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 ( pprNonSym )
40 import PragmaInfo ( PragmaInfo(..) )
42 import RnHsSyn ( RnName ) -- instances
43 import Type ( mkTyVarTy, mkTyVarTys, isTyVarTy,
44 mkSigmaTy, splitSigmaTy,
45 splitRhoTy, mkForAllTy, splitForAllTy )
46 import Util ( isIn, panic )
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 tys_to_gen = mkTyVarTys tyvars_to_gen
255 dicts_to_gen = map instToId (bagToList lie_to_gen)
256 dict_tys = map tcIdType dicts_to_gen
258 mk_poly binder local_id = mkUserId (getName binder) ty noPragmaInfo
260 ty = mkForAllTys 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 all_sig_infos = sig_infos ++ more_sig_infos -- Contains a "signature" for each binder
273 -- Now generalise the bindings
275 -- local_binds is a bunch of bindings of the form
276 -- f_mono = f_poly tyvars dicts
277 -- one for each binder, f, that lacks a type signature.
278 -- This bunch of bindings is put at the top of the RHS of every
279 -- binding in the group, so as to bind all the f_monos.
281 local_binds = [ (local_id, mkHsDictApp (mkHsTyApp (HsVar local_id) tys_to_gen) dicts_to_gen)
282 | local_id <- nosig_local_ids
285 find_sig lid = head [ (pid, tvs, ds, lie)
286 | SigInfo _ pid lid' tvs ds lie,
291 = tcSimplifyWithExtraGlobals tyvars_not_to_gen tyvars_to_gen avail lie
292 `thenTc` \ (lie_free, dict_binds) ->
293 returnTc (AbsBind tyvars_to_gen_here
295 (local_ids `zipEqual` poly_ids)
296 (dict_binds ++ local_binds)
300 local_ids = bindersOf bind
301 local_sigs = [sig | sig@(SigInfo _ _ local_id _ _) <- all_sig_infos,
302 local_id `elem` local_ids
305 (tyvars_to_gen_here, dicts, avail)
306 = case (local_ids, sigs) of
308 ([local_id], [SigInfo _ _ _ tyvars_to_gen dicts lie])
309 -> (tyvars_to_gen, dicts, lie)
311 other -> (tyvars_to_gen, dicts, avail)
314 @getImplicitStuffToGen@ decides what type variables
315 and LIE to generalise over.
317 For a "restricted group" -- see the monomorphism restriction
318 for a definition -- we bind no dictionaries, and
319 remove from tyvars_to_gen any constrained type variables
321 *Don't* simplify dicts at this point, because we aren't going
322 to generalise over these dicts. By the time we do simplify them
323 we may well know more. For example (this actually came up)
325 f x = array ... xs where xs = [1,2,3,4,5]
326 We don't want to generate lots of (fromInt Int 1), (fromInt Int 2)
327 stuff. If we simplify only at the f-binding (not the xs-binding)
328 we'll know that the literals are all Ints, and we can just produce
331 Find all the type variables involved in overloading, the "constrained_tyvars"
332 These are the ones we *aren't* going to generalise.
333 We must be careful about doing this:
334 (a) If we fail to generalise a tyvar which is not actually
335 constrained, then it will never, ever get bound, and lands
336 up printed out in interface files! Notorious example:
337 instance Eq a => Eq (Foo a b) where ..
338 Here, b is not constrained, even though it looks as if it is.
339 Another, more common, example is when there's a Method inst in
340 the LIE, whose type might very well involve non-overloaded
342 (b) On the other hand, we mustn't generalise tyvars which are constrained,
343 because we are going to pass on out the unmodified LIE, with those
344 tyvars in it. They won't be in scope if we've generalised them.
346 So we are careful, and do a complete simplification just to find the
347 constrained tyvars. We don't use any of the results, except to
348 find which tyvars are constrained.
351 getImplicitStuffToGen is_restricted sig_ids binds_w_lies
352 | isUnRestrictedGroup tysig_vars bind
353 = tcSimplify tyvars_to_gen lie `thenTc` \ (_, _, dicts_to_gen) ->
354 returnNF_Tc (emptyTyVarSet, tyvars_to_gen, dicts_to_gen)
357 = tcSimplify tyvars_to_gen lie `thenTc` \ (_, _, constrained_dicts) ->
359 -- ASSERT: dicts_sig is already zonked!
