import NameSet
import TyCon
import TcType
+import BuildTyCl
+import BasicTypes
import Var
import VarSet
import PrelNames
import SrcLoc
+import UniqSupply
import Util
import ListSetOps
import Outputable
3. Add the derived bindings, generating InstInfos
+
\begin{code}
-- DerivSpec is purely local to this module
data DerivSpec = DS { ds_loc :: SrcSpan
- , ds_orig :: InstOrigin
+ , ds_orig :: CtOrigin
, ds_name :: Name
, ds_tvs :: [TyVar]
, ds_theta :: ThetaType
-- df :: forall tvs. theta => C tys
-- The Name is the name for the DFun we'll build
-- The tyvars bind all the variables in the theta
- -- For family indexes, the tycon in
+ -- For type families, the tycon in
-- in ds_tys is the *family* tycon
-- in ds_tc, ds_tc_args is the *representation* tycon
-- For non-family tycons, both are the same
-- ds_newtype = True <=> Newtype deriving
-- False <=> Vanilla deriving
+\end{code}
+
+Example:
+
+ newtype instance T [a] = MkT (Tree a) deriving( C s )
+==>
+ axiom T [a] = :RTList a
+ axiom :RTList a = Tree a
+
+ DS { ds_tvs = [a,s], ds_cls = C, ds_tys = [s, T [a]]
+ , ds_tc = :RTList, ds_tc_args = [a]
+ , ds_newtype = True }
+\begin{code}
type DerivContext = Maybe ThetaType
-- Nothing <=> Vanilla deriving; infer the context of the instance decl
-- Just theta <=> Standalone deriving: context supplied by programmer
ds_cls = c, ds_tys = tys, ds_theta = rhs })
= parens (hsep [ppr l, ppr n, ppr tvs, ppr c, ppr tys]
<+> equals <+> ppr rhs)
+
+instance Outputable DerivSpec where
+ ppr = pprDerivSpec
\end{code}
tcDeriving :: [LTyClDecl Name] -- All type constructors
-> [LInstDecl Name] -- All instance declarations
-> [LDerivDecl Name] -- All stand-alone deriving declarations
- -> TcM ([InstInfo Name], -- The generated "instance decls"
- HsValBinds Name, -- Extra generated top-level bindings
- DefUses)
+ -> TcM ([InstInfo Name] -- The generated "instance decls"
+ ,HsValBinds Name -- Extra generated top-level bindings
+ ,DefUses
+ ,[TyCon] -- Extra generated top-level types
+ ,[TyCon]) -- Extra generated type family instances
tcDeriving tycl_decls inst_decls deriv_decls
- = recoverM (return ([], emptyValBindsOut, emptyDUs)) $
+ = recoverM (return ([], emptyValBindsOut, emptyDUs, [], [])) $
do { -- Fish the "deriving"-related information out of the TcEnv
-- And make the necessary "equations".
is_boot <- tcIsHsBoot
- ; traceTc (text "tcDeriving" <+> ppr is_boot)
- ; early_specs <- makeDerivSpecs is_boot tycl_decls inst_decls deriv_decls
+ ; traceTc "tcDeriving" (ppr is_boot)
+ ; (early_specs, genericsExtras)
+ <- makeDerivSpecs is_boot tycl_decls inst_decls deriv_decls
+ ; let (repMetaTys, repTyCons, metaInsts) = unzip3 genericsExtras
; overlap_flag <- getOverlapFlag
; let (infer_specs, given_specs) = splitEithers early_specs
; insts2 <- mapM (genInst False overlap_flag) final_specs
- -- Generate the generic to/from functions from each type declaration
- ; gen_binds <- mkGenericBinds is_boot tycl_decls
- ; (inst_info, rn_binds, rn_dus) <- renameDeriv is_boot gen_binds (insts1 ++ insts2)
+ -- We no longer generate the old generic to/from functions
+ -- from each type declaration, so this is emptyBag
+ ; gen_binds <- return emptyBag -- mkGenericBinds is_boot tycl_decls
+
+ ; (inst_info, rn_binds, rn_dus)
+ <- renameDeriv is_boot gen_binds (insts1 ++ insts2 ++ concat metaInsts)
; dflags <- getDOpts
; liftIO (dumpIfSet_dyn dflags Opt_D_dump_deriv "Derived instances"
- (ddump_deriving inst_info rn_binds))
-
- ; return (inst_info, rn_binds, rn_dus) }
+ (ddump_deriving inst_info rn_binds repMetaTys repTyCons metaInsts))
+{-
+ ; when (not (null inst_info)) $
+ dumpDerivingInfo (ddump_deriving inst_info rn_binds)
+-}
+ ; return ( inst_info, rn_binds, rn_dus
+ , concat (map metaTyCons2TyCons repMetaTys), repTyCons) }
where
- ddump_deriving :: [InstInfo Name] -> HsValBinds Name -> SDoc
- ddump_deriving inst_infos extra_binds
- = vcat (map pprInstInfoDetails inst_infos) $$ ppr extra_binds
+ ddump_deriving :: [InstInfo Name] -> HsValBinds Name
+ -> [MetaTyCons] -- ^ Empty data constructors
+ -> [TyCon] -- ^ Rep type family instances
+ -> [[(InstInfo RdrName, DerivAuxBinds)]]
+ -- ^ Instances for the repMetaTys
+ -> SDoc
+ ddump_deriving inst_infos extra_binds repMetaTys repTyCons metaInsts
+ = hang (ptext (sLit "Derived instances"))
+ 2 (vcat (map (\i -> pprInstInfoDetails i $$ text "") inst_infos)
+ $$ ppr extra_binds)
+ $$ hangP "Generic representation" (
+ hangP "Generated datatypes for meta-information"
+ (vcat (map ppr repMetaTys))
+ -- The Outputable instance for TyCon unfortunately only prints the name...
