tcDeriving :: [LTyClDecl Name] -- All type constructors
-> [LInstDecl Name] -- All instance declarations
-> [LDerivDecl Name] -- All stand-alone deriving declarations
- -> TcM ([InstInfo], -- The generated "instance decls"
+ -> TcM ([InstInfo Name], -- The generated "instance decls"
HsValBinds Name) -- Extra generated top-level bindings
tcDeriving tycl_decls inst_decls deriv_decls
= recoverM (return ([], emptyValBindsOut)) $
do { -- Fish the "deriving"-related information out of the TcEnv
-- And make the necessary "equations".
- ; early_specs <- makeDerivSpecs tycl_decls inst_decls deriv_decls
+ is_boot <- tcIsHsBoot
+ ; traceTc (text "tcDeriving" <+> ppr is_boot)
+ ; early_specs <- makeDerivSpecs is_boot tycl_decls inst_decls deriv_decls
; overlap_flag <- getOverlapFlag
; let (infer_specs, given_specs) = splitEithers early_specs
- ; (insts1, aux_binds1) <- mapAndUnzipM (genInst overlap_flag) given_specs
+ ; insts1 <- mapM (genInst overlap_flag) given_specs
- ; final_specs <- extendLocalInstEnv (map iSpec insts1) $
+ ; final_specs <- extendLocalInstEnv (map (iSpec . fst) insts1) $
inferInstanceContexts overlap_flag infer_specs
- ; (insts2, aux_binds2) <- mapAndUnzipM (genInst overlap_flag) final_specs
+ ; insts2 <- mapM (genInst overlap_flag) final_specs
- ; is_boot <- tcIsHsBoot
- ; rn_binds <- makeAuxBinds is_boot tycl_decls
- (concat aux_binds1 ++ concat aux_binds2)
-
- ; let inst_info = insts1 ++ insts2
+ -- Generate the generic to/from functions from each type declaration
+ ; gen_binds <- mkGenericBinds is_boot
+ ; (inst_info, rn_binds) <- renameDeriv is_boot gen_binds (insts1 ++ insts2)
; dflags <- getDOpts
; liftIO (dumpIfSet_dyn dflags Opt_D_dump_deriv "Derived instances"
; return (inst_info, rn_binds) }
where
- ddump_deriving :: [InstInfo] -> HsValBinds Name -> SDoc
+ ddump_deriving :: [InstInfo Name] -> HsValBinds Name -> SDoc
ddump_deriving inst_infos extra_binds
= vcat (map pprInstInfoDetails inst_infos) $$ ppr extra_binds
-makeAuxBinds :: Bool -> [LTyClDecl Name] -> DerivAuxBinds -> TcM (HsValBinds Name)
-makeAuxBinds is_boot tycl_decls deriv_aux_binds
- | is_boot -- If we are compiling a hs-boot file,
- -- don't generate any derived bindings
- = return emptyValBindsOut
+renameDeriv :: Bool -> LHsBinds RdrName
+ -> [(InstInfo RdrName, DerivAuxBinds)]
+ -> TcM ([InstInfo Name], HsValBinds Name)
+renameDeriv is_boot gen_binds insts
+ | is_boot -- If we are compiling a hs-boot file, don't generate any derived bindings
+ -- The inst-info bindings will all be empty, but it's easier to
+ -- just use rn_inst_info to change the type appropriately
+ = do { rn_inst_infos <- mapM rn_inst_info inst_infos
+ ; return (rn_inst_infos, emptyValBindsOut) }
| otherwise
- = do { let aux_binds = listToBag (map genAuxBind (rm_dups [] deriv_aux_binds))
- -- Generate any extra not-one-inst-decl-specific binds,
+ = discardWarnings $ -- Discard warnings about unused bindings etc
+ do { (rn_gen, dus_gen) <- setOptM Opt_ScopedTypeVariables $ -- Type signatures in patterns
+ -- are used in the generic binds
+ rnTopBinds (ValBindsIn gen_binds [])
+ ; keepAliveSetTc (duDefs dus_gen) -- Mark these guys to be kept alive
+
+ -- Generate and rename any extra not-one-inst-decl-specific binds,
-- notably "con2tag" and/or "tag2con" functions.
