%
-% (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, mkImplicitClassBinds,
+ tcMethodBind, checkFromThisClass
+ ) where
#include "HsVersions.h"
-import HsSyn ( HsDecl(..), ClassDecl(..), Sig(..), MonoBinds(..),
- InPat(..), andMonoBinds, getTyVarName
+import HsSyn ( HsDecl(..), TyClDecl(..), Sig(..), MonoBinds(..),
+ InPat(..), HsBinds(..), GRHSs(..),
+ HsExpr(..), HsLit(..), HsType(..), HsPred(..),
+ pprHsClassAssertion, unguardedRHS,
+ andMonoBinds, andMonoBindList, getTyVarName,
+ isClassDecl, isClassOpSig, isPragSig, collectMonoBinders
)
import HsPragmas ( ClassPragmas(..) )
import BasicTypes ( NewOrData(..), TopLevelFlag(..), RecFlag(..) )
-import RnHsSyn ( RenamedClassDecl(..), RenamedClassPragmas(..),
- RenamedClassOpSig(..), RenamedMonoBinds,
- RenamedContext(..), RenamedHsDecl, RenamedSig
+import RnHsSyn ( RenamedTyClDecl, RenamedClassPragmas,
+ RenamedClassOpSig, RenamedMonoBinds,
+ RenamedContext, RenamedHsDecl, RenamedSig
)
-import TcHsSyn ( TcMonoBinds )
+import TcHsSyn ( TcMonoBinds, idsToMonoBinds )
-import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, newDicts, newMethod )
-import TcEnv ( TcIdOcc(..), tcAddImportedIdInfo,
- tcLookupClass, tcLookupTyVar,
- tcExtendGlobalTyVars, tcExtendLocalValEnv
+import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, plusLIEs, newDicts, newMethod )
+import TcEnv ( TcId, ValueEnv, TcTyThing(..), tcAddImportedIdInfo,
+ tcLookupClass, tcLookupTy, tcExtendTyVarEnvForMeths, tcExtendGlobalTyVars,
+ tcExtendLocalValEnv
)
-import TcBinds ( tcBindWithSigs, checkSigTyVars, sigCtxt, tcPragmaSigs, TcSigInfo(..) )
-import TcKind ( unifyKinds, TcKind )
+import TcBinds ( tcBindWithSigs, tcSpecSigs )
+import TcTyDecls ( mkNewTyConRep )
+import TcUnify ( unifyKinds )
import TcMonad
-import TcMonoType ( tcHsType, tcContext )
-import TcSimplify ( tcSimplifyAndCheck )
-import TcType ( TcType, TcTyVar, TcTyVarSet, tcInstSigTyVars,
- zonkSigTyVar, tcInstSigTcType
+import TcMonoType ( kcHsType, tcHsTopType, tcExtendTopTyVarScope,
+ tcContext, checkSigTyVars, sigCtxt, mkTcSig
)
+import TcSimplify ( tcSimplifyAndCheck, bindInstsOfLocalFuns )
+import TcType ( TcType, TcTyVar, tcInstTyVars, zonkTcTyVarBndr, tcGetTyVar )
+import TcInstUtil ( classDataCon )
+import PrelInfo ( nO_METHOD_BINDING_ERROR_ID )
import FieldLabel ( firstFieldLabelTag )
-import Bag ( unionManyBags )
-import Class ( mkClass, classBigSig, Class )
-import CmdLineOpts ( opt_GlasgowExts )
-import MkId ( mkDataCon, mkSuperDictSelId,
- mkMethodSelId, mkDefaultMethodId
- )
-import Id ( Id, StrictnessMark(..),
- getIdUnfolding, idType
- )
-import CoreUnfold ( getUnfoldingTemplate )
+import Bag ( unionManyBags, bagToList )
+import Class ( mkClass, classBigSig, classSelIds, Class, ClassOpItem )
+import CmdLineOpts ( opt_GlasgowExts, opt_WarnMissingMethods )
