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 ( SYN_IE(RenamedHsBinds), SYN_IE(RenamedBind), RenamedSig(..),
18 SYN_IE(RenamedMonoBinds), RnName(..)
20 import TcHsSyn ( SYN_IE(TcHsBinds), SYN_IE(TcBind), SYN_IE(TcMonoBinds),
21 TcIdOcc(..), SYN_IE(TcIdBndr) )
23 import TcMonad hiding ( rnMtoTcM )
24 import GenSpecEtc ( checkSigTyVars, genBinds, TcSigInfo(..) )
25 import Inst ( Inst, SYN_IE(LIE), emptyLIE, plusLIE, InstOrigin(..) )
26 import TcEnv ( tcExtendLocalValEnv, tcLookupLocalValueOK, newMonoIds )
27 import SpecEnv ( SpecEnv )
28 IMPORT_DELOOPER(TcLoop) ( tcGRHSsAndBinds )
29 import TcMatches ( tcMatchesFun )
30 import TcMonoType ( tcPolyType )
31 import TcPat ( tcPat )
32 import TcSimplify ( bindInstsOfLocalFuns )
33 import TcType ( newTcTyVar, tcInstSigType )
34 import Unify ( unifyTauTy )
36 import Kind ( mkBoxedTypeKind, mkTypeKind )
37 import Id ( GenId, idType, mkUserId )
38 import IdInfo ( noIdInfo )
39 import Maybes ( assocMaybe, catMaybes )
40 import Name ( pprNonSym, Name )
41 import PragmaInfo ( PragmaInfo(..) )
43 import Type ( mkTyVarTy, mkTyVarTys, isTyVarTy,
44 mkSigmaTy, splitSigmaTy,
45 splitRhoTy, mkForAllTy, splitForAllTy )
46 import Util ( isIn, zipEqual, 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 _ -> mkTypeKind -- Recursive, so no unboxed types
213 RecBind _ -> mkBoxedTypeKind -- 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 *** CHECK FOR UNBOXED TYVARS HERE! ***
256 -- Make poly_ids for all the binders that don't have type signatures
258 tys_to_gen = mkTyVarTys tyvars_to_gen
259 dicts_to_gen = map instToId (bagToList lie_to_gen)
260 dict_tys = map tcIdType dicts_to_gen
262 mk_poly binder local_id = mkUserId (getName binder) ty noPragmaInfo
264 ty = mkForAllTys tyvars_to_gen $
268 more_sig_infos = [ SigInfo binder (mk_poly binder local_id)
269 local_id tys_to_gen dicts_to_gen lie_to_gen
270 | (binder, local_id) <- zipEqual "???" nosig_binders nosig_local_ids
273 all_sig_infos = sig_infos ++ more_sig_infos -- Contains a "signature" for each binder
277 -- Now generalise the bindings
279 -- local_binds is a bunch of bindings of the form
280 -- f_mono = f_poly tyvars dicts
281 -- one for each binder, f, that lacks a type signature.
282 -- This bunch of bindings is put at the top of the RHS of every
283 -- binding in the group, so as to bind all the f_monos.
285 local_binds = [ (local_id, mkHsDictApp (mkHsTyApp (HsVar local_id) tys_to_gen) dicts_to_gen)
286 | local_id <- nosig_local_ids
289 find_sig lid = head [ (pid, tvs, ds, lie)
290 | SigInfo _ pid lid' tvs ds lie,
295 = tcSimplifyWithExtraGlobals tyvars_not_to_gen tyvars_to_gen avail lie
296 `thenTc` \ (lie_free, dict_binds) ->
297 returnTc (AbsBind tyvars_to_gen_here
299 (zipEqual "gen_bind" local_ids poly_ids)
300 (dict_binds ++ local_binds)
304 local_ids = bindersOf bind
305 local_sigs = [sig | sig@(SigInfo _ _ local_id _ _) <- all_sig_infos,
306 local_id `elem` local_ids
309 (tyvars_to_gen_here, dicts, avail)
310 = case (local_ids, sigs) of
312 ([local_id], [SigInfo _ _ _ tyvars_to_gen dicts lie])
313 -> (tyvars_to_gen, dicts, lie)
315 other -> (tyvars_to_gen, dicts, avail)
318 @getImplicitStuffToGen@ decides what type variables
319 and LIE to generalise over.
