%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcDeriv]{Deriving}
Handles @deriving@ clauses on @data@ declarations.
\begin{code}
-#include "HsVersions.h"
-
module TcDeriv ( tcDeriving ) where
-IMP_Ubiq()
+#include "HsVersions.h"
-import HsSyn ( HsDecl, FixityDecl, Fixity, InstDecl,
- Sig, HsBinds(..), MonoBinds(..),
- GRHSsAndBinds, Match, HsExpr, HsLit, InPat,
- ArithSeqInfo, Fake, HsType,
- collectMonoBinders
- )
-import HsPragmas ( InstancePragmas(..) )
-import RdrHsSyn ( RdrName, SYN_IE(RdrNameMonoBinds) )
-import RnHsSyn ( SYN_IE(RenamedHsBinds), SYN_IE(RenamedMonoBinds), SYN_IE(RenamedFixityDecl) )
-import TcHsSyn ( TcIdOcc )
+import HsSyn ( HsBinds(..), MonoBinds(..), collectMonoBinders )
+import RdrHsSyn ( RdrNameMonoBinds )
+import RnHsSyn ( RenamedHsBinds, RenamedMonoBinds )
+import CmdLineOpts ( opt_D_dump_deriv )
import TcMonad
-import Inst ( SYN_IE(InstanceMapper) )
-import TcEnv ( getEnv_TyCons, tcLookupClassByKey )
-import SpecEnv ( SpecEnv )
-import TcKind ( TcKind )
+import Inst ( InstanceMapper )
+import TcEnv ( getEnvTyCons )
import TcGenDeriv -- Deriv stuff
-import TcInstUtil ( InstInfo(..), mkInstanceRelatedIds, buildInstanceEnvs )
+import TcInstUtil ( InstInfo(..), buildInstanceEnvs )
import TcSimplify ( tcSimplifyThetas )
import RnBinds ( rnMethodBinds, rnTopMonoBinds )
-import RnEnv ( newDfunName, bindLocatedLocalsRn )
-import RnMonad ( SYN_IE(RnM), RnDown, GDown, SDown, RnNameSupply(..),
- setNameSupplyRn, renameSourceCode, thenRn, mapRn, returnRn )
-
-import Bag ( Bag, isEmptyBag, unionBags, listToBag )
-import Class ( classKey, GenClass, SYN_IE(Class) )
-import ErrUtils ( pprBagOfErrors, addErrLoc, SYN_IE(Error) )
-import Id ( dataConArgTys, isNullaryDataCon, mkDictFunId )
+import RnEnv ( newDFunName, bindLocatedLocalsRn )
+import RnMonad ( RnNameSupply,
+ renameSourceCode, thenRn, mapRn, returnRn )
+
+import Bag ( Bag, emptyBag, unionBags, listToBag )
+import Class ( classKey, Class )
+import ErrUtils ( dumpIfSet, Message, pprBagOfErrors )
+import MkId ( mkDictFunId )
+import Id ( mkVanillaId )
+import DataCon ( dataConArgTys, isNullaryDataCon, isExistentialDataCon )
import PrelInfo ( needsDataDeclCtxtClassKeys )
-import Maybes ( maybeToBool )
-import Name ( isLocallyDefined, getSrcLoc, ExportFlag(..), Provenance,
- Name{--O only-}, SYN_IE(Module)
+import Maybes ( maybeToBool, catMaybes )
+import Module ( ModuleName )
+import Name ( isLocallyDefined, getSrcLoc,
+ Name, NamedThing(..),
+ OccName, nameOccName
)
-import Outputable ( PprStyle(..), Outputable(..){-instances e.g., (,)-} )
-import PprType ( GenType, GenTyVar, GenClass, TyCon )
-import Pretty ( ($$), vcat, hsep, hcat,
- ptext, text, char, hang, Doc )
+import RdrName ( RdrName )
+import RnMonad ( Fixities )
import SrcLoc ( mkGeneratedSrcLoc, SrcLoc )
import TyCon ( tyConTyVars, tyConDataCons, tyConDerivings,
- tyConTheta, maybeTyConSingleCon,
+ tyConTheta, maybeTyConSingleCon, isDataTyCon,
isEnumerationTyCon, isAlgTyCon, TyCon
)
-import Type ( GenType(..), SYN_IE(TauType), mkTyVarTys, applyTyCon,
- mkSigmaTy, mkDictTy, isPrimType, instantiateTy,
- getAppDataTyCon, getAppTyCon
+import Type ( TauType, mkTyVarTys, mkTyConApp,
+ mkSigmaTy, mkDictTy, isUnboxedType,
+ splitAlgTyConApp, classesToPreds
)
-import TysPrim ( voidTy )
-import TyVar ( GenTyVar, SYN_IE(TyVar) )
-import UniqFM ( emptyUFM )
+import TysWiredIn ( voidTy )
+import Var ( TyVar )
import Unique -- Keys stuff
import Bag ( bagToList )
-import Util ( zipWithEqual, zipEqual, sortLt, removeDups, assoc,
- thenCmp, cmpList, panic, panic#, pprPanic, pprPanic#,
- Ord3(..), assertPanic-- , pprTrace{-ToDo:rm-}
-
- )
+import Util ( zipWithEqual, sortLt, removeDups, assoc, thenCmp )
+import Outputable
\end{code}
%************************************************************************
-- NEW: it's convenient to re-use InstInfo
-- We'll "panic" out some fields...