+ -- Bring those names into scope before renaming the instances themselves
+ ; loc <- getSrcSpanM -- Generic loc for shared bindings
+ ; let aux_binds = listToBag $ map (genAuxBind loc) $
+ rm_dups [] $ concat deriv_aux_binds
+ ; rn_aux_lhs <- rnTopBindsLHS emptyFsEnv (ValBindsIn aux_binds [])
+ ; let aux_names = map unLoc (collectHsValBinders rn_aux_lhs)
+
+ ; bindLocalNames aux_names $
+ do { (rn_aux, _dus) <- rnTopBindsRHS aux_names rn_aux_lhs
+ ; rn_inst_infos <- mapM rn_inst_info inst_infos
+ ; return (rn_inst_infos, rn_aux `plusHsValBinds` rn_gen) } }
- -- Generate the generic to/from functions from each type declaration
- ; gen_binds <- mkGenericBinds tycl_decls
-
- -- Rename these extra bindings, discarding warnings about unused bindings etc
- -- Type signatures in patterns are used in the generic binds
- ; discardWarnings $
- setOptM Opt_PatternSignatures $
- do { (rn_deriv, _dus1) <- rnTopBinds (ValBindsIn aux_binds [])
- ; (rn_gen, dus_gen) <- rnTopBinds (ValBindsIn gen_binds [])
- ; keepAliveSetTc (duDefs dus_gen) -- Mark these guys to
- -- be kept alive
- ; return (rn_deriv `plusHsValBinds` rn_gen) } }
where
+ (inst_infos, deriv_aux_binds) = unzip insts
+
-- Remove duplicate requests for auxilliary bindings
rm_dups acc [] = acc
rm_dups acc (b:bs) | any (isDupAux b) acc = rm_dups acc bs
| otherwise = rm_dups (b:acc) bs
+
+ rn_inst_info (InstInfo { iSpec = inst, iBinds = NewTypeDerived })
+ = return (InstInfo { iSpec = inst, iBinds = NewTypeDerived })
+
+ rn_inst_info (InstInfo { iSpec = inst, iBinds = VanillaInst binds sigs })
+ = -- Bring the right type variables into
+ -- scope (yuk), and rename the method binds
+ ASSERT( null sigs )
+ bindLocalNames (map Var.varName tyvars) $
+ do { (rn_binds, _fvs) <- rnMethodBinds clas_nm (\_ -> []) [] binds
+ ; return (InstInfo { iSpec = inst, iBinds = VanillaInst rn_binds [] }) }
+ where
+ (tyvars,_,clas,_) = instanceHead inst
+ clas_nm = className clas
+
-----------------------------------------
-mkGenericBinds :: [LTyClDecl Name] -> TcM (LHsBinds RdrName)
-mkGenericBinds tycl_decls
- = do { tcs <- mapM tcLookupTyCon
- [ tc_name |
- L _ (TyData { tcdLName = L _ tc_name }) <- tycl_decls]
- -- We are only interested in the data type declarations
+mkGenericBinds :: Bool -> TcM (LHsBinds RdrName)
+mkGenericBinds is_boot
+ | is_boot
+ = return emptyBag
+ | otherwise
+ = do { gbl_env <- getGblEnv
+ ; let tcs = typeEnvTyCons (tcg_type_env gbl_env)
; return (unionManyBags [ mkTyConGenericBinds tc |
tc <- tcs, tyConHasGenerics tc ]) }
- -- And then only in the ones whose 'has-generics' flag is on
+ -- We are only interested in the data type declarations,
+ -- and then only in the ones whose 'has-generics' flag is on
+ -- The predicate tyConHasGenerics finds both of these
\end{code}
all those.
