\begin{code}
module TcClassDcl ( tcClassSigs, tcClassDecl2,
- findMethodBind, tcInstanceMethodBody,
- mkGenericDefMethBind, getGenericInstances, mkDefMethRdrName,
+ findMethodBind, instantiateMethod, tcInstanceMethodBody,
+ mkGenericDefMethBind, getGenericInstances,
tcAddDeclCtxt, badMethodErr, badATErr, omittedATWarn
) where
import HsSyn
import RnHsSyn
import RnExpr
-import RnEnv
import Inst
import InstEnv
+import TcPat( addInlinePrags )
import TcEnv
import TcBinds
-import TcSimplify
+import TcUnify
import TcHsType
import TcMType
import TcType
import TcRnMonad
+import BuildTyCl( TcMethInfo )
import Generics
import Class
import TyCon
import Var
import NameEnv
import NameSet
-import RdrName
import Outputable
import PrelNames
import DynFlags
import ListSetOps
import SrcLoc
import Maybes
-import List
import BasicTypes
import Bag
import FastString
import Control.Monad
+import Data.List
\end{code}
-> LHsBinds Name
-> TcM [TcMethInfo]
-type TcMethInfo = (Name, DefMeth, Type) -- A temporary intermediate, to communicate
- -- between tcClassSigs and buildClass
tcClassSigs clas sigs def_methods
- = do { dm_env <- checkDefaultBinds clas op_names def_methods
- ; mapM (tcClassSig dm_env) op_sigs }
+ = do { dm_env <- mapM (addLocM (checkDefaultBind clas op_names))
+ (bagToList def_methods)
+ ; mapM (tcClassSig (mkNameEnv dm_env)) op_sigs }
where
op_sigs = [sig | sig@(L _ (TypeSig _ _)) <- sigs]
op_names = [n | (L _ (TypeSig (L _ n) _)) <- op_sigs]
-
-checkDefaultBinds :: Name -> [Name] -> LHsBinds Name -> TcM (NameEnv Bool)
+checkDefaultBind :: Name -> [Name] -> HsBindLR Name Name -> TcM (Name, DefMethSpec)
-- Check default bindings
-- a) must be for a class op for this class
-- b) must be all generic or all non-generic
- -- and return a mapping from class-op to Bool
- -- where True <=> it's a generic default method
-checkDefaultBinds clas ops binds
- = do dm_infos <- mapM (addLocM (checkDefaultBind clas ops)) (bagToList binds)
- return (mkNameEnv dm_infos)
-
-checkDefaultBind :: Name -> [Name] -> HsBindLR Name Name -> TcM (Name, Bool)
checkDefaultBind clas ops (FunBind {fun_id = L _ op, fun_matches = MatchGroup matches _ })
= do { -- Check that the op is from this class
- checkTc (op `elem` ops) (badMethodErr clas op)
+ checkTc (op `elem` ops) (badMethodErr clas op)
-- Check that all the defns ar generic, or none are
- ; checkTc (all_generic || none_generic) (mixedGenericErr op)
-
- ; return (op, all_generic)
+ ; case (none_generic, all_generic) of
+ (True, _) -> return (op, VanillaDM)
+ (_, True) -> return (op, GenericDM)
+ _ -> failWith (mixedGenericErr op)
}
where
n_generic = count (isJust . maybeGenericMatch) matches
none_generic = n_generic == 0
all_generic = matches `lengthIs` n_generic
+
checkDefaultBind _ _ b = pprPanic "checkDefaultBind" (ppr b)
-tcClassSig :: NameEnv Bool -- Info about default methods;
+tcClassSig :: NameEnv DefMethSpec -- Info about default methods;
-> LSig Name
-> TcM TcMethInfo
tcClassSig dm_env (L loc (TypeSig (L _ op_name) op_hs_ty))
= setSrcSpan loc $ do
{ op_ty <- tcHsKindedType op_hs_ty -- Class tyvars already in scope
- ; let dm = case lookupNameEnv dm_env op_name of
- Nothing -> NoDefMeth
- Just False -> DefMeth
- Just True -> GenDefMeth
+ ; let dm = lookupNameEnv dm_env op_name `orElse` NoDM
; return (op_name, dm, op_ty) }
tcClassSig _ s = pprPanic "tcClassSig" (ppr s)
\end{code}
\begin{code}
tcClassDecl2 :: LTyClDecl Name -- The class declaration
- -> TcM (LHsBinds Id, [Id])
+ -> TcM (LHsBinds Id)
tcClassDecl2 (L loc (ClassDecl {tcdLName = class_name, tcdSigs = sigs,
tcdMeths = default_binds}))
- = recoverM (return (emptyLHsBinds, [])) $
- setSrcSpan loc $
+ = recoverM (return emptyLHsBinds) $
+ setSrcSpan loc $
do { clas <- tcLookupLocatedClass class_name
-- We make a separate binding for each default method.