-type DerivRhs = [(Class, TauType)] -- Same as a ThetaType!
+type DerivRhs = [(Class, [TauType])] -- Same as a ThetaType!
type DerivSoln = DerivRhs
\end{code}
%************************************************************************
\begin{code}
-tcDeriving :: Module -- name of module under scrutiny
+tcDeriving :: ModuleName -- name of module under scrutiny
+ -> Fixities -- 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".
- RenamedHsBinds, -- Extra generated bindings
- PprStyle -> Doc) -- Printable derived instance decls;
- -- for debugging via -ddump-derivings.
+ RenamedHsBinds) -- Extra generated bindings
-tcDeriving modname rn_name_supply inst_decl_infos_in
- = -- Fish the "deriving"-related information out of the TcEnv
+tcDeriving modname fixs rn_name_supply inst_decl_infos_in
+ = recoverTc (returnTc (emptyBag, EmptyBinds)) $
+
+ -- Fish the "deriving"-related information out of the TcEnv
-- and make the necessary "equations".
makeDerivEqns `thenTc` \ eqns ->
+ if null eqns then
+ returnTc (emptyBag, EmptyBinds)
+ else
-- Take the equation list and solve it, to deliver a list of
-- solutions, a.k.a. the contexts for the instance decls
let
extra_mbind_list = map gen_tag_n_con_monobind nm_alist_etc
extra_mbinds = foldr AndMonoBinds EmptyMonoBinds extra_mbind_list
- method_binds_s = map gen_bind new_inst_infos
+ method_binds_s = map (gen_bind fixs) new_inst_infos
mbinders = bagToList (collectMonoBinders extra_mbinds)
-- Rename to get RenamedBinds.
-- method bindings for the instances.
(dfun_names_w_method_binds, rn_extra_binds)
= renameSourceCode modname rn_name_supply (
- bindLocatedLocalsRn (\_ -> text "deriving") mbinders $ \ _ ->
- rnTopMonoBinds extra_mbinds [] `thenRn` \ rn_extra_binds ->
+ bindLocatedLocalsRn (ptext (SLIT("deriving"))) mbinders $ \ _ ->
+ rnTopMonoBinds extra_mbinds [] `thenRn` \ (rn_extra_binds, _) ->
mapRn rn_one method_binds_s `thenRn` \ dfun_names_w_method_binds ->
returnRn (dfun_names_w_method_binds, rn_extra_binds)
)
- rn_one meth_binds = newDfunName Nothing mkGeneratedSrcLoc `thenRn` \ dfun_name ->
- rnMethodBinds meth_binds `thenRn` \ rn_meth_binds ->
- returnRn (dfun_name, rn_meth_binds)
- in
+ rn_one (cl_nm, tycon_nm, 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 = zipWith gen_inst_info
+ new_inst_infos
+ dfun_names_w_method_binds
- mapTc (gen_inst_info modname)
- (new_inst_infos `zip` dfun_names_w_method_binds) `thenTc` \ really_new_inst_infos ->
- let
ddump_deriv = ddump_deriving really_new_inst_infos rn_extra_binds
in
- --pprTrace "derived:\n" (ddump_deriv PprDebug) $
+ ioToTc (dumpIfSet opt_D_dump_deriv "Derived instances" ddump_deriv) `thenTc_`
- returnTc (listToBag really_new_inst_infos,
- rn_extra_binds,
- ddump_deriv)
+ returnTc (listToBag really_new_inst_infos, rn_extra_binds)
where
- ddump_deriving :: [InstInfo] -> RenamedHsBinds -> (PprStyle -> Doc)
-
- ddump_deriving inst_infos extra_binds sty
- = vcat ((map pp_info inst_infos) ++ [ppr sty extra_binds])
+ ddump_deriving :: [InstInfo] -> RenamedHsBinds -> SDoc
+ ddump_deriving inst_infos extra_binds
+ = vcat (map pp_info inst_infos) $$ ppr extra_binds
where
