%
-% (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}
-#include "HsVersions.h"
-
-module TcClassDcl ( tcClassDecl1, tcClassDecls2,
- badMethodErr, tcMethodBind
+module TcClassDcl ( kcClassDecl, tcClassDecl1, tcClassDecls2,
+ tcMethodBind, checkFromThisClass
) where
-IMP_Ubiq()
+#include "HsVersions.h"
-import HsSyn ( HsDecl(..), ClassDecl(..), HsBinds(..), MonoBinds(..),
- Match(..), GRHSsAndBinds(..), GRHS(..), HsExpr(..),
- DefaultDecl, TyDecl, InstDecl, IfaceSig, Fixity,
- HsLit(..), OutPat(..), Sig(..), HsType(..), HsTyVar, InPat(..),
- SYN_IE(RecFlag), nonRecursive, andMonoBinds, collectMonoBinders,
- Stmt, DoOrListComp, ArithSeqInfo, Fake )
-import HsTypes ( getTyVarName )
+import HsSyn ( HsDecl(..), TyClDecl(..), Sig(..), MonoBinds(..),
+ InPat(..), HsBinds(..), GRHSs(..),
+ HsExpr(..), HsLit(..), HsType(..), pprClassAssertion,
+ unguardedRHS, andMonoBinds, andMonoBindList, getTyVarName,
+ isClassDecl, isClassOpSig, collectMonoBinders
+ )
import HsPragmas ( ClassPragmas(..) )
-import RnHsSyn ( RenamedClassDecl(..), RenamedClassPragmas(..),
- RenamedClassOpSig(..), SYN_IE(RenamedMonoBinds),
- RenamedGenPragmas(..), RenamedContext(..), SYN_IE(RenamedHsDecl)
+import BasicTypes ( NewOrData(..), TopLevelFlag(..), RecFlag(..) )
+import RnHsSyn ( RenamedTyClDecl, RenamedClassPragmas,
+ RenamedClassOpSig, RenamedMonoBinds,
+ RenamedContext, RenamedHsDecl, RenamedSig
)
-import TcHsSyn ( SYN_IE(TcHsBinds), SYN_IE(TcMonoBinds), SYN_IE(TcExpr),
- mkHsTyApp, mkHsTyLam, mkHsDictApp, mkHsDictLam, tcIdType )
-
-import Inst ( Inst, InstOrigin(..), SYN_IE(LIE), emptyLIE, plusLIE, newDicts, newMethod )
-import TcEnv ( tcLookupClass, tcLookupTyVar, newLocalIds, tcAddImportedIdInfo,
- tcExtendGlobalTyVars )
-import TcBinds ( tcBindWithSigs, TcSigInfo(..) )
-import TcKind ( unifyKind, TcKind )
+import TcHsSyn ( TcMonoBinds )
+
+import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, newDicts, newMethod )
+import TcEnv ( TcId, ValueEnv, TcTyThing(..), tcAddImportedIdInfo,
+ tcLookupClass, tcLookupTy, tcExtendTyVarEnvForMeths, tcExtendGlobalTyVars,
+ tcExtendLocalValEnv
+ )
+import TcBinds ( tcBindWithSigs, tcSpecSigs )
+import TcUnify ( unifyKinds )
import TcMonad
-import TcMonoType ( tcHsType, tcContext )
-import TcSimplify ( tcSimplifyAndCheck )
-import TcType ( TcIdOcc(..), SYN_IE(TcType), SYN_IE(TcTyVar), tcInstType, tcInstSigTyVars,
- tcInstSigType, tcInstSigTcType )
-import PragmaInfo ( PragmaInfo(..) )
-
-import Bag ( bagToList, unionManyBags )
-import Class ( GenClass, mkClass, classBigSig,
- classDefaultMethodId,
- SYN_IE(Class)
+import TcMonoType ( tcHsType, tcHsTopType, tcExtendTopTyVarScope,
+ tcContext, checkSigTyVars, sigCtxt, mkTcSig
)
-import CmdLineOpts ( opt_PprUserLength )
-import Id ( GenId, mkSuperDictSelId, mkMethodSelId,
- mkDefaultMethodId, getIdUnfolding,
