\section[TcInstDecls]{Typechecking instance declarations}
\begin{code}
-#include "HsVersions.h"
-
module TcInstDcls (
tcInstDecls1,
tcInstDecls2
) where
+#include "HsVersions.h"
-IMP_Ubiq()
-
-import HsSyn ( HsDecl(..), InstDecl(..), TyDecl, ClassDecl, DefaultDecl,
- FixityDecl, IfaceSig, Sig(..),
- SpecInstSig(..), HsBinds(..),
- MonoBinds(..), GRHSsAndBinds(..), GRHS(..), Match,
- InPat(..), OutPat(..), HsExpr(..), HsLit(..),
- Stmt, DoOrListComp, ArithSeqInfo, Fake, Fixity,
- HsType(..), HsTyVar,
- SYN_IE(RecFlag), recursive, nonRecursive, collectMonoBinders,
- andMonoBinds
+import HsSyn ( HsDecl(..), InstDecl(..),
+ HsBinds(..), MonoBinds(..), GRHSsAndBinds(..), GRHS(..),
+ HsExpr(..), InPat(..), HsLit(..),
+ unguardedRHS,
+ collectMonoBinders, andMonoBinds
)
-import RnHsSyn ( SYN_IE(RenamedHsBinds), SYN_IE(RenamedMonoBinds),
- SYN_IE(RenamedInstDecl), SYN_IE(RenamedFixityDecl), SYN_IE(RenamedHsExpr),
- SYN_IE(RenamedSig), SYN_IE(RenamedSpecInstSig), SYN_IE(RenamedHsDecl)
+import RnHsSyn ( RenamedHsBinds, RenamedMonoBinds,
+ RenamedInstDecl, RenamedHsExpr,
+ RenamedSig, RenamedHsDecl
)
-import TcHsSyn ( SYN_IE(TcHsBinds),
- SYN_IE(TcMonoBinds), SYN_IE(TcExpr), tcIdType,
- mkHsTyLam, mkHsTyApp,
- mkHsDictLam, mkHsDictApp )
+import TcHsSyn ( TcMonoBinds, TcIdOcc(..), TcIdBndr,
+ maybeBoxedPrimType, mkHsTyLam, mkHsTyApp,
+ )
-import TcBinds ( tcPragmaSigs )
+import TcBinds ( tcPragmaSigs, sigThetaCtxt )
import TcClassDcl ( tcMethodBind, badMethodErr )
import TcMonad
-import RnMonad ( SYN_IE(RnNameSupply) )
-import Inst ( Inst, InstOrigin(..), SYN_IE(InstanceMapper),
- instToId, newDicts, newMethod, SYN_IE(LIE), emptyLIE, plusLIE )
+import RnMonad ( RnNameSupply )
+import Inst ( Inst, InstOrigin(..),
+ newDicts, LIE, emptyLIE, plusLIE )
import PragmaInfo ( PragmaInfo(..) )
import TcDeriv ( tcDeriving )
-import TcEnv ( tcLookupClass, newLocalId, tcExtendGlobalTyVars, tcGetGlobalTyVars,
- tcExtendGlobalValEnv, tcAddImportedIdInfo
- )
-import SpecEnv ( SpecEnv )
-import TcGRHSs ( tcGRHSsAndBinds )
-import TcInstUtil ( InstInfo(..), mkInstanceRelatedIds, buildInstanceEnvs )
+import TcEnv ( tcExtendGlobalValEnv, tcAddImportedIdInfo )
+import TcInstUtil ( InstInfo(..), mkInstanceRelatedIds, classDataCon )
import TcKind ( TcKind, unifyKind )
-import TcMatches ( tcMatchesFun )
-import TcMonoType ( tcTyVarScope, tcContext, tcHsTypeKind )
+import TcMonoType ( tcHsType )
import TcSimplify ( tcSimplifyAndCheck )
-import TcType ( TcIdOcc(..), SYN_IE(TcIdBndr), SYN_IE(TcType), SYN_IE(TcTyVar), SYN_IE(TcTyVarSet),
