler/typecheck/TcBinds.lhs @@ -1,50 +1,66 @@ % -% (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, tcTopBinds, + 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 CmdLineOpts ( opt_NoMonomorphismRestriction ) +import HsSyn ( HsExpr(..), HsBinds(..), MonoBinds(..), Sig(..), + Match(..), HsMatchContext(..), + collectMonoBinders, andMonoBinds + ) +import RnHsSyn ( RenamedHsBinds, RenamedSig, RenamedMonoBinds ) +import TcHsSyn ( TcMonoBinds, TcId, zonkId, mkHsLet ) + +import TcMonad +import Inst ( LIE, emptyLIE, mkLIE, plusLIE, InstOrigin(..), + newDicts, instToId + ) +import TcEnv ( tcExtendLocalValEnv, + newSpecPragmaId, newLocalId + ) +import TcSimplify ( tcSimplifyInfer, tcSimplifyInferCheck, tcSimplifyCheck, tcSimplifyRestricted, tcSimplifyToDicts ) +import TcMonoType ( tcHsSigType, checkSigTyVars, + TcSigInfo(..), tcTySig, maybeSig, sigCtxt + ) import 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 ( newTyVarTy, newTyVar, + zonkTcTyVarToTyVar + ) +import TcUnify ( unifyTauTy, unifyTauTyLists ) + +import CoreFVs ( idFreeTyVars ) +import Id ( mkLocalId, setInlinePragma ) +import Var ( idType, idName ) +import IdInfo ( InlinePragInfo(..) ) +import Name ( Name, getOccName, getSrcLoc ) +import NameSet +import Type ( mkTyVarTy, tyVarsOfTypes, + mkForAllTys, mkFunTys, tyVarsOfType, + mkPredTy, mkForAllTy, isUnLiftedType, + unliftedTypeKind, liftedTypeKind, openTypeKind + ) +import Var ( tyVarKind ) +import VarSet +import Bag +import Util ( isIn ) +import ListSetOps ( minusList ) +import Maybes ( maybeToBool ) +import BasicTypes ( TopLevelFlag(..), RecFlag(..), isNonRec, isNotTopLevel ) +import FiniteMap ( listToFM, lookupFM ) +import Outputable \end{code} + %************************************************************************ %* * \subsection{Type-checking bindings} @@ -62,7 +78,7 @@ 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 @@ -77,264 +93,637 @@ 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 - -> 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 - -tcBindsAndThen combiner (BindWith bind sigs) do_next - = tcBindAndThen combiner bind sigs do_next - -tcBindsAndThen combiner (ThenBinds binds1 binds2) do_next - = tcBindsAndThen combiner binds1 (tcBindsAndThen combiner binds2 do_next) -\end{code} +tcTopBinds :: RenamedHsBinds -> TcM ((TcMonoBinds, TcEnv), LIE) +tcTopBinds binds + = tc_binds_and_then TopLevel glue binds $ + tcGetEnv `thenNF_Tc` \ env -> + returnTc ((EmptyMonoBinds, env), emptyLIE) + where + glue is_rec binds1 (binds2, thing) = (binds1 `AndMonoBinds` binds2, 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 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 + :: (RecFlag -> TcMonoBinds -> thing -> thing) -- Combinator + -> RenamedHsBinds + -> TcM (thing, LIE) + -> TcM (thing, LIE) + +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 (BindWith bind sigs) do_next - = tcBindAndThen bind sigs do_next + -- Now do whatever happens next, in the augmented envt + do_next `thenTc` \ (thing, thing_lie) -> -tcBindsAndThen (ThenBinds binds1 binds2) do_next - = tcBindsAndThen binds1 (tcBindsAndThen binds2 do_next) - `thenTc` \ ((binds1', (binds2', thing')), lie1, thing_ty) -> + -- Create specialisations of functions bound here + -- We want to keep non-recursive things non-recursive + -- so that we desugar unlifted bindings correctly + case (top_lvl, is_rec) of + + -- For the top level don't bother will all this bindInstsOfLocalFuns stuff + -- All the top level things are rec'd together anyway, so it's fine to + -- leave them to the tcSimplifyTop, and quite a bit faster too + (TopLevel, _) + -> returnTc (combiner Recursive (poly_binds `andMonoBinds` prag_binds) thing, + thing_lie `plusLIE` prag_lie `plusLIE` poly_lie) + + (NotTopLevel, NonRecursive) + -> bindInstsOfLocalFuns + (thing_lie `plusLIE` prag_lie) + poly_ids `thenTc` \ (thing_lie', lie_binds) -> + + returnTc ( + combiner NonRecursive