#include "HsVersions.h"
-import HsSyn ( HsBinds(..), MonoBinds(..), TyClDecl(..),
- collectMonoBinders )
+import HsSyn ( HsBinds(..), TyClDecl(..), MonoBinds(..),
+ andMonoBindList, collectMonoBinders )
import RdrHsSyn ( RdrNameMonoBinds )
-import RnHsSyn ( RenamedHsBinds, RenamedMonoBinds, RenamedTyClDecl, RenamedHsPred )
+import RnHsSyn ( RenamedHsBinds, RenamedTyClDecl, RenamedHsPred )
import CmdLineOpts ( DynFlag(..) )
import TcRnMonad
import TcSimplify ( tcSimplifyDeriv )
import RnBinds ( rnMethodBinds, rnTopMonoBinds )
-import RnEnv ( bindLocalsFV )
+import RnEnv ( bindLocalsFV, extendTyVarEnvFVRn )
import TcRnMonad ( thenM, returnM, mapAndUnzipM )
import HscTypes ( DFunId )
import Subst ( mkTyVarSubst, substTheta )
import ErrUtils ( dumpIfSet_dyn )
import MkId ( mkDictFunId )
-import DataCon ( dataConRepArgTys, dataConOrigArgTys, isNullaryDataCon, isExistentialDataCon )
+import DataCon ( dataConOrigArgTys, isNullaryDataCon, isExistentialDataCon )
import Maybes ( maybeToBool, catMaybes )
-import Name ( Name, getSrcLoc, nameUnique )
+import Name ( Name, getSrcLoc )
+import Unique ( Unique, getUnique )
import NameSet
import RdrName ( RdrName )
import TyCon ( tyConTyVars, tyConDataCons, tyConArity,
- tyConTheta, maybeTyConSingleCon, isDataTyCon,
+ tyConTheta, isProductTyCon, isDataTyCon,
isEnumerationTyCon, isRecursiveTyCon, TyCon
)
-import TcType ( TcType, ThetaType, mkTyVarTys, mkTyConApp, getClassPredTys_maybe,
- isUnLiftedType, mkClassPred, tyVarsOfTypes, tcSplitFunTys,
- tcEqTypes, tcSplitAppTys, mkAppTys )
-import Var ( TyVar, tyVarKind )
+import TcType ( TcType, ThetaType, mkTyVarTy, mkTyVarTys, mkTyConApp,
+ getClassPredTys_maybe,
+ isUnLiftedType, mkClassPred, tyVarsOfTypes, tcSplitFunTys, isTypeKind,
+ tcEqTypes, tcSplitAppTys, mkAppTys, tcSplitDFunTy )
+import Var ( TyVar, tyVarKind, idType, varName )
import VarSet ( mkVarSet, subVarSet )
import PrelNames
import Util ( zipWithEqual, sortLt, notNull )
let
extra_mbind_list = map gen_tag_n_con_monobind nm_alist_etc
- extra_mbinds = foldr AndMonoBinds EmptyMonoBinds extra_mbind_list
+ extra_mbinds = andMonoBindList extra_mbind_list
mbinders = collectMonoBinders extra_mbinds
in
- mappM gen_bind new_dfuns `thenM` \ method_binds_s ->
+ mappM gen_bind new_dfuns `thenM` \ rdr_name_inst_infos ->
- traceTc (text "tcDeriv" <+> ppr method_binds_s) `thenM_`
- getModule `thenM` \ this_mod ->
+ traceTc (text "tcDeriv" <+> vcat (map ppr rdr_name_inst_infos)) `thenM_`
+ getModule `thenM` \ this_mod ->
initRn (InterfaceMode this_mod) (
-- Rename to get RenamedBinds.
