import Bag ( Bag, emptyBag, unionBags, listToBag )
import Class ( classKey, Class )
-import ErrUtils ( dumpIfSet, Message )
+import ErrUtils ( dumpIfSet, Message, pprBagOfErrors )
import MkId ( mkDictFunId )
import Id ( mkVanillaId )
-import DataCon ( dataConArgTys, isNullaryDataCon )
+import DataCon ( dataConArgTys, isNullaryDataCon, isExistentialDataCon )
import PrelInfo ( needsDataDeclCtxtClassKeys )
-import Maybes ( maybeToBool )
-import Module ( Module )
+import Maybes ( maybeToBool, catMaybes )
+import Module ( ModuleName )
import Name ( isLocallyDefined, getSrcLoc,
Name, NamedThing(..),
OccName, nameOccName
)
import RdrName ( RdrName )
-import RnMonad ( Fixities )
+import RnMonad ( FixityEnv )
import SrcLoc ( mkGeneratedSrcLoc, SrcLoc )
import TyCon ( tyConTyVars, tyConDataCons, tyConDerivings,
tyConTheta, maybeTyConSingleCon, isDataTyCon,
)
import Type ( TauType, mkTyVarTys, mkTyConApp,
mkSigmaTy, mkDictTy, isUnboxedType,
- splitAlgTyConApp
+ splitAlgTyConApp, classesToPreds
)
+import PprType ( {- instance Outputable Type -} )
import TysWiredIn ( voidTy )
import Var ( TyVar )
import Unique -- Keys stuff
%************************************************************************
\begin{code}
-tcDeriving :: Module -- name of module under scrutiny
- -> Fixities -- for the deriving code (Show/Read.)
+tcDeriving :: ModuleName -- name of module under scrutiny
+ -> FixityEnv -- for the deriving code (Show/Read.)
-> RnNameSupply -- for "renaming" bits of generated code
-> Bag InstInfo -- What we already know about instances
-> TcM s (Bag InstInfo, -- The generated "instance decls".
-- Now augment the InstInfos, adding in the rather boring
-- actual-code-to-do-the-methods binds. We may also need to
-- generate extra not-one-inst-decl-specific binds, notably
- -- the "con2tag" function. We do these
+ -- "con2tag" and/or "tag2con" functions. We do these
-- separately.
gen_taggery_Names new_inst_infos `thenTc` \ nm_alist_etc ->
returnRn (dfun_names_w_method_binds, rn_extra_binds)
)
rn_one (cl_nm, tycon_nm, meth_binds)
- = newDFunName cl_nm tycon_nm
- Nothing mkGeneratedSrcLoc `thenRn` \ dfun_name ->
- rnMethodBinds meth_binds `thenRn` \ (rn_meth_binds, _) ->
+ = newDFunName (cl_nm, tycon_nm)
+ mkGeneratedSrcLoc `thenRn` \ dfun_name ->
+ rnMethodBinds meth_binds `thenRn` \ (rn_meth_binds, _) ->
returnRn (dfun_name, rn_meth_binds)
- really_new_inst_infos = map (gen_inst_info modname)
- (new_inst_infos `zip` dfun_names_w_method_binds)
+ really_new_inst_infos = zipWith gen_inst_info
+ new_inst_infos
+ dfun_names_w_method_binds
ddump_deriv = ddump_deriving really_new_inst_infos rn_extra_binds
in
= vcat (map pp_info inst_infos) $$ ppr extra_binds
where
pp_info (InstInfo clas tvs [ty] inst_decl_theta _ mbinds _ _)
- = ppr (mkSigmaTy tvs inst_decl_theta (mkDictTy clas [ty]))
+ = ppr (mkSigmaTy tvs inst_decl_theta' (mkDictTy clas [ty]))
$$
ppr mbinds
+ where inst_decl_theta' = classesToPreds inst_decl_theta
\end{code}
if null local_data_tycons then
returnTc [] -- Bale out now
else
- mapTc chk_out think_about_deriving `thenTc_`
- returnTc eqns
+ mapTc mk_eqn derive_these `thenTc` \ maybe_eqns ->
+ returnTc (catMaybes maybe_eqns)
where
------------------------------------------------------------------
need_deriving :: [TyCon] -> [(Class, TyCon)]
tycons_to_consider
------------------------------------------------------------------
- chk_out :: (Class, TyCon) -> TcM s ()
- chk_out this_one@(clas, tycon)
- = let
- clas_key = classKey clas
-
- is_enumeration = isEnumerationTyCon tycon
- is_single_con = maybeToBool (maybeTyConSingleCon tycon)
-
- single_nullary_why = SLIT("one constructor data type or type with all nullary constructors expected")
- nullary_why = SLIT("data type with all nullary constructors expected")
-
- chk_clas clas_uniq clas_str clas_why cond
- = if (clas_uniq == clas_key)
- then checkTc cond (derivingThingErr clas_str clas_why tycon)
- else returnTc ()
- in
- -- Are things OK for deriving Enum (if appropriate)?