poly_binds $ + combiner NonRecursive prag_binds $ + combiner Recursive lie_binds $ + -- 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} - returnTc ((binds1' `ThenBinds` binds2', thing'), lie1, thing_ty) -\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 (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 liftedTypeKind `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 = collectMonoBinders mbind + poly_ids = map mk_dummy binder_names + mk_dummy name = case maybeSig tc_ty_sigs name of + Just (TySigInfo _ poly_id _ _ _ _ _ _) -> poly_id -- Signature + Nothing -> mkLocalId name forall_a_a -- No signature in - returnTc (EmptyBinds, 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) + returnTc (EmptyMonoBinds, emptyLIE, poly_ids) + ) $ + + -- TYPECHECK THE BINDINGS + tcMonoBinds mbind tc_ty_sigs is_rec `thenTc` \ (mbind', lie_req, binder_names, mono_ids) -> + let + tau_tvs = varSetElems (foldr (unionVarSet . tyVarsOfType . idType) emptyVarSet mono_ids) + in + + -- GENERALISE + generalise binder_names mbind tau_tvs lie_req tc_ty_sigs + `thenTc` \ (tc_tyvars_to_gen, lie_free, dict_binds, dict_ids) -> + + + -- 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. + mapNF_Tc zonkTcTyVarToTyVar tc_tyvars_to_gen `thenNF_Tc` \ real_tyvars_to_gen -> + + -- ZONK THE Ids + -- It's important that the dict Ids are zonked, including the boxity set + -- in the previous step, because they are later used to form the type of + -- the polymorphic thing, and forall-types must be zonked so far as + -- their bound variables are concerned + mapNF_Tc zonkId dict_ids `thenNF_Tc` \ zonked_dict_ids -> + mapNF_Tc zonkId mono_ids `thenNF_Tc` \ zonked_mono_ids -> + + -- CHECK FOR BOGUS UNLIFTED BINDINGS + checkUnliftedBinds top_lvl is_rec real_tyvars_to_gen mbind zonked_mono_ids `thenTc_` + + -- BUILD THE POLYMORPHIC RESULT IDs + let + exports = zipWith mk_export binder_names zonked_mono_ids + dict_tys = map idType zonked_dict_ids + + inlines = mkNameSet [name | InlineSig name _ loc <- inline_sigs] + no_inlines = listToFM ([(name, IMustNotBeINLINEd False phase) | NoInlineSig name phase loc <- inline_sigs] ++ + [(name, IMustNotBeINLINEd True phase) | InlineSig name phase loc <- inline_sigs, maybeToBool phase]) + -- "INLINE n foo" means inline foo, but not until at least phase n + -- "NOINLINE n foo" means don't inline foo until at least phase n, and even + -- then only if it is small enough etc. + -- "NOINLINE foo" means don't inline foo ever, which we signal with a (IMustNotBeINLINEd Nothing) + -- See comments in CoreUnfold.blackListed for the Authorised Version + + 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, 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. + in + + traceTc (text "binding:" <+> ppr ((zonked_dict_ids, dict_binds), + exports, [idType poly_id | (_, poly_id, _) <- exports])) `thenTc_` + + -- BUILD RESULTS + returnTc ( + AbsBinds real_tyvars_to_gen + zonked_dict_ids + exports + inlines + (dict_binds `andMonoBinds` mbind'), + lie_free, + [poly_id | (_, poly_id, _) <- exports] ) - `thenTc` \ (mono_ids, bind', lie, sig_info) -> - -- Notice that genBinds gets the old (non-extended) environment - genBinds binder_names mono_ids bind' lie sig_info prag_info_fn +attachNoInlinePrag no_inlines bndr + = case lookupFM no_inlines (idName bndr) of + Just prag -> bndr `setInlinePragma` prag + Nothing -> bndr + +checkUnliftedBinds top_lvl is_rec real_tyvars_to_gen mbind zonked_mono_ids + = ASSERT( not (any ((== unliftedTypeKind) . tyVarKind) real_tyvars_to_gen) ) + -- 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. + + -- Check that pattern-bound variables are not unlifted + (if or [ (idName id `elem` pat_binders) && isUnLiftedType (idType id) + | id <- zonked_mono_ids ] then + addErrTc (unliftedBindErr "Pattern" mbind) + else + returnTc () + ) `thenTc_` + + -- Unlifted bindings must be non-recursive, + -- not top level, non-polymorphic, and