-- The only tricky bit is that the extra_binds must scope
-- over the method bindings for the instances.
bindLocalsFV (ptext (SLIT("deriving"))) mbinders $ \ _ ->
rnTopMonoBinds extra_mbinds [] `thenM` \ (rn_extra_binds, dus) ->
- mapAndUnzipM rn_meths method_binds_s `thenM` \ (rn_method_binds_s, fvs_s) ->
- returnM ((rn_method_binds_s, rn_extra_binds),
- duUses dus `plusFV` plusFVs fvs_s)
- ) `thenM` \ ((rn_method_binds_s, rn_extra_binds), fvs) ->
- let
- new_inst_infos = zipWith gen_inst_info new_dfuns rn_method_binds_s
- in
- returnM (new_inst_infos, rn_extra_binds, fvs)
- where
- -- Make a Real dfun instead of the dummy one we have so far
- gen_inst_info :: DFunId -> RenamedMonoBinds -> InstInfo
- gen_inst_info dfun binds
- = InstInfo { iDFunId = dfun, iBinds = VanillaInst binds [] }
+ mapAndUnzipM rn_inst_info rdr_name_inst_infos `thenM` \ (pairs, fvs_s) ->
- rn_meths (cls, meths) = rnMethodBinds cls [] meths
+ let
+ (rn_inst_infos, aux_binds_s) = unzip pairs
+ all_binds = rn_extra_binds `ThenBinds` foldr ThenBinds EmptyBinds aux_binds_s
+ in
+ returnM ((rn_inst_infos, all_binds),
+ duUses dus `plusFV` plusFVs fvs_s)
+ ) `thenM` \ ((rn_inst_infos, rn_extra_binds), fvs) ->
+ returnM (rn_inst_infos, rn_extra_binds, fvs)
+
+ where
+ rn_inst_info (dfun, (meth_binds, aux_binds))
+ = -- Rename the auxiliary bindings
+ bindLocalsFV (ptext (SLIT("deriving"))) mbinders $ \ _ ->
+ rnTopMonoBinds aux_binds [] `thenM` \ (rn_aux_binds, dus) ->
+
+ -- Bring the right type variables into scope
+ extendTyVarEnvFVRn (map varName tyvars) $
+ rnMethodBinds (className cls) [] meth_binds `thenM` \ (rn_meth_binds, fvs) ->
+
+ return ((InstInfo { iDFunId = dfun, iBinds = VanillaInst rn_meth_binds [] },
+ rn_aux_binds),
+ duUses dus `plusFV` fvs)
+ where
+ mbinders = collectMonoBinders aux_binds
+ (tyvars, _, cls, _) = tcSplitDFunTy (idType dfun)
\end{code}
tcHsPred pred `thenM` \ pred' ->
case getClassPredTys_maybe pred' of
Nothing -> bale_out (malformedPredErr tycon pred)
- Just (clas, tys) -> mk_eqn_help new_or_data tycon clas tys
+ Just (clas, tys) -> doptM Opt_GlasgowExts `thenM` \ gla_exts ->
+ mk_eqn_help gla_exts new_or_data tycon clas tys
------------------------------------------------------------------
- mk_eqn_help DataType tycon clas tys
- | Just err <- chk_out clas tycon tys
+ mk_eqn_help gla_exts DataType tycon clas tys
+ | Just err <- checkSideConditions gla_exts clas tycon tys
= bale_out (derivingThingErr clas tys tycon tyvars err)
| otherwise
= new_dfun_name clas tycon `thenM` \ dfun_name ->
where
tyvars = tyConTyVars tycon
data_cons = tyConDataCons tycon
- constraints = extra_constraints ++
- [ mkClassPred clas [arg_ty]
- | data_con <- tyConDataCons tycon,
- arg_ty <- dataConRepArgTys data_con, -- dataConOrigArgTys???
- -- Use the same type variables
- -- as the type constructor,
- -- hence no need to instantiate
- not (isUnLiftedType arg_ty) -- No constraints for unlifted types?
- ]
-
- -- "extra_constraints": see note [Data decl contexts] above
+ constraints = extra_constraints ++ ordinary_constraints
+ -- "extra_constraints": see note [Data decl contexts] above
extra_constraints = tyConTheta tycon
- mk_eqn_help NewType tycon clas tys
- = doptM Opt_GlasgowExts `thenM` \ gla_exts ->
- if can_derive_via_isomorphism && (gla_exts || standard_instance) then
- -- Go ahead and use the isomorphism
+ ordinary_constraints
+ | clas `hasKey` typeableClassKey -- For the Typeable class, the constraints
+ -- don't involve the constructor ags, only
+ -- the tycon tyvars
+ -- e.g. data T a b = ...
