%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1995
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcClassDcl]{Typechecking class declarations}
\begin{code}
-module TcClassDcl ( tcClassDecl1, tcClassDecls2, tcMethodBind, badMethodErr ) where
+module TcClassDcl ( kcClassDecl, tcClassDecl1, tcClassDecls2, tcMethodBind, badMethodErr ) where
#include "HsVersions.h"
-import HsSyn ( HsDecl(..), ClassDecl(..), Sig(..), MonoBinds(..),
- InPat(..), HsBinds(..), GRHSsAndBinds(..), GRHS(..),
- HsExpr(..), HsLit(..),
- unguardedRHS, andMonoBinds, getTyVarName
+import HsSyn ( HsDecl(..), TyClDecl(..), Sig(..), MonoBinds(..),
+ InPat(..), HsBinds(..), GRHSs(..),
+ HsExpr(..), HsLit(..), HsType(..), pprClassAssertion,
+ unguardedRHS, andMonoBinds, andMonoBindList, getTyVarName,
+ isClassDecl
)
import HsPragmas ( ClassPragmas(..) )
-import BasicTypes ( NewOrData(..), TopLevelFlag(..), RecFlag(..) )
-import RnHsSyn ( RenamedClassDecl, RenamedClassPragmas,
+import BasicTypes ( NewOrData(..), TopLevelFlag(..), RecFlag(..), StrictnessMark(..) )
+import RnHsSyn ( RenamedTyClDecl, RenamedClassPragmas,
RenamedClassOpSig, RenamedMonoBinds,
RenamedContext, RenamedHsDecl, RenamedSig
)
import TcHsSyn ( TcMonoBinds )
import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, newDicts, newMethod )
-import TcEnv ( TcIdOcc(..), GlobalValueEnv, tcAddImportedIdInfo,
- tcLookupClass, tcLookupTyVar,
- tcExtendGlobalTyVars, tcExtendLocalValEnv
+import TcEnv ( TcId, ValueEnv, TcTyThing(..), tcAddImportedIdInfo,
+ tcLookupClass, tcLookupTy, tcExtendTyVarEnvForMeths, tcExtendGlobalTyVars,
+ tcExtendLocalValEnv
)
-import TcBinds ( tcBindWithSigs, bindInstsOfLocalFuns,
- checkSigTyVars, sigCtxt, tcPragmaSigs, TcSigInfo(..)
- )
-import TcKind ( unifyKinds, TcKind )
+import TcBinds ( tcBindWithSigs, tcPragmaSigs )
+import TcUnify ( unifyKinds )
import TcMonad
-import TcMonoType ( tcHsType, tcContext )
-import TcSimplify ( tcSimplifyAndCheck )
-import TcType ( TcType, TcTyVar, TcTyVarSet, tcInstSigTyVars,
- zonkSigTyVar, tcInstSigTcType
+import TcMonoType ( tcHsType, tcHsTopType, tcExtendTopTyVarScope,
+ tcContext, checkSigTyVars, sigCtxt, mkTcSig
)
+import TcSimplify ( tcSimplifyAndCheck, bindInstsOfLocalFuns )
+import TcType ( TcType, TcTyVar, tcInstTyVars, zonkTcTyVarBndr, tcGetTyVar )
import PrelVals ( nO_METHOD_BINDING_ERROR_ID )
import FieldLabel ( firstFieldLabelTag )
import Bag ( unionManyBags )
import Class ( mkClass, classBigSig, Class )
import CmdLineOpts ( opt_GlasgowExts, opt_WarnMissingMethods )
-import MkId ( mkDataCon, mkSuperDictSelId,
+import MkId ( mkSuperDictSelId, mkDataConId,
mkMethodSelId, mkDefaultMethodId
)
-import Id ( Id, StrictnessMark(..),
+import DataCon ( mkDataCon )
+import Id ( Id,
getIdUnfolding, idType, idName
)
import CoreUnfold ( getUnfoldingTemplate )
import IdInfo
-import Name ( Name, isLocallyDefined, OccName, nameOccName,
- NamedThing(..) )
+import Name ( Name, isLocallyDefined, NamedThing(..) )
import Outputable
-import Type ( mkFunTy, mkTyVarTy, mkTyVarTys, mkDictTy, splitRhoTy,
- mkSigmaTy, mkForAllTys, Type, ThetaType
+import Type ( mkFunTy, mkTyVarTy, mkTyVarTys, mkDictTy,
+ mkSigmaTy, mkForAllTys, Type, ThetaType,
+ boxedTypeKind, mkArrowKind
)
-import TyVar ( mkTyVarSet, tyVarKind, TyVar )
-import TyCon ( mkDataTyCon )
-import Kind ( mkBoxedTypeKind, mkArrowKind )
+import Var ( tyVarKind, TyVar )
+import VarSet ( mkVarSet )
+import TyCon ( mkAlgTyCon )
import Unique ( Unique, Uniquable(..) )
import Util
-import Maybes ( assocMaybe, maybeToBool, seqMaybe )
+import Maybes ( seqMaybe )
-- import TcPragmas ( tcGenPragmas, tcClassOpPragmas )
Death to "ExpandingDicts".