+import MkId ( mkDictSelId, mkDataConId, mkDataConWrapId, mkDefaultMethodId )
+import DataCon ( mkDataCon, dataConId, dataConWrapId, notMarkedStrict )
+import Id ( Id, setInlinePragma, idUnfolding, idType, idName )
+import CoreUnfold ( unfoldingTemplate )
import IdInfo
-import Name ( Name, isLocallyDefined, OccName, nameOccName,
- NamedThing(..) )
+import Name ( Name, nameOccName, isLocallyDefined, NamedThing(..) )
+import NameSet ( emptyNameSet )
import Outputable
-import Type ( mkFunTy, mkTyVarTy, mkTyVarTys, mkDictTy, splitRhoTy,
- mkSigmaTy, mkForAllTys, Type, ThetaType
+import Type ( Type, ThetaType, ClassContext,
+ mkFunTy, mkTyVarTy, mkTyVarTys, mkDictTy, mkDictTys,
+ mkSigmaTy, mkForAllTys, mkClassPred, classesOfPreds,
+ boxedTypeKind, mkArrowKind
)
-import TyVar ( mkTyVarSet, tyVarKind, TyVar )
-import TyCon ( mkDataTyCon )
-import Kind ( mkBoxedTypeKind, mkArrowKind )
+import Var ( tyVarKind, TyVar )
+import VarSet ( mkVarSet, emptyVarSet )
+import TyCon ( AlgTyConFlavour(..), mkClassTyCon )
import Unique ( Unique, Uniquable(..) )
import Util
-import Maybes ( assocMaybe, maybeToBool )
-
-
--- import TcPragmas ( tcGenPragmas, tcClassOpPragmas )
-tcGenPragmas ty id ps = returnNF_Tc noIdInfo
-tcClassOpPragmas ty sel def spec ps = returnNF_Tc (spec `setSpecInfo` noIdInfo,
- noIdInfo)
+import Maybes ( seqMaybe )
+import FiniteMap ( lookupWithDefaultFM )
\end{code}
Death to "ExpandingDicts".
-\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)
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (classDeclCtxt class_name) $
+%************************************************************************
+%* *
+\subsection{Kind checking}
+%* *
+%************************************************************************
- -- CHECK ARITY 1 FOR HASKELL 1.4
+\begin{code}
+kcClassDecl (ClassDecl context class_name
+ tyvar_names fundeps class_sigs def_methods pragmas
+ _ _ _ _ src_loc)
+ = -- 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 the_class_sigs `thenTc_`
- -- FORCE THE CLASS AND ITS TYVAR TO HAVE SAME KIND
- unifyKinds class_kinds tyvar_kinds `thenTc_`
+ returnTc ()
+ where
+ the_class_sigs = filter isClassOpSig class_sigs
+
+ kc_sig (ClassOpSig _ _ _ op_ty loc) = tcAddSrcLoc loc (kcHsType op_ty)
+\end{code}
+
+%************************************************************************
+%* *
+\subsection{Type checking}
+%* *
+%************************************************************************
+
+\begin{code}
+tcClassDecl1 rec_env rec_inst_mapper rec_vrcs
+ (ClassDecl context class_name
+ tyvar_names fundeps class_sigs def_methods pragmas
+ tycon_name datacon_name datacon_wkr_name sc_sel_names 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 sc_sel_names
`thenTc` \ (sc_theta, sc_tys, sc_sel_ids) ->
+-- traceTc (text "tcClassCtxt done" <+> ppr class_name) `thenTc_`
+