+ $$ hangP "Representation types"
+ (vcat (map ppr repTyCons))
+ $$ hangP "Meta-information instances"
+ (vcat (map (pprInstInfoDetails . fst) (concat metaInsts))))
+
+ hangP s x = text "" $$ hang (ptext (sLit s)) 2 x
+
renameDeriv :: Bool -> LHsBinds RdrName
-> [(InstInfo RdrName, DerivAuxBinds)]
-- 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_aux) <- rnTopBindsRHS (mkNameSet aux_names) rn_aux_lhs
+ ; let (aux_binds, aux_sigs) = unzip $ map (genAuxBind loc) $
+ rm_dups [] $ concat deriv_aux_binds
+ aux_val_binds = ValBindsIn (listToBag aux_binds) aux_sigs
+ ; rn_aux_lhs <- rnTopBindsLHS emptyFsEnv aux_val_binds
+ ; bindLocalNames (collectHsValBinders rn_aux_lhs) $
+ do { (rn_aux, dus_aux) <- rnTopBindsRHS rn_aux_lhs
; (rn_inst_infos, fvs_insts) <- mapAndUnzipM rn_inst_info inst_infos
; return (rn_inst_infos, rn_aux `plusHsValBinds` rn_gen,
dus_gen `plusDU` dus_aux `plusDU` usesOnly (plusFVs fvs_insts)) } }
| otherwise = rm_dups (b:acc) bs
- rn_inst_info (InstInfo { iSpec = inst, iBinds = NewTypeDerived co })
- = return (InstInfo { iSpec = inst, iBinds = NewTypeDerived co }, emptyFVs)
+ rn_inst_info :: InstInfo RdrName -> TcM (InstInfo Name, FreeVars)
+ rn_inst_info info@(InstInfo { iBinds = NewTypeDerived coi tc })
+ = return ( info { iBinds = NewTypeDerived coi tc }
+ , mkFVs (map dataConName (tyConDataCons tc)))
+ -- See Note [Newtype deriving and unused constructors]
- rn_inst_info (InstInfo { iSpec = inst, iBinds = VanillaInst binds sigs standalone_deriv })
+ rn_inst_info inst_info@(InstInfo { iSpec = inst, iBinds = VanillaInst binds sigs standalone_deriv })
= -- 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
+ do { (rn_binds, fvs) <- rnMethodBinds clas_nm (\_ -> []) binds
; let binds' = VanillaInst rn_binds [] standalone_deriv
- ; return (InstInfo { iSpec = inst, iBinds = binds' }, fvs) }
+ ; return (inst_info { iBinds = binds' }, fvs) }
where
(tyvars,_, clas,_) = instanceHead inst
clas_nm = className clas
-
------------------------------------------
-mkGenericBinds :: Bool -> [LTyClDecl Name] -> TcM (LHsBinds RdrName)
-mkGenericBinds is_boot tycl_decls
- | is_boot
- = return emptyBag
- | otherwise
- = do { tcs <- mapM tcLookupTyCon [ tcdName d
- | L _ d <- tycl_decls, isDataDecl d ]
- ; return (unionManyBags [ mkTyConGenericBinds tc
- | tc <- tcs, tyConHasGenerics tc ]) }
- -- 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}
+Note [Newtype deriving and unused constructors]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Consider this (see Trac #1954):
+
+ module Bug(P) where
+ newtype P a = MkP (IO a) deriving Monad
+
+If you compile with -fwarn-unused-binds you do not expect the warning
+"Defined but not used: data consructor MkP". Yet the newtype deriving
+code does not explicitly mention MkP, but it should behave as if you
+had written
+ instance Monad P where
+ return x = MkP (return x)
+ ...etc...
+
+So we want to signal a user of the data constructor 'MkP'. That's
+what we do in rn_inst_info, and it's the only reason we have the TyCon
+stored in NewTypeDerived.
+
%************************************************************************
%* *
@makeDerivSpecs@ fishes around to find the info about needed derived instances.
\begin{code}
+-- Make the "extras" for the generic representation
+mkGenDerivExtras :: TyCon
+ -> TcRn (MetaTyCons, TyCon, [(InstInfo RdrName, DerivAuxBinds)])
+mkGenDerivExtras tc = do
+ { (metaTyCons, rep0TyInst) <- genGenericRepExtras tc
+ ; metaInsts <- genDtMeta (tc, metaTyCons)
+ ; return (metaTyCons, rep0TyInst, metaInsts) }
+
makeDerivSpecs :: Bool
-> [LTyClDecl Name]
- -> [LInstDecl Name]
+ -> [LInstDecl Name]
-> [LDerivDecl Name]
- -> TcM [EarlyDerivSpec]
-
+ -> TcM ( [EarlyDerivSpec]
+ , [(MetaTyCons, TyCon, [(InstInfo RdrName, DerivAuxBinds)])])
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 [] }
+ | 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 (eqns1 ++ eqns2) }
+ = do { eqns1 <- mapAndRecoverM deriveTyData all_tydata
+ ; eqns2 <- mapAndRecoverM deriveStandalone deriv_decls
+
+ -- Generic representation stuff: we might need to add some "extras"
+ -- to the instances
+ ; xDerRep <- getDOpts >>= return . xopt Opt_DeriveGeneric
+ ; generic_extras_deriv <- if not xDerRep
+ -- No extras if the flag is off
+ then (return [])
+ else do {
+ let allTyNames = [ tcdName d | L _ d <- tycl_decls, isDataDecl d ]
+ -- Select only those types that derive Generic
+ ; let sel_tydata = [ tcdName t | (L _ c, L _ t) <- all_tydata
+ , getClassName c == Just genClassName ]
+ ; let sel_deriv_decls = catMaybes [ getTypeName t
+ | L _ (DerivDecl (L _ t)) <- deriv_decls
+ , getClassName t == Just genClassName ]
+ ; derTyDecls <- mapM tcLookupTyCon $
+ filter (needsExtras xDerRep
+ (sel_tydata ++ sel_deriv_decls)) allTyNames
+ -- We need to generate the extras to add to what has
+ -- already been derived
+ ; {- pprTrace "sel_tydata" (ppr sel_tydata) $
+ pprTrace "sel_deriv_decls" (ppr sel_deriv_decls) $
+ pprTrace "derTyDecls" (ppr derTyDecls) $
+ pprTrace "deriv_decls" (ppr deriv_decls) $ -}
+ mapM mkGenDerivExtras derTyDecls }
+
+ -- Merge and return
+ ; return ( eqns1 ++ eqns2, generic_extras_deriv) }
where
+ -- We need extras if the flag DeriveGeneric is on and this type is
+ -- deriving Generic
+ needsExtras xDerRep tydata tc_name = xDerRep && tc_name `elem` tydata
+
+ -- Extracts the name of the class in the deriving
+ getClassName :: HsType Name -> Maybe Name
+ getClassName (HsForAllTy _ _ _ (L _ n)) = getClassName n
+ getClassName (HsPredTy (HsClassP n _)) = Just n
+ getClassName _ = Nothing
+
+ -- Extracts the name of the type in the deriving
+ -- This function (and also getClassName above) is not really nice, and I
+ -- might not have covered all possible cases. I wonder if there is no easier
+ -- way to extract class and type name from a LDerivDecl...