+%************************************************************************
+%* *
+\subsection{Kind checking}
+%* *
+%************************************************************************
+
\begin{code}
-tcClassDecl1 rec_env rec_inst_mapper
- (ClassDecl context class_name
+kcClassDecl (ClassDecl context class_name
tyvar_names class_sigs def_methods pragmas
tycon_name datacon_name src_loc)
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (classDeclCtxt class_name) $
-
- -- CHECK ARITY 1 FOR HASKELL 1.4
+ = -- CHECK ARITY 1 FOR HASKELL 1.4
checkTc (opt_GlasgowExts || length tyvar_names == 1)
(classArityErr class_name) `thenTc_`
- -- LOOK THINGS UP IN THE ENVIRONMENT
- tcLookupClass class_name `thenTc` \ (class_kinds, rec_class) ->
- mapAndUnzipNF_Tc (tcLookupTyVar . getTyVarName) tyvar_names
- `thenNF_Tc` \ (tyvar_kinds, rec_tyvars) ->
+ -- Get the (mutable) class kind
+ tcLookupTy class_name `thenNF_Tc` \ (kind, _, _) ->
+
+ -- Make suitable tyvars and do kind checking
+ -- The net effect is to mutate the class kind
+ tcExtendTopTyVarScope kind tyvar_names $ \ _ _ ->
+ tcContext context `thenTc_`
+ mapTc kc_sig class_sigs `thenTc_`
+
+ returnTc ()
+ where
+ kc_sig (ClassOpSig _ _ op_ty loc) = tcAddSrcLoc loc (tcHsType op_ty)
+\end{code}
+
- -- FORCE THE CLASS AND ITS TYVAR TO HAVE SAME KIND
- unifyKinds class_kinds tyvar_kinds `thenTc_`
+%************************************************************************
+%* *
+\subsection{Type checking}
+%* *
+%************************************************************************
+\begin{code}
+tcClassDecl1 rec_env rec_inst_mapper
+ (ClassDecl context class_name
+ tyvar_names class_sigs def_methods pragmas
+ tycon_name datacon_name src_loc)
+ = -- LOOK THINGS UP IN THE ENVIRONMENT
+ tcLookupTy class_name `thenTc` \ (class_kind, _, AClass rec_class) ->
+ tcExtendTopTyVarScope class_kind tyvar_names $ \ tyvars _ ->
+ -- The class kind is by now immutable
+
-- CHECK THE CONTEXT
- tcClassContext rec_class rec_tyvars context pragmas
+-- traceTc (text "tcClassCtxt" <+> ppr class_name) `thenTc_`
+ tcClassContext class_name rec_class tyvars context pragmas
`thenTc` \ (sc_theta, sc_tys, sc_sel_ids) ->
+-- traceTc (text "tcClassCtxt done" <+> ppr class_name) `thenTc_`
-- CHECK THE CLASS SIGNATURES,
- mapTc (tcClassSig rec_env rec_class rec_tyvars) class_sigs
+ mapTc (tcClassSig rec_env rec_class tyvars) class_sigs
`thenTc` \ sig_stuff ->
-- MAKE THE CLASS OBJECT ITSELF
let
(op_tys, op_sel_ids, defm_ids) = unzip3 sig_stuff
rec_class_inst_env = rec_inst_mapper rec_class
- clas = mkClass (getName class_name) rec_tyvars
+ clas = mkClass class_name tyvars
sc_theta sc_sel_ids op_sel_ids defm_ids
tycon
rec_class_inst_env
[_] -> NewType
other -> DataType
- dict_con_id = mkDataCon datacon_name
+ dict_con = mkDataCon datacon_name
[NotMarkedStrict | _ <- dict_component_tys]