+ -- CHECK THE FUNCTIONAL DEPENDENCIES,
+ tcFundeps fundeps `thenTc` \ fds ->
-- CHECK THE CLASS SIGNATURES,
- mapTc (tcClassSig rec_env rec_class rec_tyvars) class_sigs
+ mapTc (tcClassSig rec_env rec_class tyvars)
+ (filter isClassOpSig class_sigs)
`thenTc` \ sig_stuff ->
-- MAKE THE CLASS OBJECT ITSELF
let
- (op_tys, op_sel_ids, defm_ids) = unzip3 sig_stuff
+ (op_tys, op_items) = unzip sig_stuff
rec_class_inst_env = rec_inst_mapper rec_class
- clas = mkClass (getName class_name) rec_tyvars
- sc_theta sc_sel_ids op_sel_ids defm_ids
+ clas = mkClass class_name tyvars fds
+ sc_theta sc_sel_ids op_items
tycon
rec_class_inst_env
dict_component_tys = sc_tys ++ op_tys
new_or_data = case dict_component_tys of
- [_] -> NewType
- other -> DataType
+ [_] -> NewTyCon (mkNewTyConRep tycon)
+ other -> DataTyCon
- dict_con_id = mkDataCon datacon_name
- [NotMarkedStrict | _ <- dict_component_tys]
+ 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 = mkDataTyCon tycon_name
- (foldr (mkArrowKind . tyVarKind) mkBoxedTypeKind rec_tyvars)
- rec_tyvars
- [] -- No context
- [dict_con_id] -- Constructors
- [] -- No derivings
- (Just clas) -- Yes! It's a dictionary
- new_or_data
- NonRecursive
+ tycon dict_con_id dict_wrap_id
+
+ dict_con_id = mkDataConId datacon_wkr_name dict_con
+ dict_wrap_id = mkDataConWrapId dict_con
+
+ argvrcs = lookupWithDefaultFM rec_vrcs (pprPanic "tcClassDecl1: argvrcs:" $
+ ppr tycon_name)
+ tycon_name
+
+ tycon = mkClassTyCon tycon_name
+ class_kind
+ tyvars
+ argvrcs
+ dict_con -- Constructors
+ clas -- Yes! It's a dictionary
+ new_or_data
in
returnTc clas
\end{code}
+\begin{code}
+tcFundeps = mapTc tc_fundep
+tc_fundep (us, vs) =
+ mapTc tc_fd_tyvar us `thenTc` \ us' ->
+ mapTc tc_fd_tyvar vs `thenTc` \ vs' ->
+ returnTc (us', vs')
+tc_fd_tyvar v =
+ tcLookupTy v `thenTc` \(_, _, thing) ->
+ case thing of
+ ATyVar tv -> returnTc tv
+ -- ZZ else should fail more gracefully
+\end{code}
\begin{code}
-tcClassContext :: Class -> [TyVar]
+tcClassContext :: Name -> Class -> [TyVar]
-> RenamedContext -- class context
- -> RenamedClassPragmas -- pragmas for superclasses
- -> TcM s (ThetaType, -- the superclass context
+ -> [Name] -- Names for superclass selectors
+ -> TcM s (ClassContext, -- 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 sc_sel_names
= -- 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]
+ sc_theta' = classesOfPreds sc_theta
+ sc_tys = mkDictTys sc_theta'
+ sc_sel_ids = zipWithEqual "tcClassContext" mk_super_id sc_sel_names sc_tys
in
-
- -- Make super-class selector ids
- -- We number them off, 1, 2, 3 etc so that we can construct
- -- names for the selectors. Thus
- -- class (C a, C b) => D a b where ...
- -- gives superclass selectors
- -- D_sc1, D_sc2
- -- (We used to call them D_C, but now we can have two different
- -- superclasses both called C!)