\begin{code}
-makeDerivSpecs :: [LTyClDecl Name]
+makeDerivSpecs :: Bool
+ -> [LTyClDecl Name]
-> [LInstDecl Name]
-> [LDerivDecl Name]
-> TcM [EarlyDerivSpec]
-makeDerivSpecs tycl_decls inst_decls deriv_decls
- = do { eqns1 <- mapAndRecoverM deriveTyData $
- extractTyDataPreds tycl_decls ++
- [ pd -- traverse assoc data families
- | L _ (InstDecl _ _ _ ats) <- inst_decls
- , pd <- extractTyDataPreds ats ]
+makeDerivSpecs is_boot tycl_decls inst_decls deriv_decls
+ | is_boot -- No 'deriving' at all in hs-boot files
+ = do { mapM_ add_deriv_err deriv_locs
+ ; return [] }
+ | otherwise
+ = do { eqns1 <- mapAndRecoverM deriveTyData all_tydata
; eqns2 <- mapAndRecoverM deriveStandalone deriv_decls
; return (catMaybes (eqns1 ++ eqns2)) }
where
- extractTyDataPreds decls =
- [(p, d) | d@(L _ (TyData {tcdDerivs = Just preds})) <- decls, p <- preds]
+ extractTyDataPreds decls
+ = [(p, d) | d@(L _ (TyData {tcdDerivs = Just preds})) <- decls, p <- preds]
+
+ all_tydata :: [(LHsType Name, LTyClDecl Name)]
+ -- Derived predicate paired with its data type declaration
+ all_tydata = extractTyDataPreds tycl_decls ++
+ [ pd -- Traverse assoc data families
+ | L _ (InstDecl _ _ _ ats) <- inst_decls
+ , pd <- extractTyDataPreds ats ]
+ deriv_locs = map (getLoc . snd) all_tydata
+ ++ map getLoc deriv_decls
+
+ add_deriv_err loc = setSrcSpan loc $
+ addErr (hang (ptext (sLit "Deriving not permitted in hs-boot file"))
+ 2 (ptext (sLit "Use an instance declaration instead")))
------------------------------------------------------------------
deriveStandalone :: LDerivDecl Name -> TcM (Maybe EarlyDerivSpec)
-- Standalone deriving declarations
--- e.g. deriving instance show a => Show (T a)
+-- e.g. deriving instance Show a => Show (T a)
-- Rather like tcLocalInstDecl
deriveStandalone (L loc (DerivDecl deriv_ty))
= setSrcSpan loc $
<+> text "theta:" <+> ppr theta
<+> text "tau:" <+> ppr tau)
; (cls, inst_tys) <- checkValidInstHead tau
+ ; checkValidInstance tvs theta cls inst_tys
+ -- C.f. TcInstDcls.tcLocalInstDecl1
+
; let cls_tys = take (length inst_tys - 1) inst_tys
inst_ty = last inst_tys
-
; traceTc (text "standalone deriving;"
<+> text "class:" <+> ppr cls
<+> text "class types:" <+> ppr cls_tys
------------------------------------------------------------------
deriveTyData :: (LHsType Name, LTyClDecl Name) -> TcM (Maybe EarlyDerivSpec)
-deriveTyData (deriv_pred, L loc decl@(TyData { tcdLName = L _ tycon_name,
- tcdTyVars = tv_names,
- tcdTyPats = ty_pats }))
- = setSrcSpan loc $
- tcAddDeclCtxt decl $
+deriveTyData (L loc deriv_pred, L _ decl@(TyData { tcdLName = L _ tycon_name,
+ tcdTyVars = tv_names,
+ tcdTyPats = ty_pats }))
+ = setSrcSpan loc $ -- Use the location of the 'deriving' item
+ tcAddDeclCtxt decl $
do { let hs_ty_args = ty_pats `orElse` map (nlHsTyVar . hsLTyVarName) tv_names
hs_app = nlHsTyConApp tycon_name hs_ty_args
-- We get kinding info for the tyvars by typechecking (T a b)
-> TcRn (Maybe EarlyDerivSpec)
mkEqnHelp orig tvs cls cls_tys tc_app mtheta
| Just (tycon, tc_args) <- tcSplitTyConApp_maybe tc_app
- = do {
+ , isAlgTyCon tycon -- Check for functions, primitive types etc
+ = do { (rep_tc, rep_tc_args) <- tcLookupFamInstExact tycon tc_args
+ -- Be careful to test rep_tc here: in the case of families,
+ -- we want to check the instance tycon, not the family tycon
+
-- For standalone deriving (mtheta /= Nothing),
- -- check that all the data constructors are in scope
+ -- check that all the data constructors are in scope.