+ -- we want
+ -- instance (Typeable a, Typable b)
+ -- => Typeable (T a b) where
+ = [mkClassPred clas [mkTyVarTy tv] | tv <- tyvars]
+ | otherwise
+ = [ mkClassPred clas [arg_ty]
+ | data_con <- tyConDataCons tycon,
+ arg_ty <- dataConOrigArgTys data_con,
+ -- Use the same type variables
+ -- as the type constructor,
+ -- hence no need to instantiate
+ not (isUnLiftedType arg_ty) -- No constraints for unlifted types?
+ ]
+
+ mk_eqn_help gla_exts NewType tycon clas tys
+ | can_derive_via_isomorphism && (gla_exts || standard_class gla_exts clas)
+ = -- Go ahead and use the isomorphism
traceTc (text "newtype deriving:" <+> ppr tycon <+> ppr rep_tys) `thenM_`
new_dfun_name clas tycon `thenM` \ dfun_name ->
returnM (Nothing, Just (InstInfo { iDFunId = mk_dfun dfun_name,
iBinds = NewTypeDerived rep_tys }))
- else
- if standard_instance then
- mk_eqn_help DataType tycon clas [] -- Go via bale-out route
- else
- -- Non-standard instance
- if gla_exts then
- -- Too hard
- bale_out cant_derive_err
- else
- -- Just complain about being a non-std instance
- bale_out non_std_err
+ | standard_class gla_exts clas
+ = mk_eqn_help gla_exts DataType tycon clas tys -- Go via bale-out route
+
+ | otherwise -- Non-standard instance
+ = bale_out (if gla_exts then
+ cant_derive_err -- Too hard
+ else
+ non_std_err) -- Just complain about being a non-std instance
where
-- Here is the plan for newtype derivings. We see
-- newtype T a1...an = T (t ak...an) deriving (.., C s1 .. sm, ...)
-------------------------------------------------------------------
-- Figuring out whether we can only do this newtype-deriving thing
- standard_instance = null tys && classKey clas `elem` derivableClassKeys
+ right_arity = length tys + 1 == classArity clas
+ -- Never derive Read,Show,Typeable,Data this way
+ non_iso_classes = [readClassKey, showClassKey, typeableClassKey, dataClassKey]
can_derive_via_isomorphism
- = not (clas `hasKey` readClassKey) -- Never derive Read,Show this way
- && not (clas `hasKey` showClassKey)
- && length tys + 1 == classArity clas -- Well kinded;
+ = not (getUnique clas `elem` non_iso_classes)
+ && right_arity -- Well kinded;
-- eg not: newtype T ... deriving( ST )
-- because ST needs *2* type params
- && n_tyvars_to_keep >= 0 -- Well kinded;
+ && n_tyvars_to_keep >= 0 -- Type constructor has right kind:
-- eg not: newtype T = T Int deriving( Monad )
- && n_args_to_keep >= 0 -- Well kinded:
+ && n_args_to_keep >= 0 -- Rep type has right kind:
-- eg not: newtype T a = T Int deriving( Monad )
&& eta_ok -- Eta reduction works
&& not (isRecursiveTyCon tycon) -- Does not work for recursive tycons:
-- Don't want
-- instance Eq [A] => Eq A !!
+ -- Here's a recursive newtype that's actually OK
+ -- newtype S1 = S1 [T1 ()]
+ -- newtype T1 a = T1 (StateT S1 IO a ) deriving( Monad )
+ -- It's currently rejected. Oh well.