- mapTc mk_super_id (sc_theta `zip` [firstFieldLabelTag..]) `thenTc` \ sc_sel_ids ->
-
-- Done
- returnTc (sc_theta, sc_tys, sc_sel_ids)
+ returnTc (sc_theta', sc_tys, sc_sel_ids)
where
rec_tyvar_tys = mkTyVarTys rec_tyvars
- mk_super_id ((super_class, tys), index)
- = tcGetUnique `thenNF_Tc` \ uniq ->
- let
- ty = mkForAllTys rec_tyvars $
- mkFunTy (mkDictTy rec_class rec_tyvar_tys) (mkDictTy super_class tys)
- in
- returnTc (mkSuperDictSelId uniq rec_class index ty)
+ mk_super_id name dict_ty
+ = mkDictSelId name rec_class {- SUP:??? ty
+ where
+ ty = mkForAllTys rec_tyvars $
+ mkFunTy (mkDictTy rec_class rec_tyvar_tys) dict_ty -}
+
+ check_constraint (HsPClass c tys) = checkTc (all is_tyvar tys)
+ (superClassErr class_name (c, tys))
+ is_tyvar (MonoTyVar _) = True
+ is_tyvar other = False
-tcClassSig :: TcEnv s -- Knot tying only!
+
+tcClassSig :: ValueEnv -- Knot tying only!
-> Class -- ...ditto...
-> [TyVar] -- The class type variable, used for error check only
-> RenamedClassOpSig
-> TcM s (Type, -- Type of the method
- Id, -- selector id
- Maybe Id) -- default-method ids
+ ClassOpItem) -- Selector Id, default-method Id, True if explicit default binding
+
tcClassSig rec_env rec_clas rec_clas_tyvars
- (ClassOpSig op_name maybe_dm_name
- op_ty
- src_loc)
+ (ClassOpSig op_name dm_name explicit_dm
+ op_ty src_loc)
= tcAddSrcLoc src_loc $
-- Check the type signature. NB that the envt *already has*
-- 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)]
+ [mkClassPred 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
- Just dm_name -> let
- dm_id = mkDefaultMethodId dm_name rec_clas global_ty
- in
- Just (tcAddImportedIdInfo rec_env dm_id)
+ sel_id = mkDictSelId op_name rec_clas {- SUP:??? global_ty -}
+ dm_id = mkDefaultMethodId dm_name rec_clas global_ty
+ final_dm_id = tcAddImportedIdInfo rec_env dm_id
in
- returnTc (local_ty, sel_id, maybe_dm_id)
+-- traceTc (text "tcClassSig done" <+> ppr op_name) `thenTc_`
+ returnTc (local_ty, (sel_id, final_dm_id, explicit_dm))
\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)
+ tyvar_names _ class_sigs default_binds pragmas _ _ _ _ src_loc)
| not (isLocallyDefined class_name)
= returnNF_Tc (emptyLIE, EmptyMonoBinds)
| otherwise -- It is locally defined
= recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $
tcAddSrcLoc src_loc $
+ tcLookupClass class_name `thenNF_Tc` \ clas ->
+ tcDefaultMethodBinds clas default_binds class_sigs
+\end{code}
- -- Get the relevant class
- tcLookupClass class_name `thenTc` \ (_, clas) ->
- let
- (tyvars, sc_theta, sc_sel_ids, op_sel_ids, defm_ids) = classBigSig clas
-
+\begin{code}
+mkImplicitClassBinds :: [Class] -> NF_TcM s ([Id], TcMonoBinds)
+mkImplicitClassBinds classes
+ = returnNF_Tc (concat cls_ids_s, andMonoBindList binds_s)
-- 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
- ]
+ where
+ (cls_ids_s, binds_s) = unzip (map mk_implicit classes)
- final_sel_binds = andMonoBinds sel_binds
- in
- -- Generate bindings for the default methods
- tcDefaultMethodBinds clas default_binds `thenTc` \ (const_insts, meth_binds) ->
+ mk_implicit clas = (all_cls_ids, binds)
+ where
+ dict_con = classDataCon clas
+ all_cls_ids = dataConId dict_con : cls_ids
+ cls_ids = dataConWrapId dict_con : classSelIds clas
- returnTc (const_insts,
- final_sel_binds `AndMonoBinds` meth_binds)
+ -- The wrapper and selectors get bindings, the worker does not
+ binds | isLocallyDefined clas = idsToMonoBinds cls_ids
+ | otherwise = EmptyMonoBinds
\end{code}
%************************************************************************
defm.Foo.op1 :: forall a. Foo a => a -> Bool
defm.Foo.op1 = /\a -> \dfoo -> \x -> True
-====================== OLD ==================
-\begin{verbatim}
-defm.Foo.op2 :: forall a, b. (Foo a, Ord b) => a -> b -> b -> b
-defm.Foo.op2 = /\ a b -> \ dfoo dord -> \x y z ->
- if (op1 a dfoo x) && (< b dord y z) then y else z
-\end{verbatim}
-Notice that, like all ids, the foralls of defm.Foo.op2 are at the top.