321 For a "restricted group" -- see the monomorphism restriction
322 for a definition -- we bind no dictionaries, and
323 remove from tyvars_to_gen any constrained type variables
325 *Don't* simplify dicts at this point, because we aren't going
326 to generalise over these dicts. By the time we do simplify them
327 we may well know more. For example (this actually came up)
329 f x = array ... xs where xs = [1,2,3,4,5]
330 We don't want to generate lots of (fromInt Int 1), (fromInt Int 2)
331 stuff. If we simplify only at the f-binding (not the xs-binding)
332 we'll know that the literals are all Ints, and we can just produce
335 Find all the type variables involved in overloading, the "constrained_tyvars"
336 These are the ones we *aren't* going to generalise.
337 We must be careful about doing this:
338 (a) If we fail to generalise a tyvar which is not actually
339 constrained, then it will never, ever get bound, and lands
340 up printed out in interface files! Notorious example:
341 instance Eq a => Eq (Foo a b) where ..
342 Here, b is not constrained, even though it looks as if it is.
343 Another, more common, example is when there's a Method inst in
344 the LIE, whose type might very well involve non-overloaded
346 (b) On the other hand, we mustn't generalise tyvars which are constrained,
347 because we are going to pass on out the unmodified LIE, with those
348 tyvars in it. They won't be in scope if we've generalised them.
350 So we are careful, and do a complete simplification just to find the
351 constrained tyvars. We don't use any of the results, except to
352 find which tyvars are constrained.
355 getImplicitStuffToGen is_restricted sig_ids binds_w_lies
356 | isUnRestrictedGroup tysig_vars bind
357 = tcSimplify tyvars_to_gen lie `thenTc` \ (_, _, dicts_to_gen) ->
358 returnNF_Tc (emptyTyVarSet, tyvars_to_gen, dicts_to_gen)
361 = tcSimplify tyvars_to_gen lie `thenTc` \ (_, _, constrained_dicts) ->
363 -- ASSERT: dicts_sig is already zonked!
364 constrained_tyvars = foldBag unionTyVarSets tyVarsOfInst emptyTyVarSet constrained_dicts
365 reduced_tyvars_to_gen = tyvars_to_gen `minusTyVarSet` constrained_tyvars
367 returnTc (constrained_tyvars, reduced_tyvars_to_gen, emptyLIE)
370 sig_vars = [sig_var | (TySigInfo sig_var _ _ _ _) <- ty_sigs]
372 (tyvars_to_gen, lie) = foldBag (\(tv1,lie2) (tv2,lie2) -> (tv1 `unionTyVarSets` tv2,
373 lie1 `plusLIE` lie2))
375 (emptyTyVarSet, emptyLIE)
378 = case bindersOf bind of
379 [local_id] | local_id `in` sig_ids -> -- A simple binding with
381 (emptyTyVarSet, emptyLIE)
383 local_ids -> -- Complex binding or no type sig
384 (foldr (unionTyVarSets . tcIdType) emptyTyVarSet local_ids,
392 tc_bind :: RenamedBind -> TcM s (TcBind s, LIE s)
394 tc_bind (NonRecBind mono_binds)
395 = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) ->
396 returnTc (NonRecBind mono_binds2, lie)
398 tc_bind (RecBind mono_binds)
399 = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) ->
400 returnTc (RecBind mono_binds2, lie)
404 tcMonoBinds :: RenamedMonoBinds -> TcM s (TcMonoBinds s, LIE s)
406 tcMonoBinds EmptyMonoBinds = returnTc (EmptyMonoBinds, emptyLIE)
408 tcMonoBinds (AndMonoBinds mb1 mb2)
409 = tcMonoBinds mb1 `thenTc` \ (mb1a, lie1) ->
410 tcMonoBinds mb2 `thenTc` \ (mb2a, lie2) ->
411 returnTc (AndMonoBinds mb1a mb2a, lie1 `plusLIE` lie2)