360 constrained_tyvars = foldBag unionTyVarSets tyVarsOfInst emptyTyVarSet constrained_dicts
361 reduced_tyvars_to_gen = tyvars_to_gen `minusTyVarSet` constrained_tyvars
363 returnTc (constrained_tyvars, reduced_tyvars_to_gen, emptyLIE)
366 sig_vars = [sig_var | (TySigInfo sig_var _ _ _ _) <- ty_sigs]
368 (tyvars_to_gen, lie) = foldBag (\(tv1,lie2) (tv2,lie2) -> (tv1 `unionTyVarSets` tv2,
369 lie1 `plusLIE` lie2))
371 (emptyTyVarSet, emptyLIE)
374 = case bindersOf bind of
375 [local_id] | local_id `in` sig_ids -> -- A simple binding with
377 (emptyTyVarSet, emptyLIE)
379 local_ids -> -- Complex binding or no type sig
380 (foldr (unionTyVarSets . tcIdType) emptyTyVarSet local_ids,
388 tc_bind :: RenamedBind -> TcM s (TcBind s, LIE s)
390 tc_bind (NonRecBind mono_binds)
391 = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) ->
392 returnTc (NonRecBind mono_binds2, lie)
394 tc_bind (RecBind mono_binds)
395 = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) ->
396 returnTc (RecBind mono_binds2, lie)
400 tcMonoBinds :: RenamedMonoBinds -> TcM s (TcMonoBinds s, LIE s)
402 tcMonoBinds EmptyMonoBinds = returnTc (EmptyMonoBinds, emptyLIE)
404 tcMonoBinds (AndMonoBinds mb1 mb2)
405 = tcMonoBinds mb1 `thenTc` \ (mb1a, lie1) ->
406 tcMonoBinds mb2 `thenTc` \ (mb2a, lie2) ->
407 returnTc (AndMonoBinds mb1a mb2a, lie1 `plusLIE` lie2)
409 tcMonoBinds bind@(PatMonoBind pat grhss_and_binds locn)
413 tcPat pat `thenTc` \ (pat2, lie_pat, pat_ty) ->
415 -- BINDINGS AND GRHSS
416 tcGRHSsAndBinds grhss_and_binds `thenTc` \ (grhss_and_binds2, lie, grhss_ty) ->
418 -- Unify the two sides
419 tcAddErrCtxt (patMonoBindsCtxt bind) $
420 unifyTauTy pat_ty grhss_ty `thenTc_`
423 returnTc (PatMonoBind pat2 grhss_and_binds2 locn,
426 tcMonoBinds (FunMonoBind name inf matches locn)
428 tcLookupLocalValueOK "tcMonoBinds" name `thenNF_Tc` \ id ->
429 tcMatchesFun name (idType id) matches `thenTc` \ (matches', lie) ->
430 returnTc (FunMonoBind (TcId id) inf matches' locn, lie)
433 %************************************************************************
435 \subsection{Signatures}
437 %************************************************************************
439 @tcSigs@ checks the signatures for validity, and returns a list of
440 {\em freshly-instantiated} signatures. That is, the types are already
441 split up, and have fresh type variables installed. All non-type-signature
442 "RenamedSigs" are ignored.
445 tcTySigs :: [RenamedSig] -> TcM s [TcSigInfo s]
447 tcTySigs (Sig v ty _ src_loc : other_sigs)
448 = tcAddSrcLoc src_loc (
449 tcPolyType ty `thenTc` \ sigma_ty ->
450 tcInstType [] sigma_ty `thenNF_Tc` \ sigma_ty' ->
452 (tyvars', theta', tau') = splitSigmaTy sigma_ty'
455 tcLookupLocalValueOK "tcSig1" v `thenNF_Tc` \ val ->
456 unifyTauTy (idType val) tau' `thenTc_`
458 returnTc (TySigInfo val tyvars' theta' tau' src_loc)
459 ) `thenTc` \ sig_info1 ->
461 tcTySigs other_sigs `thenTc` \ sig_infos ->
462 returnTc (sig_info1 : sig_infos)
464 tcTySigs (other : sigs) = tcTySigs sigs
465 tcTySigs [] = returnTc []
469 %************************************************************************
471 \subsection{SPECIALIZE pragmas}
473 %************************************************************************
476 @tcPragmaSigs@ munches up the "signatures" that arise through *user*
477 pragmas. It is convenient for them to appear in the @[RenamedSig]@
478 part of a binding because then the same machinery can be used for
479 moving them into place as is done for type signatures.