- tcInstSigTyVars, tcInstType, tcInstSigTcType,
- tcInstTheta, tcInstTcType, tcInstSigType
+import TcType ( TcType, TcTyVar, TcTyVarSet,
+ zonkSigTyVar, tcInstSigTyVars, tcInstType, tcInstTheta
)
-import Unify ( unifyTauTy, unifyTauTyLists )
-
import Bag ( emptyBag, unitBag, unionBags, unionManyBags,
- concatBag, foldBag, bagToList, listToBag,
- Bag )
-import CmdLineOpts ( opt_GlasgowExts,
- opt_PprUserLength, opt_SpecialiseOverloaded,
- opt_WarnMissingMethods
+ foldBag, bagToList, Bag
)
-import Class ( GenClass,
- classBigSig,
- classDefaultMethodId, SYN_IE(Class)
- )
-import Id ( GenId, idType, replacePragmaInfo,
- isNullaryDataCon, dataConArgTys, SYN_IE(Id) )
-import ListSetOps ( minusList )
-import Maybes ( maybeToBool, expectJust, seqMaybe, catMaybes )
-import Name ( nameOccName, getSrcLoc, mkLocalName,
- isLocallyDefined, OccName, Name{--O only-}, SYN_IE(Module),
+import CmdLineOpts ( opt_GlasgowExts, opt_WarnMissingMethods )
+import Class ( classBigSig, Class )
+import Id ( idType, isNullaryDataCon, dataConArgTys, Id )
+import Maybes ( maybeToBool, seqMaybe, catMaybes )
+import Name ( nameOccName, mkLocalName,
+ isLocallyDefined, Module,
NamedThing(..)
)
-import PrelVals ( nO_EXPLICIT_METHOD_ERROR_ID, nO_DEFAULT_METHOD_ERROR_ID )
-import PprType ( GenType, GenTyVar, GenClass, TyCon,
- pprParendGenType
- )
-import Outputable
+import PrelVals ( nO_METHOD_BINDING_ERROR_ID )
+import PprType ( pprParendGenType, pprConstraint )
import SrcLoc ( SrcLoc, noSrcLoc )
-import Pretty
-import TyCon ( isSynTyCon, isDataTyCon, derivedClasses )
-import Type ( GenType(..), SYN_IE(ThetaType), mkTyVarTys, isPrimType,
- splitSigmaTy, splitAppTys, isTyVarTy, matchTy, mkSigmaTy,
- getTyCon_maybe, maybeAppTyCon, SYN_IE(Type), getTyVar,
- maybeBoxedPrimType, maybeAppDataTyCon, splitRhoTy, eqTy
+import TyCon ( isSynTyCon, isDataTyCon, tyConDerivings )
+import Type ( Type, ThetaType, isUnpointedType,
+ splitSigmaTy, isTyVarTy, mkSigmaTy,
+ splitTyConApp_maybe, splitDictTy_maybe,
+ splitAlgTyConApp_maybe, splitRhoTy,
+ tyVarsOfTypes
)
-import TyVar ( GenTyVar, SYN_IE(GenTyVarSet), tyVarSetToList,
- mkTyVarSet, unionTyVarSets, SYN_IE(TyVar) )
+import TyVar ( zipTyVarEnv, mkTyVarSet, tyVarSetToList, TyVar )
import TysPrim ( byteArrayPrimTyCon, mutableByteArrayPrimTyCon )
import TysWiredIn ( stringTy )
import Unique ( Unique, cCallableClassKey, cReturnableClassKey, Uniquable(..) )
-import Util ( zipEqual, panic, pprPanic, pprTrace, removeDups, Ord3(..)