- chk_clas enumClassKey (SLIT("Enum")) nullary_why is_enumeration `thenTc_`
-
- -- Are things OK for deriving Bounded (if appropriate)?
- chk_clas boundedClassKey (SLIT("Bounded")) single_nullary_why
- (is_enumeration || is_single_con) `thenTc_`
-
- -- Are things OK for deriving Ix (if appropriate)?
- chk_clas ixClassKey (SLIT("Ix.Ix")) single_nullary_why
- (is_enumeration || is_single_con)
-
- ------------------------------------------------------------------
cmp_deriv :: (Class, TyCon) -> (Class, TyCon) -> Ordering
cmp_deriv (c1, t1) (c2, t2)
= (c1 `compare` c2) `thenCmp` (t1 `compare` t2)
------------------------------------------------------------------
- mk_eqn :: (Class, TyCon) -> DerivEqn
+ mk_eqn :: (Class, TyCon) -> NF_TcM s (Maybe DerivEqn)
-- we swizzle the tyvars and datacons out of the tycon
-- to make the rest of the equation
mk_eqn (clas, tycon)
- = (clas, tycon, tyvars, constraints)
+ = case chk_out clas tycon of
+ Just err -> addErrTc err `thenNF_Tc_`
+ returnNF_Tc Nothing
+ Nothing -> returnNF_Tc (Just (clas, tycon, tyvars, constraints))
where
clas_key = classKey clas
tyvars = tyConTyVars tycon -- ToDo: Do we need new tyvars ???
]
where
instd_arg_tys = dataConArgTys data_con tyvar_tys
+
+ ------------------------------------------------------------------
+ chk_out :: Class -> TyCon -> Maybe Message
+ chk_out clas tycon
+ | clas `hasKey` enumClassKey && not is_enumeration = bog_out nullary_why
+ | clas `hasKey` boundedClassKey && not is_enumeration_or_single = bog_out single_nullary_why
+ | clas `hasKey` ixClassKey && not is_enumeration_or_single = bog_out single_nullary_why
+ | any isExistentialDataCon (tyConDataCons tycon) = Just (existentialErr clas tycon)
+ | otherwise = Nothing
+ where
+ is_enumeration = isEnumerationTyCon tycon
+ is_single_con = maybeToBool (maybeTyConSingleCon tycon)
+ is_enumeration_or_single = is_enumeration || is_single_con
+
+ single_nullary_why = SLIT("one constructor data type or type with all nullary constructors expected")
+ nullary_why = SLIT("data type with all nullary constructors expected")
+
+ bog_out why = Just (derivingThingErr clas tycon why)
\end{code}
%************************************************************************
= mkVanillaId (getName tycon) dummy_dfun_ty
-- The name is getSrcLoc'd in an error message
- dummy_dfun_ty = mkSigmaTy tyvars theta voidTy
+ theta' = classesToPreds theta
+ dummy_dfun_ty = mkSigmaTy tyvars theta' voidTy
-- All we need from the dfun is its "theta" part, used during
-- equation simplification (tcSimplifyThetas). The final
-- dfun_id will have the superclass dictionaries as arguments too,
clearer.
\item
+Much less often (really just for deriving @Ix@), we use a
+@_tag2con_<tycon>@ function. See the examples.
+
+\item
We use the renamer!!! Reason: we're supposed to be
producing @RenamedMonoBinds@ for the methods, but that means
producing correctly-uniquified code on the fly. This is entirely
-- Generate the method bindings for the required instance
-- (paired with class name, as we need that when generating dict
-- names.)