[{- No labelled fields -}]
- rec_tyvars
+ tyvars
[{-No context-}]
[{-No existential tyvars-}] [{-Or context-}]
dict_component_tys
- tycon
+ tycon dict_con_id
+ dict_con_id = mkDataConId dict_con
- tycon = mkDataTyCon tycon_name
- (foldr (mkArrowKind . tyVarKind) mkBoxedTypeKind rec_tyvars)
- rec_tyvars
+ tycon = mkAlgTyCon tycon_name
+ class_kind
+ tyvars
[] -- No context
- [dict_con_id] -- Constructors
+ [dict_con] -- Constructors
[] -- No derivings
(Just clas) -- Yes! It's a dictionary
new_or_data
\begin{code}
-tcClassContext :: Class -> [TyVar]
+tcClassContext :: Name -> Class -> [TyVar]
-> RenamedContext -- class context
-> RenamedClassPragmas -- pragmas for superclasses
-> TcM s (ThetaType, -- the superclass context
[Type], -- types of the superclass dictionaries
[Id]) -- superclass selector Ids
-tcClassContext rec_class rec_tyvars context pragmas
+tcClassContext class_name rec_class rec_tyvars context pragmas
= -- Check the context.
-- The renamer has already checked that the context mentions
-- only the type variable of the class decl.
+
+ -- For std Haskell check that the context constrains only tyvars
+ (if opt_GlasgowExts then
+ returnTc []
+ else
+ mapTc check_constraint context
+ ) `thenTc_`
+
tcContext context `thenTc` \ sc_theta ->
+
let
sc_tys = [mkDictTy sc tys | (sc,tys) <- sc_theta]
in
in
returnTc (mkSuperDictSelId uniq rec_class index ty)
+ check_constraint (c, tys) = checkTc (all is_tyvar tys)
+ (superClassErr class_name (c, tys))
+
+ is_tyvar (MonoTyVar _) = True
+ is_tyvar other = False
+
-tcClassSig :: GlobalValueEnv -- Knot tying only!
+tcClassSig :: ValueEnv -- Knot tying only!
-> Class -- ...ditto...
-> [TyVar] -- The class type variable, used for error check only
-> RenamedClassOpSig
-- NB: Renamer checks that the class type variable is mentioned in local_ty,
-- and that it is not constrained by theta
- tcHsType op_ty `thenTc` \ local_ty ->
+-- traceTc (text "tcClassSig" <+> ppr op_name) `thenTc_`
+ tcHsTopType op_ty `thenTc` \ local_ty ->
let
global_ty = mkSigmaTy rec_clas_tyvars
[(rec_clas, mkTyVarTys rec_clas_tyvars)]
local_ty
- in
-- Build the selector id and default method id
- let
sel_id = mkMethodSelId op_name rec_clas global_ty
maybe_dm_id = case maybe_dm_name of
Nothing -> Nothing
in
Just (tcAddImportedIdInfo rec_env dm_id)
in
+-- traceTc (text "tcClassSig done" <+> ppr op_name) `thenTc_`
returnTc (local_ty, sel_id, maybe_dm_id)
\end{code}
\begin{code}
tcClassDecls2 :: [RenamedHsDecl]
- -> NF_TcM s (LIE s, TcMonoBinds s)
+ -> NF_TcM s (LIE, TcMonoBinds)
tcClassDecls2 decls
= foldr combine
(returnNF_Tc (emptyLIE, EmptyMonoBinds))
- [tcClassDecl2 cls_decl | ClD cls_decl <- decls]
+ [tcClassDecl2 cls_decl | TyClD cls_decl <- decls, isClassDecl cls_decl]
where
combine tc1 tc2 = tc1 `thenNF_Tc` \ (lie1, binds1) ->
tc2 `thenNF_Tc` \ (lie2, binds2) ->
@tcClassDecl2@ is the business end of things.