-#if __GLASGOW_HASKELL__ < 202
- , trace
-#endif
- )
+import Outputable
\end{code}
Typechecking instance declarations is done in two passes. The first
-> RnNameSupply -- for renaming derivings
-> TcM s (Bag InstInfo,
RenamedHsBinds,
- PprStyle -> Doc)
+ SDoc)
tcInstDecls1 unf_env decls mod_name rn_name_supply
= -- Do the ordinary instance declarations
recoverNF_Tc (returnNF_Tc emptyBag) $
tcAddSrcLoc src_loc $
- -- Look things up
- tcLookupClass class_name `thenTc` \ (clas_kind, clas) ->
-
- -- Typecheck the context and instance type
- tcTyVarScope tyvar_names (\ tyvars ->
- tcContext context `thenTc` \ theta ->
- tcHsTypeKind inst_ty `thenTc` \ (tau_kind, tau) ->
- unifyKind clas_kind tau_kind `thenTc_`
- returnTc (tyvars, theta, tau)
- ) `thenTc` \ (inst_tyvars, inst_theta, inst_tau) ->
+ -- Type-check all the stuff before the "where"
+ tcHsType poly_ty `thenTc` \ poly_ty' ->
+ let
+ (tyvars, theta, dict_ty) = splitSigmaTy poly_ty'
+ (clas, inst_tys) = case splitDictTy_maybe dict_ty of
+ Nothing -> pprPanic "tcInstDecl1" (ppr poly_ty)
+ Just pair -> pair
+ in
-- Check for respectable instance type
- scrutiniseInstanceType dfun_name clas inst_tau
- `thenTc` \ (inst_tycon,arg_tys) ->
+ scrutiniseInstanceType clas inst_tys `thenTc_`
-- Make the dfun id and constant-method ids
let
(dfun_id, dfun_theta) = mkInstanceRelatedIds dfun_name
- clas inst_tyvars inst_tau inst_theta
+ clas tyvars inst_tys theta
-- Add info from interface file
final_dfun_id = tcAddImportedIdInfo unf_env dfun_id
in
- returnTc (unitBag (InstInfo clas inst_tyvars inst_tau inst_theta
- dfun_theta final_dfun_id
+ returnTc (unitBag (InstInfo clas tyvars inst_tys theta
+ dfun_theta final_dfun_id
binds src_loc uprags))
- where
- (tyvar_names, context, dict_ty) = case poly_ty of
- HsForAllTy tvs cxt dict_ty -> (tvs, cxt, dict_ty)
- other -> ([], [], poly_ty)
- (class_name, inst_ty) = case dict_ty of
- MonoDictTy cls ty -> (cls,ty)
- other -> pprPanic "Malformed instance decl" (ppr PprDebug poly_ty)
\end{code}
\begin{code}
tcInstDecl2 :: InstInfo -> NF_TcM s (LIE s, TcMonoBinds s)
-tcInstDecl2 (InstInfo clas inst_tyvars inst_ty
+tcInstDecl2 (InstInfo clas inst_tyvars inst_tys
inst_decl_theta dfun_theta
dfun_id monobinds
locn uprags)
tcAddSrcLoc locn $
-- Get the class signature
- tcInstSigTyVars inst_tyvars `thenNF_Tc` \ (inst_tyvars', _, tenv) ->
let
origin = InstanceDeclOrigin
- (class_tyvar,
- super_classes, sc_sel_ids,
+ (class_tyvars,
+ sc_theta, sc_sel_ids,
op_sel_ids, defm_ids) = classBigSig clas
in
- tcInstType tenv inst_ty `thenNF_Tc` \ inst_ty' ->
+
+ -- Instantiate the instance decl with tc-style type variables
+ tcInstSigTyVars inst_tyvars `thenNF_Tc` \ (inst_tyvars', _, tenv) ->
+ mapNF_Tc (tcInstType tenv) inst_tys `thenNF_Tc` \ inst_tys' ->
tcInstTheta tenv dfun_theta `thenNF_Tc` \ dfun_theta' ->
tcInstTheta tenv inst_decl_theta `thenNF_Tc` \ inst_decl_theta' ->
- let
- sc_theta' = super_classes `zip` repeat inst_ty'
- in
+
+ -- Instantiate the super-class context with inst_tys
+
+ tcInstTheta (zipTyVarEnv class_tyvars inst_tys') sc_theta `thenNF_Tc` \ sc_theta' ->
+
-- Create dictionary Ids from the specified instance contexts.