+ getTypeName :: HsType Name -> Maybe Name
+ getTypeName (HsForAllTy _ _ _ (L _ n)) = getTypeName n
+ getTypeName (HsTyVar n) = Just n
+ getTypeName (HsOpTy _ (L _ n) _) = Just n
+ getTypeName (HsPredTy (HsClassP _ [L _ n])) = getTypeName n
+ getTypeName (HsAppTy (L _ n) _) = getTypeName n
+ getTypeName (HsParTy (L _ n)) = getTypeName n
+ getTypeName (HsKindSig (L _ n) _) = getTypeName n
+ getTypeName _ = Nothing
+
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 ]
+ -- Derived predicate paired with its data type declaration
+ all_tydata = extractTyDataPreds (instDeclATs inst_decls ++ tycl_decls)
deriv_locs = map (getLoc . snd) all_tydata
- ++ map getLoc deriv_decls
+ ++ 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")))
+ addErr (hang (ptext (sLit "Deriving not permitted in hs-boot file"))
+ 2 (ptext (sLit "Use an instance declaration instead")))
------------------------------------------------------------------
deriveStandalone :: LDerivDecl Name -> TcM EarlyDerivSpec
deriveStandalone (L loc (DerivDecl deriv_ty))
= setSrcSpan loc $
addErrCtxt (standaloneCtxt deriv_ty) $
- do { traceTc (text "standalone deriving decl for" <+> ppr deriv_ty)
- ; (tvs, theta, tau) <- tcHsInstHead deriv_ty
- ; traceTc (text "standalone deriving;"
- <+> text "tvs:" <+> ppr tvs
- <+> text "theta:" <+> ppr theta
- <+> text "tau:" <+> ppr tau)
- ; (cls, inst_tys) <- checkValidInstHead tau
- ; checkValidInstance tvs theta cls inst_tys
+ do { traceTc "Standalone deriving decl for" (ppr deriv_ty)
+ ; (tvs, theta, cls, inst_tys) <- tcHsInstHead deriv_ty
+ ; traceTc "Standalone deriving;" $ vcat
+ [ text "tvs:" <+> ppr tvs
+ , text "theta:" <+> ppr theta
+ , text "cls:" <+> ppr cls
+ , text "tys:" <+> ppr inst_tys ]
+ ; checkValidInstance deriv_ty 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
- <+> text "type:" <+> ppr inst_ty)
+ ; traceTc "Standalone deriving:" $ vcat
+ [ text "class:" <+> ppr cls
+ , text "class types:" <+> ppr cls_tys
+ , text "type:" <+> ppr inst_ty ]
; mkEqnHelp StandAloneDerivOrigin tvs cls cls_tys inst_ty
(Just theta) }
-- Type families can't be partially applied
-- e.g. newtype instance T Int a = MkT [a] deriving( Monad )
-- Note [Deriving, type families, and partial applications]
- ; checkTc (not (isOpenTyCon tc) || n_args_to_drop == 0)
+ ; checkTc (not (isFamilyTyCon tc) || n_args_to_drop == 0)
(typeFamilyPapErr tc cls cls_tys inst_ty)
; mkEqnHelp DerivOrigin (varSetElems univ_tvs) cls cls_tys inst_ty Nothing } }
newtype S a = MkS [a]
-- :CoS :: S ~ [] -- Eta-reduced
- instance Eq [a] => Eq (S a) -- by coercion sym (Eq (coMkS a)) : Eq [a] ~ Eq (S a)
- instance Monad [] => Monad S -- by coercion sym (Monad coMkS) : Monad [] ~ Monad S
+ instance Eq [a] => Eq (S a) -- by coercion sym (Eq (:CoS a)) : Eq [a] ~ Eq (S a)
+ instance Monad [] => Monad S -- by coercion sym (Monad :CoS) : Monad [] ~ Monad S
When type familes are involved it's trickier:
... etc ...
\begin{code}
-mkEqnHelp :: InstOrigin -> [TyVar] -> Class -> [Type] -> Type
+mkEqnHelp :: CtOrigin -> [TyVar] -> Class -> [Type] -> Type
-> DerivContext -- Just => context supplied (standalone deriving)
-- Nothing => context inferred (deriving on data decl)
-> TcRn EarlyDerivSpec
mkEqnHelp orig tvs cls cls_tys tc_app mtheta
| Just (tycon, tc_args) <- tcSplitTyConApp_maybe tc_app
, 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.
- -- No need for this when deriving Typeable, becuase we don't need
- -- the constructors for that.
- ; 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)
-
- ; dflags <- getDOpts
- ; if isDataTyCon rep_tc then
- mkDataTypeEqn orig dflags tvs cls cls_tys
- tycon tc_args rep_tc rep_tc_args mtheta
- else
- mkNewTypeEqn orig dflags tvs cls cls_tys
- tycon tc_args rep_tc rep_tc_args mtheta }
+ = mk_alg_eqn tycon tc_args
| otherwise
= failWithTc (derivingThingErr False cls cls_tys tc_app
(ptext (sLit "The last argument of the instance must be a data or newtype application")))
-\end{code}
-Note [Looking up family instances for deriving]
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-tcLookupFamInstExact is an auxiliary lookup wrapper which requires
-that looked-up family instances exist. If called with a vanilla
-tycon, the old type application is simply returned.
-
-If we have
- data instance F () = ... deriving Eq
- data instance F () = ... deriving Eq
-then tcLookupFamInstExact will be confused by the two matches;
-but that can't happen because tcInstDecls1 doesn't call tcDeriving
-if there are any overlaps.
-
-There are two other things that might go wrong with the lookup.
-First, we might see a standalone deriving clause
- deriving Eq (F ())
-when there is no data instance F () in scope.
-
-Note that it's OK to have
- data instance F [a] = ...
- deriving Eq (F [(a,b)])
-where the match is not exact; the same holds for ordinary data types
-with standalone deriving declrations.
+ where
+ bale_out msg = failWithTc (derivingThingErr False cls cls_tys tc_app msg)
-\begin{code}
-tcLookupFamInstExact :: TyCon -> [Type] -> TcM (TyCon, [Type])
-tcLookupFamInstExact tycon tys
- | not (isOpenTyCon tycon)
- = return (tycon, tys)
- | otherwise
- = do { maybeFamInst <- tcLookupFamInst tycon tys
- ; case maybeFamInst of
- Nothing -> famInstNotFound tycon tys
- Just famInst -> return famInst
- }
-
-famInstNotFound :: TyCon -> [Type] -> TcM a
-famInstNotFound tycon tys
- = failWithTc (ptext (sLit "No family instance for")
- <+> quotes (pprTypeApp tycon tys))
+ mk_alg_eqn tycon tc_args
+ | className cls `elem` typeableClassNames
+ = do { dflags <- getDOpts
+ ; case checkTypeableConditions (dflags, tycon) of
+ Just err -> bale_out err
+ Nothing -> mk_typeable_eqn orig tvs cls tycon tc_args mtheta }
+
+ | isDataFamilyTyCon tycon
+ , length tc_args /= tyConArity tycon
+ = bale_out (ptext (sLit "Unsaturated data family application"))
+
+ | otherwise
+ = do { (rep_tc, rep_tc_args) <- tcLookupDataFamInst 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.