\begin{code}
-tcClassDecl2 :: RenamedClassDecl -- The class declaration
- -> NF_TcM s (LIE s, TcMonoBinds s)
+tcClassDecl2 :: RenamedTyClDecl -- The class declaration
+ -> NF_TcM s (LIE, TcMonoBinds)
tcClassDecl2 (ClassDecl context class_name
tyvar_names class_sigs default_binds pragmas _ _ src_loc)
tcAddSrcLoc src_loc $
-- Get the relevant class
- tcLookupClass class_name `thenTc` \ (_, clas) ->
+ tcLookupClass class_name `thenNF_Tc` \ clas ->
let
(tyvars, sc_theta, sc_sel_ids, op_sel_ids, defm_ids) = classBigSig clas
-- The selector binds are already in the selector Id's unfoldings
- sel_binds = [ CoreMonoBind (RealId sel_id) (getUnfoldingTemplate (getIdUnfolding sel_id))
- | sel_id <- sc_sel_ids ++ op_sel_ids,
- isLocallyDefined sel_id
- ]
-
- final_sel_binds = andMonoBinds sel_binds
+-- sel_binds = [ CoreMonoBind sel_id (getUnfoldingTemplate (getIdUnfolding sel_id))
+-- | sel_id <- sc_sel_ids ++ op_sel_ids,
+-- isLocallyDefined sel_id
+-- ]
+--
+-- final_sel_binds = andMonoBindList sel_binds
in
-- Generate bindings for the default methods
tcDefaultMethodBinds clas default_binds `thenTc` \ (const_insts, meth_binds) ->
- returnTc (const_insts,
- final_sel_binds `AndMonoBinds` meth_binds)
+ returnTc (const_insts, meth_binds)
+-- final_sel_binds `AndMonoBinds` meth_binds)
+-- Leave 'em out for now. They always get inlined anyway. SLPJ June '98
\end{code}
%************************************************************************
tcDefaultMethodBinds
:: Class
-> RenamedMonoBinds
- -> TcM s (LIE s, TcMonoBinds s)
+ -> TcM s (LIE, TcMonoBinds)
tcDefaultMethodBinds clas default_binds
= -- Construct suitable signatures
- tcInstSigTyVars tyvars `thenNF_Tc` \ (clas_tyvars, inst_tys, inst_env) ->
+ tcInstTyVars tyvars `thenNF_Tc` \ (clas_tyvars, inst_tys, inst_env) ->
-- Typecheck the default bindings
let
+ theta = [(clas,inst_tys)]
tc_dm sel_id_w_dm@(_, Just dm_id)
- = tcMethodBind clas origin inst_tys clas_tyvars
+ = tcMethodBind clas origin clas_tyvars inst_tys theta
default_binds [{-no prags-}] False
sel_id_w_dm `thenTc` \ (bind, insts, (_, local_dm_id)) ->
- returnTc (bind, insts, (clas_tyvars, RealId dm_id, local_dm_id))
- in
- mapAndUnzip3Tc tc_dm sel_ids_w_dms `thenTc` \ (defm_binds, insts_needed, abs_bind_stuff) ->
+ returnTc (bind, insts, (clas_tyvars, dm_id, local_dm_id))
+ in
+ tcExtendTyVarEnvForMeths tyvars clas_tyvars (
+ mapAndUnzip3Tc tc_dm sel_ids_w_dms
+ ) `thenTc` \ (defm_binds, insts_needed, abs_bind_stuff) ->
+
-- Check the context
- newDicts origin [(clas,inst_tys)] `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
+ newDicts origin theta `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
let
avail_insts = this_dict
in
- tcAddErrCtxt (classDeclCtxt clas) $
- mapNF_Tc zonkSigTyVar clas_tyvars `thenNF_Tc` \ clas_tyvars' ->
+ tcAddErrCtxt (defltMethCtxt clas) $
+
+ -- 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
+ mapNF_Tc zonkTcTyVarBndr clas_tyvars `thenNF_Tc` \ clas_tyvars' ->
+
tcSimplifyAndCheck
(ptext SLIT("class") <+> ppr clas)
- (mkTyVarSet clas_tyvars')
+ (mkVarSet clas_tyvars')
avail_insts
(unionManyBags insts_needed) `thenTc` \ (const_lie, dict_binds) ->
clas_tyvars'
[this_dict_id]
abs_bind_stuff
- (dict_binds `AndMonoBinds` andMonoBinds defm_binds)
+ (dict_binds `andMonoBinds` andMonoBindList defm_binds)
in
returnTc (const_lie, full_binds)
\begin{code}
tcMethodBind
:: Class
- -> InstOrigin s
- -> [TcType s] -- Instance types
- -> [TcTyVar s] -- Free variables of those instance types
- -- they'll be signature tyvars, and we
- -- want to check that they don't bound
+ -> InstOrigin
+ -> [TcTyVar] -- Instantiated type variables for the
+ -- enclosing class/instance decl.
