Commit bf6dd833 authored by simonpj@microsoft.com's avatar simonpj@microsoft.com

Deriving Typeable changes

* Fix a bug that led to a crash with
    data family T a
    deriving Functor T

* Allow deriving Typeable for data families
    data family T a
    deriving Typeable1 T

* Some refactoring and tidying
parent 30f26dda
......@@ -595,32 +595,46 @@ mkEqnHelp :: CtOrigin -> [TyVar] -> Class -> [Type] -> Type
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) <- 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.
-- 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")))
where
bale_out msg = failWithTc (derivingThingErr False cls cls_tys tc_app msg)
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}
......@@ -655,15 +669,10 @@ mkDataTypeEqn orig dflags tvs cls cls_tys
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
:: CtOrigin -> [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]
......@@ -678,7 +687,11 @@ mk_data_eqn orig tvs cls tycon tc_args rep_tc rep_tc_args mtheta
; 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
......@@ -692,7 +705,7 @@ mk_typeable_eqn orig tvs cls tycon tc_args rep_tc rep_tc_args mtheta
= 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)
......@@ -703,10 +716,10 @@ mk_typeable_eqn orig tvs cls tycon tc_args rep_tc rep_tc_args mtheta
; 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
......@@ -792,6 +805,9 @@ checkSideConditions dflags mtheta cls cls_tys rep_tc
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")
......@@ -812,7 +828,6 @@ sideConditions mtheta cls
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)
| otherwise = Nothing
where
cls_key = getUnique cls
......@@ -900,20 +915,16 @@ 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) <+>
too_many = quotes (pprSourceTyCon tc) <+>
ptext (sLit "has too many arguments")
bad_kind = quotes (pprSourceTyCon rep_tc) <+>
bad_kind = quotes (pprSourceTyCon tc) <+>
ptext (sLit "has arguments of kind other than `*'")
fam_inst = quotes (pprSourceTyCon rep_tc) <+>
ptext (sLit "is a type family")
functorLikeClassKeys :: [Unique]
functorLikeClassKeys = [functorClassKey, foldableClassKey, traversableClassKey]
......
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