import CmdLineOpts ( DynFlag(..), dopt )
-import HsSyn ( HsDecl(..), InstDecl(..), TyClDecl(..),
+import HsSyn ( HsDecl(..), InstDecl(..), TyClDecl(..), HsType(..),
MonoBinds(..), HsExpr(..), HsLit(..), Sig(..),
- andMonoBindList, collectMonoBinders, isClassDecl
+ andMonoBindList, collectMonoBinders, isClassDecl, toHsType
)
-import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedHsDecl, RenamedMonoBinds,
- RenamedTyClDecl, RenamedHsType,
+import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedHsDecl,
+ RenamedMonoBinds, RenamedTyClDecl, RenamedHsType,
extractHsTyVars, maybeGenericMatch
)
import TcHsSyn ( TcMonoBinds, mkHsConApp )
import TcBinds ( tcSpecSigs )
import TcClassDcl ( tcMethodBind, badMethodErr )
import TcMonad
+import TcType ( tcInstType )
import Inst ( InstOrigin(..),
- newDicts, newClassDicts,
- LIE, emptyLIE, plusLIE, plusLIEs )
+ newDicts, instToId,
+ LIE, mkLIE, emptyLIE, plusLIE, plusLIEs )
import TcDeriv ( tcDeriving )
import TcEnv ( TcEnv, tcExtendGlobalValEnv,
tcExtendTyVarEnvForMeths,
- tcAddImportedIdInfo, tcInstId, tcLookupClass,
- InstInfo(..), pprInstInfo, simpleInstInfoTyCon, simpleInstInfoTy,
- newDFunName, tcExtendTyVarEnv
+ tcAddImportedIdInfo, tcLookupClass,
+ InstInfo(..), pprInstInfo, simpleInstInfoTyCon,
+ simpleInstInfoTy, newDFunName, tcExtendTyVarEnv,
+ isLocalThing,
)
import InstEnv ( InstEnv, extendInstEnv )
-import TcMonoType ( tcTyVars, tcHsSigType, kcHsSigType )
-import TcSimplify ( tcSimplifyAndCheck )
-import TcType ( zonkTcSigTyVars )
+import TcMonoType ( tcTyVars, tcHsSigType, kcHsSigType, checkSigTyVars )
+import TcSimplify ( tcSimplifyCheck )
import HscTypes ( HomeSymbolTable, DFunId,
ModDetails(..), PackageInstEnv, PersistentRenamerState
)
-import Bag ( unionManyBags )
import DataCon ( classDataCon )
import Class ( Class, DefMeth(..), classBigSig )
import Var ( idName, idType )
+import VarSet ( emptyVarSet )
import Maybes ( maybeToBool )
import MkId ( mkDictFunId )
+import FunDeps ( checkInstFDs )
import Generics ( validGenericInstanceType )
import Module ( Module, foldModuleEnv )
import Name ( getSrcLoc )
-import NameSet ( emptyNameSet, nameSetToList )
+import NameSet ( emptyNameSet, unitNameSet, nameSetToList )
import PrelInfo ( eRROR_ID )
-import PprType ( pprConstraint, pprPred )
+import PprType ( pprClassPred, pprPred )
import TyCon ( TyCon, isSynTyCon )
import Type ( splitDFunTy, isTyVarTy,
splitTyConApp_maybe, splitDictTy,
splitForAllTys,
tyVarsOfTypes, mkClassPred, mkTyVarTy,
- getClassTys_maybe
+ isTyVarClassPred, inheritablePred
)
-import Subst ( mkTopTyVarSubst, substClasses )
-import VarSet ( mkVarSet, varSetElems )
-import TysWiredIn ( genericTyCons, isFFIArgumentTy, isFFIResultTy )
+import Subst ( mkTopTyVarSubst, substTheta )
+import VarSet ( varSetElems )
+import TysWiredIn ( genericTyCons, isFFIArgumentTy, isFFIImportResultTy )
import PrelNames ( cCallableClassKey, cReturnableClassKey, hasKey )
import Name ( Name )
import SrcLoc ( SrcLoc )
-> TcEnv -- Contains IdInfo for dfun ids
-> (Name -> Maybe Fixity) -- for deriving Show and Read
