From 922de8ca1aa3f2a1796e8cfa9bf8e52d7b959d9b Mon Sep 17 00:00:00 2001 From: Ian Lynagh Date: Sun, 8 Jul 2007 14:43:54 +0000 Subject: [PATCH] Implement -XGeneralizedNewtypeDeriving --- compiler/main/DynFlags.hs | 3 +++ compiler/typecheck/TcDeriv.lhs | 49 +++++++++++++++++++++++----------------- 2 files changed, 31 insertions(+), 21 deletions(-) diff --git a/compiler/main/DynFlags.hs b/compiler/main/DynFlags.hs index 93add2b..26948e1 100644 --- a/compiler/main/DynFlags.hs +++ b/compiler/main/DynFlags.hs @@ -188,6 +188,7 @@ data DynFlag | Opt_EmptyDataDecls | Opt_KindSignatures | Opt_ParallelListComp + | Opt_GeneralizedNewtypeDeriving -- optimisation opts | Opt_Strictness @@ -1130,6 +1131,7 @@ xFlags = [ ( "ImplicitParams", Opt_ImplicitParams ), ( "ScopedTypeVariables", Opt_ScopedTypeVariables ), ( "MultiParamTypeClasses", Opt_MultiParamTypeClasses ), + ( "GeneralizedNewtypeDeriving", Opt_GeneralizedNewtypeDeriving ), ( "AllowOverlappingInstances", Opt_AllowOverlappingInstances ), ( "AllowUndecidableInstances", Opt_AllowUndecidableInstances ), ( "AllowIncoherentInstances", Opt_AllowIncoherentInstances ) @@ -1150,6 +1152,7 @@ glasgowExtsFlags = [ Opt_GlasgowExts , Opt_ParallelListComp , Opt_EmptyDataDecls , Opt_KindSignatures + , Opt_GeneralizedNewtypeDeriving , Opt_TypeFamilies ] ------------------ diff --git a/compiler/typecheck/TcDeriv.lhs b/compiler/typecheck/TcDeriv.lhs index ba11079..0272c54 100644 --- a/compiler/typecheck/TcDeriv.lhs +++ b/compiler/typecheck/TcDeriv.lhs @@ -408,16 +408,18 @@ mkEqnHelp orig tvs cls cls_tys tc_app ; (rep_tc, rep_tc_args) <- tcLookupFamInstExact tycon full_tc_args - ; gla_exts <- doptM Opt_GlasgowExts + ; mayDeriveDataTypeable <- doptM Opt_GlasgowExts + ; newtype_deriving <- doptM Opt_GeneralizedNewtypeDeriving ; overlap_flag <- getOverlapFlag -- 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 gla_exts full_tvs cls cls_tys + mkDataTypeEqn orig mayDeriveDataTypeable full_tvs cls cls_tys tycon full_tc_args rep_tc rep_tc_args else - mkNewTypeEqn orig gla_exts overlap_flag full_tvs cls cls_tys + mkNewTypeEqn orig mayDeriveDataTypeable newtype_deriving overlap_flag + full_tvs cls cls_tys tycon full_tc_args rep_tc rep_tc_args } | otherwise = baleOut (derivingThingErr cls cls_tys tc_app @@ -455,8 +457,9 @@ tcLookupFamInstExact tycon tys %************************************************************************ \begin{code} -mkDataTypeEqn orig gla_exts tvs cls cls_tys tycon tc_args rep_tc rep_tc_args - | Just err <- checkSideConditions gla_exts cls cls_tys rep_tc +mkDataTypeEqn orig mayDeriveDataTypeable tvs cls cls_tys + tycon tc_args rep_tc rep_tc_args + | Just err <- checkSideConditions mayDeriveDataTypeable cls cls_tys rep_tc -- NB: pass the *representation* tycon to checkSideConditions = baleOut (derivingThingErr cls cls_tys (mkTyConApp tycon tc_args) err) @@ -509,13 +512,13 @@ mk_data_eqn loc orig tvs cls tycon tc_args rep_tc rep_tc_args -- family tycon (with indexes) in error messages. checkSideConditions :: Bool -> Class -> [TcType] -> TyCon -> Maybe SDoc -checkSideConditions gla_exts cls cls_tys rep_tc +checkSideConditions mayDeriveDataTypeable cls cls_tys rep_tc | notNull cls_tys = Just ty_args_why -- e.g. deriving( Foo s ) | otherwise = case [cond | (key,cond) <- sideConditions, key == getUnique cls] of [] -> Just (non_std_why cls) - [cond] -> cond (gla_exts, rep_tc) + [cond] -> cond (mayDeriveDataTypeable, rep_tc) other -> pprPanic "checkSideConditions" (ppr cls) where ty_args_why = quotes (ppr (mkClassPred