+ -- No need for this when deriving Typeable, becuase we don't need
+ -- the constructors for that.
-- By this time we know that the thing is algebraic
-- because we've called checkInstHead in derivingStandalone
- rdr_env <- getGlobalRdrEnv
- ; let hidden_data_cons = filter not_in_scope (tyConDataCons tycon)
- not_in_scope dc = null (lookupGRE_Name rdr_env (dataConName dc))
- ; checkTc (isNothing mtheta || null hidden_data_cons)
+ ; rdr_env <- getGlobalRdrEnv
+ ; let hidden_data_cons = isAbstractTyCon rep_tc || any not_in_scope (tyConDataCons rep_tc)
+ not_in_scope dc = null (lookupGRE_Name rdr_env (dataConName dc))
+ ; checkTc (isNothing mtheta ||
+ not hidden_data_cons ||
+ className cls `elem` typeableClassNames)
(derivingHiddenErr tycon)
; mayDeriveDataTypeable <- doptM Opt_DeriveDataTypeable
; newtype_deriving <- doptM Opt_GeneralizedNewtypeDeriving
- ; (rep_tc, rep_tc_args) <- tcLookupFamInstExact tycon tc_args
-
- -- Be careful to test rep_tc here: in the case of families, we want
- -- to check the instance tycon, not the family tycon
; if isDataTyCon rep_tc then
mkDataTypeEqn orig mayDeriveDataTypeable tvs cls cls_tys
tycon tc_args rep_tc rep_tc_args mtheta
tycon tc_args rep_tc rep_tc_args mtheta }
| otherwise
= baleOut (derivingThingErr cls cls_tys tc_app
- (ptext (sLit "Last argument of the instance must be a type application")))
+ (ptext (sLit "The last argument of the instance must be a data or newtype application")))
baleOut :: Message -> TcM (Maybe a)
baleOut err = do { addErrTc err; return Nothing }
famInstNotFound :: TyCon -> [Type] -> TcM a
famInstNotFound tycon tys
= failWithTc (ptext (sLit "No family instance for")
- <+> quotes (pprTypeApp tycon (ppr tycon) tys))
+ <+> quotes (pprTypeApp tycon tys))
\end{code}
mkDataTypeEqn orig mayDeriveDataTypeable tvs cls cls_tys
tycon tc_args rep_tc rep_tc_args mtheta
- | Just err <- checkSideConditions mayDeriveDataTypeable cls cls_tys rep_tc
+ = case checkSideConditions mayDeriveDataTypeable cls cls_tys rep_tc of
-- NB: pass the *representation* tycon to checkSideConditions
- = baleOut (derivingThingErr cls cls_tys (mkTyConApp tycon tc_args) err)
-
- | otherwise
- = ASSERT( null cls_tys )
- mk_data_eqn orig tvs cls tycon tc_args rep_tc rep_tc_args mtheta
+ CanDerive -> mk_data_eqn orig tvs cls tycon tc_args rep_tc rep_tc_args mtheta
+ NonDerivableClass -> bale_out (nonStdErr cls)
+ DerivableClassError msg -> bale_out msg
+ where
+ bale_out msg = baleOut (derivingThingErr cls cls_tys (mkTyConApp tycon tc_args) msg)
mk_data_eqn, mk_typeable_eqn
:: InstOrigin -> [TyVar] -> Class
-- the data constructors - but we need to be careful to fall back to the
-- family tycon (with indexes) in error messages.
