2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
4 \section[TcBinds]{TcBinds}
7 #include "HsVersions.h"
9 module TcBinds ( tcBindsAndThen, tcPragmaSigs ) where
13 import HsSyn ( HsBinds(..), Bind(..), Sig(..), MonoBinds(..),
14 HsExpr, Match, PolyType, InPat, OutPat,
15 GRHSsAndBinds, ArithSeqInfo, HsLit, Fake,
17 import RnHsSyn ( RenamedHsBinds(..), RenamedBind(..), RenamedSig(..),
18 RenamedMonoBinds(..), RnName(..)
20 import TcHsSyn ( TcHsBinds(..), TcBind(..), TcMonoBinds(..),
21 TcIdOcc(..), TcIdBndr(..) )
24 import GenSpecEtc ( checkSigTyVars, genBinds, TcSigInfo(..) )
25 import Inst ( Inst, LIE(..), emptyLIE, plusLIE, InstOrigin(..) )
26 import TcEnv ( tcExtendLocalValEnv, tcLookupLocalValueOK, newMonoIds )
27 import TcLoop ( tcGRHSsAndBinds )
28 import TcMatches ( tcMatchesFun )
29 import TcMonoType ( tcPolyType )
30 import TcPat ( tcPat )
31 import TcSimplify ( bindInstsOfLocalFuns )
32 import TcType ( newTcTyVar, tcInstType )
33 import Unify ( unifyTauTy )
35 import Kind ( mkBoxedTypeKind, mkTypeKind )
36 import Id ( GenId, idType, mkUserId )
37 import IdInfo ( noIdInfo )
38 import Maybes ( assocMaybe, catMaybes, Maybe(..) )
39 import Name ( pprNonOp )
40 import PragmaInfo ( PragmaInfo(..) )
42 import RnHsSyn ( RnName ) -- instances
43 import Type ( mkTyVarTy, mkTyVarTys, isTyVarTy,
44 mkSigmaTy, splitSigmaTy,
45 splitRhoTy, mkForAllTy, splitForAllTy )
49 %************************************************************************
51 \subsection{Type-checking bindings}
53 %************************************************************************
55 @tcBindsAndThen@ typechecks a @HsBinds@. The "and then" part is because
56 it needs to know something about the {\em usage} of the things bound,
57 so that it can create specialisations of them. So @tcBindsAndThen@
58 takes a function which, given an extended environment, E, typechecks
59 the scope of the bindings returning a typechecked thing and (most
60 important) an LIE. It is this LIE which is then used as the basis for
61 specialising the things bound.
63 @tcBindsAndThen@ also takes a "combiner" which glues together the
64 bindings and the "thing" to make a new "thing".
66 The real work is done by @tcBindAndThen@.
68 Recursive and non-recursive binds are handled in essentially the same
69 way: because of uniques there are no scoping issues left. The only
70 difference is that non-recursive bindings can bind primitive values.
72 Even for non-recursive binding groups we add typings for each binder
73 to the LVE for the following reason. When each individual binding is
74 checked the type of its LHS is unified with that of its RHS; and
75 type-checking the LHS of course requires that the binder is in scope.
77 At the top-level the LIE is sure to contain nothing but constant
78 dictionaries, which we resolve at the module level.