-> Module -- Module for deriving
- -> [TyCon]
-> [RenamedHsDecl]
-> TcM (PackageInstEnv, InstEnv, [InstInfo], RenamedHsBinds)
-tcInstDecls1 inst_env0 prs hst unf_env get_fixity mod tycons decls
+tcInstDecls1 inst_env0 prs hst unf_env get_fixity this_mod decls
= let
inst_decls = [inst_decl | InstD inst_decl <- decls]
tycl_decls = [decl | TyClD decl <- decls]
clas_decls = filter isClassDecl tycl_decls
in
-- (1) Do the ordinary instance declarations
- mapNF_Tc (tcInstDecl1 mod unf_env) inst_decls `thenNF_Tc` \ inst_infos ->
+ mapNF_Tc tcInstDecl1 inst_decls `thenNF_Tc` \ inst_infos ->
-- (2) Instances from generic class declarations
- getGenericInstances mod clas_decls `thenTc` \ generic_inst_info ->
+ getGenericInstances clas_decls `thenTc` \ generic_inst_info ->
-- Next, construct the instance environment so far, consisting of
-- a) cached non-home-package InstEnv (gotten from pcs) pcs_insts pcs
-- e) generic instances inst_env4
-- The result of (b) replaces the cached InstEnv in the PCS
let
- (local_inst_info, imported_inst_info) = partition iLocal (concat inst_infos)
+ (local_inst_info, imported_inst_info)
+ = partition (isLocalThing this_mod . iDFunId) (concat inst_infos)
imported_dfuns = map (tcAddImportedIdInfo unf_env . iDFunId)
imported_inst_info
-- we ignore deriving decls from interfaces!
-- This stuff computes a context for the derived instance decl, so it
-- needs to know about all the instances possible; hecne inst_env4
- tcDeriving prs mod inst_env4 get_fixity tycl_decls `thenTc` \ (deriv_inst_info, deriv_binds) ->
+ tcDeriving prs this_mod inst_env4 get_fixity tycl_decls
+ `thenTc` \ (deriv_inst_info, deriv_binds) ->
addInstInfos inst_env4 deriv_inst_info `thenNF_Tc` \ final_inst_env ->
returnTc (inst_env1,
addInstDFuns :: InstEnv -> [DFunId] -> NF_TcM InstEnv
addInstDFuns dfuns infos
= getDOptsTc `thenTc` \ dflags ->
- extendInstEnv dflags dfuns infos `bind` \ (inst_env', errs) ->
+ let
+ (inst_env', errs) = extendInstEnv dflags dfuns infos
+ in
addErrsTc errs `thenNF_Tc_`
returnTc inst_env'
- where
- bind x f = f x
-
\end{code}
\begin{code}
-tcInstDecl1 :: Module -> TcEnv -> RenamedInstDecl -> NF_TcM [InstInfo]
+tcInstDecl1 :: RenamedInstDecl -> NF_TcM [InstInfo]
-- Deal with a single instance declaration
-tcInstDecl1 mod unf_env (InstDecl poly_ty binds uprags maybe_dfun_name src_loc)
+tcInstDecl1 decl@(InstDecl poly_ty binds uprags maybe_dfun_name src_loc)
= -- Prime error recovery, set source location
recoverNF_Tc (returnNF_Tc []) $
tcAddSrcLoc src_loc $
-- Type-check all the stuff before the "where"
- tcHsSigType poly_ty `thenTc` \ poly_ty' ->
+ tcAddErrCtxt (instDeclCtxt poly_ty) (
+ tcHsSigType poly_ty
+ ) `thenTc` \ poly_ty' ->
let
(tyvars, theta, clas, inst_tys) = splitDFunTy poly_ty'
in
-- Imported ones should have been checked already, and may indeed
-- contain something illegal in normal Haskell, notably
-- instance CCallable [Char]
- scrutiniseInstanceHead clas inst_tys `thenNF_Tc_`
- mapNF_Tc scrutiniseInstanceConstraint theta `thenNF_Tc_`
+ getDOptsTc `thenTc` \ dflags ->