; let
(tyvars, _, _, op_items) = classBigSig clas
rigid_info = ClsSkol clas
- prag_fn = mkPragFun sigs
- sig_fn = mkTcSigFun sigs
+ prag_fn = mkPragFun sigs default_binds
+ sig_fn = mkSigFun sigs
clas_tyvars = tcSkolSigTyVars rigid_info tyvars
pred = mkClassPred clas (mkTyVarTys clas_tyvars)
- ; inst_loc <- getInstLoc (SigOrigin rigid_info)
- ; this_dict <- newDictBndr inst_loc pred
+ ; this_dict <- newEvVar pred
- ; let tc_dm = tcDefMeth rigid_info clas clas_tyvars [pred]
+ ; let tc_dm = tcDefMeth clas clas_tyvars
this_dict default_binds
sig_fn prag_fn
- -- tc_dm is called only for a sel_id
- -- that has a binding in default_binds
-
- dm_sel_ids = [sel_id | (sel_id, DefMeth) <- op_items]
- -- Generate code for polymorphic default methods only (hence DefMeth)
- -- (Generic default methods have turned into instance decls by now.)
- -- This is incompatible with Hugs, which expects a polymorphic
- -- default method for every class op, regardless of whether or not
- -- the programmer supplied an explicit default decl for the class.
- -- (If necessary we can fix that, but we don't have a convenient Id to hand.)
- ; (defm_binds, dm_ids) <- tcExtendTyVarEnv clas_tyvars $
- mapAndUnzipM tc_dm dm_sel_ids
+ ; dm_binds <- tcExtendTyVarEnv clas_tyvars $
+ mapM tc_dm op_items
- ; return (unionManyBags defm_binds, dm_ids) }
+ ; return (listToBag (catMaybes dm_binds)) }
tcClassDecl2 d = pprPanic "tcClassDecl2" (ppr d)
-tcDefMeth :: SkolemInfo -> Class -> [TyVar] -> ThetaType -> Inst -> LHsBinds Name
- -> TcSigFun -> TcPragFun -> Id
- -> TcM (LHsBinds Id, Id)
-tcDefMeth rigid_info clas tyvars theta this_dict binds_in sig_fn prag_fn sel_id
- = do { let sel_name = idName sel_id
+tcDefMeth :: Class -> [TyVar] -> EvVar -> LHsBinds Name
+ -> SigFun -> PragFun -> ClassOpItem
+ -> TcM (Maybe (LHsBind Id))
+-- Generate code for polymorphic default methods only (hence DefMeth)
+-- (Generic default methods have turned into instance decls by now.)
+-- This is incompatible with Hugs, which expects a polymorphic
+-- default method for every class op, regardless of whether or not
+-- the programmer supplied an explicit default decl for the class.
+-- (If necessary we can fix that, but we don't have a convenient Id to hand.)