82 :: (TcHsBinds s -> thing -> thing) -- Combinator
84 -> TcM s (thing, LIE s, thing_ty)
85 -> TcM s (thing, LIE s, thing_ty)
87 tcBindsAndThen combiner EmptyBinds do_next
88 = do_next `thenTc` \ (thing, lie, thing_ty) ->
89 returnTc (combiner EmptyBinds thing, lie, thing_ty)
91 tcBindsAndThen combiner (SingleBind bind) do_next
92 = tcBindAndThen combiner bind [] do_next
94 tcBindsAndThen combiner (BindWith bind sigs) do_next
95 = tcBindAndThen combiner bind sigs do_next
97 tcBindsAndThen combiner (ThenBinds binds1 binds2) do_next
98 = tcBindsAndThen combiner binds1 (tcBindsAndThen combiner binds2 do_next)
101 An aside. The original version of @tcBindsAndThen@ which lacks a
102 combiner function, appears below. Though it is perfectly well
103 behaved, it cannot be typed by Haskell, because the recursive call is
104 at a different type to the definition itself. There aren't too many
105 examples of this, which is why I thought it worth preserving! [SLPJ]
110 -> TcM s (thing, LIE s, thing_ty))
111 -> TcM s ((TcHsBinds s, thing), LIE s, thing_ty)
113 tcBindsAndThen EmptyBinds do_next
114 = do_next `thenTc` \ (thing, lie, thing_ty) ->
115 returnTc ((EmptyBinds, thing), lie, thing_ty)
117 tcBindsAndThen (SingleBind bind) do_next
118 = tcBindAndThen bind [] do_next
120 tcBindsAndThen (BindWith bind sigs) do_next
121 = tcBindAndThen bind sigs do_next
123 tcBindsAndThen (ThenBinds binds1 binds2) do_next
124 = tcBindsAndThen binds1 (tcBindsAndThen binds2 do_next)
125 `thenTc` \ ((binds1', (binds2', thing')), lie1, thing_ty) ->
127 returnTc ((binds1' `ThenBinds` binds2', thing'), lie1, thing_ty)
130 %************************************************************************
134 %************************************************************************
138 :: (TcHsBinds s -> thing -> thing) -- Combinator
139 -> RenamedBind -- The Bind to typecheck
140 -> [RenamedSig] -- ...and its signatures
141 -> TcM s (thing, LIE s, thing_ty) -- Thing to type check in
143 -> TcM s (thing, LIE s, thing_ty) -- Results, incl the
145 tcBindAndThen combiner bind sigs do_next
146 = fixTc (\ ~(prag_info_fn, _) ->
147 -- This is the usual prag_info fix; the PragmaInfo field of an Id
148 -- is not inspected till ages later in the compiler, so there
149 -- should be no black-hole problems here.
151 tcBindAndSigs binder_names bind
152 sigs prag_info_fn `thenTc` \ (poly_binds, poly_lie, poly_ids) ->
154 -- Extend the environment to bind the new polymorphic Ids
155 tcExtendLocalValEnv binder_names poly_ids $
157 -- Build bindings and IdInfos corresponding to user pragmas
158 tcPragmaSigs sigs `thenTc` \ (prag_info_fn, prag_binds, prag_lie) ->
160 -- Now do whatever happens next, in the augmented envt
161 do_next `thenTc` \ (thing, thing_lie, thing_ty) ->
163 -- Create specialisations of functions bound here
164 bindInstsOfLocalFuns (prag_lie `plusLIE` thing_lie)
165 poly_ids `thenTc` \ (lie2, inst_mbinds) ->
169 final_lie = lie2 `plusLIE` poly_lie
170 final_binds = poly_binds `ThenBinds`
171 SingleBind (NonRecBind inst_mbinds) `ThenBinds`
174 returnTc (prag_info_fn, (combiner final_binds thing, final_lie, thing_ty))
175 ) `thenTc` \ (_, result) ->
178 binder_names = collectBinders bind
181 tcBindAndSigs binder_rn_names bind sigs prag_info_fn
183 binder_names = map de_rn binder_rn_names
187 -- If typechecking the binds fails, then return with each
188 -- binder given type (forall a.a), to minimise subsequent
190 newTcTyVar mkBoxedTypeKind `thenNF_Tc` \ alpha_tv ->
192 forall_a_a = mkForAllTy alpha_tv (mkTyVarTy alpha_tv)
193 poly_ids = [ mkUserId name forall_a_a (prag_info_fn name)
194 | name <- binder_names]
196 returnTc (EmptyBinds, emptyLIE, poly_ids)
199 -- Create a new identifier for each binder, with each being given
200 -- a type-variable type.