-gen_bind :: Fixities -> InstInfo -> ({-class-}OccName, {-tyCon-}OccName, RdrNameMonoBinds)
+gen_bind :: FixityEnv -> InstInfo -> ({-class-}OccName, {-tyCon-}OccName, RdrNameMonoBinds)
gen_bind fixities (InstInfo clas _ [ty] _ _ _ _ _)
| not from_here
= (clas_nm, tycon_nm, EmptyMonoBinds)
- | ckey == showClassKey
+ | clas `hasKey` showClassKey
= (clas_nm, tycon_nm, gen_Show_binds fixities tycon)
- | ckey == readClassKey
+ | clas `hasKey` readClassKey
= (clas_nm, tycon_nm, gen_Read_binds fixities tycon)
| otherwise
= (clas_nm, tycon_nm,
,(boundedClassKey, gen_Bounded_binds)
,(ixClassKey, gen_Ix_binds)
]
- ckey
+ (classKey clas)
tycon)
where
clas_nm = nameOccName (getName clas)
tycon_nm = nameOccName (getName tycon)
from_here = isLocallyDefined tycon
(tycon,_,_) = splitAlgTyConApp ty
- ckey = classKey clas
-
-gen_inst_info :: Module -- Module name
- -> (InstInfo, (Name, RenamedMonoBinds)) -- the main stuff to work on
+gen_inst_info :: InstInfo
+ -> (Name, RenamedMonoBinds)
-> InstInfo -- the gen'd (filled-in) "instance decl"
-gen_inst_info modname
- (InstInfo clas tyvars tys@(ty:_) inst_decl_theta _ _ locn _, (dfun_name, meth_binds))
+gen_inst_info (InstInfo clas tyvars tys@(ty:_) inst_decl_theta _ _ locn _)
+ (dfun_name, meth_binds)
=
-- Generate the various instance-related Ids
InstInfo clas tyvars tys inst_decl_theta
%************************************************************************
%* *
-\subsection[TcDeriv-taggery-Names]{What con2tag functions are available?}
+\subsection[TcDeriv-taggery-Names]{What con2tag/tag2con functions are available?}
%* *
%************************************************************************
data Foo ... = ...
con2tag_Foo :: Foo ... -> Int#
+tag2con_Foo :: Int -> Foo ... -- easier if Int, not Int#
maxtag_Foo :: Int -- ditto (NB: not unboxed)
(enum type only????)
\end{itemize}
+We have a @tag2con@ function for a tycon if:
+\begin{itemize}
+\item
+We're deriving @Enum@, or @Ix@ (enum type only???)
+\end{itemize}
+
+If we have a @tag2con@ function, we also generate a @maxtag@ constant.
+
\begin{code}
gen_taggery_Names :: [InstInfo]
-> TcM s [(RdrName, -- for an assoc list
gen_taggery_Names inst_infos
= --pprTrace "gen_taggery:\n" (vcat [hsep [ppr c, ppr t] | (c,t) <- all_CTs]) $
foldlTc do_con2tag [] tycons_of_interest `thenTc` \ names_so_far ->
- foldlTc do_maxtag names_so_far tycons_of_interest
+ foldlTc do_tag2con names_so_far tycons_of_interest
where
all_CTs = [ (c, get_tycon ty) | (InstInfo c _ [ty] _ _ _ _ _) <- inst_infos ]
| otherwise
= returnTc acc_Names
- do_maxtag acc_Names tycon
+ do_tag2con acc_Names tycon
| isDataTyCon tycon &&
(we_are_deriving enumClassKey tycon ||
- we_are_deriving ixClassKey tycon)
- = returnTc ( (maxtag_RDR tycon, tycon, GenMaxTag)
+ we_are_deriving ixClassKey tycon
+ && isEnumerationTyCon tycon)
+ = returnTc ( (tag2con_RDR tycon, tycon, GenTag2Con)
+ : (maxtag_RDR tycon, tycon, GenMaxTag)
: acc_Names)
| otherwise
= returnTc acc_Names
\end{code}
\begin{code}
-derivingThingErr :: FAST_STRING -> FAST_STRING -> TyCon -> Message
+derivingThingErr :: Class -> TyCon -> FAST_STRING -> Message
+
+derivingThingErr clas tycon why
+ = sep [hsep [ptext SLIT("Can't make a derived instance of"), quotes (ppr clas)],
+ hsep [ptext SLIT("for the type"), quotes (ppr tycon)],
+ parens (ptext why)]
-derivingThingErr thing why tycon
- = hang (hsep [ptext SLIT("Can't make a derived instance of"), ptext thing])
- 0 (hang (hsep [ptext SLIT("for the type"), quotes (ppr tycon)])
- 0 (parens (ptext why)))
+existentialErr clas tycon
+ = sep [ptext SLIT("Can't derive any instances for type") <+> quotes (ppr tycon),
+ ptext SLIT("because it has existentially-quantified constructor(s)")]
derivCtxt tycon
= ptext SLIT("When deriving classes for") <+> quotes (ppr tycon)
projects / ghc-hetmet.git / blobdiff