+tcDefMeth clas tyvars this_dict binds_in sig_fn prag_fn (sel_id, dm_info)
+ = case dm_info of
+ NoDefMeth -> return Nothing
+ GenDefMeth -> return Nothing
+ DefMeth dm_name -> do
+ { let sel_name = idName sel_id
; local_dm_name <- newLocalName sel_name
- ; let meth_bind = findMethodBind sel_name local_dm_name binds_in
+ -- Base the local_dm_name on the selector name, because
+ -- type errors from tcInstanceMethodBody come from here
+
+ -- See Note [Silly default-method bind]
+ -- (possibly out of date)
+
+ ; let meth_bind = findMethodBind sel_name binds_in
`orElse` pprPanic "tcDefMeth" (ppr sel_id)
- -- We only call tcDefMeth on selectors for which
- -- there is a binding in binds_in
+ -- dm_info = DefMeth dm_name only if there is a binding in binds_in
+
+ dm_sig_fn _ = sig_fn sel_name
+ dm_id = mkDefaultMethodId sel_id dm_name
+ local_dm_type = instantiateMethod clas sel_id (mkTyVarTys tyvars)
+ local_dm_id = mkLocalId local_dm_name local_dm_type
+ prags = prag_fn sel_name
+
+ ; dm_id_w_inline <- addInlinePrags dm_id prags
+ ; spec_prags <- tcSpecPrags dm_id prags
+
+ ; warnTc (not (null spec_prags))
+ (ptext (sLit "Ignoring SPECIALISE pragmas on default method")
+ <+> quotes (ppr sel_name))
+
+ ; liftM Just $
+ tcInstanceMethodBody (ClsSkol clas)
+ tyvars
+ [this_dict]
+ Nothing
+ dm_id_w_inline local_dm_id
+ dm_sig_fn IsDefaultMethod meth_bind }
+
+---------------
+tcInstanceMethodBody :: SkolemInfo -> [TcTyVar] -> [EvVar]
+ -> Maybe EvBind
+ -> Id -> Id
+ -> SigFun -> TcSpecPrags -> LHsBind Name
+ -> TcM (LHsBind Id)
+tcInstanceMethodBody skol_info tyvars dfun_ev_vars
+ this_dict meth_id local_meth_id
+ meth_sig_fn specs
+ (L loc bind)
+ = do { -- Typecheck the binding, first extending the envt
+ -- so that when tcInstSig looks up the local_meth_id to find
+ -- its signature, we'll find it in the environment
+ let full_given = case this_dict of
+ Nothing -> dfun_ev_vars
+ Just (EvBind dict _) -> dict : dfun_ev_vars
+ lm_bind = L loc (bind { fun_id = L loc (idName local_meth_id) })
+ -- Substitue the local_meth_name for the binder
+ -- NB: the binding is always a FunBind
+
+ ; (ev_binds, (tc_bind, _))
+ <- checkConstraints skol_info tyvars full_given $
+ tcExtendIdEnv [local_meth_id] $
+ tcPolyBinds TopLevel meth_sig_fn no_prag_fn
+ NonRecursive NonRecursive
+ [lm_bind]
+
+ -- Add the binding for this_dict, if we have one
+ ; ev_binds' <- case this_dict of
+ Nothing -> return ev_binds
+ Just (EvBind self rhs) -> extendTcEvBinds ev_binds self rhs
+
+ ; let full_bind = AbsBinds { abs_tvs = tyvars, abs_ev_vars = dfun_ev_vars
+ , abs_exports = [(tyvars, meth_id, local_meth_id, specs)]
+ , abs_ev_binds = ev_binds'
+ , abs_binds = tc_bind }
+
+ ; return (L loc full_bind) }
+ where
+ no_prag_fn _ = [] -- No pragmas for local_meth_id;
+ -- they are all for meth_id
+\end{code}
- meth_sig_fn _ = sig_fn sel_name
- meth_prag_fn _ = prag_fn sel_name
+\begin{code}