201 newMonoIds binder_rn_names kind (\ mono_ids ->
202 tcTySigs sigs `thenTc` \ sig_info ->
203 tc_bind bind `thenTc` \ (bind', lie) ->
204 returnTc (mono_ids, bind', lie, sig_info)
206 `thenTc` \ (mono_ids, bind', lie, sig_info) ->
208 -- Notice that genBinds gets the old (non-extended) environment
209 genBinds binder_names mono_ids bind' lie sig_info prag_info_fn
212 NonRecBind _ -> mkBoxedTypeKind -- Recursive, so no unboxed types
213 RecBind _ -> mkTypeKind -- Non-recursive, so we permit unboxed types
223 (TcIdBndr s) -- Polymorpic version
224 (TcIdBndr s) -- Monomorphic verstion
225 [TcType s] [TcIdOcc s] -- Instance information for the monomorphic version
229 -- Deal with type signatures
230 tcTySigs sigs `thenTc` \ sig_infos ->
232 sig_binders = [binder | SigInfo binder _ _ _ _ <- sig_infos]
233 poly_sigs = [(name,poly) | SigInfo name poly _ _ _ <- sig_infos]
234 mono_sigs = [(name,mono) | SigInfo name _ mono _ _ <- sig_infos]
235 nosig_binders = binders `minusList` sig_binders
239 -- Typecheck the binding group
240 tcExtendLocalEnv poly_sigs (
241 newMonoIds nosig_binders kind (\ nosig_local_ids ->
242 tcMonoBinds mono_sigs mono_binds `thenTc` \ binds_w_lies ->
243 returnTc (nosig_local_ids, binds_w_lies)
244 )) `thenTc` \ (nosig_local_ids, binds_w_lies) ->
247 -- Decide what to generalise over
248 getImplicitStuffToGen sig_ids binds_w_lies
249 `thenTc` \ (tyvars_not_to_gen, tyvars_to_gen, lie_to_gen) ->
252 -- Make poly_ids for all the binders that don't have type signatures
254 dicts_to_gen = map instToId (bagToList lie_to_gen)
255 dict_tys = map tcIdType dicts_to_gen
257 mk_poly binder local_id = mkUserId (getName binder) ty noPragmaInfo
259 ty = mkForAllTys tyvars_to_gen $
263 tys_to_gen = mkTyVarTys tyvars_to_gen
264 more_sig_infos = [ SigInfo binder (mk_poly binder local_id)
265 local_id tys_to_gen dicts_to_gen lie_to_gen
266 | (binder, local_id) <- nosig_binders `zipEqual` nosig_local_ids
269 local_binds = [ (local_id, DictApp (mkHsTyApp (HsVar local_id) inst_tys) dicts)
270 | SigInfo _ _ local_id inst_tys dicts <- more_sig_infos
273 all_sig_infos = sig_infos ++ more_sig_infos -- Contains a "signature" for each binder
277 -- Now generalise the bindings
279 find_sig lid = head [ (pid, tvs, ds, lie)
280 | SigInfo _ pid lid' tvs ds lie,
283 -- Do it again, but with increased free_tyvars/reduced_tyvars_to_gen:
284 -- We still need to do this simplification, because some dictionaries
285 -- may gratuitously constrain some tyvars over which we *are* going
287 -- For example d::Eq (Foo a b), where Foo is instanced as above.