cls cls_tys)) <+> ptext SLIT("is not a class") @@ -531,12 +534,12 @@ sideConditions (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_typeableOK), - (dataClassKey, cond_glaExts `andCond` cond_std) + (typeableClassKey, cond_mayDeriveDataTypeable `andCond` cond_typeableOK), + (dataClassKey, cond_mayDeriveDataTypeable `andCond` cond_std) ] type Condition = (Bool, TyCon) -> Maybe SDoc - -- Bool is gla-exts flag + -- Bool is whether or not we are allowed to derive Data and Typeable -- TyCon is the *representation* tycon if the -- data type is an indexed one -- Nothing => OK @@ -555,7 +558,7 @@ andCond c1 c2 tc = case c1 tc of Just x -> Just x -- c1 fails cond_std :: Condition -cond_std (gla_exts, rep_tc) +cond_std (_, rep_tc) | any (not . isVanillaDataCon) data_cons = Just existential_why | null data_cons = Just no_cons_why | otherwise = Nothing @@ -567,7 +570,7 @@ cond_std (gla_exts, rep_tc) ptext SLIT("has non-Haskell-98 constructor(s)") cond_isEnumeration :: Condition -cond_isEnumeration (gla_exts, rep_tc) +cond_isEnumeration (_, rep_tc) | isEnumerationTyCon rep_tc = Nothing | otherwise = Just why where @@ -575,7 +578,7 @@ cond_isEnumeration (gla_exts, rep_tc) ptext SLIT("has non-nullary constructors") cond_isProduct :: Condition -cond_isProduct (gla_exts, rep_tc) +cond_isProduct (_, rep_tc) | isProductTyCon rep_tc = Nothing | otherwise = Just why where @@ -586,7 +589,7 @@ cond_typeableOK :: Condition -- OK for Typeable class -- Currently: (a) args all of kind * -- (b) 7 or fewer args -cond_typeableOK (gla_exts, rep_tc) +cond_typeableOK (_, rep_tc) | tyConArity rep_tc > 7 = Just too_many | not (all (isSubArgTypeKind . tyVarKind) (tyConTyVars rep_tc)) = Just bad_kind @@ -600,9 +603,10 @@ cond_typeableOK (gla_exts, rep_tc) fam_inst = quotes (pprSourceTyCon rep_tc) <+> ptext SLIT("is a type family") -cond_glaExts :: Condition -cond_glaExts (gla_exts, _rep_tc) | gla_exts = Nothing - | otherwise = Just why +cond_mayDeriveDataTypeable :: Condition +cond_mayDeriveDataTypeable (mayDeriveDataTypeable, _) + | mayDeriveDataTypeable = Nothing + | otherwise = Just why where why = ptext SLIT("You need -fglasgow-exts to derive an instance for this class") @@ -627,10 +631,13 @@ new_dfun_name clas tycon -- Just a simple wrapper %************************************************************************ \begin{code} -mkNewTypeEqn orig gla_exts overlap_flag tvs cls cls_tys +mkNewTypeEqn :: InstOrigin -> Bool -> Bool -> OverlapFlag -> [Var] -> Class + -> [Type] -> TyCon -> [Type] -> TyCon -> [Type] + -> TcRn (Maybe DerivEqn, Maybe InstInfo) +mkNewTypeEqn orig mayDeriveDataTypeable newtype_deriving overlap_flag tvs cls cls_tys tycon tc_args rep_tycon rep_tc_args - | can_derive_via_isomorphism && (gla_exts || std_class_via_iso cls) + | can_derive_via_isomorphism && (newtype_deriving || std_class_via_iso cls) = do { traceTc (text "newtype deriving:" <+> ppr tycon <+> ppr rep_tys) ; -- Go ahead and use the isomorphism dfun_name <- new_dfun_name cls tycon @@ -643,10 +650,10 @@ mkNewTypeEqn orig gla_exts overlap_flag tvs cls cls_tys ; return (Just eqn, Nothing) } -- Otherwise we can't derive - | gla_exts = baleOut cant_derive_err -- Too hard + | newtype_deriving = baleOut cant_derive_err -- Too hard | otherwise = baleOut std_err -- Just complain about being a non-std instance where - mb_std_err = checkSideConditions gla_exts cls cls_tys rep_tycon + 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 -fglasgow-exts for GHC's newtype-deriving extension")] -- 1.7.10.4