newDicts origin sc_theta' `thenNF_Tc` \ (sc_dicts, sc_dict_ids) ->
newDicts origin dfun_theta' `thenNF_Tc` \ (dfun_arg_dicts, dfun_arg_dicts_ids) ->
newDicts origin inst_decl_theta' `thenNF_Tc` \ (inst_decl_dicts, _) ->
- newDicts origin [(clas,inst_ty')] `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
+ newDicts origin [(clas,inst_tys')] `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
-- Now process any INLINE or SPECIALIZE pragmas for the methods
-- ...[NB May 97; all ignored except INLINE]
- tcPragmaSigs uprags `thenTc` \ (prag_fn, spec_binds, spec_lie) ->
+ tcPragmaSigs uprags `thenTc` \ (prag_fn, spec_binds, spec_lie) ->
-- Check that all the method bindings come from this class
let
- inst_tyvars_set' = mkTyVarSet inst_tyvars'
check_from_this_class (bndr, loc)
- | nameOccName bndr `elem` sel_names = returnTc ()
- | otherwise = recoverTc (returnTc ()) $
- tcAddSrcLoc loc $
- failTc (badMethodErr bndr clas)
+ | nameOccName bndr `elem` sel_names = returnNF_Tc ()
+ | otherwise = tcAddSrcLoc loc $
+ addErrTc (badMethodErr bndr clas)
sel_names = map getOccName op_sel_ids
+ bndrs = bagToList (collectMonoBinders monobinds)
in
- mapTc check_from_this_class (bagToList (collectMonoBinders monobinds)) `thenTc_`
+ mapNF_Tc check_from_this_class bndrs `thenNF_Tc_`
- -- Type check the method bindings themselves
- tcExtendGlobalTyVars inst_tyvars_set' (
- tcExtendGlobalValEnv (catMaybes defm_ids) $
- -- Default-method Ids may be mentioned in synthesised RHSs
+ tcExtendGlobalValEnv (catMaybes defm_ids) (
- mapAndUnzip3Tc (tcInstMethodBind clas inst_ty' monobinds)
+ -- Default-method Ids may be mentioned in synthesised RHSs
+ mapAndUnzip3Tc (tcInstMethodBind clas inst_tys' inst_tyvars' monobinds)
(op_sel_ids `zip` defm_ids)
) `thenTc` \ (method_binds_s, insts_needed_s, meth_lies_w_ids) ->
-- Check the overloading constraints of the methods and superclasses
+ mapNF_Tc zonkSigTyVar inst_tyvars' `thenNF_Tc` \ zonked_inst_tyvars ->
+
let
+ inst_tyvars_set = mkTyVarSet zonked_inst_tyvars
+
(meth_lies, meth_ids) = unzip meth_lies_w_ids
- avail_insts -- These insts are in scope; quite a few, eh?
- = this_dict `plusLIE` dfun_arg_dicts `plusLIE` unionManyBags meth_lies
+
+ -- These insts are in scope; quite a few, eh?
+ avail_insts = this_dict `plusLIE`
+ dfun_arg_dicts `plusLIE`
+ sc_dicts `plusLIE`
+ unionManyBags meth_lies
in
- tcAddErrCtxt bindSigCtxt (
- tcSimplifyAndCheck
- inst_tyvars_set' -- Local tyvars
+ tcAddErrCtxt superClassCtxt $
+ tcAddErrCtxtM (sigThetaCtxt sc_dicts) $
+
+
+ -- Deal with the LIE arising from the method bindings
+ tcSimplifyAndCheck (text "inst decl1a")
+ inst_tyvars_set -- Local tyvars
avail_insts
- (sc_dicts `unionBags`
- unionManyBags insts_needed_s) -- Need to get defns for all these
- ) `thenTc` \ (const_lie, super_binds) ->
+ (unionManyBags insts_needed_s) -- Need to get defns for all these
+ `thenTc` \ (const_lie1, op_binds) ->
+
+ -- Deal with the super-class bindings
+ -- Ignore errors because they come from the *next* tcSimplify
+ discardErrsTc (
+ tcSimplifyAndCheck (text "inst decl1b")
+ inst_tyvars_set
+ dfun_arg_dicts -- NB! Don't include this_dict here, else the sc_dicts
+ -- get bound by just selecting from this_dict!!
+ sc_dicts
+ ) `thenTc` \ (const_lie2, sc_binds) ->
+
-- Check that we *could* construct the superclass dictionaries,
-- even though we are *actually* going to pass the superclass dicts in;
-- the check ensures that the caller will never have a problem building
-- them.
- tcAddErrCtxt superClassSigCtxt (
- tcSimplifyAndCheck
- inst_tyvars_set' -- Local tyvars
+ tcSimplifyAndCheck (text "inst decl1c")
+ inst_tyvars_set -- Local tyvars
inst_decl_dicts -- The instance dictionaries available
sc_dicts -- The superclass dicationaries reqd
- ) `thenTc_`
+ `thenTc_`
-- Ignore the result; we're only doing
-- this to make sure it can be done.