-====================== END OF OLD ===================
-
-NEW:
-\begin{verbatim}
defm.Foo.op2 :: forall a. Foo a => forall b. Ord b => a -> b -> b -> b
defm.Foo.op2 = /\ a -> \ dfoo -> /\ b -> \ dord -> \x y z ->
if (op1 a dfoo x) && (< b dord y z) then y else z
\end{verbatim}
-
When we come across an instance decl, we may need to use the default
methods:
\begin{verbatim}
tcDefaultMethodBinds
:: Class
-> RenamedMonoBinds
- -> TcM s (LIE s, TcMonoBinds s)
+ -> [RenamedSig]
+ -> TcM s (LIE, TcMonoBinds)
+
+tcDefaultMethodBinds clas default_binds sigs
+ = -- Check that the default bindings come from this class
+ checkFromThisClass clas op_items default_binds `thenNF_Tc_`
+
+ -- Do each default method separately
+ -- For Hugs compatibility we make a default-method for every
+ -- class op, regardless of whether or not the programmer supplied an
+ -- explicit default decl for the class. GHC will actually never
+ -- call the default method for such operations, because it'll whip up
+ -- a more-informative default method at each instance decl.
+ mapAndUnzipTc tc_dm op_items `thenTc` \ (defm_binds, const_lies) ->
+
+ returnTc (plusLIEs const_lies, andMonoBindList defm_binds)
+ where
+ prags = filter isPragSig sigs
-tcDefaultMethodBinds clas default_binds
- = -- Construct suitable signatures
- tcInstSigTyVars tyvars `thenNF_Tc` \ (clas_tyvars, inst_tys, inst_env) ->
+ (tyvars, _, _, op_items) = classBigSig clas
- -- Typecheck the default bindings
- let
- tc_dm meth_bind
- | not (maybeToBool maybe_stuff)
- = -- Binding for something that isn't in the class signature
- failWithTc (badMethodErr bndr_name clas)
-
- | otherwise
- = -- Normal case
- tcMethodBind clas origin inst_tys clas_tyvars sel_id meth_bind [{- No prags -}]
- `thenTc` \ (bind, insts, (_, local_dm_id)) ->
- returnTc (bind, insts, (clas_tyvars, RealId dm_id, local_dm_id))
- where
- bndr_name = case meth_bind of
- FunMonoBind name _ _ _ -> name
- PatMonoBind (VarPatIn name) _ _ -> name
-
- maybe_stuff = assocMaybe assoc_list (nameOccName bndr_name)
- assoc_list = [ (getOccName sel_id, pair)
- | pair@(sel_id, dm_ie) <- op_sel_ids `zip` defm_ids
- ]
- Just (sel_id, Just dm_id) = maybe_stuff
- -- We're looking at a default-method binding, so the dm_id
- -- is sure to be there! Hence the inner "Just".
- in
- mapAndUnzip3Tc tc_dm
- (flatten default_binds []) `thenTc` \ (defm_binds, insts_needed, abs_bind_stuff) ->
-
- -- Check the context
- newDicts origin [(clas,inst_tys)] `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' ->
- tcSimplifyAndCheck
- (ptext SLIT("class") <+> ppr clas)
- (mkTyVarSet clas_tyvars')
- avail_insts
- (unionManyBags insts_needed) `thenTc` \ (const_lie, dict_binds) ->
+ origin = ClassDeclOrigin
- let
- full_binds = AbsBinds
- clas_tyvars'
- [this_dict_id]
- abs_bind_stuff
- (dict_binds `AndMonoBinds` andMonoBinds defm_binds)
- in
- returnTc (const_lie, full_binds)
+ -- We make a separate binding for each default method.