+instantiateMethod :: Class -> Id -> [TcType] -> TcType
+-- Take a class operation, say
+-- op :: forall ab. C a => forall c. Ix c => (b,c) -> a
+-- Instantiate it at [ty1,ty2]
+-- Return the "local method type":
+-- forall c. Ix x => (ty2,c) -> ty1
+instantiateMethod clas sel_id inst_tys
+ = ASSERT( ok_first_pred ) local_meth_ty
+ where
+ (sel_tyvars,sel_rho) = tcSplitForAllTys (idType sel_id)
+ rho_ty = ASSERT( length sel_tyvars == length inst_tys )
+ substTyWith sel_tyvars inst_tys sel_rho
- ; (top_dm_id, bind) <- tcInstanceMethodBody rigid_info
- clas tyvars [this_dict] theta (mkTyVarTys tyvars)
- Nothing sel_id
- local_dm_name
- meth_sig_fn meth_prag_fn
- meth_bind
+ (first_pred, local_meth_ty) = tcSplitPredFunTy_maybe rho_ty
+ `orElse` pprPanic "tcInstanceMethod" (ppr sel_id)
- ; return (bind, top_dm_id) }
+ ok_first_pred = case getClassPredTys_maybe first_pred of
+ Just (clas1, _tys) -> clas == clas1
+ Nothing -> False
+ -- The first predicate should be of form (C a b)
+ -- where C is the class in question
-mkDefMethRdrName :: Name -> RdrName
-mkDefMethRdrName sel_name = mkDerivedRdrName sel_name mkDefaultMethodOcc
---------------------------
--- 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.
-findMethodBind :: Name -> Name -- Selector and method name
+findMethodBind :: Name -- Selector name
-> LHsBinds Name -- A group of bindings
- -> Maybe (LHsBind Name) -- The binding, with meth_name replacing sel_name
-findMethodBind sel_name meth_name binds
+ -> Maybe (LHsBind Name) -- The binding
+findMethodBind sel_name binds
= foldlBag mplus Nothing (mapBag f binds)
where
- f (L loc1 bind@(FunBind { fun_id = L loc2 op_name }))
- | op_name == sel_name
- = Just (L loc1 (bind { fun_id = L loc2 meth_name }))
- f _other = Nothing
-
----------------
-tcInstanceMethodBody :: SkolemInfo -> Class -> [TcTyVar] -> [Inst]
- -> TcThetaType -> [TcType]
- -> Maybe (Inst, LHsBind Id) -> Id
- -> Name -- The local method name
- -> TcSigFun -> TcPragFun -> LHsBind Name
- -> TcM (Id, LHsBinds Id)
-tcInstanceMethodBody rigid_info clas tyvars dfun_dicts theta inst_tys
- mb_this_bind sel_id local_meth_name
- sig_fn prag_fn bind@(L loc _)
- = do { let (sel_tyvars,sel_rho) = tcSplitForAllTys (idType sel_id)
- rho_ty = ASSERT( length sel_tyvars == length inst_tys )
- substTyWith sel_tyvars inst_tys sel_rho
-
- (first_pred, local_meth_ty) = tcSplitPredFunTy_maybe rho_ty
- `orElse` pprPanic "tcInstanceMethod" (ppr sel_id)
-
- local_meth_id = mkLocalId local_meth_name local_meth_ty
- meth_ty = mkSigmaTy tyvars theta local_meth_ty
- sel_name = idName sel_id
-
- -- The first predicate should be of form (C a b)
- -- where C is the class in question
- ; MASSERT( case getClassPredTys_maybe first_pred of
- { Just (clas1, _tys) -> clas == clas1 ; Nothing -> False } )
-
- -- Typecheck the binding, first extending the envt
- -- so that when tcInstSig looks up the local_meth_id to find
- -- its signature, we'll find it in the environment