-- Create the result bindings
let
- dict_bind = VarMonoBind this_dict_id (Dictionary sc_dict_ids meth_ids)
+ const_lie = const_lie1 `plusLIE` const_lie2
+ lie_binds = op_binds `AndMonoBinds` sc_binds
+
+ dict_constr = classDataCon clas
+
+ con_app = foldl HsApp (TyApp (HsVar (RealId dict_constr)) inst_tys')
+ (map HsVar (sc_dict_ids ++ meth_ids))
+ -- We don't produce a binding for the dict_constr; instead we
+ -- rely on the simplifier to unfold this saturated application
+
+ dict_bind = VarMonoBind this_dict_id con_app
method_binds = andMonoBinds method_binds_s
main_bind
= AbsBinds
- inst_tyvars'
+ zonked_inst_tyvars
dfun_arg_dicts_ids
[(inst_tyvars', RealId dfun_id, this_dict_id)]
- (super_binds `AndMonoBinds`
+ (lie_binds `AndMonoBinds`
method_binds `AndMonoBinds`
dict_bind)
in
\begin{code}
tcInstMethodBind
:: Class
- -> TcType s -- Instance type
+ -> [TcType s] -- Instance types
+ -> [TcTyVar s] -- and their free (sig) tyvars
-> RenamedMonoBinds -- Method binding
-> (Id, Maybe Id) -- Selector id and default-method id
-> TcM s (TcMonoBinds s, LIE s, (LIE s, TcIdOcc s))
-tcInstMethodBind clas inst_ty meth_binds (sel_id, maybe_dm_id)
+tcInstMethodBind clas inst_tys inst_tyvars meth_binds (sel_id, maybe_dm_id)
= tcGetSrcLoc `thenNF_Tc` \ loc ->
tcGetUnique `thenNF_Tc` \ uniq ->
let
maybe_meth_bind = find meth_occ meth_binds
the_meth_bind = case maybe_meth_bind of
Just stuff -> stuff
- Nothing -> mk_default_bind default_meth_name
+ Nothing -> mk_default_bind default_meth_name loc
in
-- Warn if no method binding, only if -fwarn-missing-methods
(omittedMethodWarn sel_id clas) `thenNF_Tc_`
-- Typecheck the method binding
- tcMethodBind clas origin inst_ty sel_id the_meth_bind
+ tcMethodBind clas origin inst_tys inst_tyvars sel_id the_meth_bind
where
origin = InstanceDeclOrigin -- Poor
find occ other = panic "Urk! Bad instance method binding"
- mk_default_bind local_meth_name
+ mk_default_bind local_meth_name loc
= PatMonoBind (VarPatIn local_meth_name)
- (GRHSsAndBindsIn [OtherwiseGRHS default_expr noSrcLoc] EmptyBinds)
- noSrcLoc
+ (GRHSsAndBindsIn (unguardedRHS (default_expr loc) loc) EmptyBinds)
+ loc
- default_expr = case maybe_dm_id of
- Just dm_id -> HsVar (getName dm_id) -- There's a default method
- Nothing -> error_expr -- No default method
+ default_expr loc
+ = case maybe_dm_id of
+ Just dm_id -> HsVar (getName dm_id) -- There's a default method
+ Nothing -> error_expr loc -- No default method
- error_expr = HsApp (HsVar (getName nO_DEFAULT_METHOD_ERROR_ID))
- (HsLit (HsString (_PK_ error_msg)))
+ error_expr loc
+ = HsApp (HsVar (getName nO_METHOD_BINDING_ERROR_ID))
+ (HsLit (HsString (_PK_ (error_msg loc))))
+
+ error_msg loc = showSDoc (hcat [ppr loc, text "|", ppr sel_id ])
- error_msg = show (hcat [ppr (PprForUser opt_PprUserLength) (getSrcLoc sel_id), text "|",
- ppr (PprForUser opt_PprUserLength) sel_id
- ])
\end{code}
babyTcMtoTcM (tcInstanceType ce tce tmpl_e True src_loc ty)
`thenTc` \ inst_ty ->
let
- maybe_tycon = case maybeAppDataTyCon inst_ty of