- idType, SYN_IE(Id)
+import TcSimplify ( tcSimplifyAndCheck, bindInstsOfLocalFuns )
+import TcType ( TcType, TcTyVar, tcInstTyVars, zonkTcTyVarBndr, tcGetTyVar )
+import PrelInfo ( nO_METHOD_BINDING_ERROR_ID )
+import FieldLabel ( firstFieldLabelTag )
+import Bag ( unionManyBags, bagToList )
+import Class ( mkClass, classBigSig, Class )
+import CmdLineOpts ( opt_GlasgowExts, opt_WarnMissingMethods )
+import MkId ( mkDictSelId, mkDataConId, mkDefaultMethodId )
+import DataCon ( mkDataCon, notMarkedStrict )
+import Id ( Id,
+ getIdUnfolding, idType, idName
)
import CoreUnfold ( getUnfoldingTemplate )
import IdInfo
-import Name ( Name, isLocallyDefined, moduleString, getSrcLoc,
- OccName, nameOccName,
- nameString, NamedThing(..) )
+import Name ( Name, nameOccName, isLocallyDefined, NamedThing(..) )
+import NameSet ( emptyNameSet )
import Outputable
-import Pretty
-import PprType ( GenClass, GenType, GenTyVar )
-import SpecEnv ( SpecEnv )
-import SrcLoc ( mkGeneratedSrcLoc )
-import Type ( mkFunTy, mkTyVarTy, mkTyVarTys, mkDictTy, splitRhoTy,
- mkForAllTy, mkSigmaTy, splitSigmaTy, SYN_IE(Type)
+import Type ( mkFunTy, mkTyVarTy, mkTyVarTys, mkDictTy,
+ mkSigmaTy, mkForAllTys, Type, ThetaType,
+ boxedTypeKind, mkArrowKind
)
-import TysWiredIn ( stringTy )
-import TyVar ( unitTyVarSet, GenTyVar, SYN_IE(TyVar) )
+import Var ( tyVarKind, TyVar )
+import VarSet ( mkVarSet )
+import TyCon ( mkAlgTyCon )
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 (noIdInfo `addSpecInfo` spec,
- noIdInfo)
+import Maybes ( seqMaybe )
+import FiniteMap ( lookupWithDefaultFM )
\end{code}
Death to "ExpandingDicts".
+%************************************************************************
+%* *
+\subsection{Kind checking}
+%* *
+%************************************************************************
+
\begin{code}
-tcClassDecl1 rec_env rec_inst_mapper
- (ClassDecl context class_name
- tyvar_name class_sigs def_methods pragmas src_loc)
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (classDeclCtxt class_name) $
+kcClassDecl (ClassDecl context class_name
+ tyvar_names class_sigs def_methods pragmas
+ tycon_name datacon_name sc_sel_names src_loc)
+ = -- CHECK ARITY 1 FOR HASKELL 1.4
+ checkTc (opt_GlasgowExts || length tyvar_names == 1)
+ (classArityErr class_name) `thenTc_`
+
+ -- 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_`
+
+ returnTc ()
+ where
+ the_class_sigs = filter isClassOpSig class_sigs
+
+ kc_sig (ClassOpSig _ _ op_ty loc) = tcAddSrcLoc loc (tcHsType op_ty)
+\end{code}
- -- LOOK THINGS UP IN THE ENVIRONMENT
- tcLookupClass class_name `thenTc` \ (class_kind, rec_class) ->
- tcLookupTyVar (getTyVarName tyvar_name) `thenNF_Tc` \ (tyvar_kind, rec_tyvar) ->
- let
- rec_class_inst_env = rec_inst_mapper rec_class
- in
