-{- LATER
-tcSpecInstSigs :: E -> CE -> TCE
- -> Bag InstInfo -- inst decls seen (declared and derived)
- -> [RenamedSpecInstSig] -- specialise instance upragmas
- -> TcM (Bag InstInfo) -- new, overlapped, inst decls
-
-tcSpecInstSigs e ce tce inst_infos []
- = returnTc emptyBag
-
-tcSpecInstSigs e ce tce inst_infos sigs
- = buildInstanceEnvs inst_infos `thenTc` \ inst_mapper ->
- tc_inst_spec_sigs inst_mapper sigs `thenNF_Tc` \ spec_inst_infos ->
- returnTc spec_inst_infos
- where
- tc_inst_spec_sigs inst_mapper []
- = returnNF_Tc emptyBag
- tc_inst_spec_sigs inst_mapper (sig:sigs)
- = tcSpecInstSig e ce tce inst_infos inst_mapper sig `thenNF_Tc` \ info_sig ->
- tc_inst_spec_sigs inst_mapper sigs `thenNF_Tc` \ info_sigs ->
- returnNF_Tc (info_sig `unionBags` info_sigs)
-
-tcSpecInstSig :: E -> CE -> TCE
- -> Bag InstInfo
- -> InstanceMapper
- -> RenamedSpecInstSig
- -> NF_TcM (Bag InstInfo)
-
-tcSpecInstSig e ce tce inst_infos inst_mapper (SpecInstSig class_name ty src_loc)
- = recoverTc emptyBag (
- tcAddSrcLoc src_loc (
- let
- clas = lookupCE ce class_name -- Renamer ensures this can't fail
-
- -- Make some new type variables, named as in the specialised instance type
- ty_names = extractMonoTyNames ???is_tyvarish_name??? ty
- (tmpl_e,inst_tmpls,inst_tmpl_tys) = mkTVE ty_names
- in
- babyTcMtoTcM (tcInstanceType ce tce tmpl_e True src_loc ty)
- `thenTc` \ inst_ty ->
- let
- maybe_tycon = case maybeAppDataTyCon inst_ty of
- Just (tc,_,_) -> Just tc
- Nothing -> Nothing
-
- maybe_unspec_inst = lookup_unspec_inst clas maybe_tycon inst_infos
- in
- -- Check that we have a local instance declaration to specialise
- checkMaybeTc maybe_unspec_inst
- (specInstUnspecInstNotFoundErr clas inst_ty src_loc) `thenTc_`
-
- -- Create tvs to substitute for tmpls while simplifying the context
- copyTyVars inst_tmpls `thenNF_Tc` \ (tv_e, inst_tvs, inst_tv_tys) ->
- let
- Just (InstInfo _ unspec_tyvars unspec_inst_ty unspec_theta
- _ _ _ binds True{-from here-} mod _ uprag) = maybe_unspec_inst
-
- subst = case matchTy unspec_inst_ty inst_ty of
- Just subst -> subst
- Nothing -> panic "tcSpecInstSig:matchTy"
-
- subst_theta = instantiateThetaTy subst unspec_theta
- subst_tv_theta = instantiateThetaTy tv_e subst_theta
-
- mk_spec_origin clas ty
- = InstanceSpecOrigin inst_mapper clas ty src_loc
- -- I'm VERY SUSPICIOUS ABOUT THIS
- -- the inst-mapper is in a knot at this point so it's no good
- -- looking at it in tcSimplify...