+ maybe_tycon = case splitAlgTyConApp_maybe inst_ty of
Just (tc,_,_) -> Just tc
Nothing -> Nothing
tv_tmpl_map = zipEqual "tcSpecInstSig" inst_tv_tys inst_tmpl_tys
tv_to_tmpl tv = assoc "tcSpecInstSig" tv_tmpl_map tv
in
- mkInstanceRelatedIds
- clas inst_tmpls inst_ty simpl_theta uprag
+ mkInstanceRelatedIds clas inst_tmpls inst_ty simpl_theta uprag
`thenNF_Tc` \ (dfun_id, dfun_theta, const_meth_ids) ->
getSwitchCheckerTc `thenNF_Tc` \ sw_chkr ->
(if sw_chkr SpecialiseTrace then
pprTrace "Specialised Instance: "
- (vcat [hsep [if null simpl_theta then empty else ppr PprDebug simpl_theta,
+ (vcat [hsep [if null simpl_theta then empty else ppr simpl_theta,
if null simpl_theta then empty else ptext SLIT("=>"),
- ppr PprDebug clas,
- pprParendGenType PprDebug inst_ty],
+ ppr clas,
+ pprParendGenType inst_ty],
hsep [ptext SLIT(" derived from:"),
- if null unspec_theta then empty else ppr PprDebug unspec_theta,
+ if null unspec_theta then empty else ppr unspec_theta,
if null unspec_theta then empty else ptext SLIT("=>"),
- ppr PprDebug clas,
- pprParendGenType PprDebug unspec_inst_ty]])
+ ppr clas,
+ pprParendGenType unspec_inst_ty]])
else id) (
returnTc (unitBag (InstInfo clas inst_tmpls inst_ty simpl_theta
Just tycon -> match_tycon tycon
Nothing -> match_fun
- match_tycon tycon inst_ty = case (maybeAppDataTyCon inst_ty) of
+ match_tycon tycon inst_ty = case (splitAlgTyConApp_maybe inst_ty) of
Just (inst_tc,_,_) -> tycon == inst_tc
Nothing -> False
is_plain_instance inst_ty
- = case (maybeAppDataTyCon inst_ty) of
+ = case (splitAlgTyConApp_maybe inst_ty) of
Just (_,tys,_) -> all isTyVarTemplateTy tys
Nothing -> case maybeUnpackFunTy inst_ty of
Just (arg, res) -> isTyVarTemplateTy arg && isTyVarTemplateTy res
We can also have instances for functions: @instance Foo (a -> b) ...@.
\begin{code}
-scrutiniseInstanceType dfun_name clas inst_tau
- -- TYCON CHECK
- | not (maybeToBool inst_tycon_maybe) || isSynTyCon inst_tycon
- = failTc (instTypeErr inst_tau)
-
- -- IMPORTED INSTANCES ARE OK (but see tcInstDecl1)
- | not (isLocallyDefined dfun_name)
- = returnTc (inst_tycon,arg_tys)
-
- -- TYVARS CHECK
- | not (opt_GlasgowExts ||
- (all isTyVarTy arg_tys && null tyvar_dups)
- )
- = 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 `elem` (derivedClasses inst_tycon)
- && all isTyVarTy arg_tys
- = failTc (derivingWhenInstanceExistsErr clas inst_tycon)
-
- | -- CCALL CHECK
+scrutiniseInstanceType clas inst_taus
+ | -- CCALL CHECK (a).... urgh!
-- To verify that a user declaration of a CCallable/CReturnable
-- instance is OK, we must be able to see the constructor(s)
-- of the instance type (see next guard.)
--
(uniqueOf clas == cCallableClassKey && not constructors_visible) ||
(uniqueOf clas == cReturnableClassKey && not constructors_visible)
- = failTc (invisibleDataConPrimCCallErr clas inst_tau)
+ = failWithTc (invisibleDataConPrimCCallErr clas first_inst_tau)
- | -- CCALL CHECK
+ | -- CCALL CHECK (b)
-- A user declaration of a CCallable/CReturnable instance
-- must be for a "boxed primitive" type.