+ checkInstValidity dflags theta clas inst_tys `thenTc_`
-- Make the dfun id and return it
- newDFunName mod clas inst_tys src_loc `thenNF_Tc` \ dfun_name ->
+ newDFunName clas inst_tys src_loc `thenNF_Tc` \ dfun_name ->
returnNF_Tc (True, dfun_name)
Just dfun_name -> -- An interface-file instance declaration
let
dfun_id = mkDictFunId dfun_name clas tyvars inst_tys theta
in
- returnTc [InstInfo { iLocal = is_local, iDFunId = dfun_id,
+ returnTc [InstInfo { iDFunId = dfun_id,
iBinds = binds, iPrags = uprags }]
\end{code}
\begin{code}
-getGenericInstances :: Module -> [RenamedTyClDecl] -> TcM [InstInfo]
-getGenericInstances mod class_decls
- = mapTc (get_generics mod) class_decls `thenTc` \ gen_inst_infos ->
+getGenericInstances :: [RenamedTyClDecl] -> TcM [InstInfo]
+getGenericInstances class_decls
+ = mapTc get_generics class_decls `thenTc` \ gen_inst_infos ->
let
gen_inst_info = concat gen_inst_infos
in
+ if null gen_inst_info then
+ returnTc []
+ else
getDOptsTc `thenTc` \ dflags ->
ioToTc (dumpIfSet_dyn dflags Opt_D_dump_deriv "Generic instances"
(vcat (map pprInstInfo gen_inst_info)))
`thenNF_Tc_`
returnTc gen_inst_info
-get_generics mod decl@(ClassDecl context class_name tyvar_names
- fundeps class_sigs def_methods
- name_list loc)
+get_generics decl@(ClassDecl {tcdMeths = Nothing})
+ = returnTc [] -- Imported class decls
+
+get_generics decl@(ClassDecl {tcdName = class_name, tcdMeths = Just def_methods, tcdLoc = loc})
| null groups
- = returnTc [] -- The comon case:
- -- no generic default methods, or
- -- its an imported class decl (=> has no methods at all)
+ = returnTc [] -- The comon case: no generic default methods
| otherwise -- A local class decl with generic default methods
= recoverNF_Tc (returnNF_Tc []) $
tcLookupClass class_name `thenTc` \ clas ->
-- Make an InstInfo out of each group
- mapTc (mkGenericInstance mod clas loc) groups `thenTc` \ inst_infos ->
+ mapTc (mkGenericInstance clas loc) groups `thenTc` \ inst_infos ->
-- Check that there is only one InstInfo for each type constructor
-- The main way this can fail is if you write
wrap ms = FunMonoBind id infixop ms loc
---------------------------------
-mkGenericInstance :: Module -> Class -> SrcLoc
+mkGenericInstance :: Class -> SrcLoc
-> (RenamedHsType, RenamedMonoBinds)
-> TcM InstInfo
-mkGenericInstance mod clas loc (hs_ty, binds)
+mkGenericInstance clas loc (hs_ty, binds)
-- Make a generic instance declaration
-- For example: instance (C a, C b) => C (a+b) where { binds }
(badGenericInstanceType binds) `thenTc_`
-- Make the dictionary function.
- newDFunName mod clas [inst_ty] loc `thenNF_Tc` \ dfun_name ->
+ newDFunName clas [inst_ty] loc `thenNF_Tc` \ dfun_name ->
let
inst_theta = [mkClassPred clas [mkTyVarTy tv] | tv <- tyvars]
inst_tys = [inst_ty]
dfun_id = mkDictFunId dfun_name clas tyvars inst_tys inst_theta
in
- returnTc (InstInfo { iLocal = True, iDFunId = dfun_id,
+ returnTc (InstInfo { iDFunId = dfun_id,
iBinds = binds, iPrags = [] })
\end{code}
First comes the easy case of a non-local instance decl.
