%
-% (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 ) where
+module TcClassDcl ( tcClassDecl1, tcClassDecls2, tcMethodBind, badMethodErr ) where
-IMP_Ubiq()
+#include "HsVersions.h"
-import HsSyn ( HsDecl(..), ClassDecl(..), HsBinds(..), Bind(..), MonoBinds(..),
- Match(..), GRHSsAndBinds(..), GRHS(..), HsExpr(..),
- DefaultDecl, TyDecl, InstDecl, IfaceSig, Fixity,
- HsLit(..), OutPat(..), Sig(..), HsType(..), HsTyVar,
- Stmt, Qualifier, ArithSeqInfo, InPat, Fake )
-import HsTypes ( getTyVarName )
+import HsSyn ( HsDecl(..), ClassDecl(..), Sig(..), MonoBinds(..),
+ InPat(..), HsBinds(..), GRHSsAndBinds(..),
+ HsExpr(..), HsLit(..), HsType(..), pprClassAssertion,
+ unguardedRHS, andMonoBinds, andMonoBindList, getTyVarName
+ )
import HsPragmas ( ClassPragmas(..) )
-import RnHsSyn ( RenamedClassDecl(..), RenamedClassPragmas(..),
- RenamedClassOpSig(..), SYN_IE(RenamedMonoBinds),
- RenamedGenPragmas(..), RenamedContext(..), SYN_IE(RenamedHsDecl)
+import BasicTypes ( NewOrData(..), TopLevelFlag(..), RecFlag(..), StrictnessMark(..) )
+import RnHsSyn ( RenamedClassDecl, RenamedClassPragmas,
+ RenamedClassOpSig, RenamedMonoBinds,
+ RenamedContext, RenamedHsDecl, RenamedSig
)
-import TcHsSyn ( TcIdOcc(..), SYN_IE(TcHsBinds), SYN_IE(TcMonoBinds), SYN_IE(TcExpr),
- mkHsTyApp, mkHsTyLam, mkHsDictApp, mkHsDictLam, tcIdType )
+import TcHsSyn ( TcMonoBinds )
-import Inst ( Inst, InstOrigin(..), SYN_IE(LIE), emptyLIE, plusLIE, newDicts, newMethod )
-import TcEnv ( tcLookupClass, tcLookupTyVar, tcLookupTyCon, newLocalIds, tcExtendGlobalTyVars )
-import TcInstDcls ( processInstBinds )
-import TcKind ( unifyKind, TcKind )
+import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, newDicts, newMethod )
+import TcEnv ( TcIdOcc(..), GlobalValueEnv, tcAddImportedIdInfo,
+ tcLookupClass, tcLookupTyVar,
+ tcExtendGlobalTyVars, tcExtendLocalValEnv
+ )
+import TcBinds ( tcBindWithSigs, tcPragmaSigs )
+import TcUnify ( unifyKinds )
import TcMonad
-import TcMonoType ( tcHsType, tcContext )
-import TcSimplify ( tcSimplifyAndCheck )
-import TcType ( SYN_IE(TcType), SYN_IE(TcTyVar), tcInstType, tcInstSigTyVars, tcInstSigType )
-
-import Bag ( foldBag, unionManyBags )
-import Class ( GenClass, GenClassOp, mkClass, mkClassOp, classBigSig,
- classOps, classOpString, classOpLocalType,
- classOpTagByOccName, SYN_IE(ClassOp)
+import TcMonoType ( tcHsType, tcContext, checkSigTyVars, sigCtxt, mkTcSig )
+import TcSimplify ( tcSimplifyAndCheck, bindInstsOfLocalFuns )
+import TcType ( TcType, TcTyVar, tcInstTyVars, zonkTcTyVarBndr )
+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 ( mkSuperDictSelId, mkDataConId,
+ mkMethodSelId, mkDefaultMethodId
+ )
+import DataCon ( mkDataCon )
+import Id ( Id,
+ getIdUnfolding, idType, idName
)
-import Id ( GenId, mkSuperDictSelId, mkMethodSelId, mkDefaultMethodId, getIdUnfolding,
- idType )
import CoreUnfold ( getUnfoldingTemplate )
import IdInfo
-import Name ( Name, isLocallyDefined, moduleString, modAndOcc, nameString )