- -- FORCE THE CLASS AND ITS TYVAR TO HAVE SAME KIND
- unifyKind class_kind tyvar_kind `thenTc_`
+%************************************************************************
+%* *
+\subsection{Type checking}
+%* *
+%************************************************************************
+\begin{code}
+tcClassDecl1 rec_env rec_inst_mapper rec_vrcs
+ (ClassDecl context class_name
+ tyvar_names class_sigs def_methods pragmas
+ tycon_name datacon_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_tyvar context pragmas
- `thenTc` \ (scs, sc_sel_ids) ->
+-- 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 CLASS SIGNATURES,
- mapTc (tcClassSig rec_env rec_class rec_tyvar) class_sigs
- `thenTc` \ sig_stuff ->
+ mapTc (tcClassSig rec_env rec_class tyvars)
+ (filter isClassOpSig class_sigs)
+ `thenTc` \ sig_stuff ->
-- MAKE THE CLASS OBJECT ITSELF
let
- (op_sel_ids, defm_ids) = unzip sig_stuff
- clas = mkClass (uniqueOf class_name) (getName class_name) rec_tyvar
- scs sc_sel_ids op_sel_ids defm_ids
+ (op_tys, op_sel_ids, defm_ids) = unzip3 sig_stuff
+ rec_class_inst_env = rec_inst_mapper rec_class
+ clas = mkClass class_name tyvars
+ sc_theta sc_sel_ids op_sel_ids defm_ids
+ tycon
rec_class_inst_env
- in
- returnTc clas
-\end{code}
-
- let
- clas_ty = mkTyVarTy clas_tyvar
- dict_component_tys = classDictArgTys clas_ty
+ dict_component_tys = sc_tys ++ op_tys
new_or_data = case dict_component_tys of
[_] -> NewType
other -> DataType
- dict_con_id = mkDataCon class_name
- [NotMarkedStrict]
+ dict_con = mkDataCon datacon_name
+ [notMarkedStrict | _ <- dict_component_tys]
[{- No labelled fields -}]
- [clas_tyvar]
+ tyvars
[{-No context-}]
+ [{-No existential tyvars-}] [{-Or context-}]
dict_component_tys
- tycon
-
- tycon = mkDataTyCon class_name
- (tyVarKind rec_tyvar `mkArrowKind` mkBoxedTypeKind)
- [rec_tyvar]
- [{- Empty context -}]
- [dict_con_id]
- [{- No derived classes -}]
+ tycon dict_con_id
+ dict_con_id = mkDataConId dict_con
+
+ argvrcs = lookupWithDefaultFM rec_vrcs (pprPanic "tcClassDecl1: argvrcs:" $
+ ppr tycon_name)
+ tycon_name
+
+ tycon = mkAlgTyCon tycon_name
+ class_kind
+ tyvars
+ [] -- No context
+ argvrcs
+ [dict_con] -- Constructors
+ [] -- No derivings
+ (Just clas) -- Yes! It's a dictionary
new_or_data
+ NonRecursive
in
+ returnTc clas
+\end{code}
\begin{code}
-tcClassContext :: Class -> TyVar
+tcClassContext :: Name -> Class -> [TyVar]
-> RenamedContext -- class context
- -> RenamedClassPragmas -- pragmas for superclasses
- -> TcM s ([Class], -- the superclasses
- [Id]) -- superclass selector Ids
+ -> [Name] -- Names for superclass selectors
+ -> TcM s (ThetaType, -- the superclass context
+ [Type], -- types of the superclass dictionaries
+ [Id]) -- superclass selector Ids
-tcClassContext rec_class rec_tyvar 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.