+ ; 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))
+ ; unless (isNothing mtheta || not hidden_data_cons)
+ (bale_out (derivingHiddenErr tycon))
+
+ ; dflags <- getDOpts
+ ; if isDataTyCon rep_tc then
+ mkDataTypeEqn orig dflags tvs cls cls_tys
+ tycon tc_args rep_tc rep_tc_args mtheta
+ else
+ mkNewTypeEqn orig dflags tvs cls cls_tys
+ tycon tc_args rep_tc rep_tc_args mtheta }
\end{code}
%************************************************************************
\begin{code}
-mkDataTypeEqn :: InstOrigin
+mkDataTypeEqn :: CtOrigin
-> DynFlags
-> [Var] -- Universally quantified type variables in the instance
-> Class -- Class for which we need to derive an instance
go_for_it = mk_data_eqn orig tvs cls tycon tc_args rep_tc rep_tc_args mtheta
bale_out msg = failWithTc (derivingThingErr False cls cls_tys (mkTyConApp tycon tc_args) msg)
-mk_data_eqn, mk_typeable_eqn
- :: InstOrigin -> [TyVar] -> Class
- -> TyCon -> [TcType] -> TyCon -> [TcType] -> DerivContext
- -> TcM EarlyDerivSpec
+mk_data_eqn :: CtOrigin -> [TyVar] -> Class
+ -> TyCon -> [TcType] -> TyCon -> [TcType] -> DerivContext
+ -> TcM EarlyDerivSpec
mk_data_eqn orig tvs cls tycon tc_args rep_tc rep_tc_args mtheta
- | getName cls `elem` typeableClassNames
- = mk_typeable_eqn orig tvs cls tycon tc_args rep_tc rep_tc_args mtheta
-
- | otherwise
= do { dfun_name <- new_dfun_name cls tycon
; loc <- getSrcSpanM
; let inst_tys = [mkTyConApp tycon tc_args]
; return (if isJust mtheta then Right spec -- Specified context
else Left spec) } -- Infer context
-mk_typeable_eqn orig tvs cls tycon tc_args rep_tc rep_tc_args mtheta
+----------------------
+mk_typeable_eqn :: CtOrigin -> [TyVar] -> Class
+ -> TyCon -> [TcType] -> DerivContext
+ -> TcM EarlyDerivSpec
+mk_typeable_eqn orig tvs cls tycon tc_args mtheta
-- The Typeable class is special in several ways
-- data T a b = ... deriving( Typeable )
-- gives
= do { checkTc (cls `hasKey` typeableClassKey)
(ptext (sLit "Use deriving( Typeable ) on a data type declaration"))
; real_cls <- tcLookupClass (typeableClassNames !! tyConArity tycon)
- ; mk_typeable_eqn orig tvs real_cls tycon [] rep_tc [] (Just []) }
+ ; mk_typeable_eqn orig tvs real_cls tycon [] (Just []) }
| otherwise -- standaone deriving
= do { checkTc (null tc_args)
; return (Right $
DS { ds_loc = loc, ds_orig = orig, ds_name = dfun_name, ds_tvs = []
, ds_cls = cls, ds_tys = [mkTyConApp tycon []]
- , ds_tc = rep_tc, ds_tc_args = rep_tc_args
+ , ds_tc = tycon, ds_tc_args = []
, ds_theta = mtheta `orElse` [], ds_newtype = False }) }
-
+----------------------
inferConstraints :: [TyVar] -> Class -> [TcType] -> TyCon -> [TcType] -> ThetaType
-- Generate a sufficiently large set of constraints that typechecking the
-- generated method definitions should succeed. This set will be simplified
-- before being used in the instance declaration
-inferConstraints tvs cls inst_tys rep_tc rep_tc_args
+inferConstraints _ cls inst_tys rep_tc rep_tc_args
+ -- Generic constraints are easy
+ | cls `hasKey` genClassKey
+ = []
+ -- The others are a bit more complicated
+ | otherwise
= ASSERT2( equalLength rep_tc_tvs all_rep_tc_args, ppr cls <+> ppr rep_tc )
stupid_constraints ++ extra_constraints
++ sc_constraints ++ con_arg_constraints
get_constrained_tys :: [Type] -> [Type]
get_constrained_tys tys
- | is_functor_like = concatMap (deepSubtypesContaining last_tv) tys
+ | is_functor_like = concatMap (deepSubtypesContaining last_tv) tys
| otherwise = tys
rep_tc_tvs = tyConTyVars rep_tc
stupid_constraints = substTheta subst (tyConStupidTheta rep_tc)
subst = zipTopTvSubst rep_tc_tvs all_rep_tc_args
- -- Extra constraints
+ -- Extra Data constraints
-- The Data class (only) requires that for
- -- instance (...) => Data (T a b)
- -- then (Data a, Data b) are among the (...) constraints
- -- Reason: that's what you need to typecheck the method
- -- dataCast1 f = gcast1 f
+ -- instance (...) => Data (T t1 t2)
+ -- IF t1:*, t2:*
+ -- THEN (Data t1, Data t2) are among the (...) constraints
+ -- Reason: when the IF holds, we generate a method
+ -- dataCast2 f = gcast2 f
+ -- and we need the Data constraints to typecheck the method
extra_constraints
- | cls `hasKey` dataClassKey = [mkClassPred cls [mkTyVarTy tv] | tv <- tvs]
- | otherwise = []
+ | cls `hasKey` dataClassKey
+ , all (isLiftedTypeKind . typeKind) rep_tc_args
+ = [mkClassPred cls [ty] | ty <- rep_tc_args]
+ | otherwise
+ = []
------------------------------------------------------------------
-- Check side conditions that dis-allow derivability for particular classes
where
ty_args_why = quotes (ppr (mkClassPred cls cls_tys)) <+> ptext (sLit "is not a class")
+checkTypeableConditions :: Condition
+checkTypeableConditions = checkFlag Opt_DeriveDataTypeable `andCond` cond_typeableOK
+
nonStdErr :: Class -> SDoc
nonStdErr cls = quotes (ppr cls) <+> ptext (sLit "is not a derivable class")
cond_functorOK False) -- Functor/Fold/Trav works ok for rank-n types
| cls_key == traversableClassKey = Just (checkFlag Opt_DeriveTraversable `andCond`
cond_functorOK False)
- | getName cls `elem` typeableClassNames = Just (checkFlag Opt_DeriveDataTypeable `andCond` cond_typeableOK)
+ | cls_key == genClassKey = Just (cond_RepresentableOk `andCond`
+ checkFlag Opt_DeriveGeneric)
| otherwise = Nothing
where
cls_key = getUnique cls
orCond :: Condition -> Condition -> Condition
orCond c1 c2 tc
= case c1 tc of