-import PrelVals ( nO_DEFAULT_METHOD_ERROR_ID )
-import PprStyle
-import Pretty
-import PprType ( GenType, GenTyVar, GenClassOp )
-import SpecEnv ( SpecEnv )
-import SrcLoc ( mkGeneratedSrcLoc )
+import Name ( Name, isLocallyDefined, NamedThing(..) )
+import Outputable
import Type ( mkFunTy, mkTyVarTy, mkTyVarTys, mkDictTy,
- mkForAllTy, mkSigmaTy, splitSigmaTy)
-import TysWiredIn ( stringTy )
-import TyVar ( unitTyVarSet, GenTyVar )
-import Unique ( Unique )
+ mkSigmaTy, mkForAllTys, Type, ThetaType,
+ boxedTypeKind, mkArrowKind
+ )
+import Var ( tyVarKind, TyVar )
+import VarSet ( mkVarSet )
+import TyCon ( mkAlgTyCon )
+import Unique ( Unique, Uniquable(..) )
import Util
+import Maybes ( seqMaybe )
-- import TcPragmas ( tcGenPragmas, tcClassOpPragmas )
tcGenPragmas ty id ps = returnNF_Tc noIdInfo
-tcClassOpPragmas ty sel def spec ps = returnNF_Tc (noIdInfo `addSpecInfo` spec,
+tcClassOpPragmas ty sel def spec ps = returnNF_Tc (spec `setSpecInfo` noIdInfo,
noIdInfo)
\end{code}
\begin{code}
-tcClassDecl1 rec_inst_mapper
+tcClassDecl1 rec_env rec_inst_mapper
(ClassDecl context class_name
- tyvar_name class_sigs def_methods pragmas src_loc)
+ 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
+ checkTc (opt_GlasgowExts || length tyvar_names == 1)
+ (classArityErr class_name) `thenTc_`
+
-- 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_class_op_inst_fn) = rec_inst_mapper rec_class
- in
+ tcLookupClass class_name `thenTc` \ (class_kinds, rec_class) ->
+ mapAndUnzipNF_Tc (tcLookupTyVar . getTyVarName) tyvar_names
+ `thenNF_Tc` \ (tyvar_kinds, rec_tyvars) ->
-- FORCE THE CLASS AND ITS TYVAR TO HAVE SAME KIND
- unifyKind class_kind tyvar_kind `thenTc_`
+ unifyKinds class_kinds tyvar_kinds `thenTc_`
-- CHECK THE CONTEXT
- tcClassContext rec_class rec_tyvar context pragmas
- `thenTc` \ (scs, sc_sel_ids) ->
+ tcClassContext class_name rec_class rec_tyvars context pragmas
+ `thenTc` \ (sc_theta, sc_tys, sc_sel_ids) ->
-- CHECK THE CLASS SIGNATURES,
- mapTc (tcClassSig rec_class rec_tyvar rec_class_op_inst_fn) class_sigs
- `thenTc` \ sig_stuff ->
+ mapTc (tcClassSig rec_env rec_class rec_tyvars) class_sigs
+ `thenTc` \ sig_stuff ->
-- MAKE THE CLASS OBJECT ITSELF
let
- (ops, op_sel_ids, defm_ids) = unzip3 sig_stuff
- clas = mkClass (uniqueOf class_name) (getName class_name) rec_tyvar
- scs sc_sel_ids ops 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 (getName class_name) rec_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 = [mkDictTy sc clas_ty | sc <- scs] ++
- [classOpLocalType op | op <- ops])
+ 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]
+ rec_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
+
+ tycon = mkAlgTyCon tycon_name
+ (foldr (mkArrowKind . tyVarKind) boxedTypeKind rec_tyvars)
+ rec_tyvars
+ [] -- No context
+ [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
+ -> 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 pragmas
= -- Check the context.