+
\begin{code}
tcInstDecl2 :: InstInfo -> NF_TcM (LIE, TcMonoBinds)
+-- tcInstDecl2 is called *only* on InstInfos
-tcInstDecl2 (InstInfo { iLocal = is_local, iDFunId = dfun_id,
+tcInstDecl2 (InstInfo { iDFunId = dfun_id,
iBinds = monobinds, iPrags = uprags })
- | not is_local
- = returnNF_Tc (emptyLIE, EmptyMonoBinds)
-
- | otherwise
= -- Prime error recovery
- recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $
- tcAddSrcLoc (getSrcLoc dfun_id) $
+ recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $
+ tcAddSrcLoc (getSrcLoc dfun_id) $
+ tcAddErrCtxt (instDeclCtxt (toHsType (idType dfun_id))) $
-- Instantiate the instance decl with tc-style type variables
- tcInstId dfun_id `thenNF_Tc` \ (inst_tyvars', dfun_theta', dict_ty') ->
+ tcInstType (idType dfun_id) `thenNF_Tc` \ (inst_tyvars', dfun_theta', dict_ty') ->
let
(clas, inst_tys') = splitDictTy dict_ty'
origin = InstanceDeclOrigin
sel_names = [idName sel_id | (sel_id, _) <- op_items]
-- Instantiate the super-class context with inst_tys
- sc_theta' = substClasses (mkTopTyVarSubst class_tyvars inst_tys') sc_theta
+ sc_theta' = substTheta (mkTopTyVarSubst class_tyvars inst_tys') sc_theta
-- Find any definitions in monobinds that aren't from the class
bad_bndrs = collectMonoBinders monobinds `minusList` sel_names
mapTc (addErrTc . badMethodErr clas) bad_bndrs `thenNF_Tc_`
-- Create dictionary Ids from the specified instance contexts.
- newClassDicts origin sc_theta' `thenNF_Tc` \ (sc_dicts, sc_dict_ids) ->
- newDicts origin dfun_theta' `thenNF_Tc` \ (dfun_arg_dicts, dfun_arg_dicts_ids) ->
- newClassDicts origin [(clas,inst_tys')] `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
+ newDicts origin sc_theta' `thenNF_Tc` \ sc_dicts ->
+ newDicts origin dfun_theta' `thenNF_Tc` \ dfun_arg_dicts ->
+ newDicts origin [mkClassPred clas inst_tys'] `thenNF_Tc` \ [this_dict] ->
tcExtendTyVarEnvForMeths inst_tyvars inst_tyvars' (
tcExtendGlobalValEnv dm_ids (
dfun_theta'
monobinds uprags True)
op_items
- )) `thenTc` \ (method_binds_s, insts_needed_s, meth_lies_w_ids) ->
+ )) `thenTc` \ (method_binds_s, insts_needed_s, meth_insts) ->
-- Deal with SPECIALISE instance pragmas by making them
-- look like SPECIALISE pragmas for the dfun
) `thenTc` \ (prag_binds, prag_lie) ->
-- Check the overloading constraints of the methods and superclasses
-
- -- tcMethodBind has checked that the class_tyvars havn't
- -- been unified with each other or another type, but we must
- -- still zonk them before passing them to tcSimplifyAndCheck
- zonkTcSigTyVars inst_tyvars' `thenNF_Tc` \ zonked_inst_tyvars ->
let
- inst_tyvars_set = mkVarSet zonked_inst_tyvars
-
- (meth_lies, meth_ids) = unzip meth_lies_w_ids
-
-- These insts are in scope; quite a few, eh?
- avail_insts = this_dict `plusLIE`
- dfun_arg_dicts `plusLIE`
- sc_dicts `plusLIE`
- unionManyBags meth_lies
+ avail_insts = [this_dict] ++
+ dfun_arg_dicts ++
+ sc_dicts ++
+ meth_insts
- methods_lie = plusLIEs insts_needed_s
+ methods_lie = plusLIEs insts_needed_s
in
-- Simplify the constraints from methods
tcAddErrCtxt methodCtxt (
- tcSimplifyAndCheck
+ tcSimplifyCheck
(ptext SLIT("instance declaration context"))
- inst_tyvars_set -- Local tyvars
+ inst_tyvars'
avail_insts
methods_lie
) `thenTc` \ (const_lie1, lie_binds1) ->
-- Figure out bindings for the superclass context
tcAddErrCtxt superClassCtxt (
- tcSimplifyAndCheck
+ tcSimplifyCheck
(ptext SLIT("instance declaration context"))
- inst_tyvars_set
+ inst_tyvars'
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, lie_binds2) ->
-
+ (mkLIE sc_dicts)
+ ) `thenTc` \ (const_lie2, lie_binds2) ->
+
+ checkSigTyVars inst_tyvars' emptyVarSet `thenNF_Tc` \ zonked_inst_tyvars ->
-- Create the result bindings
let
dict_constr = classDataCon clas
- scs_and_meths = sc_dict_ids ++ meth_ids
+ scs_and_meths = map instToId (sc_dicts ++ meth_insts)
+ this_dict_id = instToId this_dict
+ inlines = unitNameSet (idName dfun_id)
+ -- Always inline the dfun; this is an experimental decision
+ -- because it makes a big performance difference sometimes.