- Nothing -> Nothing -- c1 succeeds
- Just x -> case c2 tc of -- c1 fails
+ Nothing -> Nothing -- c1 succeeds
+ Just x -> case c2 tc of -- c1 fails
Nothing -> Nothing
- Just y -> Just (x $$ ptext (sLit " and") $$ y)
- -- Both fail
+ Just y -> Just (x $$ ptext (sLit " or") $$ y)
+ -- Both fail
andCond :: Condition -> Condition -> Condition
andCond c1 c2 tc = case c1 tc of
cond_stdOK (Just _) _
= Nothing -- Don't check these conservative conditions for
-- standalone deriving; just generate the code
+ -- and let the typechecker handle the result
cond_stdOK Nothing (_, rep_tc)
- | null data_cons = Just (no_cons_why $$ suggestion)
+ | null data_cons = Just (no_cons_why rep_tc $$ suggestion)
| not (null con_whys) = Just (vcat con_whys $$ suggestion)
| otherwise = Nothing
where
suggestion = ptext (sLit "Possible fix: use a standalone deriving declaration instead")
data_cons = tyConDataCons rep_tc
- no_cons_why = quotes (pprSourceTyCon rep_tc) <+>
- ptext (sLit "has no data constructors")
-
con_whys = mapCatMaybes check_con data_cons
check_con :: DataCon -> Maybe SDoc
check_con con
| isVanillaDataCon con
, all isTauTy (dataConOrigArgTys con) = Nothing
- | otherwise = Just (badCon con (ptext (sLit "does not have a Haskell-98 type")))
+ | otherwise = Just (badCon con (ptext (sLit "must have a Haskell-98 type")))
+no_cons_why :: TyCon -> SDoc
+no_cons_why rep_tc = quotes (pprSourceTyCon rep_tc) <+>
+ ptext (sLit "must have at least one data constructor")
+
+cond_RepresentableOk :: Condition
+cond_RepresentableOk (_,t) = canDoGenerics t
+
cond_enumOrProduct :: Condition
cond_enumOrProduct = cond_isEnumeration `orCond`
(cond_isProduct `andCond` cond_noUnliftedArgs)
where
bad_cons = [ con | con <- tyConDataCons tc
, any isUnLiftedType (dataConOrigArgTys con) ]
- why = badCon (head bad_cons) (ptext (sLit "has arguments of unlifted type"))
+ why = badCon (head bad_cons) (ptext (sLit "must have only arguments of lifted type"))
cond_isEnumeration :: Condition
cond_isEnumeration (_, rep_tc)
- | isEnumerationTyCon rep_tc = Nothing
- | otherwise = Just why
+ | isEnumerationTyCon rep_tc = Nothing
+ | otherwise = Just why
where
- why = quotes (pprSourceTyCon rep_tc) <+>
- ptext (sLit "has non-nullary constructors")
+ why = sep [ quotes (pprSourceTyCon rep_tc) <+>
+ ptext (sLit "must be an enumeration type")
+ , ptext (sLit "(an enumeration consists of one or more nullary, non-GADT constructors)") ]
+ -- See Note [Enumeration types] in TyCon
cond_isProduct :: Condition
cond_isProduct (_, rep_tc)
| otherwise = Just why
where
why = quotes (pprSourceTyCon rep_tc) <+>
- ptext (sLit "has more than one constructor")
+ ptext (sLit "must have precisely one constructor")
cond_typeableOK :: Condition
-- OK for Typeable class
-- Currently: (a) args all of kind *
-- (b) 7 or fewer args
-cond_typeableOK (_, rep_tc)
- | tyConArity rep_tc > 7 = Just too_many
- | not (all (isSubArgTypeKind . tyVarKind) (tyConTyVars rep_tc))
- = Just bad_kind
- | isFamInstTyCon rep_tc = Just fam_inst -- no Typable for family insts
- | otherwise = Nothing
+cond_typeableOK (_, tc)
+ | tyConArity tc > 7 = Just too_many
+ | not (all (isSubArgTypeKind . tyVarKind) (tyConTyVars tc))
+ = Just bad_kind
+ | otherwise = Nothing
where
- too_many = quotes (pprSourceTyCon rep_tc) <+>
- ptext (sLit "has too many arguments")
- bad_kind = quotes (pprSourceTyCon rep_tc) <+>
- ptext (sLit "has arguments of kind other than `*'")
- fam_inst = quotes (pprSourceTyCon rep_tc) <+>
- ptext (sLit "is a type family")
-
+ too_many = quotes (pprSourceTyCon tc) <+>
+ ptext (sLit "must have 7 or fewer arguments")
+ bad_kind = quotes (pprSourceTyCon tc) <+>
+ ptext (sLit "must only have arguments of kind `*'")
functorLikeClassKeys :: [Unique]
functorLikeClassKeys = [functorClassKey, foldableClassKey, traversableClassKey]
cond_functorOK :: Bool -> Condition
--- OK for Functor class
+-- OK for Functor/Foldable/Traversable class
-- Currently: (a) at least one argument
-- (b) don't use argument contravariantly
-- (c) don't use argument in the wrong place, e.g. data T a = T (X a a)
-- (d) optionally: don't use function types
-cond_functorOK allowFunctions (dflags, rep_tc)
- | not (dopt Opt_DeriveFunctor dflags)
- = Just (ptext (sLit "You need -XDeriveFunctor to derive an instance for this class"))
+-- (e) no "stupid context" on data type
+cond_functorOK allowFunctions (_, rep_tc)
+ | null tc_tvs
+ = Just (ptext (sLit "Data type") <+> quotes (ppr rep_tc)
+ <+> ptext (sLit "must have some type parameters"))
+
+ | not (null bad_stupid_theta)
+ = Just (ptext (sLit "Data type") <+> quotes (ppr rep_tc)
+ <+> ptext (sLit "must not have a class context") <+> pprTheta bad_stupid_theta)
+
| otherwise
= msum (map check_con data_cons) -- msum picks the first 'Just', if any
where
+ tc_tvs = tyConTyVars rep_tc
+ Just (_, last_tv) = snocView tc_tvs
+ bad_stupid_theta = filter is_bad (tyConStupidTheta rep_tc)
+ is_bad pred = last_tv `elemVarSet` tyVarsOfPred pred
+
data_cons = tyConDataCons rep_tc
check_con con = msum (check_vanilla con : foldDataConArgs (ft_check con) con)
, ft_bad_app = Just (badCon con wrong_arg)
, ft_forall = \_ x -> x }
- existential = ptext (sLit "has existential arguments")
- covariant = ptext (sLit "uses the type variable in a function argument")
- functions = ptext (sLit "contains function types")
- wrong_arg = ptext (sLit "uses the type variable in an argument other than the last")