289 = tcSimplifyWithExtraGlobals tyvars_not_to_gen tyvars_to_gen avail lie
290 `thenTc` \ (lie_free, dict_binds) ->
291 returnTc (AbsBind tyvars_to_gen_here
293 (local_ids `zipEqual` poly_ids)
294 (dict_binds ++ local_binds)
298 local_ids = bindersOf bind
299 local_sigs = [sig | sig@(SigInfo _ _ local_id _ _) <- all_sig_infos,
300 local_id `elem` local_ids
303 (tyvars_to_gen_here, dicts, avail)
304 = case (local_ids, sigs) of
306 ([local_id], [SigInfo _ _ _ tyvars_to_gen dicts lie])
307 -> (tyvars_to_gen, dicts, lie)
309 other -> (tyvars_to_gen, dicts, avail)
312 @getImplicitStuffToGen@ decides what type variables
313 and LIE to generalise over.
315 For a "restricted group" -- see the monomorphism restriction
316 for a definition -- we bind no dictionaries, and
317 remove from tyvars_to_gen any constrained type variables
319 *Don't* simplify dicts at this point, because we aren't going
320 to generalise over these dicts. By the time we do simplify them
321 we may well know more. For example (this actually came up)
323 f x = array ... xs where xs = [1,2,3,4,5]
324 We don't want to generate lots of (fromInt Int 1), (fromInt Int 2)
325 stuff. If we simplify only at the f-binding (not the xs-binding)
326 we'll know that the literals are all Ints, and we can just produce
329 Find all the type variables involved in overloading, the "constrained_tyvars"
330 These are the ones we *aren't* going to generalise.
331 We must be careful about doing this:
332 (a) If we fail to generalise a tyvar which is not actually
333 constrained, then it will never, ever get bound, and lands
334 up printed out in interface files! Notorious example:
335 instance Eq a => Eq (Foo a b) where ..
336 Here, b is not constrained, even though it looks as if it is.
337 Another, more common, example is when there's a Method inst in
338 the LIE, whose type might very well involve non-overloaded
340 (b) On the other hand, we mustn't generalise tyvars which are constrained,
341 because we are going to pass on out the unmodified LIE, with those
342 tyvars in it. They won't be in scope if we've generalised them.
344 So we are careful, and do a complete simplification just to find the
345 constrained tyvars. We don't use any of the results, except to
346 find which tyvars are constrained.
349 getImplicitStuffToGen is_restricted sig_ids binds_w_lies
350 | isUnRestrictedGroup tysig_vars bind
351 = tcSimplify tyvars_to_gen lie `thenTc` \ (_, _, dicts_to_gen) ->
352 returnNF_Tc (emptyTyVarSet, tyvars_to_gen, dicts_to_gen)
355 = tcSimplify tyvars_to_gen lie `thenTc` \ (_, _, constrained_dicts) ->
357 -- ASSERT: dicts_sig is already zonked!
358 constrained_tyvars = foldBag unionTyVarSets tyVarsOfInst emptyTyVarSet constrained_dicts
359 reduced_tyvars_to_gen = tyvars_to_gen `minusTyVarSet` constrained_tyvars
361 returnTc (constrained_tyvars, reduced_tyvars_to_gen, emptyLIE)
364 sig_ids = [sig_var | (TySigInfo sig_id _ _ _ _) <- ty_sigs]
366 (tyvars_to_gen, lie) = foldBag (\(tv1,lie2) (tv2,lie2) -> (tv1 `unionTyVarSets` tv2,
367 lie1 `plusLIE` lie2))
369 (emptyTyVarSet, emptyLIE)
372 = case bindersOf bind of
373 [local_id] | local_id `in` sig_ids -> -- A simple binding with
375 (emptyTyVarSet, emptyLIE)
377 local_ids -> -- Complex binding or no type sig
378 (foldr (unionTyVarSets . tcIdType) emptyTyVarSet local_ids,
386 tc_bind :: RenamedBind -> TcM s (TcBind s, LIE s)
388 tc_bind (NonRecBind mono_binds)
389 = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) ->
390 returnTc (NonRecBind mono_binds2, lie)