+ -- They'll be signature tyvars, and we
+ -- want to check that they don't get bound
+ -> [TcType] -- Instance types
+ -> TcThetaType -- Available theta; this could be used to check
+ -- the method signature, but actually that's done by
+ -- the caller; here, it's just used for the error message
-> RenamedMonoBinds -- Method binding (pick the right one from in here)
-> [RenamedSig] -- Pramgas (just for this one)
-> Bool -- True <=> supply default decl if no explicit decl
-- This is true for instance decls,
-- false for class decls
-> (Id, Maybe Id) -- The method selector and default-method Id
- -> TcM s (TcMonoBinds s, LIE s, (LIE s, TcIdOcc s))
+ -> TcM s (TcMonoBinds, LIE, (LIE, TcId))
-tcMethodBind clas origin inst_tys inst_tyvars
+tcMethodBind clas origin inst_tyvars inst_tys inst_theta
meth_binds prags supply_default_bind
(sel_id, maybe_dm_id)
- | no_user_bind && not supply_default_bind
- = pprPanic "tcMethodBind" (ppr clas <+> ppr inst_tys)
-
- | otherwise
= tcGetSrcLoc `thenNF_Tc` \ loc ->
- -- Warn if no method binding, only if -fwarn-missing-methods
- warnTc (opt_WarnMissingMethods && no_user_bind && no_user_default)
- (omittedMethodWarn sel_id clas) `thenNF_Tc_`
+ newMethod origin sel_id inst_tys `thenNF_Tc` \ meth@(_, meth_id) ->
+ mkTcSig meth_id loc `thenNF_Tc` \ sig_info ->
- newMethod origin (RealId sel_id) inst_tys `thenNF_Tc` \ meth@(_, TcId meth_id) ->
- tcInstSigTcType (idType meth_id) `thenNF_Tc` \ (tyvars', rho_ty') ->
let
- (theta', tau') = splitRhoTy rho_ty'
+ meth_name = idName meth_id
+ maybe_user_bind = find_bind meth_name meth_binds
+
+ no_user_bind = case maybe_user_bind of {Nothing -> True; other -> False}
+ no_user_default = case maybe_dm_id of {Nothing -> True; other -> False}
+
+ meth_bind = case maybe_user_bind of
+ Just bind -> bind
+ Nothing -> mk_default_bind meth_name loc
- meth_name = idName meth_id
- sig_info = TySigInfo meth_name meth_id tyvars' theta' tau' loc
- meth_bind = mk_meth_bind meth_name loc
meth_prags = find_prags meth_name prags
in
- tcExtendLocalValEnv [meth_name] [meth_id] (
+
+ -- Warn if no method binding, only if -fwarn-missing-methods
+ if no_user_bind && not supply_default_bind then
+ pprPanic "tcMethodBind" (ppr clas <+> ppr inst_tys)
+ else
+ warnTc (opt_WarnMissingMethods && no_user_bind && no_user_default)
+ (omittedMethodWarn sel_id clas) `thenNF_Tc_`
+
+ -- Check the pragmas
+ tcExtendLocalValEnv [(meth_name, meth_id)] (
tcPragmaSigs meth_prags
) `thenTc` \ (prag_info_fn, prag_binds1, prag_lie) ->
- -- Check that the signatures match
- tcExtendGlobalTyVars inst_tyvars (
+ -- Check the bindings; first add inst_tyvars to the envt
+ -- so that we don't quantify over them in nested places
+ -- The *caller* put the class/inst decl tyvars into the envt
+ tcExtendGlobalTyVars (mkVarSet inst_tyvars) (
tcAddErrCtxt (methodCtxt sel_id) $
- tcBindWithSigs NotTopLevel [meth_name] meth_bind [sig_info]
+ tcBindWithSigs NotTopLevel meth_bind [sig_info]
NonRecursive prag_info_fn
- ) `thenTc` \ (binds, insts, _) ->
+ ) `thenTc` \ (binds, insts, _) ->
+
-- The prag_lie for a SPECIALISE pragma will mention the function
-- itself, so we have to simplify them away right now lest they float
-- outwards!