-- The renamer has already checked that the context mentions
-- only the type variable of the class decl.
- tcContext context `thenTc` \ theta ->
+
+ -- 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
- super_classes = [ supers | (supers, _) <- theta ]
+ sc_tys = [mkDictTy sc tys | (sc,tys) <- sc_theta]
in
-- Make super-class selector ids
- mapTc (mk_super_id rec_class) super_classes `thenTc` \ sc_sel_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 (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 rec_class super_class
+ mk_super_id ((super_class, tys), index)
= tcGetUnique `thenNF_Tc` \ uniq ->
let
- ty = mkForAllTy rec_tyvar $
- mkFunTy (mkDictTy rec_class rec_tyvar_ty)
- (mkDictTy super_class rec_tyvar_ty)
+ ty = mkForAllTys rec_tyvars $
+ mkFunTy (mkDictTy rec_class rec_tyvar_tys) (mkDictTy super_class tys)
in
- returnTc (mkSuperDictSelId uniq rec_class super_class ty)
+ 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 :: Class -- Knot tying only!
- -> TyVar -- The class type variable, used for error check only
- -> (ClassOp -> SpecEnv) -- Ditto; the spec info for the class ops
+
+tcClassSig :: GlobalValueEnv -- Knot tying only!
+ -> Class -- ...ditto...
+ -> [TyVar] -- The class type variable, used for error check only
-> RenamedClassOpSig
- -> TcM s (ClassOp, -- class op
+ -> TcM s (Type, -- Type of the method
Id, -- selector id
- Id) -- default-method ids
+ Maybe Id) -- default-method ids
-tcClassSig rec_clas rec_clas_tyvar rec_classop_spec_fn
- (ClassOpSig op_name
+tcClassSig rec_env rec_clas rec_clas_tyvars
+ (ClassOpSig op_name maybe_dm_name
op_ty
- pragmas src_loc)
+ src_loc)
= tcAddSrcLoc src_loc $
- fixTc ( \ ~(_, rec_sel_id, rec_defm_id) -> -- Knot for pragmas
-- Check the type signature. NB that the envt *already has*
-- bindings for the type variables; see comments in TcTyAndClassDcls.
-- and that it is not constrained by theta
tcHsType 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
- class_op_nm = getOccName op_name
- class_op = mkClassOp class_op_nm
- (classOpTagByOccName rec_clas{-yeeps!-} class_op_nm)
- local_ty
in
-- Build the selector id and default method id
- tcGetUnique `thenNF_Tc` \ d_uniq ->
let
- sel_id = mkMethodSelId op_name rec_clas class_op global_ty
- defm_id = mkDefaultMethodId op_name d_uniq rec_clas class_op False global_ty
- -- ToDo: improve the "False"
+ 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)
in
- returnTc (class_op, sel_id, defm_id)
- )
+ returnTc (local_ty, sel_id, maybe_dm_id)
\end{code}
\begin{code}
tcClassDecls2 :: [RenamedHsDecl]
- -> NF_TcM s (LIE s, TcHsBinds s)
+ -> NF_TcM s (LIE s, TcMonoBinds s)
tcClassDecls2 decls
= foldr combine
- (returnNF_Tc (emptyLIE, EmptyBinds))
+ (returnNF_Tc (emptyLIE, EmptyMonoBinds))
[tcClassDecl2 cls_decl | ClD cls_decl <- decls]
where
combine tc1 tc2 = tc1 `thenNF_Tc` \ (lie1, binds1) ->
tc2 `thenNF_Tc` \ (lie2, binds2) ->
returnNF_Tc (lie1 `plusLIE` lie2,
- binds1 `ThenBinds` binds2)
+ binds1 `AndMonoBinds` binds2)
\end{code}
@tcClassDecl2@ is the business end of things.