392 tc_bind (RecBind mono_binds)
393 = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) ->
394 returnTc (RecBind mono_binds2, lie)
398 tcMonoBinds :: RenamedMonoBinds -> TcM s (TcMonoBinds s, LIE s)
400 tcMonoBinds EmptyMonoBinds = returnTc (EmptyMonoBinds, emptyLIE)
402 tcMonoBinds (AndMonoBinds mb1 mb2)
403 = tcMonoBinds mb1 `thenTc` \ (mb1a, lie1) ->
404 tcMonoBinds mb2 `thenTc` \ (mb2a, lie2) ->
405 returnTc (AndMonoBinds mb1a mb2a, lie1 `plusLIE` lie2)
407 tcMonoBinds bind@(PatMonoBind pat grhss_and_binds locn)
411 tcPat pat `thenTc` \ (pat2, lie_pat, pat_ty) ->
413 -- BINDINGS AND GRHSS
414 tcGRHSsAndBinds grhss_and_binds `thenTc` \ (grhss_and_binds2, lie, grhss_ty) ->
416 -- Unify the two sides
417 tcAddErrCtxt (patMonoBindsCtxt bind) $
418 unifyTauTy pat_ty grhss_ty `thenTc_`
421 returnTc (PatMonoBind pat2 grhss_and_binds2 locn,
424 tcMonoBinds (FunMonoBind name matches locn)
426 tcLookupLocalValueOK "tcMonoBinds" name `thenNF_Tc` \ id ->
427 tcMatchesFun name (idType id) matches `thenTc` \ (matches', lie) ->
428 returnTc (FunMonoBind (TcId id) matches' locn, lie)
431 %************************************************************************
433 \subsection{Signatures}
435 %************************************************************************
437 @tcSigs@ checks the signatures for validity, and returns a list of
438 {\em freshly-instantiated} signatures. That is, the types are already
439 split up, and have fresh type variables installed. All non-type-signature
440 "RenamedSigs" are ignored.
443 tcTySigs :: [RenamedSig] -> TcM s [TcSigInfo s]
445 tcTySigs (Sig v ty _ src_loc : other_sigs)
446 = tcAddSrcLoc src_loc (
447 tcPolyType ty `thenTc` \ sigma_ty ->
448 tcInstType [] sigma_ty `thenNF_Tc` \ sigma_ty' ->
450 (tyvars', theta', tau') = splitSigmaTy sigma_ty'
453 tcLookupLocalValueOK "tcSig1" v `thenNF_Tc` \ val ->
454 unifyTauTy (idType val) tau' `thenTc_`
456 returnTc (TySigInfo val tyvars' theta' tau' src_loc)
457 ) `thenTc` \ sig_info1 ->
459 tcTySigs other_sigs `thenTc` \ sig_infos ->
460 returnTc (sig_info1 : sig_infos)
462 tcTySigs (other : sigs) = tcTySigs sigs
463 tcTySigs [] = returnTc []
467 %************************************************************************
469 \subsection{SPECIALIZE pragmas}
471 %************************************************************************
474 @tcPragmaSigs@ munches up the "signatures" that arise through *user*
475 pragmas. It is convenient for them to appear in the @[RenamedSig]@
476 part of a binding because then the same machinery can be used for
477 moving them into place as is done for type signatures.
480 tcPragmaSigs :: [RenamedSig] -- The pragma signatures
481 -> TcM s (Name -> PragmaInfo, -- Maps name to the appropriate PragmaInfo
485 tcPragmaSigs sigs = returnTc ( \name -> NoPragmaInfo, EmptyBinds, emptyLIE )
489 = mapAndUnzip3Tc tcPragmaSig sigs `thenTc` \ (names_w_id_infos, binds, lies) ->
491 name_to_info name = foldr ($) noIdInfo
492 [info_fn | (n,info_fn) <- names_w_id_infos, n==name]
494 returnTc (name_to_info,
495 foldr ThenBinds EmptyBinds binds,
496 foldr plusLIE emptyLIE lies)
499 Here are the easy cases for tcPragmaSigs
502 tcPragmaSig (DeforestSig name loc)
503 = returnTc ((name, addInfo DoDeforest),EmptyBinds,emptyLIE)
504 tcPragmaSig (InlineSig name loc)
505 = returnTc ((name, addInfo_UF (iWantToBeINLINEd UnfoldAlways)), EmptyBinds, emptyLIE)
506 tcPragmaSig (MagicUnfoldingSig name string loc)
507 = returnTc ((name, addInfo_UF (mkMagicUnfolding string)), EmptyBinds, emptyLIE)