- ; ((tc_bind, _), lie) <- getLIE $
- tcExtendIdEnv [local_meth_id] $
- tcPolyBinds TopLevel sig_fn prag_fn
- NonRecursive NonRecursive
- (unitBag bind)
-
- ; meth_id <- case rigid_info of
- ClsSkol _ -> do { dm_name <- lookupTopBndrRn (mkDefMethRdrName sel_name)
- ; return (mkDefaultMethodId dm_name meth_ty) }
- _other -> do { meth_name <- newLocalName sel_name
- ; return (mkLocalId meth_name meth_ty) }
-
- ; let (avails, this_dict_bind)
- = case mb_this_bind of
- Nothing -> (dfun_dicts, emptyBag)
- Just (this, bind) -> (this : dfun_dicts, unitBag bind)
-
- ; inst_loc <- getInstLoc (SigOrigin rigid_info)
- ; lie_binds <- tcSimplifyCheck inst_loc tyvars avails lie
-
- ; let full_bind = L loc $
- AbsBinds tyvars dfun_lam_vars
- [(tyvars, meth_id, local_meth_id, [])]
- (this_dict_bind `unionBags` lie_binds
- `unionBags` tc_bind)
-
- dfun_lam_vars = map instToVar dfun_dicts -- Includes equalities
-
- ; return (meth_id, unitBag full_bind) }
+ f bind@(L _ (FunBind { fun_id = L _ op_name }))
+ | op_name == sel_name
+ = Just bind
+ f _other = Nothing
\end{code}
Note [Polymorphic methods]
instance C 1 where
op Unit = ...
-
\begin{code}
-mkGenericDefMethBind :: Class -> [Type] -> Id -> Name -> TcM (LHsBind Name)
-mkGenericDefMethBind clas inst_tys sel_id meth_name
+mkGenericDefMethBind :: Class -> [Type] -> Id -> TcM (LHsBind Name)
+mkGenericDefMethBind clas inst_tys sel_id
= -- A generic default method
-- If the method is defined generically, we can only do the job if the
-- instance declaration is for a single-parameter type class with
-- Rename it before returning it
; (rn_rhs, _) <- rnLExpr rhs
- ; return (noLoc $ mkFunBind (noLoc meth_name) [mkSimpleMatch [] rn_rhs]) }
+ ; return (noLoc $ mkFunBind (noLoc (idName sel_id))
+ [mkSimpleMatch [] rn_rhs]) }
where
rhs = mkGenericRhs sel_id clas_tyvar tycon
-- and wrap them as forall'd tyvars, so that kind inference
-- works in the standard way
let
- sig_tvs = map (noLoc.UserTyVar) (nameSetToList (extractHsTyVars (noLoc hs_ty)))
+ sig_tvs = userHsTyVarBndrs $ map noLoc $ nameSetToList $
+ extractHsTyVars (noLoc hs_ty)
hs_forall_ty = noLoc $ mkExplicitHsForAllTy sig_tvs (noLoc []) (noLoc hs_ty)
-- Type-check the instance type, and check its form
badGenericInstanceType :: LHsBinds Name -> SDoc
badGenericInstanceType binds
= vcat [ptext (sLit "Illegal type pattern in the generic bindings"),
- nest 4 (ppr binds)]
+ nest 2 (ppr binds)]
missingGenericInstances :: [Name] -> SDoc
missingGenericInstances missing
dupGenericInsts :: [(TyCon, InstInfo a)] -> SDoc
dupGenericInsts tc_inst_infos
= vcat [ptext (sLit "More than one type pattern for a single generic type constructor:"),
- nest 4 (vcat (map ppr_inst_ty tc_inst_infos)),
+ nest 2 (vcat (map ppr_inst_ty tc_inst_infos)),
ptext (sLit "All the type patterns for a generic type constructor must be identical")
]
where
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