\begin{code}
tcClassDecl2 :: RenamedClassDecl -- The class declaration
- -> NF_TcM s (LIE s, TcHsBinds s)
+ -> NF_TcM s (LIE s, TcMonoBinds s)
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, EmptyBinds)
+ = returnNF_Tc (emptyLIE, EmptyMonoBinds)
| otherwise -- It is locally defined
- = recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyBinds)) $
- tcAddSrcLoc src_loc $
+ = recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $
+ tcAddSrcLoc src_loc $
-- Get the relevant class
tcLookupClass class_name `thenTc` \ (_, clas) ->
let
- (tyvar, scs, sc_sel_ids, ops, 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 = SingleBind $ NonRecBind $ foldr AndMonoBinds EmptyMonoBinds $
- [ CoreMonoBind (RealId sel_id) (getUnfoldingTemplate (getIdUnfolding sel_id))
- | sel_id <- sc_sel_ids ++ op_sel_ids,
- isLocallyDefined sel_id
- ]
+-- sel_binds = [ CoreMonoBind (RealId 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
- tcInstSigTyVars [tyvar] `thenNF_Tc` \ ([clas_tyvar], _, _) ->
- buildDefaultMethodBinds clas clas_tyvar defm_ids default_binds
- `thenTc` \ (const_insts, meth_binds) ->
+ tcDefaultMethodBinds clas default_binds `thenTc` \ (const_insts, meth_binds) ->
- returnTc (const_insts, sel_binds `ThenBinds` 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}
%************************************************************************
\end{verbatim}
\begin{code}
-buildDefaultMethodBinds
+tcDefaultMethodBinds
:: Class
- -> TcTyVar s
- -> [Id]
-> RenamedMonoBinds
- -> TcM s (LIE s, TcHsBinds s)
+ -> TcM s (LIE s, TcMonoBinds s)
+
+tcDefaultMethodBinds clas default_binds
+ = -- Construct suitable signatures
+ tcInstTyVars tyvars `thenNF_Tc` \ (clas_tyvars, inst_tys, inst_env) ->
-buildDefaultMethodBinds clas clas_tyvar
- default_method_ids default_binds
- = newDicts origin [(clas,inst_ty)] `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
- mapAndUnzipNF_Tc mk_method default_method_ids `thenNF_Tc` \ (insts_s, local_defm_ids) ->
+ -- Typecheck the default bindings
let
- avail_insts = this_dict `plusLIE` unionManyBags insts_s -- Insts available
- clas_tyvar_set = unitTyVarSet clas_tyvar
+ tc_dm sel_id_w_dm@(_, Just dm_id)
+ = tcMethodBind clas origin inst_tys clas_tyvars
+ 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) ->
+
+ -- Check the context
+ newDicts origin [(clas,inst_tys)] `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
+ let
+ avail_insts = this_dict
in
- tcExtendGlobalTyVars clas_tyvar_set (
- processInstBinds
- clas
- (makeClassDeclDefaultMethodRhs clas local_defm_ids)
- avail_insts
- local_defm_ids
- default_binds
- ) `thenTc` \ (insts_needed, default_binds') ->
+ tcAddErrCtxt (classDeclCtxt clas) $
+
+ -- tcMethodBind has checked that the class_tyvars havn't
+ -- been unified with each other or another type, but we must
+ -- still zonk them
+ mapNF_Tc zonkTcTyVarBndr clas_tyvars `thenNF_Tc` \ clas_tyvars' ->
tcSimplifyAndCheck
- clas_tyvar_set
+ (ptext SLIT("class") <+> ppr clas)
+ (mkVarSet clas_tyvars')
avail_insts
- insts_needed `thenTc` \ (const_lie, dict_binds) ->
-
+ (unionManyBags insts_needed) `thenTc` \ (const_lie, dict_binds) ->
let
- defm_binds = AbsBinds
- [clas_tyvar]
+ full_binds = AbsBinds
+ clas_tyvars'
[this_dict_id]
- (local_defm_ids `zip` map RealId default_method_ids)
- dict_binds
- (RecBind default_binds')
+ abs_bind_stuff
+ (dict_binds `andMonoBinds` andMonoBindList defm_binds)
in
- returnTc (const_lie, defm_binds)
+ returnTc (const_lie, full_binds)
+
where
- inst_ty = mkTyVarTy clas_tyvar
- mk_method defm_id = newMethod origin (RealId defm_id) [inst_ty]
+ (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}
-@makeClassDeclDefaultMethodRhs@ builds the default method for a
-class declaration when no explicit default method is given.