413 tcMonoBinds bind@(PatMonoBind pat grhss_and_binds locn)
417 tcPat pat `thenTc` \ (pat2, lie_pat, pat_ty) ->
419 -- BINDINGS AND GRHSS
420 tcGRHSsAndBinds grhss_and_binds `thenTc` \ (grhss_and_binds2, lie, grhss_ty) ->
422 -- Unify the two sides
423 tcAddErrCtxt (patMonoBindsCtxt bind) $
424 unifyTauTy pat_ty grhss_ty `thenTc_`
427 returnTc (PatMonoBind pat2 grhss_and_binds2 locn,
430 tcMonoBinds (FunMonoBind name inf matches locn)
432 tcLookupLocalValueOK "tcMonoBinds" name `thenNF_Tc` \ id ->
433 tcMatchesFun name (idType id) matches `thenTc` \ (matches', lie) ->
434 returnTc (FunMonoBind (TcId id) inf matches' locn, lie)
437 %************************************************************************
439 \subsection{Signatures}
441 %************************************************************************
443 @tcSigs@ checks the signatures for validity, and returns a list of
444 {\em freshly-instantiated} signatures. That is, the types are already
445 split up, and have fresh type variables installed. All non-type-signature
446 "RenamedSigs" are ignored.
449 tcTySigs :: [RenamedSig] -> TcM s [TcSigInfo s]
451 tcTySigs (Sig v ty _ src_loc : other_sigs)
452 = tcAddSrcLoc src_loc (
453 tcPolyType ty `thenTc` \ sigma_ty ->
454 tcInstSigType sigma_ty `thenNF_Tc` \ sigma_ty' ->
456 (tyvars', theta', tau') = splitSigmaTy sigma_ty'
459 tcLookupLocalValueOK "tcSig1" v `thenNF_Tc` \ val ->
460 unifyTauTy (idType val) tau' `thenTc_`
462 returnTc (TySigInfo val tyvars' theta' tau' src_loc)
463 ) `thenTc` \ sig_info1 ->
465 tcTySigs other_sigs `thenTc` \ sig_infos ->
466 returnTc (sig_info1 : sig_infos)
468 tcTySigs (other : sigs) = tcTySigs sigs
469 tcTySigs [] = returnTc []
473 %************************************************************************
475 \subsection{SPECIALIZE pragmas}
477 %************************************************************************
480 @tcPragmaSigs@ munches up the "signatures" that arise through *user*
481 pragmas. It is convenient for them to appear in the @[RenamedSig]@
482 part of a binding because then the same machinery can be used for
483 moving them into place as is done for type signatures.
486 tcPragmaSigs :: [RenamedSig] -- The pragma signatures
487 -> TcM s (Name -> PragmaInfo, -- Maps name to the appropriate PragmaInfo
491 tcPragmaSigs sigs = returnTc ( \name -> NoPragmaInfo, EmptyBinds, emptyLIE )
495 = mapAndUnzip3Tc tcPragmaSig sigs `thenTc` \ (names_w_id_infos, binds, lies) ->
497 name_to_info name = foldr ($) noIdInfo
498 [info_fn | (n,info_fn) <- names_w_id_infos, n==name]
500 returnTc (name_to_info,
501 foldr ThenBinds EmptyBinds binds,
502 foldr plusLIE emptyLIE lies)
505 Here are the easy cases for tcPragmaSigs
508 tcPragmaSig (DeforestSig name loc)
509 = returnTc ((name, addInfo DoDeforest),EmptyBinds,emptyLIE)
510 tcPragmaSig (InlineSig name loc)
511 = returnTc ((name, addInfo_UF (iWantToBeINLINEd UnfoldAlways)), EmptyBinds, emptyLIE)
512 tcPragmaSig (MagicUnfoldingSig name string loc)
513 = returnTc ((name, addInfo_UF (mkMagicUnfolding string)), EmptyBinds, emptyLIE)
516 The interesting case is for SPECIALISE pragmas. There are two forms.
517 Here's the first form:
519 f :: Ord a => [a] -> b -> b
520 {-# SPECIALIZE f :: [Int] -> b -> b #-}
523 For this we generate:
525 f* = /\ b -> let d1 = ...