-checkSideConditions :: Bool -> Class -> [TcType] -> TyCon -> Maybe SDoc
+data DerivStatus = CanDerive
+ | NonDerivableClass
+ | DerivableClassError SDoc
+
+checkSideConditions :: Bool -> Class -> [TcType] -> TyCon -> DerivStatus
checkSideConditions mayDeriveDataTypeable cls cls_tys rep_tc
| notNull cls_tys
- = Just ty_args_why -- e.g. deriving( Foo s )
+ = DerivableClassError ty_args_why -- e.g. deriving( Foo s )
| otherwise
= case sideConditions cls of
- Just cond -> cond (mayDeriveDataTypeable, rep_tc)
- Nothing -> Just non_std_why
+ Nothing -> NonDerivableClass
+ Just cond -> case (cond (mayDeriveDataTypeable, rep_tc)) of
+ Nothing -> CanDerive
+ Just err -> DerivableClassError err
where
ty_args_why = quotes (ppr (mkClassPred cls cls_tys)) <+> ptext (sLit "is not a class")
- non_std_why = quotes (ppr cls) <+> ptext (sLit "is not a derivable class")
+
+nonStdErr :: Class -> SDoc
+nonStdErr cls = quotes (ppr cls) <+> ptext (sLit "is not a derivable class")
sideConditions :: Class -> Maybe Condition
sideConditions cls
new_dfun_name :: Class -> TyCon -> TcM Name
new_dfun_name clas tycon -- Just a simple wrapper
- = newDFunName clas [mkTyConApp tycon []] (getSrcSpan tycon)
+ = do { loc <- getSrcSpanM -- The location of the instance decl, not of the tycon
+ ; newDFunName clas [mkTyConApp tycon []] loc }
-- The type passed to newDFunName is only used to generate
-- a suitable string; hence the empty type arg list
\end{code}
; return (if isJust mtheta then Just (Right spec)
else Just (Left spec)) }
- | isNothing mb_std_err -- Use the standard H98 method
- = mk_data_eqn orig tvs cls tycon tc_args rep_tycon rep_tc_args mtheta
-
- -- Otherwise we can't derive
- | newtype_deriving = baleOut cant_derive_err -- Too hard
- | otherwise = baleOut std_err -- Just complain about being a non-std instance
+ | otherwise
+ = case check_conditions of
+ CanDerive -> mk_data_eqn orig tvs cls tycon tc_args rep_tycon rep_tc_args mtheta
+ -- Use the standard H98 method
+ DerivableClassError msg -> bale_out msg -- Error with standard class
+ NonDerivableClass -- Must use newtype deriving
+ | newtype_deriving -> bale_out cant_derive_err -- Too hard, even with newtype deriving
+ | otherwise -> bale_out non_std_err -- Try newtype deriving!
where
- mb_std_err = checkSideConditions mayDeriveDataTypeable cls cls_tys rep_tycon
- std_err = derivingThingErr cls cls_tys tc_app $
- vcat [fromJust mb_std_err,
- ptext (sLit "Try -XGeneralizedNewtypeDeriving for GHC's newtype-deriving extension")]
+ check_conditions = checkSideConditions mayDeriveDataTypeable cls cls_tys rep_tycon
+ bale_out msg = baleOut (derivingThingErr cls cls_tys tc_app msg)
+
+ non_std_err = nonStdErr cls $$
+ ptext (sLit "Try -XGeneralizedNewtypeDeriving for GHC's newtype-deriving extension")
-- Here is the plan for newtype derivings. We see
-- newtype T a1...an = MkT (t ak+1...an) deriving (.., C s1 .. sm, ...)
right_arity = length cls_tys + 1 == classArity cls
-- Never derive Read,Show,Typeable,Data this way
- non_iso_classes = [readClassKey, showClassKey, typeableClassKey, dataClassKey]
+ non_iso_class cls = className cls `elem` ([readClassName, showClassName, dataClassName] ++
+ typeableClassNames)
can_derive_via_isomorphism
- = not (getUnique cls `elem` non_iso_classes)
+ = not (non_iso_class cls)
&& right_arity -- Well kinded;
-- eg not: newtype T ... deriving( ST )
-- because ST needs *2* type params
-- (d) in case of newtype family instances, the eta-dropped
-- arguments must be type variables (not more complex indexes)
- cant_derive_err = derivingThingErr cls cls_tys tc_app
- (vcat [ptext (sLit "even with cunning newtype deriving:"),
- if isRecursiveTyCon tycon then
- ptext (sLit "the newtype may be recursive")
- else empty,
- if not right_arity then
- quotes (ppr (mkClassPred cls cls_tys)) <+> ptext (sLit "does not have arity 1")
- else empty,
- if not (n_tyargs_to_keep >= 0) then
- ptext (sLit "the type constructor has wrong kind")
- else if not (n_args_to_keep >= 0) then
- ptext (sLit "the representation type has wrong kind")
- else if not eta_ok then
- ptext (sLit "the eta-reduction property does not hold")
- else empty
- ])
+ cant_derive_err = vcat [ptext (sLit "even with cunning newtype deriving:"),
+ if isRecursiveTyCon tycon then
+ ptext (sLit "the newtype may be recursive")
+ else empty,
+ if not right_arity then
+ quotes (ppr (mkClassPred cls cls_tys)) <+> ptext (sLit "does not have arity 1")
+ else empty,
+ if not (n_tyargs_to_keep >= 0) then
+ ptext (sLit "the type constructor has wrong kind")
+ else if not (n_args_to_keep >= 0) then
+ ptext (sLit "the representation type has wrong kind")
+ else if not eta_ok then
+ ptext (sLit "the eta-reduction property does not hold")
+ else empty
+ ]
\end{code}
-- Representation tycons differ from the tycon in the instance signature in
-- case of instances for indexed families.