- tcContext context `thenTc` \ theta ->
- let
- super_classes = [ supers | (supers, _) <- theta ]
- in
- -- Make super-class selector ids
- mapTc (mk_super_id rec_class) super_classes `thenTc` \ sc_sel_ids ->
+ -- 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_sel_ids = zipWithEqual "tcClassContext" mk_super_id sc_sel_names sc_tys
+ in
-- Done
- returnTc (super_classes, sc_sel_ids)
+ returnTc (sc_theta, sc_tys, sc_sel_ids)
where
- rec_tyvar_ty = mkTyVarTy rec_tyvar
+ rec_tyvar_tys = mkTyVarTys rec_tyvars
+
+ mk_super_id name dict_ty
+ = mkDictSelId name rec_class ty
+ where
+ ty = mkForAllTys rec_tyvars $
+ mkFunTy (mkDictTy rec_class rec_tyvar_tys) dict_ty
- mk_super_id rec_class super_class
- = tcGetUnique `thenNF_Tc` \ uniq ->
- let
- ty = mkForAllTy rec_tyvar $
- mkFunTy (mkDictTy rec_class rec_tyvar_ty)
- (mkDictTy super_class rec_tyvar_ty)
- in
- returnTc (mkSuperDictSelId uniq rec_class super_class ty)
+ check_constraint (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
+ -> [TyVar] -- The class type variable, used for error check only
-> RenamedClassOpSig
- -> TcM s (Id, -- selector id
+ -> TcM s (Type, -- Type of the method
+ Id, -- selector id
Maybe Id) -- default-method ids
-tcClassSig rec_env rec_clas rec_clas_tyvar
+tcClassSig rec_env rec_clas rec_clas_tyvars
(ClassOpSig op_name maybe_dm_name
op_ty
src_loc)
-- 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_tyvar]
- [(rec_clas, mkTyVarTy rec_clas_tyvar)]
+ 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
+ sel_id = mkDictSelId op_name rec_clas global_ty
maybe_dm_id = case maybe_dm_name of
Nothing -> Nothing
Just dm_name -> let
in
Just (tcAddImportedIdInfo rec_env dm_id)
in
- returnTc (sel_id, maybe_dm_id)
+-- 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_name class_sigs default_binds pragmas src_loc)
+ tyvar_names class_sigs default_binds pragmas _ _ _ src_loc)
| not (isLocallyDefined class_name)
= returnNF_Tc (emptyLIE, EmptyMonoBinds)
tcAddSrcLoc src_loc $
-- Get the relevant class
- tcLookupClass class_name `thenTc` \ (_, clas) ->
+ tcLookupClass class_name `thenNF_Tc` \ clas ->
let
- (tyvar, scs, sc_sel_ids, op_sel_ids, defm_ids) = classBigSig clas
+ (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
+ sel_binds = [ CoreMonoBind sel_id (getUnfoldingTemplate (getIdUnfolding sel_id))
+ | sel_id <- sc_sel_ids ++ op_sel_ids
]
-
- final_sel_binds = andMonoBinds 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 `AndMonoBinds` andMonoBindList sel_binds)
\end{code}
%************************************************************************
tcDefaultMethodBinds
:: Class
-> RenamedMonoBinds
- -> TcM s (LIE s, TcMonoBinds s)
+ -> TcM s (LIE, TcMonoBinds)
tcDefaultMethodBinds clas default_binds
= -- Construct suitable signatures
- tcInstSigTyVars [tyvar] `thenNF_Tc` \ ([clas_tyvar], [inst_ty], inst_env) ->
+ tcInstTyVars tyvars `thenNF_Tc` \ (clas_tyvars, inst_tys, _) ->
+
+ -- Check that the default bindings come from this class
+ checkFromThisClass clas op_sel_ids default_binds `thenNF_Tc_`
-- Typecheck the default bindings
let
- clas_tyvar_set = unitTyVarSet clas_tyvar
-
- tc_dm meth_bind
- | not (maybeToBool maybe_stuff)
- = -- Binding for something that isn't in the class signature
- failTc (badMethodErr bndr_name clas)
-
- | otherwise
- = -- Normal case
- tcMethodBind clas origin inst_ty sel_id meth_bind
- `thenTc` \ (bind, insts, (_, local_dm_id)) ->
- returnTc (bind, insts, ([clas_tyvar], 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
- tcExtendGlobalTyVars clas_tyvar_set (
- mapAndUnzip3Tc tc_dm (flatten default_binds [])
+ theta = [(clas,inst_tys)]
+ tc_dm sel_id_w_dm@(_, Just dm_id)
+ = 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, 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_ty)] `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