- in
- tcSimplifyThetas mk_spec_origin subst_tv_theta
- `thenTc` \ simpl_tv_theta ->
- let
- simpl_theta = [ (clas, tv_to_tmpl tv) | (clas, tv) <- simpl_tv_theta ]
-
- tv_tmpl_map = zipEqual "tcSpecInstSig" inst_tv_tys inst_tmpl_tys
- tv_to_tmpl tv = assoc "tcSpecInstSig" tv_tmpl_map tv
- in
- mkInstanceRelatedIds e True{-from here-} src_loc mod NoInstancePragmas
- clas inst_tmpls inst_ty simpl_theta uprag
- `thenTc` \ (dfun_id, dfun_theta, const_meth_ids) ->
-
- getSwitchCheckerTc `thenNF_Tc` \ sw_chkr ->
- (if sw_chkr SpecialiseTrace then
- pprTrace "Specialised Instance: "
- (ppAboves [ppCat [if null simpl_theta then ppNil else ppr PprDebug simpl_theta,
- if null simpl_theta then ppNil else ppStr "=>",
- ppr PprDebug clas,
- pprParendGenType PprDebug inst_ty],
- ppCat [ppStr " derived from:",
- if null unspec_theta then ppNil else ppr PprDebug unspec_theta,
- if null unspec_theta then ppNil else ppStr "=>",
- ppr PprDebug clas,
- pprParendGenType PprDebug unspec_inst_ty]])
- else id) (
-
- returnTc (unitBag (InstInfo clas inst_tmpls inst_ty simpl_theta
- dfun_theta dfun_id const_meth_ids
- binds True{-from here-} mod src_loc uprag))
- )))
-
-
-lookup_unspec_inst clas maybe_tycon inst_infos
- = case filter (match_info match_inst_ty) (bagToList inst_infos) of
- [] -> Nothing
- (info:_) -> Just info
- where
- match_info match_ty (InstInfo inst_clas _ inst_ty _ _ _ _ _ from_here _ _ _)
- = from_here && clas == inst_clas &&
- match_ty inst_ty && is_plain_instance inst_ty
-
- match_inst_ty = case maybe_tycon of
- Just tycon -> match_tycon tycon
- Nothing -> match_fun
-
- match_tycon tycon inst_ty = case (maybeAppDataTyCon inst_ty) of
- Just (inst_tc,_,_) -> tycon == inst_tc
- Nothing -> False
-
- match_fun inst_ty = isFunType inst_ty
-
-
-is_plain_instance inst_ty
- = case (maybeAppDataTyCon inst_ty) of
- Just (_,tys,_) -> all isTyVarTemplateTy tys
- Nothing -> case maybeUnpackFunTy inst_ty of
- Just (arg, res) -> isTyVarTemplateTy arg && isTyVarTemplateTy res
- Nothing -> error "TcInstDecls:is_plain_instance"
--}
-\end{code}
-
-
-Checking for a decent instance type
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-@scrutiniseInstanceType@ checks the type {\em and} its syntactic constraints:
-it must normally look like: @instance Foo (Tycon a b c ...) ...@
-
-The exceptions to this syntactic checking: (1)~if the @GlasgowExts@
-flag is on, or (2)~the instance is imported (they must have been
-compiled elsewhere). In these cases, we let them go through anyway.
-
-We can also have instances for functions: @instance Foo (a -> b) ...@.
-
-\begin{code}
-scrutiniseInstanceType from_here clas inst_tau
- -- TYCON CHECK
- | not (maybeToBool inst_tycon_maybe) || isSynTyCon inst_tycon
- = failTc (instTypeErr inst_tau)
-
- -- IMPORTED INSTANCES ARE OK (but see tcInstDecl1)
- | from_here
- = returnTc (inst_tycon,arg_tys)
-
- -- TYVARS CHECK
- | not (all isTyVarTy arg_tys ||
- not from_here ||
- opt_GlasgowExts)
- = failTc (instTypeErr inst_tau)
-
- -- DERIVING CHECK
- -- It is obviously illegal to have an explicit instance
- -- for something that we are also planning to `derive'
- -- Though we can have an explicit instance which is more
- -- specific than the derived instance
- | clas `derivedFor` inst_tycon
- && all isTyVarTy arg_tys
- = failTc (derivingWhenInstanceExistsErr clas inst_tycon)
-
- | -- CCALL CHECK
- -- A user declaration of a CCallable/CReturnable instance
- -- must be for a "boxed primitive" type.
- isCcallishClass clas
--- && not opt_CompilingPrelude -- which allows anything
- && not (maybeToBool (maybeBoxedPrimType inst_tau))
- = failTc (nonBoxedPrimCCallErr clas inst_tau)
-
- | otherwise
- = returnTc (inst_tycon,arg_tys)
-