+@tcMethodBind@ is used to type-check both default-method and
+instance-decl method declarations. We must type-check methods one at a
+time, because their signatures may have different contexts and
+tyvar sets.
\begin{code}
-makeClassDeclDefaultMethodRhs
+tcMethodBind
:: Class
- -> [TcIdOcc s]
- -> Int
- -> NF_TcM s (TcExpr s)
-
-makeClassDeclDefaultMethodRhs clas method_ids tag
- = -- Return the expression
- -- error ty "No default method for ..."
- -- The interesting thing is that method_ty is a for-all type;
- -- this is fun, although unusual in a type application!
+ -> 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
+ -> 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))
+
+tcMethodBind clas origin inst_tys inst_tyvars
+ meth_binds prags supply_default_bind
+ (sel_id, maybe_dm_id)
+ = tcGetSrcLoc `thenNF_Tc` \ loc ->
+
+ newMethod origin (RealId sel_id) inst_tys `thenNF_Tc` \ meth@(_, TcId meth_id) ->
+ mkTcSig meth_id loc `thenNF_Tc` \ sig_info ->
+
+ let
+ 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
+
+ -- 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 the bindings
+ tcExtendGlobalTyVars (mkVarSet inst_tyvars) (
+ tcAddErrCtxt (methodCtxt sel_id) $
+ tcBindWithSigs NotTopLevel meth_bind [sig_info]
+ NonRecursive prag_info_fn
+ ) `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
+ tcAddErrCtxtM (sigCtxt (quotes (ppr sel_id)) (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
+
+ -- 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) rhs loc)
+ | op_name == sel_name = Just (PatMonoBind (VarPatIn meth_name) rhs 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 spec loc : prags)
+ | name == sel_name = SpecSig meth_name ty spec 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)
+ (GRHSsAndBindsIn (unguardedRHS (default_expr loc) loc) EmptyBinds)
+ 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}
- returnNF_Tc (HsApp (mkHsTyApp (HsVar (RealId nO_DEFAULT_METHOD_ERROR_ID)) [tcIdType method_id])
- (HsLitOut (HsString (_PK_ error_msg)) stringTy))
+Contexts and errors
+~~~~~~~~~~~~~~~~~~~
+\begin{code}
+classArityErr class_name
+ = ptext SLIT("Too many parameters for class") <+> quotes (ppr class_name)
- where
- (clas_mod, clas_name) = modAndOcc clas
+classDeclCtxt class_name
+ = ptext SLIT("In the class declaration for") <+> quotes (ppr class_name)
- method_id = method_ids !! (tag-1)
- class_op = (classOps clas) !! (tag-1)
+superClassErr class_name sc
+ = ptext SLIT("Illegal superclass constraint") <+> quotes (pprClassAssertion sc)
+ <+> ptext SLIT("in declaration for class") <+> quotes (ppr class_name)
- error_msg = _UNPK_ (nameString (getName clas))
- ++ (ppShow 80 (ppr PprForUser class_op))
--- ++ "\"" Don't know what this trailing quote is for!
-\end{code}
+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)]
-Contexts
-~~~~~~~~
-\begin{code}
-classDeclCtxt class_name sty
- = ppCat [ppStr "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