482 tcPragmaSigs :: [RenamedSig] -- The pragma signatures
483 -> TcM s (Name -> PragmaInfo, -- Maps name to the appropriate PragmaInfo
487 tcPragmaSigs sigs = returnTc ( \name -> NoPragmaInfo, EmptyBinds, emptyLIE )
491 = mapAndUnzip3Tc tcPragmaSig sigs `thenTc` \ (names_w_id_infos, binds, lies) ->
493 name_to_info name = foldr ($) noIdInfo
494 [info_fn | (n,info_fn) <- names_w_id_infos, n==name]
496 returnTc (name_to_info,
497 foldr ThenBinds EmptyBinds binds,
498 foldr plusLIE emptyLIE lies)
501 Here are the easy cases for tcPragmaSigs
504 tcPragmaSig (DeforestSig name loc)
505 = returnTc ((name, addInfo DoDeforest),EmptyBinds,emptyLIE)
506 tcPragmaSig (InlineSig name loc)
507 = returnTc ((name, addInfo_UF (iWantToBeINLINEd UnfoldAlways)), EmptyBinds, emptyLIE)
508 tcPragmaSig (MagicUnfoldingSig name string loc)
509 = returnTc ((name, addInfo_UF (mkMagicUnfolding string)), EmptyBinds, emptyLIE)
512 The interesting case is for SPECIALISE pragmas. There are two forms.
513 Here's the first form:
515 f :: Ord a => [a] -> b -> b
516 {-# SPECIALIZE f :: [Int] -> b -> b #-}
519 For this we generate:
521 f* = /\ b -> let d1 = ...
525 where f* is a SpecPragmaId. The **sole** purpose of SpecPragmaIds is to
526 retain a right-hand-side that the simplifier will otherwise discard as
527 dead code... the simplifier has a flag that tells it not to discard
528 SpecPragmaId bindings.
530 In this case the f* retains a call-instance of the overloaded
531 function, f, (including appropriate dictionaries) so that the
532 specialiser will subsequently discover that there's a call of @f@ at
533 Int, and will create a specialisation for @f@. After that, the
534 binding for @f*@ can be discarded.
536 The second form is this:
538 f :: Ord a => [a] -> b -> b
539 {-# SPECIALIZE f :: [Int] -> b -> b = g #-}
542 Here @g@ is specified as a function that implements the specialised
543 version of @f@. Suppose that g has type (a->b->b); that is, g's type
544 is more general than that required. For this we generate
546 f@Int = /\b -> g Int b
550 Here @f@@Int@ is a SpecId, the specialised version of @f@. It inherits
551 f's export status etc. @f*@ is a SpecPragmaId, as before, which just serves
552 to prevent @f@@Int@ from being discarded prematurely. After specialisation,
553 if @f@@Int@ is going to be used at all it will be used explicitly, so the simplifier can
554 discard the f* binding.
556 Actually, there is really only point in giving a SPECIALISE pragma on exported things,
557 and the simplifer won't discard SpecIds for exporte things anyway, so maybe this is
561 tcPragmaSig (SpecSig name poly_ty maybe_spec_name src_loc)
562 = tcAddSrcLoc src_loc $
563 tcAddErrCtxt (valSpecSigCtxt name spec_ty) $
565 -- Get and instantiate its alleged specialised type
566 tcPolyType poly_ty `thenTc` \ sig_sigma ->
567 tcInstType [] sig_sigma `thenNF_Tc` \ sig_ty ->
569 (sig_tyvars, sig_theta, sig_tau) = splitSigmaTy sig_ty
570 origin = ValSpecOrigin name
573 -- Check that the SPECIALIZE pragma had an empty context
574 checkTc (null sig_theta)
575 (panic "SPECIALIZE non-empty context (ToDo: msg)") `thenTc_`
577 -- Get and instantiate the type of the id mentioned
578 tcLookupLocalValueOK "tcPragmaSig" name `thenNF_Tc` \ main_id ->
579 tcInstType [] (idType main_id) `thenNF_Tc` \ main_ty ->
581 (main_tyvars, main_rho) = splitForAllTy main_ty
582 (main_theta,main_tau) = splitRhoTy main_rho
583 main_arg_tys = mkTyVarTys main_tyvars
586 -- Check that the specialised type is indeed an instance of
587 -- the type of the main function.
588 unifyTauTy sig_tau main_tau `thenTc_`
589 checkSigTyVars sig_tyvars sig_tau `thenTc_`
591 -- Check that the type variables of the polymorphic function are
592 -- either left polymorphic, or instantiate to ground type.
593 -- Also check that the overloaded type variables are instantiated to
594 -- ground type; or equivalently that all dictionaries have ground type
595 mapTc zonkTcType main_arg_tys `thenNF_Tc` \ main_arg_tys' ->
596 zonkTcThetaType main_theta `thenNF_Tc` \ main_theta' ->
597 tcAddErrCtxt (specGroundnessCtxt main_arg_tys')
598 (checkTc (all isGroundOrTyVarTy main_arg_tys')) `thenTc_`
599 tcAddErrCtxt (specContextGroundnessCtxt main_theta')
600 (checkTc (and [isGroundTy ty | (_,ty) <- theta'])) `thenTc_`
602 -- Build the SpecPragmaId; it is the thing that makes sure we
603 -- don't prematurely dead-code-eliminate the binding we are really interested in.