bindInstsOfLocalFuns prag_lie [meth_id] `thenTc` \ (prag_lie', prag_binds2) ->
+
-- Now check that the instance type variables
-- (or, in the case of a class decl, the class tyvars)
-- have not been unified with anything in the environment
- tcAddErrCtxt (monoCtxt sel_id) (
- tcAddErrCtxt (sigCtxt sel_id) $
- checkSigTyVars inst_tyvars (idType meth_id)
- ) `thenTc_`
+ tcAddErrCtxtM (sigCtxt sig_msg (mkSigmaTy inst_tyvars inst_theta (idType meth_id))) $
+ checkSigTyVars inst_tyvars `thenTc_`
returnTc (binds `AndMonoBinds` prag_binds1 `AndMonoBinds` prag_binds2,
insts `plusLIE` prag_lie',
meth)
where
- sel_name = idName sel_id
+ sig_msg ty = sep [ptext SLIT("When checking the expected type for"),
+ nest 4 (ppr sel_name <+> dcolon <+> ppr ty)]
- maybe_user_bind = find meth_binds
-
- no_user_bind = case maybe_user_bind of {Nothing -> True; other -> False}
- no_user_default = case maybe_dm_id of {Nothing -> True; other -> False}
-
- find EmptyMonoBinds = Nothing
- find (AndMonoBinds b1 b2) = find b1 `seqMaybe` find b2
- find b@(FunMonoBind op_name _ _ _) = if op_name == sel_name then Just b else Nothing
- find b@(PatMonoBind (VarPatIn op_name) _ _) = if op_name == sel_name then Just b else Nothing
- find other = panic "Urk! Bad instance method binding"
+ sel_name = idName sel_id
-- The renamer just puts the selector ID as the binder in the method binding
-- but we must use the method name; so we substitute it here. Crude but simple.
- mk_meth_bind meth_name loc
- = case maybe_user_bind of
- Just (FunMonoBind _ fix matches loc) -> FunMonoBind meth_name fix matches loc
- Just (PatMonoBind (VarPatIn _) rhs loc) -> PatMonoBind (VarPatIn meth_name) rhs loc
- Nothing -> mk_default_bind meth_name loc
+ find_bind meth_name (FunMonoBind op_name fix matches loc)
+ | op_name == sel_name = Just (FunMonoBind meth_name fix matches loc)
+ find_bind meth_name (PatMonoBind (VarPatIn op_name) grhss loc)
+ | op_name == sel_name = Just (PatMonoBind (VarPatIn meth_name) grhss loc)
+ find_bind meth_name (AndMonoBinds b1 b2)
+ = find_bind meth_name b1 `seqMaybe` find_bind meth_name b2
+ find_bind meth_name other = Nothing -- Default case
+
-- Find the prags for this method, and replace the
-- selector name with the method name
mk_default_bind local_meth_name loc
= PatMonoBind (VarPatIn local_meth_name)
- (GRHSsAndBindsIn (unguardedRHS (default_expr loc) loc) EmptyBinds)
+ (GRHSs (unguardedRHS (default_expr loc) loc) EmptyBinds Nothing)
loc
default_expr loc
classArityErr class_name
= ptext SLIT("Too many parameters for class") <+> quotes (ppr class_name)
-classDeclCtxt class_name
- = ptext SLIT("In the class declaration for") <+> quotes (ppr class_name)
+superClassErr class_name sc
+ = ptext SLIT("Illegal superclass constraint") <+> quotes (pprClassAssertion sc)
+ <+> ptext SLIT("in declaration for class") <+> quotes (ppr class_name)
+
+defltMethCtxt class_name
+ = ptext SLIT("When checking the default methods for class") <+> quotes (ppr class_name)
methodCtxt sel_id
= ptext SLIT("In the definition for method") <+> quotes (ppr sel_id)
-monoCtxt sel_id
- = sep [ptext SLIT("Probable cause: the right hand side of") <+> quotes (ppr sel_id),
- nest 4 (ptext SLIT("mentions a top-level variable subject to the dreaded monomorphism restriction"))
- ]
-
badMethodErr bndr clas
= hsep [ptext SLIT("Class"), quotes (ppr clas),
ptext SLIT("does not have a method"), quotes (ppr bndr)]
projects / ghc-hetmet.git / blobdiff