--
-genInst :: OverlapFlag -> DerivSpec -> TcM (InstInfo, DerivAuxBinds)
+genInst :: OverlapFlag -> DerivSpec -> TcM (InstInfo RdrName, DerivAuxBinds)
genInst oflag spec
| ds_newtype spec
= return (InstInfo { iSpec = mkInstance1 oflag spec
, iBinds = NewTypeDerived }, [])
| otherwise
- = do { fix_env <- getFixityEnv
- ; let
- inst = mkInstance1 oflag spec
- (tyvars,_,clas,[ty]) = instanceHead inst
- clas_nm = className clas
- (visible_tycon, tyArgs) = tcSplitTyConApp ty
+ = do { let loc = getSrcSpan (ds_name spec)
+ inst = mkInstance1 oflag spec
+ (_,_,clas,[ty]) = instanceHead inst
+ (visible_tycon, tyArgs) = tcSplitTyConApp ty
-- In case of a family instance, we need to use the representation
-- tycon (after all, it has the data constructors)
; (tycon, _) <- tcLookupFamInstExact visible_tycon tyArgs
- ; let (meth_binds, aux_binds) = genDerivBinds clas fix_env tycon
-
- -- Bring the right type variables into
- -- scope, and rename the method binds
- -- It's a bit yukky that we return *renamed* InstInfo, but
- -- *non-renamed* auxiliary bindings
- ; (rn_meth_binds, _fvs) <- discardWarnings $
- bindLocalNames (map Var.varName tyvars) $
- rnMethodBinds clas_nm (\_ -> []) [] meth_binds
+ ; fix_env <- getFixityEnv
+ ; let (meth_binds, aux_binds) = genDerivBinds loc fix_env clas tycon
-- Build the InstInfo
; return (InstInfo { iSpec = inst,
- iBinds = VanillaInst rn_meth_binds [] },
+ iBinds = VanillaInst meth_binds [] },
aux_binds)
}
-genDerivBinds :: Class -> FixityEnv -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
-genDerivBinds clas fix_env tycon
+genDerivBinds :: SrcSpan -> FixityEnv -> Class -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
+genDerivBinds loc fix_env clas tycon
| className clas `elem` typeableClassNames
- = (gen_Typeable_binds tycon, [])
+ = (gen_Typeable_binds loc tycon, [])
| otherwise
= case assocMaybe gen_list (getUnique clas) of
- Just gen_fn -> gen_fn tycon
+ Just gen_fn -> gen_fn loc tycon
Nothing -> pprPanic "genDerivBinds: bad derived class" (ppr clas)
where
- gen_list :: [(Unique, TyCon -> (LHsBinds RdrName, DerivAuxBinds))]
+ gen_list :: [(Unique, SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds))]
gen_list = [(eqClassKey, gen_Eq_binds)
,(ordClassKey, gen_Ord_binds)
,(enumClassKey, gen_Enum_binds)
,(ixClassKey, gen_Ix_binds)
,(showClassKey, gen_Show_binds fix_env)
,(readClassKey, gen_Read_binds fix_env)
- ,(dataClassKey, gen_Data_binds fix_env)
+ ,(dataClassKey, gen_Data_binds)
]
\end{code}
projects / ghc-hetmet.git / blobdiff