+ -- Often it means we can do the method selection, and then
+ -- inline the method as well. Marcin's idea.
dict_rhs
| null scs_and_meths
(HsLit (HsString msg))
| otherwise -- The common case
- = mkHsConApp dict_constr inst_tys' (map HsVar (sc_dict_ids ++ meth_ids))
+ = mkHsConApp dict_constr inst_tys' (map HsVar scs_and_meths)
-- We don't produce a binding for the dict_constr; instead we
-- rely on the simplifier to unfold this saturated application
-- We do this rather than generate an HsCon directly, because
main_bind
= AbsBinds
zonked_inst_tyvars
- dfun_arg_dicts_ids
+ (map instToId dfun_arg_dicts)
[(inst_tyvars', dfun_id, this_dict_id)]
- emptyNameSet -- No inlines (yet)
+ inlines
(lie_binds1 `AndMonoBinds`
lie_binds2 `AndMonoBinds`
method_binds `AndMonoBinds`
We can also have instances for functions: @instance Foo (a -> b) ...@.
\begin{code}
-scrutiniseInstanceConstraint pred
- = getDOptsTc `thenTc` \ dflags -> case () of
- ()
- | dopt Opt_AllowUndecidableInstances dflags
- -> returnNF_Tc ()
-
- | Just (clas,tys) <- getClassTys_maybe pred,
- all isTyVarTy tys
- -> returnNF_Tc ()
-
- | otherwise
- -> addErrTc (instConstraintErr pred)
-
-scrutiniseInstanceHead clas inst_taus
- = getDOptsTc `thenTc` \ dflags -> case () of
- ()
- | -- CCALL CHECK
+checkInstValidity dflags theta clas inst_tys
+ | null errs = returnTc ()
+ | otherwise = addErrsTc errs `thenNF_Tc_` failTc
+ where
+ errs = checkInstHead dflags theta clas inst_tys ++
+ [err | pred <- theta, err <- checkInstConstraint dflags pred]
+
+checkInstConstraint dflags pred
+ -- Checks whether a predicate is legal in the
+ -- context of an instance declaration
+ | ok = []
+ | otherwise = [instConstraintErr pred]
+ where
+ ok = inheritablePred pred &&
+ (isTyVarClassPred pred || arbitrary_preds_ok)
+
+ arbitrary_preds_ok = dopt Opt_AllowUndecidableInstances dflags
+
+
+checkInstHead dflags theta clas inst_taus
+ | -- CCALL CHECK
-- A user declaration of a CCallable/CReturnable instance
-- must be for a "boxed primitive" type.
(clas `hasKey` cCallableClassKey
||
(clas `hasKey` cReturnableClassKey
&& not (creturnable_type first_inst_tau))
- -> addErrTc (nonBoxedPrimCCallErr clas first_inst_tau)
-
- -- Allow anything for AllowUndecidableInstances
- | dopt Opt_AllowUndecidableInstances dflags
- -> returnNF_Tc ()
+ = [nonBoxedPrimCCallErr clas first_inst_tau]
-- If GlasgowExts then check at least one isn't a type variable
- | dopt Opt_GlasgowExts dflags
- -> if all isTyVarTy inst_taus
- then addErrTc (instTypeErr clas inst_taus
- (text "There must be at least one non-type-variable in the instance head"))
- else returnNF_Tc ()
+ | dopt Opt_GlasgowExts dflags
+ = -- GlasgowExts case
+ check_tyvars dflags clas inst_taus ++ check_fundeps dflags theta clas inst_taus
-- WITH HASKELL 1.4, MUST HAVE C (T a b c)
- | not (length inst_taus == 1 &&
- maybeToBool maybe_tycon_app && -- Yes, there's a type constuctor
- not (isSynTyCon tycon) && -- ...but not a synonym
- all isTyVarTy arg_tys && -- Applied to type variables
- length (varSetElems (tyVarsOfTypes arg_tys)) == length arg_tys
- -- This last condition checks that all the type variables are distinct
- )
- -> addErrTc (instTypeErr clas inst_taus
- (text "the instance type must be of form (T a b c)" $$
- text "where T is not a synonym, and a,b,c are distinct type variables")