+ existential = ptext (sLit "must not have existential arguments")
+ covariant = ptext (sLit "must not use the type variable in a function argument")
+ functions = ptext (sLit "must not contain function types")
+ wrong_arg = ptext (sLit "must not use the type variable in an argument other than the last")
-checkFlag :: DynFlag -> Condition
+checkFlag :: ExtensionFlag -> Condition
checkFlag flag (dflags, _)
- | dopt flag dflags = Nothing
+ | xopt flag dflags = Nothing
| otherwise = Just why
where
why = ptext (sLit "You need -X") <> text flag_str
other -> pprPanic "checkFlag" (ppr other)
std_class_via_iso :: Class -> Bool
-std_class_via_iso clas -- These standard classes can be derived for a newtype
- -- using the isomorphism trick *even if no -fglasgow-exts*
+-- These standard classes can be derived for a newtype
+-- using the isomorphism trick *even if no -XGeneralizedNewtypeDeriving
+-- because giving so gives the same results as generating the boilerplate
+std_class_via_iso clas
= classKey clas `elem` [eqClassKey, ordClassKey, ixClassKey, boundedClassKey]
-- Not Read/Show because they respect the type
-- Not Enum, because newtypes are never in Enum
+non_iso_class :: Class -> Bool
+-- *Never* derive Read, Show, Typeable, Data, Generic by isomorphism,
+-- even with -XGeneralizedNewtypeDeriving
+non_iso_class cls
+ = classKey cls `elem` ([ readClassKey, showClassKey, dataClassKey
+ , genClassKey] ++ typeableClassKeys)
+
+typeableClassKeys :: [Unique]
+typeableClassKeys = map getUnique typeableClassNames
+
new_dfun_name :: Class -> TyCon -> TcM Name
new_dfun_name clas tycon -- Just a simple wrapper
= do { loc <- getSrcSpanM -- The location of the instance decl, not of the tycon
%************************************************************************
\begin{code}
-mkNewTypeEqn :: InstOrigin -> DynFlags -> [Var] -> Class
+mkNewTypeEqn :: CtOrigin -> DynFlags -> [Var] -> Class
-> [Type] -> TyCon -> [Type] -> TyCon -> [Type]
-> DerivContext
-> TcRn EarlyDerivSpec
cls cls_tys tycon tc_args rep_tycon rep_tc_args mtheta
-- Want: instance (...) => cls (cls_tys ++ [tycon tc_args]) where ...
| can_derive_via_isomorphism && (newtype_deriving || std_class_via_iso cls)
- = do { traceTc (text "newtype deriving:" <+> ppr tycon <+> ppr rep_tys)
+ = do { traceTc "newtype deriving:" (ppr tycon <+> ppr rep_tys <+> ppr all_preds)
; dfun_name <- new_dfun_name cls tycon
; loc <- getSrcSpanM
; let spec = DS { ds_loc = loc, ds_orig = orig
| otherwise
= case checkSideConditions dflags mtheta cls cls_tys rep_tycon of
- CanDerive -> go_for_it -- Use the standard H98 method
- DerivableClassError msg -> bale_out msg -- Error with standard class
+ CanDerive -> go_for_it -- Use the standard H98 method
+ DerivableClassError msg -- Error with standard class
+ | can_derive_via_isomorphism -> bale_out (msg $$ suggest_nd)
+ | otherwise -> bale_out msg
NonDerivableClass -- Must use newtype deriving
- | newtype_deriving -> bale_out cant_derive_err -- Too hard, even with newtype deriving
- | otherwise -> bale_out non_std_err -- Try newtype deriving!
+ | newtype_deriving -> bale_out cant_derive_err -- Too hard, even with newtype deriving
+ | can_derive_via_isomorphism -> bale_out (non_std $$ suggest_nd) -- Try newtype deriving!
+ | otherwise -> bale_out non_std
where
- newtype_deriving = dopt Opt_GeneralizedNewtypeDeriving dflags
+ newtype_deriving = xopt Opt_GeneralizedNewtypeDeriving dflags
go_for_it = mk_data_eqn orig tvs cls tycon tc_args rep_tycon rep_tc_args mtheta
bale_out msg = failWithTc (derivingThingErr newtype_deriving cls cls_tys inst_ty msg)
- non_std_err = nonStdErr cls $$
- ptext (sLit "Try -XGeneralizedNewtypeDeriving for GHC's newtype-deriving extension")
+ non_std = nonStdErr cls
+ suggest_nd = 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, ...)
&& ats_ok
-- && not (isRecursiveTyCon tycon) -- Note [Recursive newtypes]
- -- Never derive Read,Show,Typeable,Data by isomorphism
- non_iso_class cls = className cls `elem` ([readClassName, showClassName, dataClassName] ++
- typeableClassNames)
-
arity_ok = length cls_tys + 1 == classArity cls
-- Well kinded; eg not: newtype T ... deriving( ST )
-- because ST needs *2* type params
inferInstanceContexts _ [] = return []
inferInstanceContexts oflag infer_specs
- = do { traceTc (text "inferInstanceContexts" <+> vcat (map pprDerivSpec infer_specs))
+ = do { traceTc "inferInstanceContexts" $ vcat (map pprDerivSpec infer_specs)
; iterate_deriv 1 initial_solutions }
where
------------------------------------------------------------------
gen_soln (DS { ds_loc = loc, ds_orig = orig, ds_tvs = tyvars
, ds_cls = clas, ds_tys = inst_tys, ds_theta = deriv_rhs })
= setSrcSpan loc $
- addErrCtxt (derivInstCtxt clas inst_tys) $
- do { theta <- tcSimplifyDeriv orig tyvars deriv_rhs
- -- checkValidInstance tyvars theta clas inst_tys
- -- Not necessary; see Note [Exotic derived instance contexts]
- -- in TcSimplify
-
- -- Check for a bizarre corner case, when the derived instance decl should
+ addErrCtxt (derivInstCtxt the_pred) $
+ do { -- Check for a bizarre corner case, when the derived instance decl should
-- have form instance C a b => D (T a) where ...
-- Note that 'b' isn't a parameter of T. This gives rise to all sorts
-- of problems; in particular, it's hard to compare solutions for
- -- equality when finding the fixpoint. So I just rule it out for now.