not pattern bound + if any (isUnLiftedType . idType) zonked_mono_ids then + checkTc (isNotTopLevel top_lvl) + (unliftedBindErr "Top-level" mbind) `thenTc_` + checkTc (isNonRec is_rec) + (unliftedBindErr "Recursive" mbind) `thenTc_` + checkTc (null real_tyvars_to_gen) + (unliftedBindErr "Polymorphic" mbind) + else + returnTc () + where - kind = case bind of - NonRecBind _ -> mkBoxedTypeKind -- Recursive, so no unboxed types - RecBind _ -> mkTypeKind -- Non-recursive, so we permit unboxed types + pat_binders :: [Name] + pat_binders = collectMonoBinders (justPatBindings mbind EmptyMonoBinds) + + justPatBindings bind@(PatMonoBind _ _ _) binds = bind `andMonoBinds` binds + justPatBindings (AndMonoBinds b1 b2) binds = + justPatBindings b1 (justPatBindings b2 binds) + justPatBindings other_bind binds = binds \end{code} -\begin{code} -tc_bind :: RenamedBind -> TcM s (TcBind s, LIE s) -tc_bind (NonRecBind mono_binds) - = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) -> - returnTc (NonRecBind mono_binds2, lie) +Polymorphic recursion +~~~~~~~~~~~~~~~~~~~~~ +The game plan for polymorphic recursion in the code above is -tc_bind (RecBind mono_binds) - = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) -> - returnTc (RecBind mono_binds2, lie) -\end{code} + * 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. -\begin{code} -tcMonoBinds :: RenamedMonoBinds -> TcM s (TcMonoBinds s, LIE s) +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: -tcMonoBinds EmptyMonoBinds = returnTc (EmptyMonoBinds, emptyLIE) + f :: Eq a => [a] -> [a] + f xs = ...f... -tcMonoBinds (AndMonoBinds mb1 mb2) - = tcMonoBinds mb1 `thenTc` \ (mb1a, lie1) -> - tcMonoBinds mb2 `thenTc` \ (mb2a, lie2) -> - returnTc (AndMonoBinds mb1a mb2a, lie1 `plusLIE` lie2) +If we don't take care, after typechecking we get -tcMonoBinds bind@(PatMonoBind pat grhss_and_binds locn) - = tcAddSrcLoc locn $ + f = /\a -> \d::Eq a -> let f' = f a d + in + \ys:[a] -> ...f'... - -- LEFT HAND SIDE - tcPat pat `thenTc` \ (pat2, lie_pat, pat_ty) -> +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 - -- BINDINGS AND GRHSS - tcGRHSsAndBinds grhss_and_binds `thenTc` \ (grhss_and_binds2, lie, grhss_ty) -> + f = /\a -> \d::Eq a -> letrec + fm = \ys:[a] -> ...fm... + in + fm - -- Unify the two sides - tcAddErrCtxt (patMonoBindsCtxt bind) $ - unifyTauTy pat_ty grhss_ty `thenTc_` +This can lead to a massive space leak, from the following top-level defn +(post-typechecking) - -- RETURN - returnTc (PatMonoBind pat2 grhss_and_binds2 locn, - plusLIE lie_pat lie) + ff :: [Int] -> [Int] + ff = f Int dEqInt + +Now (f dEqInt) evaluates to a lambda that has f' as a free variable; but +f' is another thunk which evaluates to the same thing... and you end +up with a chain of identical values all hung onto by the CAF ff. + + ff = f Int dEqInt + + = let f' = f Int dEqInt in \ys. ...f'... + + = let f' = let f' = f Int dEqInt in \ys. ...f'... + in \ys. ...f'... + +Etc. +Solution: when typechecking the RHSs we always have in hand the +*monomorphic* Ids for each binding. So we just need to make sure that +if (Method f a d) shows up in the constraints emerging from (...f...) +we just use the monomorphic Id. We achieve this by adding monomorphic Ids +to the "givens" when simplifying constraints. That's what the "lies_avail" +is doing. -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) -\end{code} %************************************************************************ %* * -\subsection{Signatures} +\subsection{getTyVarsToGen} %* * %************************************************************************ -@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. - \begin{code} -tcTySigs :: [RenamedSig] -> TcM s [TcSigInfo s] +generalise_help doc tau_tvs lie_req sigs + +----------------------- + | null sigs + = -- INFERENCE CASE: Unrestricted group, no type signatures + tcSimplifyInfer doc + tau_tvs lie_req + +----------------------- + | otherwise + = -- CHECKING CASE: Unrestricted group, there are type signatures + -- Check signature contexts are empty + checkSigsCtxts sigs `thenTc` \ (sig_avails, sig_dicts) -> + + -- Check that the needed dicts can be + -- expressed in terms of the signature ones + tcSimplifyInferCheck doc tau_tvs sig_avails lie_req `thenTc` \ (forall_tvs, lie_free, dict_binds) -> + + -- Check that signature type variables are OK + checkSigsTyVars sigs `thenTc_` + + returnTc (forall_tvs, lie_free, dict_binds, sig_dicts) + +generalise binder_names mbind tau_tvs lie_req sigs + | is_unrestricted -- UNRESTRICTED CASE + = generalise_help doc tau_tvs lie_req sigs + + | otherwise -- RESTRICTED CASE + = -- Do a simplification to decide what type variables + -- are constrained. We can't just take the free vars + -- of lie_req because that'll have methods that may + -- incidentally mention entirely unconstrained variables + -- e.g. a call to f :: Eq a => a -> b -> b + -- Here, b is unconstrained. A good example would be + -- foo = f (3::Int) + -- We want to infer the polymorphic type + -- foo :: forall b. b -> b + generalise_help doc tau_tvs lie_req sigs `thenTc` \ (forall_tvs, lie_free, dict_binds, dict_ids) -> + + -- Check signature contexts are empty + checkTc (null sigs || null dict_ids) + (restrictedBindCtxtErr binder_names) `thenTc_` + + -- Identify constrained tyvars + let + constrained_tvs = varSetElems (tyVarsOfTypes (map idType dict_ids)) + -- The dict_ids are fully zonked + final_forall_tvs = forall_tvs `minusList` constrained_tvs + in -tcTySigs (Sig v ty _ src_loc : other_sigs) - = tcAddSrcLoc src_loc ( - tcPolyType ty `thenTc` \ sigma_ty -> - tcInstType [] sigma_ty `thenNF_Tc` \ sigma_ty' -> - let - (tyvars', theta', tau') = splitSigmaTy sigma_ty' - in + -- Now simplify with exactly that set of tyvars + -- We have to squash those Methods + tcSimplifyRestricted doc final_forall_tvs [] lie_req `thenTc` \ (lie_free, binds) -> - tcLookupLocalValueOK "tcSig1" v `thenNF_Tc` \ val -> - unifyTauTy (idType val) tau' `thenTc_` + returnTc (final_forall_tvs, lie_free, binds, []) - returnTc (TySigInfo val tyvars' theta' tau' src_loc) - ) `thenTc` \ sig_info1 -> + where + is_unrestricted | opt_NoMonomorphismRestriction = True + | otherwise = isUnRestrictedGroup tysig_names mbind + + tysig_names = [name | (TySigInfo name _ _ _ _ _ _ _) <- sigs] + + doc | null sigs = ptext SLIT("banding(s) for") <+> pprBinders binder_names + | otherwise = 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 _ id1 sig_tvs theta1 _ _ _ _ : other_sigs) + = mapTc_ check_one other_sigs `thenTc_` + if null theta1 then + returnTc ([], []) -- Non-overloaded type signatures + else + newDicts SignatureOrigin theta1 `thenNF_Tc` \ sig_dicts -> + let + -- The "sig_avails" is the stuff available. We get that from + -- the context of the type signature, BUT ALSO the lie_avail + -- so that polymorphic recursion works right (see comments at end of fn) + sig_avails = sig_dicts ++ sig_meths + in + returnTc (sig_avails, map instToId sig_dicts) + where + sig1_dict_tys = map mkPredTy theta1 + n_sig1_theta = length theta1 + sig_meths = concat [insts | TySigInfo _ _ _ _ _ _ insts _ <- sigs] + + check_one sig@(TySigInfo _ id _ theta _ _ _ src_loc) + = tcAddSrcLoc src_loc $ + tcAddErrCtxt (sigContextsCtxt id1 id) $ + checkTc (length theta == n_sig1_theta) sigContextsErr `thenTc_` + unifyTauTyLists sig1_dict_tys (map mkPredTy theta) + +checkSigsTyVars sigs = mapTc_ check_one sigs + where + check_one (TySigInfo _ id sig_tyvars sig_theta sig_tau _ _ src_loc) + = tcAddSrcLoc src_loc $ + tcAddErrCtxtM (sigCtxt (sig_msg id) sig_tyvars sig_theta sig_tau) $ + checkSigTyVars sig_tyvars (idFreeTyVars id) + + sig_msg id = ptext SLIT("When checking the type signature for") <+> quotes (ppr id) +\end{code} - tcTySigs other_sigs `thenTc` \ sig_infos -> - returnTc (sig_info1 : sig_infos) +@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. + [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 + 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. -tcTySigs (other : sigs) = tcTySigs sigs -tcTySigs [] = returnTc [] +\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{SPECIALIZE pragmas} +\subsection{tcMonoBind} %* * %************************************************************************ - -@tcPragmaSigs@ munches up the "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. +@tcMonoBinds@ deals with a single @MonoBind@. +The signatures have been dealt with already. \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) -> +tcMonoBinds :: RenamedMonoBinds + -> [TcSigInfo] + -> RecFlag + -> TcM (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 - name_to_info name = foldr ($) noIdInfo - [info_fn | (n,info_fn) <- names_w_id_infos, n==name] + 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 - returnTc (name_to_info, - foldr ThenBinds EmptyBinds binds, - foldr plusLIE emptyLIE lies) -\end{code} + -- 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 -Here are the easy cases for tcPragmaSigs + -- This function is used when dealing with a LHS binder; + -- we make a monomorphic version of the Id. + -- We check for a type signature; if there is one, we use the mono_id + -- from the signature. This is how we make sure the tau part of the + -- signature actually maatches the type of the LHS; then tc_mb_pats + -- ensures the LHS and RHS have the same type + + tc_pat_bndr name pat_ty + = case maybeSig tc_ty_sigs name of + Nothing + -> newLocalId (getOccName name) pat_ty (getSrcLoc name) + + Just (TySigInfo _ _ _ _ _ mono_id _ _) + -> tcAddSrcLoc (getSrcLoc name) $ + unifyTauTy (idType mono_id) pat_ty `thenTc_` + returnTc mono_id + + mk_bind (name, mono_id) = case maybeSig tc_ty_sigs name of + Nothing -> (name, mono_id) + Just (TySigInfo name poly_id _ _ _ _ _ _) -> (name, poly_id) + + tc_mb_pats EmptyMonoBinds + = returnTc (\ xve -> returnTc (EmptyMonoBinds, emptyLIE), emptyLIE, emptyBag, emptyBag, emptyLIE) + + tc_mb_pats (AndMonoBinds mb1 mb2) + = tc_mb_pats mb1 `thenTc` \ (complete_it1, lie_req1, tvs1, ids1, lie_avail1) -> + tc_mb_pats mb2 `thenTc` \ (complete_it2, lie_req2, tvs2, ids2, lie_avail2) -> + let + complete_it xve = complete_it1 xve `thenTc` \ (mb1', lie1) -> + complete_it2 xve `thenTc` \ (mb2', lie2) -> + returnTc (AndMonoBinds mb1' mb2', lie1 `plusLIE` lie2) + in + returnTc (complete_it, + lie_req1 `plusLIE` lie_req2, + tvs1 `unionBags` tvs2, + ids1 `unionBags` ids2, + lie_avail1 `plusLIE` lie_avail2) + + tc_mb_pats (FunMonoBind name inf matches locn) + = newTyVarTy kind `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 $ + newTyVarTy kind `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) -\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) + -- Figure out the appropriate kind for the pattern, + -- and generate a suitable type variable + kind = case is_rec of + Recursive -> liftedTypeKind -- Recursive, so no unlifted types + NonRecursive -> openTypeKind -- Non-recursive, so we permit unlifted types \end{code} -The interesting case is for SPECIALISE pragmas. There are two forms. -Here's the first form: + +%************************************************************************ +%* * +\subsection{SPECIALIZE pragmas} +%* * +%************************************************************************ + +@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. + +They look like this: + \begin{verbatim} f :: Ord a => [a] -> b -> b {-# SPECIALIZE f :: [Int] -> b -> b #-} @@ -357,151 +746,86 @@ specialiser will subsequently discover that there's a call of @f@ at Int, and will create a specialisation for @f@. After that, the binding for @f*@ can be discarded. -The second form is this: -\begin{verbatim} - f :: Ord a => [a] -> b -> b - {-# SPECIALIZE f :: [Int] -> b -> b = g #-} -\end{verbatim} - -Here @g@ is specified as a function that implements the specialised -version of @f@. Suppose that g has type (a->b->b); that is, g's type -is more general than that required. For this we generate -\begin{verbatim} - f@Int = /\b -> g Int b - f* = f@Int -\end{verbatim} - -Here @f@@Int@ is a SpecId, the specialised version of @f@. It inherits -f's export status etc. @f*@ is a SpecPragmaId, as before, which just serves -to prevent @f@@Int@ from being discarded prematurely. After specialisation, -if @f@@Int@ is going to be used at all it will be used explicitly, so the simplifier can -discard the f* binding. - -Actually, there is really only point in giving a SPECIALISE pragma on exported things, -and the simplifer won't discard SpecIds for exporte things anyway, so maybe this is -a bit of overkill. +We used to have a form + {-# SPECIALISE f :: = g #-} +which promised that g implemented f at , but we do that with +a RULE now: + {-# SPECIALISE (f:: TcM (TcMonoBinds, LIE) +tcSpecSigs (SpecSig name poly_ty src_loc : sigs) + = -- SPECIALISE f :: forall b. theta => tau = g + tcAddSrcLoc src_loc $ + tcAddErrCtxt (valSpecSigCtxt name poly_ty) $ -- Get and instantiate its alleged specialised type - 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 + tcHsSigType poly_ty `thenTc` \ sig_ty -> - -- Check that the SPECIALIZE pragma had an empty context - checkTc (null sig_theta) - (panic "SPECIALIZE non-empty context (ToDo: msg)") `thenTc_` + -- 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) -> - -- 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 + -- Squeeze out any Methods (see comments with tcSimplifyToDicts) + tcSimplifyToDicts spec_lie `thenTc` \ (spec_dicts, spec_binds) -> - -- 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) -> + -- 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 -> + + -- Do the rest and combine + tcSpecSigs sigs `thenTc` \ (binds_rest, lie_rest) -> + returnTc (binds_rest `andMonoBinds` VarMonoBind spec_id (mkHsLet spec_binds spec_expr), + lie_rest `plusLIE` mkLIE spec_dicts) + +tcSpecSigs (other_sig : sigs) = tcSpecSigs sigs +tcSpecSigs [] = returnTc (EmptyMonoBinds, emptyLIE) +\end{code} - let - pseudo_bind = VarMonoBind spec_pragma_id pseudo_rhs - pseudo_rhs = mkHsTyLam sig_tyvars (HsVar (TcId meth_id)) - in - returnTc (pseudo_bind, lie, \ info -> info) - Just spec_name -> -- Use spec_name as the specialisation value ... +%************************************************************************ +%* * +\subsection[TcBinds-errors]{Error contexts and messages} +%* * +%************************************************************************ - -- Type check a simple occurrence of the specialised Id - tcId spec_name `thenTc` \ (spec_body, spec_lie, spec_tau) -> - -- 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_` +\begin{code} +patMonoBindsCtxt bind + = hang (ptext SLIT("In a pattern binding:")) 4 (ppr bind) - -- Make a local SpecId to bind to applied spec_id - newSpecId main_id main_arg_tys sig_ty `thenNF_Tc` \ local_spec_id -> +----------------------------------------------- +valSpecSigCtxt v ty + = sep [ptext SLIT("In a SPECIALIZE pragma for a value:"), + nest 4 (ppr v <+> dcolon <+> ppr ty)] - 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} +----------------------------------------------- +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)")) -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 "'"]) --} +----------------------------------------------- +unliftedBindErr flavour mbind + = hang (text flavour <+> ptext SLIT("bindings for unlifted types aren't allowed:")) + 4 (ppr mbind) ----------------------------------------------- -specGroundnessCtxt - = panic "specGroundnessCtxt" +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")]) -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]) +-- Used in error messages +pprBinders bndrs = braces (pprWithCommas ppr bndrs) \end{code} -