529 where f* is a SpecPragmaId. The **sole** purpose of SpecPragmaIds is to
530 retain a right-hand-side that the simplifier will otherwise discard as
531 dead code... the simplifier has a flag that tells it not to discard
532 SpecPragmaId bindings.
534 In this case the f* retains a call-instance of the overloaded
535 function, f, (including appropriate dictionaries) so that the
536 specialiser will subsequently discover that there's a call of @f@ at
537 Int, and will create a specialisation for @f@. After that, the
538 binding for @f*@ can be discarded.
540 The second form is this:
542 f :: Ord a => [a] -> b -> b
543 {-# SPECIALIZE f :: [Int] -> b -> b = g #-}
546 Here @g@ is specified as a function that implements the specialised
547 version of @f@. Suppose that g has type (a->b->b); that is, g's type
548 is more general than that required. For this we generate
550 f@Int = /\b -> g Int b
554 Here @f@@Int@ is a SpecId, the specialised version of @f@. It inherits
555 f's export status etc. @f*@ is a SpecPragmaId, as before, which just serves
556 to prevent @f@@Int@ from being discarded prematurely. After specialisation,
557 if @f@@Int@ is going to be used at all it will be used explicitly, so the simplifier can
558 discard the f* binding.
560 Actually, there is really only point in giving a SPECIALISE pragma on exported things,
561 and the simplifer won't discard SpecIds for exporte things anyway, so maybe this is
565 tcPragmaSig (SpecSig name poly_ty maybe_spec_name src_loc)
566 = tcAddSrcLoc src_loc $
567 tcAddErrCtxt (valSpecSigCtxt name spec_ty) $
569 -- Get and instantiate its alleged specialised type
570 tcPolyType poly_ty `thenTc` \ sig_sigma ->
571 tcInstSigType sig_sigma `thenNF_Tc` \ sig_ty ->
573 (sig_tyvars, sig_theta, sig_tau) = splitSigmaTy sig_ty
574 origin = ValSpecOrigin name
577 -- Check that the SPECIALIZE pragma had an empty context
578 checkTc (null sig_theta)
579 (panic "SPECIALIZE non-empty context (ToDo: msg)") `thenTc_`
581 -- Get and instantiate the type of the id mentioned
582 tcLookupLocalValueOK "tcPragmaSig" name `thenNF_Tc` \ main_id ->
583 tcInstSigType [] (idType main_id) `thenNF_Tc` \ main_ty ->
585 (main_tyvars, main_rho) = splitForAllTy main_ty
586 (main_theta,main_tau) = splitRhoTy main_rho
587 main_arg_tys = mkTyVarTys main_tyvars
590 -- Check that the specialised type is indeed an instance of
591 -- the type of the main function.
592 unifyTauTy sig_tau main_tau `thenTc_`
593 checkSigTyVars sig_tyvars sig_tau `thenTc_`
595 -- Check that the type variables of the polymorphic function are
596 -- either left polymorphic, or instantiate to ground type.
597 -- Also check that the overloaded type variables are instantiated to
598 -- ground type; or equivalently that all dictionaries have ground type
599 mapTc zonkTcType main_arg_tys `thenNF_Tc` \ main_arg_tys' ->
600 zonkTcThetaType main_theta `thenNF_Tc` \ main_theta' ->
601 tcAddErrCtxt (specGroundnessCtxt main_arg_tys')
602 (checkTc (all isGroundOrTyVarTy main_arg_tys')) `thenTc_`
603 tcAddErrCtxt (specContextGroundnessCtxt main_theta')
604 (checkTc (and [isGroundTy ty | (_,ty) <- theta'])) `thenTc_`
606 -- Build the SpecPragmaId; it is the thing that makes sure we
607 -- don't prematurely dead-code-eliminate the binding we are really interested in.
608 newSpecPragmaId name sig_ty `thenNF_Tc` \ spec_pragma_id ->
610 -- Build a suitable binding; depending on whether we were given
611 -- a value (Maybe Name) to be used as the specialisation.