+ -- equality when finding the fixpoint. Moreover, simplifyDeriv
+ -- has an assert failure because it finds a TyVar when it expects
+ -- only TcTyVars. So I just rule it out for now. I'm not
+ -- even sure how it can arise.
+
; let tv_set = mkVarSet tyvars
- weird_preds = [pred | pred <- theta, not (tyVarsOfPred pred `subVarSet` tv_set)]
+ weird_preds = [pred | pred <- deriv_rhs
+ , not (tyVarsOfPred pred `subVarSet` tv_set)]
; mapM_ (addErrTc . badDerivedPred) weird_preds
+ ; theta <- simplifyDeriv orig the_pred tyvars deriv_rhs
+ -- checkValidInstance tyvars theta clas inst_tys
+ -- Not necessary; see Note [Exotic derived instance contexts]
+ -- in TcSimplify
+
+ ; traceTc "TcDeriv" (ppr deriv_rhs $$ ppr theta)
-- Claim: the result instance declaration is guaranteed valid
-- Hence no need to call:
-- checkValidInstance tyvars theta clas inst_tys
; return (sortLe (<=) theta) } -- Canonicalise before returning the solution
+ where
+ the_pred = mkClassPred clas inst_tys
------------------------------------------------------------------
mkInstance :: OverlapFlag -> ThetaType -> DerivSpec -> Instance
genInst :: Bool -- True <=> standalone deriving
-> OverlapFlag
-> DerivSpec -> TcM (InstInfo RdrName, DerivAuxBinds)
-genInst standalone_deriv oflag spec
- | ds_newtype spec
- = return (InstInfo { iSpec = mkInstance oflag (ds_theta spec) spec
- , iBinds = NewTypeDerived co }, [])
+genInst standalone_deriv oflag
+ spec@(DS { ds_tc = rep_tycon, ds_tc_args = rep_tc_args
+ , ds_theta = theta, ds_newtype = is_newtype
+ , ds_name = name, ds_cls = clas })
+ | is_newtype
+ = return (InstInfo { iSpec = inst_spec
+ , iBinds = NewTypeDerived co rep_tycon }, [])
| otherwise
- = do { let loc = getSrcSpan (ds_name spec)
- inst = mkInstance oflag (ds_theta spec) spec
- clas = ds_cls spec
-
- -- In case of a family instance, we need to use the representation
- -- tycon (after all, it has the data constructors)
- ; fix_env <- getFixityEnv
- ; let (meth_binds, aux_binds) = genDerivBinds loc fix_env clas rep_tycon
- binds = VanillaInst meth_binds [] standalone_deriv
- ; return (InstInfo { iSpec = inst, iBinds = binds }, aux_binds)
- }
+ = do { fix_env <- getFixityEnv
+ ; let loc = getSrcSpan name
+ (meth_binds, aux_binds) = genDerivBinds loc fix_env clas rep_tycon
+ -- In case of a family instance, we need to use the representation
+ -- tycon (after all, it has the data constructors)
+
+ ; return (InstInfo { iSpec = inst_spec
+ , iBinds = VanillaInst meth_binds [] standalone_deriv }
+ , aux_binds) }
where
- rep_tycon = ds_tc spec
- rep_tc_args = ds_tc_args spec
+ inst_spec = mkInstance oflag theta spec
co1 = case tyConFamilyCoercion_maybe rep_tycon of
- Nothing -> IdCo
- Just co_con -> ACo (mkTyConApp co_con rep_tc_args)
- co2 = case newTyConCo_maybe rep_tycon of
- Nothing -> IdCo -- The newtype is transparent; no need for a cast
- Just co_con -> ACo (mkTyConApp co_con rep_tc_args)
- co = co1 `mkTransCoI` co2
+ Just co_con -> mkAxInstCo co_con rep_tc_args
+ Nothing -> id_co
+ -- Not a family => rep_tycon = main tycon
+ co2 = mkAxInstCo (newTyConCo rep_tycon) rep_tc_args
+ co = co1 `mkTransCo` co2
+ id_co = mkReflCo (mkTyConApp rep_tycon rep_tc_args)
-- Example: newtype instance N [a] = N1 (Tree a)
-- deriving instance Eq b => Eq (N [(b,b)])
Nothing -> pprPanic "genDerivBinds: bad derived class" (ppr clas)
where
gen_list :: [(Unique, SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds))]
- gen_list = [(eqClassKey, gen_Eq_binds)
- ,(ordClassKey, gen_Ord_binds)
- ,(enumClassKey, gen_Enum_binds)
- ,(boundedClassKey, gen_Bounded_binds)
- ,(ixClassKey, gen_Ix_binds)
- ,(showClassKey, gen_Show_binds fix_env)
- ,(readClassKey, gen_Read_binds fix_env)
- ,(dataClassKey, gen_Data_binds)
- ,(functorClassKey, gen_Functor_binds)
- ,(foldableClassKey, gen_Foldable_binds)
- ,(traversableClassKey, gen_Traversable_binds)
+ gen_list = [(eqClassKey, gen_Eq_binds)
+ ,(ordClassKey, gen_Ord_binds)
+ ,(enumClassKey, gen_Enum_binds)
+ ,(boundedClassKey, gen_Bounded_binds)
+ ,(ixClassKey, gen_Ix_binds)
+ ,(showClassKey, gen_Show_binds fix_env)
+ ,(readClassKey, gen_Read_binds fix_env)
+ ,(dataClassKey, gen_Data_binds)
+ ,(functorClassKey, gen_Functor_binds)
+ ,(foldableClassKey, gen_Foldable_binds)
+ ,(traversableClassKey, gen_Traversable_binds)
+ ,(genClassKey, genGenericBinds)
]
\end{code}
+%************************************************************************
+%* *
+\subsection[TcDeriv-generic-binds]{Bindings for the new generic deriving mechanism}
+%* *
+%************************************************************************
+
+For the generic representation we need to generate:
+\begin{itemize}
+\item A Generic instance
+\item A Rep type instance
+\item Many auxiliary datatypes and instances for them (for the meta-information)
+\end{itemize}
+
+@genGenericBinds@ does (1)