- )
-
- | otherwise
- -> returnNF_Tc ()
+ | not (length inst_taus == 1 &&
+ maybeToBool maybe_tycon_app && -- Yes, there's a type constuctor
+ not (isSynTyCon tycon) && -- ...but not a synonym
+ all isTyVarTy arg_tys && -- Applied to type variables
+ length (varSetElems (tyVarsOfTypes arg_tys)) == length arg_tys
+ -- This last condition checks that all the type variables are distinct
+ )
+ = [instTypeErr clas inst_taus
+ (text "the instance type must be of form (T a b c)" $$
+ text "where T is not a synonym, and a,b,c are distinct type variables")]
+
+ | otherwise
+ = []
where
(first_inst_tau : _) = inst_taus
Just (tycon, arg_tys) = maybe_tycon_app
ccallable_type dflags ty = isFFIArgumentTy dflags False {- Not safe call -} ty
- creturnable_type ty = isFFIResultTy ty
+ creturnable_type ty = isFFIImportResultTy dflags ty
+
+check_tyvars dflags clas inst_taus
+ -- Check that at least one isn't a type variable
+ -- unless -fallow-undecideable-instances
+ | dopt Opt_AllowUndecidableInstances dflags = []
+ | not (all isTyVarTy inst_taus) = []
+ | otherwise = [the_err]
+ where
+ the_err = instTypeErr clas inst_taus msg
+ msg = ptext SLIT("There must be at least one non-type-variable in the instance head")
+ $$ ptext SLIT("Use -fallow-undecidable-instances to lift this restriction")
+
+check_fundeps dflags theta clas inst_taus
+ | checkInstFDs theta clas inst_taus = []
+ | otherwise = [the_err]
+ where
+ the_err = instTypeErr clas inst_taus msg
+ msg = ptext SLIT("the instance types do not agree with the functional dependencies of the class")
\end{code}
\begin{code}
tcAddDeclCtxt decl thing_inside
- = tcAddSrcLoc loc $
+ = tcAddSrcLoc (tcdLoc decl) $
tcAddErrCtxt ctxt $
thing_inside
where
- (name, loc, thing)
- = case decl of
- (ClassDecl _ name _ _ _ _ _ loc) -> (name, loc, "class")
- (TySynonym name _ _ loc) -> (name, loc, "type synonym")
- (TyData NewType _ name _ _ _ _ loc _ _) -> (name, loc, "newtype")
- (TyData DataType _ name _ _ _ _ loc _ _) -> (name, loc, "data type")
+ thing = case decl of
+ ClassDecl {} -> "class"
+ TySynonym {} -> "type synonym"
+ TyData {tcdND = NewType} -> "newtype"
+ TyData {tcdND = DataType} -> "data type"
ctxt = hsep [ptext SLIT("In the"), text thing,
- ptext SLIT("declaration for"), quotes (ppr name)]
+ ptext SLIT("declaration for"), quotes (ppr (tcdName decl))]
+
+instDeclCtxt inst_ty = ptext SLIT("In the instance declaration for") <+> quotes doc
+ where
+ doc = case inst_ty of
+ HsForAllTy _ _ (HsPredTy pred) -> ppr pred
+ HsPredTy pred -> ppr pred
+ other -> ppr inst_ty -- Don't expect this
\end{code}
\begin{code}
ppr_inst_ty (tc,inst) = ppr (simpleInstInfoTy inst)
instTypeErr clas tys msg
- = sep [ptext SLIT("Illegal instance declaration for") <+> quotes (pprConstraint clas tys),
+ = sep [ptext SLIT("Illegal instance declaration for") <+>
+ quotes (pprClassPred clas tys),
nest 4 (parens msg)
]
nonBoxedPrimCCallErr clas inst_ty
= hang (ptext SLIT("Unacceptable instance type for ccall-ish class"))
- 4 (hsep [ ptext SLIT("class"), ppr clas, ptext SLIT("type"),
- ppr inst_ty])
+ 4 (pprClassPred clas [inst_ty])
methodCtxt = ptext SLIT("When checking the methods of an instance declaration")
superClassCtxt = ptext SLIT("When checking the super-classes of an instance declaration")
projects / ghc-hetmet.git / blobdiff