604 newSpecPragmaId name sig_ty `thenNF_Tc` \ spec_pragma_id ->
606 -- Build a suitable binding; depending on whether we were given
607 -- a value (Maybe Name) to be used as the specialisation.
609 Nothing -> -- No implementation function specified
611 -- Make a Method inst for the occurrence of the overloaded function
612 newMethodWithGivenTy (OccurrenceOf name)
613 (TcId main_id) main_arg_tys main_rho `thenNF_Tc` \ (lie, meth_id) ->
616 pseudo_bind = VarMonoBind spec_pragma_id pseudo_rhs
617 pseudo_rhs = mkHsTyLam sig_tyvars (HsVar (TcId meth_id))
619 returnTc (pseudo_bind, lie, \ info -> info)
621 Just spec_name -> -- Use spec_name as the specialisation value ...
623 -- Type check a simple occurrence of the specialised Id
624 tcId spec_name `thenTc` \ (spec_body, spec_lie, spec_tau) ->
626 -- Check that it has the correct type, and doesn't constrain the
627 -- signature variables at all
628 unifyTauTy sig_tau spec_tau `thenTc_`
629 checkSigTyVars sig_tyvars sig_tau `thenTc_`
631 -- Make a local SpecId to bind to applied spec_id
632 newSpecId main_id main_arg_tys sig_ty `thenNF_Tc` \ local_spec_id ->
635 spec_rhs = mkHsTyLam sig_tyvars spec_body
636 spec_binds = VarMonoBind local_spec_id spec_rhs
638 VarMonoBind spec_pragma_id (HsVar (TcId local_spec_id))
639 spec_info = SpecInfo spec_tys (length main_theta) local_spec_id
641 returnTc ((name, addInfo spec_info), spec_binds, spec_lie)
646 %************************************************************************
648 \subsection[TcBinds-monomorphism]{The monomorphism restriction}
650 %************************************************************************
655 isUnRestrictedGroup :: [TcIdBndr s] -- Signatures given for these
659 isUnRestrictedGroup sigs EmptyBind = True
660 isUnRestrictedGroup sigs (NonRecBind monobinds) = isUnResMono sigs monobinds
661 isUnRestrictedGroup sigs (RecBind monobinds) = isUnResMono sigs monobinds
663 is_elem v vs = isIn "isUnResMono" v vs
665 isUnResMono sigs (PatMonoBind (VarPat (TcId v)) _ _) = v `is_elem` sigs
666 isUnResMono sigs (PatMonoBind other _ _) = False
667 isUnResMono sigs (VarMonoBind (TcId v) _) = v `is_elem` sigs
668 isUnResMono sigs (FunMonoBind _ _ _ _) = True
669 isUnResMono sigs (AndMonoBinds mb1 mb2) = isUnResMono sigs mb1 &&
671 isUnResMono sigs EmptyMonoBinds = True
675 %************************************************************************
677 \subsection[TcBinds-errors]{Error contexts and messages}
679 %************************************************************************
683 patMonoBindsCtxt bind sty
684 = ppHang (ppPStr SLIT("In a pattern binding:")) 4 (ppr sty bind)
686 --------------------------------------------
687 specContextGroundnessCtxt -- err_ctxt dicts sty
688 = panic "specContextGroundnessCtxt"
691 ppSep [ppBesides [ppStr "In the SPECIALIZE pragma for `", ppr sty name, ppStr "'"],
692 ppBesides [ppStr " specialised to the type `", ppr sty spec_ty, ppStr "'"],
694 ppStr "... not all overloaded type variables were instantiated",
695 ppStr "to ground types:"])
696 4 (ppAboves [ppCat [ppr sty c, ppr sty t]
697 | (c,t) <- map getDictClassAndType dicts])
699 (name, spec_ty, locn, pp_spec_id)
701 ValSpecSigCtxt n ty loc -> (n, ty, loc, \ x -> ppNil)
702 ValSpecSpecIdCtxt n ty spec loc ->
704 \ sty -> ppBesides [ppStr "... type of explicit id `", ppr sty spec, ppStr "'"])
707 -----------------------------------------------
709 = panic "specGroundnessCtxt"
712 valSpecSigCtxt v ty sty
713 = ppHang (ppPStr SLIT("In a SPECIALIZE pragma for a value:"))
714 4 (ppSep [ppBeside (pprNonSym sty v) (ppPStr SLIT(" ::")),