+
-- Check that eta reduction is OK
-- (a) the dropped-off args are identical
-- (b) the remaining type args mention
&& (tyVarsOfTypes args_to_keep `subVarSet` mkVarSet tyvars_to_keep)
cant_derive_err = derivingThingErr clas tys tycon tyvars_to_keep
- (vcat [ptext SLIT("too hard for cunning newtype deriving"),
- ptext SLIT("debug info:") <+> ppr n_tyvars_to_keep <+>
- ppr n_args_to_keep <+> ppr eta_ok <+>
- ppr (isRecursiveTyCon tycon)
+ (vcat [ptext SLIT("even with cunning newtype deriving:"),
+ if isRecursiveTyCon tycon then
+ ptext SLIT("the newtype is recursive")
+ else empty,
+ if not right_arity then
+ quotes (ppr (mkClassPred clas tys)) <+> ptext SLIT("does not have arity 1")
+ else empty,
+ if not (n_tyvars_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
])
non_std_err = derivingThingErr clas tys tycon tyvars_to_keep
ptext SLIT("Try -fglasgow-exts for GHC's newtype-deriving extension")])
bale_out err = addErrTc err `thenM_` returnM (Nothing, Nothing)
-
- ------------------------------------------------------------------
- chk_out :: Class -> TyCon -> [TcType] -> Maybe SDoc
- chk_out clas tycon tys
- | notNull tys = Just ty_args_why
- | not (getUnique clas `elem` derivableClassKeys) = Just (non_std_why clas)
- | clas `hasKey` enumClassKey && not is_enumeration = Just nullary_why
- | clas `hasKey` boundedClassKey && not is_enumeration_or_single = Just single_nullary_why
- | clas `hasKey` ixClassKey && not is_enumeration_or_single = Just single_nullary_why
- | null data_cons = Just no_cons_why
- | any isExistentialDataCon data_cons = Just existential_why
- | otherwise = Nothing
+ standard_class gla_exts clas = key `elem` derivableClassKeys
+ || (gla_exts && (key == typeableClassKey || key == dataClassKey))
where
- data_cons = tyConDataCons tycon
- is_enumeration = isEnumerationTyCon tycon
- is_single_con = maybeToBool (maybeTyConSingleCon tycon)
- is_enumeration_or_single = is_enumeration || is_single_con
+ key = classKey clas
- single_nullary_why = ptext SLIT("one constructor data type or type with all nullary constructors expected")
- nullary_why = quotes (ppr tycon) <+> ptext SLIT("has non-nullary constructors")
- no_cons_why = quotes (ppr tycon) <+> ptext SLIT("has no data constructors")
- ty_args_why = quotes (ppr pred) <+> ptext SLIT("is not a class")
- existential_why = quotes (ppr tycon) <+> ptext SLIT("has existentially-quantified constructor(s)")
- pred = mkClassPred clas tys
-non_std_why clas = quotes (ppr clas) <+> ptext SLIT("is not a derivable class")
new_dfun_name clas tycon -- Just a simple wrapper
= newDFunName clas [mkTyConApp tycon []] (getSrcLoc tycon)
-- The type passed to newDFunName is only used to generate
-- a suitable string; hence the empty type arg list
+
+
+------------------------------------------------------------------
+-- Check side conditions that dis-allow derivability for particular classes
+-- This is *apart* from the newtype-deriving mechanism
+
+checkSideConditions :: Bool -> Class -> TyCon -> [TcType] -> Maybe SDoc
+checkSideConditions gla_exts clas tycon tys
+ | notNull tys
+ = Just ty_args_why -- e.g. deriving( Foo s )
+ | otherwise
+ = case [cond | (key,cond) <- sideConditions, key == getUnique clas] of
+ [] -> Just (non_std_why clas)
+ [cond] -> cond (gla_exts, tycon)
+ other -> pprPanic "checkSideConditions" (ppr clas)
+ where
+ ty_args_why = quotes (ppr (mkClassPred clas tys)) <+> ptext SLIT("is not a class")
+
+non_std_why clas = quotes (ppr clas) <+> ptext SLIT("is not a derivable class")
+
+sideConditions :: [(Unique, Condition)]
+sideConditions
+ = [ (eqClassKey, cond_std),
+ (ordClassKey, cond_std),
+ (readClassKey, cond_std),
+ (showClassKey, cond_std),
+ (enumClassKey, cond_std `andCond` cond_isEnumeration),