- (uniqueOf clas == cCallableClassKey && not (ccallable_type inst_tau)) ||
- (uniqueOf clas == cReturnableClassKey && not (creturnable_type inst_tau))
- = failTc (nonBoxedPrimCCallErr clas inst_tau)
+ (uniqueOf clas == cCallableClassKey && not (ccallable_type first_inst_tau)) ||
+ (uniqueOf clas == cReturnableClassKey && not (creturnable_type first_inst_tau))
+ = failWithTc (nonBoxedPrimCCallErr clas first_inst_tau)
+
+ -- DERIVING CHECK
+ -- It is obviously illegal to have an explicit instance
+ -- for something that we are also planning to `derive'
+ | clas `elem` (tyConDerivings inst_tycon)
+ = failWithTc (derivingWhenInstanceExistsErr clas first_inst_tau)
+ -- Kind check will have ensured inst_taus is of length 1
+
+ -- ALL TYPE VARIABLES => bad
+ | all isTyVarTy inst_taus
+ = failWithTc (instTypeErr clas inst_taus (text "all the instance types are type variables"))
+
+ -- WITH HASKELL 1.4, MUST HAVE C (T a b c)
+ | not opt_GlasgowExts
+ && not (length inst_taus == 1 &&
+ maybeToBool tyconapp_maybe &&
+ not (isSynTyCon inst_tycon) &&
+ all isTyVarTy arg_tys &&
+ length (tyVarSetToList (tyVarsOfTypes arg_tys)) == length arg_tys
+ -- This last condition checks that all the type variables are distinct
+ )
+ = failWithTc (instTypeErr clas inst_taus
+ (text "the instance type must be of form (T a b c)" $$
+ text "where T is not a synonym, and a,b,c are distinct type variables")
+ )
| otherwise
- = returnTc (inst_tycon,arg_tys)
+ = returnTc ()
where
- (possible_tycon, arg_tys) = splitAppTys inst_tau
- inst_tycon_maybe = getTyCon_maybe possible_tycon
- inst_tycon = expectJust "tcInstDecls1:inst_tycon" inst_tycon_maybe
- (_, tyvar_dups) = removeDups cmp (map (getTyVar "tcInstDecls1:getTyVarTy") arg_tys)
+ tyconapp_maybe = splitTyConApp_maybe first_inst_tau
+ Just (inst_tycon, arg_tys) = tyconapp_maybe
+ (first_inst_tau : _) = inst_taus
constructors_visible =
- case maybeAppDataTyCon inst_tau of
+ case splitAlgTyConApp_maybe first_inst_tau of
Just (_,_,[]) -> False
everything_else -> True
-- These conditions come directly from what the DsCCall is capable of.
-- Totally grotesque. Green card should solve this.
-ccallable_type ty = isPrimType ty || -- Allow CCallable Int# etc
+ccallable_type ty = isUnpointedType ty || -- Allow CCallable Int# etc
maybeToBool (maybeBoxedPrimType ty) || -- Ditto Int etc
- ty `eqTy` stringTy ||
+ ty == stringTy ||
byte_arr_thing
where
- byte_arr_thing = case maybeAppDataTyCon ty of
+ byte_arr_thing = case splitAlgTyConApp_maybe ty of
Just (tycon, ty_args, [data_con]) | isDataTyCon tycon ->
length data_con_arg_tys == 2 &&
maybeToBool maybe_arg2_tycon &&
where
data_con_arg_tys = dataConArgTys data_con ty_args
(data_con_arg_ty1 : data_con_arg_ty2 : _) = data_con_arg_tys
- maybe_arg2_tycon = maybeAppTyCon data_con_arg_ty2
+ maybe_arg2_tycon = splitTyConApp_maybe data_con_arg_ty2
Just (arg2_tycon,_) = maybe_arg2_tycon
other -> False
creturnable_type ty = maybeToBool (maybeBoxedPrimType ty) ||
-- Or, a data type with a single nullary constructor
- case (maybeAppDataTyCon ty) of
+ case (splitAlgTyConApp_maybe ty) of
Just (tycon, tys_applied, [data_con])
-> isNullaryDataCon data_con
other -> False
\begin{code}
-instTypeErr ty sty
- = case ty of
- SynTy tc _ _ -> hsep [ptext SLIT("The type synonym"), ppr sty tc, rest_of_msg]