510 The interesting case is for SPECIALISE pragmas. There are two forms.
511 Here's the first form:
513 f :: Ord a => [a] -> b -> b
514 {-# SPECIALIZE f :: [Int] -> b -> b #-}
517 For this we generate:
519 f* = /\ b -> let d1 = ...
523 where f* is a SpecPragmaId. The **sole** purpose of SpecPragmaIds is to
524 retain a right-hand-side that the simplifier will otherwise discard as
525 dead code... the simplifier has a flag that tells it not to discard
526 SpecPragmaId bindings.
528 In this case the f* retains a call-instance of the overloaded
529 function, f, (including appropriate dictionaries) so that the
530 specialiser will subsequently discover that there's a call of @f@ at
531 Int, and will create a specialisation for @f@. After that, the
532 binding for @f*@ can be discarded.
534 The second form is this:
536 f :: Ord a => [a] -> b -> b
537 {-# SPECIALIZE f :: [Int] -> b -> b = g #-}
540 Here @g@ is specified as a function that implements the specialised
541 version of @f@. Suppose that g has type (a->b->b); that is, g's type
542 is more general than that required. For this we generate
544 f@Int = /\b -> g Int b
548 Here @f@@Int@ is a SpecId, the specialised version of @f@. It inherits
549 f's export status etc. @f*@ is a SpecPragmaId, as before, which just serves
550 to prevent @f@@Int@ from being discarded prematurely. After specialisation,
551 if @f@@Int@ is going to be used at all it will be used explicitly, so the simplifier can
552 discard the f* binding.
554 Actually, there is really only point in giving a SPECIALISE pragma on exported things,
555 and the simplifer won't discard SpecIds for exporte things anyway, so maybe this is
559 tcPragmaSig (SpecSig name poly_ty maybe_spec_name src_loc)
560 = tcAddSrcLoc src_loc $
561 tcAddErrCtxt (valSpecSigCtxt name spec_ty) $
563 -- Get and instantiate its alleged specialised type
564 tcPolyType poly_ty `thenTc` \ sig_sigma ->
565 tcInstType [] sig_sigma `thenNF_Tc` \ sig_ty ->
567 (sig_tyvars, sig_theta, sig_tau) = splitSigmaTy sig_ty
568 origin = ValSpecOrigin name
571 -- Check that the SPECIALIZE pragma had an empty context
572 checkTc (null sig_theta)
573 (panic "SPECIALIZE non-empty context (ToDo: msg)") `thenTc_`
575 -- Get and instantiate the type of the id mentioned
576 tcLookupLocalValueOK "tcPragmaSig" name `thenNF_Tc` \ main_id ->
577 tcInstType [] (idType main_id) `thenNF_Tc` \ main_ty ->
579 (main_tyvars, main_rho) = splitForAllTy main_ty
580 (main_theta,main_tau) = splitRhoTy main_rho
581 main_arg_tys = mkTyVarTys main_tyvars
584 -- Check that the specialised type is indeed an instance of
585 -- the type of the main function.
586 unifyTauTy sig_tau main_tau `thenTc_`
587 checkSigTyVars sig_tyvars sig_tau `thenTc_`
589 -- Check that the type variables of the polymorphic function are
590 -- either left polymorphic, or instantiate to ground type.