+ (ixClassKey, cond_std `andCond` (cond_isEnumeration `orCond` cond_isProduct)),
+ (boundedClassKey, cond_std `andCond` (cond_isEnumeration `orCond` cond_isProduct)),
+ (typeableClassKey, cond_glaExts `andCond` cond_allTypeKind),
+ (dataClassKey, cond_glaExts `andCond` cond_std)
+ ]
+
+type Condition = (Bool, TyCon) -> Maybe SDoc -- Nothing => OK
+
+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
+ Just y -> Just (x $$ ptext SLIT(" and") $$ y)
+ -- Both fail
+
+andCond c1 c2 tc = case c1 tc of
+ Nothing -> c2 tc -- c1 succeeds
+ Just x -> Just x -- c1 fails
+
+cond_std :: Condition
+cond_std (gla_exts, tycon)
+ | any isExistentialDataCon data_cons = Just existential_why
+ | null data_cons = Just no_cons_why
+ | otherwise = Nothing
+ where
+ data_cons = tyConDataCons tycon
+ no_cons_why = quotes (ppr tycon) <+> ptext SLIT("has no data constructors")
+ existential_why = quotes (ppr tycon) <+> ptext SLIT("has existentially-quantified constructor(s)")
+
+cond_isEnumeration :: Condition
+cond_isEnumeration (gla_exts, tycon)
+ | isEnumerationTyCon tycon = Nothing
+ | otherwise = Just why
+ where
+ why = quotes (ppr tycon) <+> ptext SLIT("has non-nullary constructors")
+
+cond_isProduct :: Condition
+cond_isProduct (gla_exts, tycon)
+ | isProductTyCon tycon = Nothing
+ | otherwise = Just why
+ where
+ why = quotes (ppr tycon) <+> ptext SLIT("has more than one constructor")
+
+cond_allTypeKind :: Condition
+cond_allTypeKind (gla_exts, tycon)
+ | all (isTypeKind . tyVarKind) (tyConTyVars tycon) = Nothing
+ | otherwise = Just why
+ where
+ why = quotes (ppr tycon) <+> ptext SLIT("is parameterised over arguments of kind other than `*'")
+
+cond_glaExts :: Condition
+cond_glaExts (gla_exts, tycon) | gla_exts = Nothing
+ | otherwise = Just why
+ where
+ why = ptext SLIT("You need -fglasgow-exts to derive an instance for this class")
\end{code}
%************************************************************************
\begin{code}
-- Generate the method bindings for the required instance
--- (paired with class name, as we need that when renaming
+-- (paired with DFunId, as we need that when renaming
-- the method binds)
-gen_bind :: DFunId -> TcM (Name, RdrNameMonoBinds)
+gen_bind :: DFunId -> TcM (DFunId, (RdrNameMonoBinds, RdrNameMonoBinds))
gen_bind dfun
= getFixityEnv `thenM` \ fix_env ->
- returnM (cls_nm, gen_binds_fn fix_env cls_nm tycon)
- where
- cls_nm = className clas
- (clas, tycon) = simpleDFunClassTyCon dfun
-
-gen_binds_fn fix_env cls_nm
- = assoc "gen_bind:bad derived class"
- gen_list (nameUnique cls_nm)
- where
- 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)
- ]
+ let
+ (clas, tycon) = simpleDFunClassTyCon dfun
+ gen_binds_fn = assoc "gen_bind:bad derived class"
+ gen_list (getUnique clas)
+
+ gen_list = [(eqClassKey, no_aux_binds gen_Eq_binds)
+ ,(ordClassKey, no_aux_binds gen_Ord_binds)
+ ,(enumClassKey, no_aux_binds gen_Enum_binds)
+ ,(boundedClassKey, no_aux_binds gen_Bounded_binds)
+ ,(ixClassKey, no_aux_binds gen_Ix_binds)
+ ,(showClassKey, no_aux_binds (gen_Show_binds fix_env))
+ ,(readClassKey, no_aux_binds (gen_Read_binds fix_env))
+ ,(typeableClassKey,no_aux_binds gen_Typeable_binds)
+ ,(dataClassKey, gen_Data_binds fix_env)
+ ]
+
+ -- Used for generators that don't need to produce
+ -- any auxiliary bindings
+ no_aux_binds f tc = (f tc, EmptyMonoBinds)
+ in
+ returnM (dfun, gen_binds_fn tycon)
\end{code}
((we_are_deriving eqClassKey tycon
&& any isNullaryDataCon (tyConDataCons tycon))
|| (we_are_deriving ordClassKey tycon
- && not (maybeToBool (maybeTyConSingleCon tycon)))
+ && not (isProductTyCon tycon))
|| (we_are_deriving enumClassKey tycon)
|| (we_are_deriving ixClassKey tycon))
projects / ghc-hetmet.git / blobdiff