+ -- At one time I used a single AbsBinds for all of them, thus
+ -- AbsBind [d] [dm1, dm2, dm3] { dm1 = ...; dm2 = ...; dm3 = ... }
+ -- But that desugars into
+ -- ds = \d -> (..., ..., ...)
+ -- dm1 = \d -> case ds d of (a,b,c) -> a
+ -- And since ds is big, it doesn't get inlined, so we don't get good
+ -- default methods. Better to make separate AbsBinds for each
+
+ tc_dm op_item@(_, dm_id, _)
+ = tcInstTyVars tyvars `thenNF_Tc` \ (clas_tyvars, inst_tys, _) ->
+ let
+ theta = [(mkClassPred clas inst_tys)]
+ in
+ newDicts origin theta `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
+ let
+ avail_insts = this_dict
+ in
+ tcExtendTyVarEnvForMeths tyvars clas_tyvars (
+ tcMethodBind clas origin clas_tyvars inst_tys theta
+ default_binds prags False
+ op_item
+ ) `thenTc` \ (defm_bind, insts_needed, (_, local_dm_id)) ->
+
+ 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' ->
+
+ -- Check the context
+ tcSimplifyAndCheck
+ (ptext SLIT("class") <+> ppr clas)
+ (mkVarSet clas_tyvars')
+ avail_insts
+ insts_needed `thenTc` \ (const_lie, dict_binds) ->
+
+ let
+ full_bind = AbsBinds
+ clas_tyvars'
+ [this_dict_id]
+ [(clas_tyvars', dm_id, local_dm_id)]
+ emptyNameSet -- No inlines (yet)
+ (dict_binds `andMonoBinds` defm_bind)
+ in
+ returnTc (full_bind, const_lie)
+\end{code}
+\begin{code}
+checkFromThisClass :: Class -> [ClassOpItem] -> RenamedMonoBinds -> NF_TcM s ()
+checkFromThisClass clas op_items mono_binds
+ = mapNF_Tc check_from_this_class bndrs `thenNF_Tc_`
+ returnNF_Tc ()
where
- (tyvars, sc_theta, sc_sel_ids, op_sel_ids, defm_ids) = classBigSig clas
- origin = ClassDeclOrigin
-
- flatten EmptyMonoBinds rest = rest
- flatten (AndMonoBinds b1 b2) rest = flatten b1 (flatten b2 rest)
- flatten a_bind rest = a_bind : rest
+ check_from_this_class (bndr, loc)
+ | nameOccName bndr `elem` sel_names = returnNF_Tc ()
+ | otherwise = tcAddSrcLoc loc $
+ addErrTc (badMethodErr bndr clas)
+ sel_names = [getOccName sel_id | (sel_id,_,_) <- op_items]
+ bndrs = bagToList (collectMonoBinders mono_binds)
\end{code}
+
@tcMethodBind@ is used to type-check both default-method and
instance-decl method declarations. We must type-check methods one at a
\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
- -> Id -- The method selector
- -> RenamedMonoBinds -- Method binding (just one)
- -> [RenamedSig] -- Pramgas (just for this one)
- -> TcM s (TcMonoBinds s, LIE s, (LIE s, TcIdOcc s))
-
-tcMethodBind clas origin inst_tys inst_tyvars sel_id meth_bind prags
- = tcAddSrcLoc src_loc $
- newMethod origin (RealId sel_id) inst_tys `thenNF_Tc` \ meth@(_, TcId local_meth_id) ->
- tcInstSigTcType (idType local_meth_id) `thenNF_Tc` \ (tyvars', rho_ty') ->
+ -> 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 <=> This method is from an instance declaration
+ -> ClassOpItem -- The method selector and default-method Id
+ -> TcM s (TcMonoBinds, LIE, (LIE, TcId))
+
+tcMethodBind clas origin inst_tyvars inst_tys inst_theta
+ meth_binds prags is_inst_decl
+ (sel_id, dm_id, explicit_dm)
+ = tcGetSrcLoc `thenNF_Tc` \ loc ->
+