+ newDicts origin theta `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
let
- avail_insts = this_dict
+ avail_insts = this_dict
in
+ 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
- clas_tyvar_set
+ (ptext SLIT("class") <+> ppr clas)
+ (mkVarSet clas_tyvars')
avail_insts
(unionManyBags insts_needed) `thenTc` \ (const_lie, dict_binds) ->
let
full_binds = AbsBinds
- [clas_tyvar]
+ clas_tyvars'
[this_dict_id]
abs_bind_stuff
- (dict_binds `AndMonoBinds` andMonoBinds defm_binds)
+ emptyNameSet -- No inlines (yet)
+ (dict_binds `andMonoBinds` andMonoBindList defm_binds)
in
returnTc (const_lie, full_binds)
where
- (tyvar, scs, sc_sel_ids, op_sel_ids, defm_ids) = classBigSig clas
+ (tyvars, sc_theta, sc_sel_ids, op_sel_ids, defm_ids) = classBigSig clas
+
+ sel_ids_w_dms = [pair | pair@(_, Just _) <- op_sel_ids `zip` defm_ids]
+ -- Just the ones for which there is an explicit
+ -- user default declaration
+
origin = ClassDeclOrigin
+\end{code}
- flatten EmptyMonoBinds rest = rest
- flatten (AndMonoBinds b1 b2) rest = flatten b1 (flatten b2 rest)
- flatten a_bind rest = a_bind : rest
+\begin{code}
+checkFromThisClass :: Class -> [Id] -> RenamedMonoBinds -> NF_TcM s ()
+checkFromThisClass clas op_sel_ids mono_binds
+ = mapNF_Tc check_from_this_class bndrs `thenNF_Tc_`
+ returnNF_Tc ()
+ where
+ check_from_this_class (bndr, loc)
+ | nameOccName bndr `elem` sel_names = returnNF_Tc ()
+ | otherwise = tcAddSrcLoc loc $
+ addErrTc (badMethodErr bndr clas)
+ sel_names = map getOccName op_sel_ids
+ 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 type
- -> Id -- The method selector
- -> RenamedMonoBinds -- Method binding (just one)
- -> TcM s (TcMonoBinds s, LIE s, (LIE s, TcIdOcc s))
-
-tcMethodBind clas origin inst_ty sel_id meth_bind
- = tcAddSrcLoc src_loc $
- newMethod origin (RealId sel_id) [inst_ty] `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 <=> 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, LIE, (LIE, TcId))
+
+tcMethodBind clas origin inst_tyvars inst_tys inst_theta
+ meth_binds prags supply_default_bind
+ (sel_id, maybe_dm_id)
+ = 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}
+ 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_prags = find_prags meth_name prags
in
- tcBindWithSigs [bndr_name] meth_bind [sig_info]
- nonRecursive (\_ -> NoPragmaInfo) `thenTc` \ (binds, insts, _) ->
- returnTc (binds, insts, meth)
- where
- (bndr_name, src_loc) = case meth_bind of
- FunMonoBind name _ _ loc -> (name, loc)
- PatMonoBind (VarPatIn name) _ loc -> (name, loc)
+ -- 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 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_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
+ 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
+ sig_msg ty = sep [ptext SLIT("When checking the expected type for"),
+ nest 4 (ppr sel_name <+> dcolon <+> ppr ty)]
+
+ 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 loc : prags)
+ | name == sel_name = InlineSig meth_name loc : find_prags meth_name prags
+ find_prags meth_name (NoInlineSig name loc : prags)
+ | name == sel_name = NoInlineSig meth_name 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
+ = 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 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
~~~~~~~~~~~~~~~~~~~
\begin{code}
-badMethodErr bndr clas sty
- = hsep [ptext SLIT("Class"), ppr sty clas, ptext SLIT("does not have a method"), ppr sty bndr]
+classArityErr class_name
+ = ptext SLIT("Too many parameters for class") <+> 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)
+
+badMethodErr bndr clas
+ = hsep [ptext SLIT("Class"), quotes (ppr clas),
+ ptext SLIT("does not have a method"), quotes (ppr bndr)]
-classDeclCtxt class_name sty
- = hsep [ptext SLIT("In the class declaration for"), ppr sty class_name]
+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