+@genGenericRepExtras@ does (2) and (3)
+@genGenericAll@ does all of them
+
+\begin{code}
+genGenericBinds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
+genGenericBinds _ tc = (mkBindsRep tc, [ {- No DerivAuxBinds -} ])
+
+genGenericRepExtras :: TyCon -> TcM (MetaTyCons, TyCon)
+genGenericRepExtras tc =
+ do uniqS <- newUniqueSupply
+ let
+ -- Uniques for everyone
+ (uniqD:uniqs) = uniqsFromSupply uniqS
+ (uniqsC,us) = splitAt (length tc_cons) uniqs
+ uniqsS :: [[Unique]] -- Unique supply for the S datatypes
+ uniqsS = mkUniqsS tc_arits us
+ mkUniqsS [] _ = []
+ mkUniqsS (n:t) us = case splitAt n us of
+ (us1,us2) -> us1 : mkUniqsS t us2
+
+ tc_name = tyConName tc
+ tc_cons = tyConDataCons tc
+ tc_arits = map dataConSourceArity tc_cons
+
+ tc_occ = nameOccName tc_name
+ d_occ = mkGenD tc_occ
+ c_occ m = mkGenC tc_occ m
+ s_occ m n = mkGenS tc_occ m n
+ mod_name = nameModule (tyConName tc)
+ d_name = mkExternalName uniqD mod_name d_occ wiredInSrcSpan
+ c_names = [ mkExternalName u mod_name (c_occ m) wiredInSrcSpan
+ | (u,m) <- zip uniqsC [0..] ]
+ s_names = [ [ mkExternalName u mod_name (s_occ m n) wiredInSrcSpan
+ | (u,n) <- zip us [0..] ] | (us,m) <- zip uniqsS [0..] ]
+
+ mkTyCon name = ASSERT( isExternalName name )
+ buildAlgTyCon name [] [] mkAbstractTyConRhs
+ NonRecursive False NoParentTyCon Nothing
+
+ metaDTyCon <- mkTyCon d_name
+ metaCTyCons <- sequence [ mkTyCon c_name | c_name <- c_names ]
+ metaSTyCons <- mapM sequence
+ [ [ mkTyCon s_name
+ | s_name <- s_namesC ] | s_namesC <- s_names ]
+
+ let metaDts = MetaTyCons metaDTyCon metaCTyCons metaSTyCons
+
+ rep0_tycon <- tc_mkRepTyCon tc metaDts
+
+ -- pprTrace "rep0" (ppr rep0_tycon) $
+ return (metaDts, rep0_tycon)
+{-
+genGenericAll :: TyCon
+ -> TcM ((InstInfo RdrName, DerivAuxBinds), MetaTyCons, TyCon)
+genGenericAll tc =
+ do (metaDts, rep0_tycon) <- genGenericRepExtras tc
+ clas <- tcLookupClass genClassName
+ dfun_name <- new_dfun_name clas tc
+ let
+ mkInstRep = (InstInfo { iSpec = inst, iBinds = binds }
+ , [ {- No DerivAuxBinds -} ])
+ inst = mkLocalInstance dfun NoOverlap
+ binds = VanillaInst (mkBindsRep tc) [] False
+
+ tvs = tyConTyVars tc
+ tc_ty = mkTyConApp tc (mkTyVarTys tvs)
+
+ dfun = mkDictFunId dfun_name (tyConTyVars tc) [] clas [tc_ty]
+ return (mkInstRep, metaDts, rep0_tycon)
+-}
+genDtMeta :: (TyCon, MetaTyCons) -> TcM [(InstInfo RdrName, DerivAuxBinds)]
+genDtMeta (tc,metaDts) =
+ do dClas <- tcLookupClass datatypeClassName
+ d_dfun_name <- new_dfun_name dClas tc
+ cClas <- tcLookupClass constructorClassName
+ c_dfun_names <- sequence [ new_dfun_name cClas tc | _ <- metaC metaDts ]
+ sClas <- tcLookupClass selectorClassName
+ s_dfun_names <- sequence (map sequence [ [ new_dfun_name sClas tc
+ | _ <- x ]
+ | x <- metaS metaDts ])
+ fix_env <- getFixityEnv
+
+ let
+ (dBinds,cBinds,sBinds) = mkBindsMetaD fix_env tc
+
+ -- Datatype
+ d_metaTycon = metaD metaDts
+ d_inst = mkLocalInstance d_dfun NoOverlap
+ d_binds = VanillaInst dBinds [] False
+ d_dfun = mkDictFunId d_dfun_name (tyConTyVars tc) [] dClas
+ [ mkTyConTy d_metaTycon ]
+ d_mkInst = (InstInfo { iSpec = d_inst, iBinds = d_binds }, [])
+
+ -- Constructor
+ c_metaTycons = metaC metaDts
+ c_insts = [ mkLocalInstance (c_dfun c ds) NoOverlap
+ | (c, ds) <- myZip1 c_metaTycons c_dfun_names ]
+ c_binds = [ VanillaInst c [] False | c <- cBinds ]
+ c_dfun c dfun_name = mkDictFunId dfun_name (tyConTyVars tc) [] cClas
+ [ mkTyConTy c ]
+ c_mkInst = [ (InstInfo { iSpec = is, iBinds = bs }, [])
+ | (is,bs) <- myZip1 c_insts c_binds ]
+
+ -- Selector
+ s_metaTycons = metaS metaDts
+ s_insts = map (map (\(s,ds) -> mkLocalInstance (s_dfun s ds) NoOverlap))
+ (myZip2 s_metaTycons s_dfun_names)
+ s_binds = [ [ VanillaInst s [] False | s <- ss ] | ss <- sBinds ]
+ s_dfun s dfun_name = mkDictFunId dfun_name (tyConTyVars tc) [] sClas
+ [ mkTyConTy s ]
+ s_mkInst = map (map (\(is,bs) -> (InstInfo {iSpec=is, iBinds=bs}, [])))
+ (myZip2 s_insts s_binds)
+
+ myZip1 :: [a] -> [b] -> [(a,b)]
+ myZip1 l1 l2 = ASSERT (length l1 == length l2) zip l1 l2
+
+ myZip2 :: [[a]] -> [[b]] -> [[(a,b)]]
+ myZip2 l1 l2 =
+ ASSERT (and (zipWith (>=) (map length l1) (map length l2)))
+ [ zip x1 x2 | (x1,x2) <- zip l1 l2 ]
+
+ return (d_mkInst : c_mkInst ++ concat s_mkInst)
+\end{code}
+
%************************************************************************
%* *
standaloneCtxt ty = hang (ptext (sLit "In the stand-alone deriving instance for"))
2 (quotes (ppr ty))
-derivInstCtxt :: Class -> [Type] -> Message
-derivInstCtxt clas inst_tys
- = ptext (sLit "When deriving the instance for") <+> parens (pprClassPred clas inst_tys)
+derivInstCtxt :: PredType -> Message
+derivInstCtxt pred
+ = ptext (sLit "When deriving the instance for") <+> parens (ppr pred)
badDerivedPred :: PredType -> Message
badDerivedPred pred
projects / ghc-hetmet.git / blobdiff