+ newMethod origin sel_id inst_tys `thenNF_Tc` \ meth@(_, meth_id) ->
+ mkTcSig meth_id loc `thenNF_Tc` \ sig_info ->
+
let
- (theta', tau') = splitRhoTy rho_ty'
- sig_info = TySigInfo bndr_name local_meth_id tyvars' theta' tau' src_loc
+ 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}
+
+ meth_bind = case maybe_user_bind of
+ Just bind -> bind
+ Nothing -> mk_default_bind meth_name loc
+
+ meth_prags = find_prags meth_name prags
in
- tcExtendLocalValEnv [bndr_name] [local_meth_id] (
- tcPragmaSigs prags
- ) `thenTc` \ (prag_info_fn, prag_binds, prag_lie) ->
- tcExtendGlobalTyVars inst_tyvars (
+ -- Warn if no method binding, only if -fwarn-missing-methods
+ warnTc (is_inst_decl && opt_WarnMissingMethods && no_user_bind && not explicit_dm)
+ (omittedMethodWarn sel_id clas) `thenNF_Tc_`
+
+ -- 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 [bndr_name] meth_bind [sig_info]
- NonRecursive prag_info_fn
- ) `thenTc` \ (binds, insts, _) ->
+ tcBindWithSigs NotTopLevel meth_bind
+ [sig_info] meth_prags NonRecursive
+ ) `thenTc` \ (binds, insts, _) ->
+
+
+ tcExtendLocalValEnv [(meth_name, meth_id)] (
+ tcSpecSigs meth_prags
+ ) `thenTc` \ (prag_binds1, prag_lie) ->
+
+ -- 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 local_meth_id)
- ) `thenTc_`
+ tcAddErrCtxtM (sigCtxt sig_msg inst_tyvars inst_theta (idType meth_id)) $
+ checkSigTyVars inst_tyvars emptyVarSet `thenTc_`
- returnTc (binds `AndMonoBinds` prag_binds,
- insts `plusLIE` prag_lie,
+ returnTc (binds `AndMonoBinds` prag_binds1 `AndMonoBinds` prag_binds2,
+ insts `plusLIE` prag_lie',
meth)
where
- (bndr_name, src_loc) = case meth_bind of
- FunMonoBind name _ _ loc -> (name, loc)
- PatMonoBind (VarPatIn name) _ loc -> (name, loc)
+ sig_msg = ptext SLIT("When checking the expected type for class method") <+> ppr sel_name
+
+ 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.
+ 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
+ find_prags meth_name [] = []
+ find_prags meth_name (SpecSig name ty loc : prags)
+ | name == sel_name = SpecSig meth_name ty loc : find_prags meth_name prags
+ find_prags meth_name (InlineSig name phase loc : prags)
+ | name == sel_name = InlineSig meth_name phase loc : find_prags meth_name prags
+ find_prags meth_name (NoInlineSig name phase loc : prags)
+ | name == sel_name = NoInlineSig meth_name phase loc : find_prags meth_name prags
+ find_prags meth_name (prag:prags) = find_prags meth_name prags
+
+ mk_default_bind local_meth_name loc
+ = PatMonoBind (VarPatIn local_meth_name)
+ (GRHSs (unguardedRHS (default_expr loc) loc) EmptyBinds Nothing)
+ loc
+
+ default_expr loc
+ | explicit_dm = HsVar (getName dm_id) -- There's a default method
+ | otherwise = error_expr loc -- No default method
+
+ 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 ])
\end{code}
Contexts and errors
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 (pprHsClassAssertion 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)]
+
+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)]
\end{code}
projects / ghc-hetmet.git / blobdiff