- TyVarTy tv -> hsep [ptext SLIT("The type variable"), ppr sty tv, rest_of_msg]
- other -> sep [ptext SLIT("The type"), nest 4 (ppr sty ty), rest_of_msg]
- where
- rest_of_msg = ptext SLIT("cannot be used as an instance type")
+instTypeErr clas tys msg
+ = sep [ptext SLIT("Illegal instance declaration for") <+> quotes (pprConstraint clas tys),
+ nest 4 (parens msg)
+ ]
+
+instBndrErr bndr clas
+ = hsep [ptext SLIT("Class"), quotes (ppr clas), ptext SLIT("does not have a method"), quotes (ppr bndr)]
-derivingWhenInstanceExistsErr clas tycon sty
+derivingWhenInstanceExistsErr clas tycon
= hang (hsep [ptext SLIT("Deriving class"),
- ppr sty clas,
- ptext SLIT("type"), ppr sty tycon])
+ quotes (ppr clas),
+ ptext SLIT("type"), quotes (ppr tycon)])
4 (ptext SLIT("when an explicit instance exists"))
-nonBoxedPrimCCallErr clas inst_ty sty
+nonBoxedPrimCCallErr clas inst_ty
= hang (ptext SLIT("Unacceptable instance type for ccall-ish class"))
- 4 (hsep [ ptext SLIT("class"), ppr sty clas, ptext SLIT("type"),
- ppr sty inst_ty])
+ 4 (hsep [ ptext SLIT("class"), ppr clas, ptext SLIT("type"),
+ ppr inst_ty])
+
+omittedMethodWarn sel_id clas
+ = sep [ptext SLIT("No explicit method nor default method for") <+> quotes (ppr sel_id),
+ ptext SLIT("in an instance declaration for") <+> quotes (ppr clas)]
{-
Declaring CCallable & CReturnable instances in a module different
abstractly (either programmatically or by the renamer being over-eager
in its pruning.)
-}
-invisibleDataConPrimCCallErr clas inst_ty sty
- = hang (hsep [(ppr sty inst_ty <> ptext SLIT("s constructors not visible when checking")),
- ppr sty clas, ptext SLIT("instance")])
- 4 (hsep [ptext SLIT("(Try either importing"), ppr sty inst_ty,
- ptext SLIT("non-abstractly or compile using -fno-prune-tydecls ..)")])
-
-omittedMethodWarn sel_id clas sty
- = sep [ptext SLIT("Warning: no explicit method nor default method for") <+> ppr sty sel_id,
- ptext SLIT("in an instance declaration for") <+> ppr sty clas]
-
-instMethodNotInClassErr occ clas sty
+invisibleDataConPrimCCallErr clas inst_ty
+ = hang (hsep [ptext SLIT("Constructors for"), quotes (ppr inst_ty),
+ ptext SLIT("not visible when checking"),
+ quotes (ppr clas), ptext SLIT("instance")])
+ 4 (hsep [text "(Try either importing", ppr inst_ty,
+ text "non-abstractly or compile using -fno-prune-tydecls ..)"])
+
+instMethodNotInClassErr occ clas
= hang (ptext SLIT("Instance mentions a method not in the class"))
- 4 (hsep [ptext SLIT("class"), ppr sty clas, ptext SLIT("method"),
- ppr sty occ])
+ 4 (hsep [ptext SLIT("class") <+> quotes (ppr clas),
+ ptext SLIT("method") <+> quotes (ppr occ)])
-patMonoBindsCtxt pbind sty
+patMonoBindsCtxt pbind
= hang (ptext SLIT("In a pattern binding:"))
- 4 (ppr sty pbind)
+ 4 (ppr pbind)
-methodSigCtxt name ty sty
+methodSigCtxt name ty
= hang (hsep [ptext SLIT("When matching the definition of class method"),
- ppr sty name, ptext SLIT("to its signature :") ])
- 4 (ppr sty ty)
-
-bindSigCtxt sty
- = ptext SLIT("When checking methods of an instance declaration")
+ quotes (ppr name), ptext SLIT("to its signature :") ])
+ 4 (ppr ty)
-superClassSigCtxt sty
- = ptext SLIT("When checking superclass constraints of an instance declaration")
+superClassCtxt = ptext SLIT("From the superclasses of the instance declaration")
\end{code}
projects / ghc-hetmet.git / blobdiff