613 Nothing -> -- No implementation function specified
615 -- Make a Method inst for the occurrence of the overloaded function
616 newMethodWithGivenTy (OccurrenceOf name)
617 (TcId main_id) main_arg_tys main_rho `thenNF_Tc` \ (lie, meth_id) ->
620 pseudo_bind = VarMonoBind spec_pragma_id pseudo_rhs
621 pseudo_rhs = mkHsTyLam sig_tyvars (HsVar (TcId meth_id))
623 returnTc (pseudo_bind, lie, \ info -> info)
625 Just spec_name -> -- Use spec_name as the specialisation value ...
627 -- Type check a simple occurrence of the specialised Id
628 tcId spec_name `thenTc` \ (spec_body, spec_lie, spec_tau) ->
630 -- Check that it has the correct type, and doesn't constrain the
631 -- signature variables at all
632 unifyTauTy sig_tau spec_tau `thenTc_`
633 checkSigTyVars sig_tyvars sig_tau `thenTc_`
635 -- Make a local SpecId to bind to applied spec_id
636 newSpecId main_id main_arg_tys sig_ty `thenNF_Tc` \ local_spec_id ->
639 spec_rhs = mkHsTyLam sig_tyvars spec_body
640 spec_binds = VarMonoBind local_spec_id spec_rhs
642 VarMonoBind spec_pragma_id (HsVar (TcId local_spec_id))
643 spec_info = SpecInfo spec_tys (length main_theta) local_spec_id
645 returnTc ((name, addInfo spec_info), spec_binds, spec_lie)
650 %************************************************************************
652 \subsection[TcBinds-monomorphism]{The monomorphism restriction}
654 %************************************************************************
659 isUnRestrictedGroup :: [TcIdBndr s] -- Signatures given for these
663 isUnRestrictedGroup sigs EmptyBind = True
664 isUnRestrictedGroup sigs (NonRecBind monobinds) = isUnResMono sigs monobinds
665 isUnRestrictedGroup sigs (RecBind monobinds) = isUnResMono sigs monobinds
667 is_elem v vs = isIn "isUnResMono" v vs
669 isUnResMono sigs (PatMonoBind (VarPat (TcId v)) _ _) = v `is_elem` sigs
670 isUnResMono sigs (PatMonoBind other _ _) = False
671 isUnResMono sigs (VarMonoBind (TcId v) _) = v `is_elem` sigs
672 isUnResMono sigs (FunMonoBind _ _ _ _) = True
673 isUnResMono sigs (AndMonoBinds mb1 mb2) = isUnResMono sigs mb1 &&
675 isUnResMono sigs EmptyMonoBinds = True
679 %************************************************************************
681 \subsection[TcBinds-errors]{Error contexts and messages}
683 %************************************************************************
687 patMonoBindsCtxt bind sty
688 = ppHang (ppPStr SLIT("In a pattern binding:")) 4 (ppr sty bind)
690 --------------------------------------------
691 specContextGroundnessCtxt -- err_ctxt dicts sty
692 = panic "specContextGroundnessCtxt"
695 ppSep [ppBesides [ppStr "In the SPECIALIZE pragma for `", ppr sty name, ppStr "'"],
696 ppBesides [ppStr " specialised to the type `", ppr sty spec_ty, ppStr "'"],
698 ppStr "... not all overloaded type variables were instantiated",
699 ppStr "to ground types:"])
700 4 (ppAboves [ppCat [ppr sty c, ppr sty t]
701 | (c,t) <- map getDictClassAndType dicts])
703 (name, spec_ty, locn, pp_spec_id)
705 ValSpecSigCtxt n ty loc -> (n, ty, loc, \ x -> ppNil)
706 ValSpecSpecIdCtxt n ty spec loc ->
708 \ sty -> ppBesides [ppStr "... type of explicit id `", ppr sty spec, ppStr "'"])
711 -----------------------------------------------
713 = panic "specGroundnessCtxt"
716 valSpecSigCtxt v ty sty
717 = ppHang (ppPStr SLIT("In a SPECIALIZE pragma for a value:"))
718 4 (ppSep [ppBeside (pprNonSym sty v) (ppPStr SLIT(" ::")),