591 -- Also check that the overloaded type variables are instantiated to
592 -- ground type; or equivalently that all dictionaries have ground type
593 mapTc zonkTcType main_arg_tys `thenNF_Tc` \ main_arg_tys' ->
594 zonkTcThetaType main_theta `thenNF_Tc` \ main_theta' ->
595 tcAddErrCtxt (specGroundnessCtxt main_arg_tys')
596 (checkTc (all isGroundOrTyVarTy main_arg_tys')) `thenTc_`
597 tcAddErrCtxt (specContextGroundnessCtxt main_theta')
598 (checkTc (and [isGroundTy ty | (_,ty) <- theta'])) `thenTc_`
600 -- Build the SpecPragmaId; it is the thing that makes sure we
601 -- don't prematurely dead-code-eliminate the binding we are really interested in.
602 newSpecPragmaId name sig_ty `thenNF_Tc` \ spec_pragma_id ->
604 -- Build a suitable binding; depending on whether we were given
605 -- a value (Maybe Name) to be used as the specialisation.
607 Nothing -> -- No implementation function specified
609 -- Make a Method inst for the occurrence of the overloaded function
610 newMethodWithGivenTy (OccurrenceOf name)
611 (TcId main_id) main_arg_tys main_rho `thenNF_Tc` \ (lie, meth_id) ->
614 pseudo_bind = VarMonoBind spec_pragma_id pseudo_rhs
615 pseudo_rhs = mkHsTyLam sig_tyvars (HsVar (TcId meth_id))
617 returnTc (pseudo_bind, lie, \ info -> info)
619 Just spec_name -> -- Use spec_name as the specialisation value ...
621 -- Type check a simple occurrence of the specialised Id
622 tcId spec_name `thenTc` \ (spec_body, spec_lie, spec_tau) ->
624 -- Check that it has the correct type, and doesn't constrain the
625 -- signature variables at all
626 unifyTauTy sig_tau spec_tau `thenTc_`
627 checkSigTyVars sig_tyvars sig_tau `thenTc_`
629 -- Make a local SpecId to bind to applied spec_id
630 newSpecId main_id main_arg_tys sig_ty `thenNF_Tc` \ local_spec_id ->
633 spec_rhs = mkHsTyLam sig_tyvars spec_body
634 spec_binds = VarMonoBind local_spec_id spec_rhs
636 VarMonoBind spec_pragma_id (HsVar (TcId local_spec_id))
637 spec_info = SpecInfo spec_tys (length main_theta) local_spec_id
639 returnTc ((name, addInfo spec_info), spec_binds, spec_lie)
644 Error contexts and messages
645 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
647 patMonoBindsCtxt bind sty
648 = ppHang (ppPStr SLIT("In a pattern binding:")) 4 (ppr sty bind)
650 --------------------------------------------
651 specContextGroundnessCtxt -- err_ctxt dicts sty
652 = panic "specContextGroundnessCtxt"
655 ppSep [ppBesides [ppStr "In the SPECIALIZE pragma for `", ppr sty name, ppStr "'"],
656 ppBesides [ppStr " specialised to the type `", ppr sty spec_ty, ppStr "'"],
658 ppStr "... not all overloaded type variables were instantiated",
659 ppStr "to ground types:"])
660 4 (ppAboves [ppCat [ppr sty c, ppr sty t]
661 | (c,t) <- map getDictClassAndType dicts])
663 (name, spec_ty, locn, pp_spec_id)
665 ValSpecSigCtxt n ty loc -> (n, ty, loc, \ x -> ppNil)
666 ValSpecSpecIdCtxt n ty spec loc ->
668 \ sty -> ppBesides [ppStr "... type of explicit id `", ppr sty spec, ppStr "'"])
671 -----------------------------------------------
673 = panic "specGroundnessCtxt"
676 valSpecSigCtxt v ty sty
677 = ppHang (ppPStr SLIT("In a SPECIALIZE pragma for a value:"))
678 4 (ppSep [ppBeside (pprNonOp sty v) (ppPStr SLIT(" ::")),