- pp_info (InstInfo clas tvs ty inst_decl_theta _ _ mbinds _ _)
- = ($$) (ppr sty (mkSigmaTy tvs inst_decl_theta (mkDictTy clas ty)))
- (ppr sty mbinds)
+ pp_info (InstInfo clas tvs [ty] inst_decl_theta _ mbinds _ _)
+ = ppr (mkSigmaTy tvs inst_decl_theta' (mkDictTy clas [ty]))
+ $$
+ ppr mbinds
+ where inst_decl_theta' = classesToPreds inst_decl_theta
\end{code}
= tcGetEnv `thenNF_Tc` \ env ->
let
local_data_tycons = filter (\tc -> isLocallyDefined tc && isAlgTyCon tc)
- (getEnv_TyCons env)
- in
- if null local_data_tycons then
- -- Bale out now; evalClass may not be loaded if there aren't any
- returnTc []
- else
- tcLookupClassByKey evalClassKey `thenNF_Tc` \ eval_clas ->
- let
- think_about_deriving = need_deriving eval_clas local_data_tycons
+ (getEnvTyCons env)
+
+ think_about_deriving = need_deriving local_data_tycons
(derive_these, _) = removeDups cmp_deriv think_about_deriving
eqns = map mk_eqn derive_these
in
- mapTc chk_out think_about_deriving `thenTc_`
- returnTc eqns
+ if null local_data_tycons then
+ returnTc [] -- Bale out now
+ else
+ mapTc mk_eqn derive_these `thenTc` \ maybe_eqns ->
+ returnTc (catMaybes maybe_eqns)
where
------------------------------------------------------------------
- need_deriving :: Class -> [TyCon] -> [(Class, TyCon)]
+ need_deriving :: [TyCon] -> [(Class, TyCon)]
-- find the tycons that have `deriving' clauses;
- -- we handle the "every datatype in Eval" by
- -- doing a dummy "deriving" for it.
-
- need_deriving eval_clas tycons_to_consider
- = foldr ( \ tycon acc ->
- let
- acc_plus = if isLocallyDefined tycon
- then (eval_clas, tycon) : acc
- else acc
- in
- case (tyConDerivings tycon) of
- [] -> acc_plus
- cs -> [ (clas,tycon) | clas <- cs ] ++ acc_plus
- )
+
+ need_deriving tycons_to_consider
+ = foldr (\ tycon acc -> [(clas,tycon) | clas <- tyConDerivings tycon] ++ acc)
[]
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)
-
- chk_clas clas_uniq clas_str cond
- = if (clas_uniq == clas_key)
- then checkTc cond (derivingThingErr clas_str tycon)
- else returnTc ()
- in
- -- Are things OK for deriving Enum (if appropriate)?
- chk_clas enumClassKey "Enum" is_enumeration `thenTc_`
-
- -- Are things OK for deriving Bounded (if appropriate)?
- chk_clas boundedClassKey "Bounded"
- (is_enumeration || is_single_con) `thenTc_`
-
- -- Are things OK for deriving Ix (if appropriate)?
- chk_clas ixClassKey "Ix.Ix" (is_enumeration || is_single_con)
-
- ------------------------------------------------------------------
- cmp_deriv :: (Class, TyCon) -> (Class, TyCon) -> TAG_
+ cmp_deriv :: (Class, TyCon) -> (Class, TyCon) -> Ordering
cmp_deriv (c1, t1) (c2, t2)
- = (c1 `cmp` c2) `thenCmp` (t1 `cmp` 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, if_not_Eval 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 ???
tyvar_tys = mkTyVarTys tyvars
data_cons = tyConDataCons tycon
- if_not_Eval cs = if clas_key == evalClassKey then [] else cs
-
constraints = extra_constraints ++ concat (map mk_constraints data_cons)
-- "extra_constraints": see notes above about contexts on data decls
offensive_class = clas_key `elem` needsDataDeclCtxtClassKeys
mk_constraints data_con
- = [ (clas, arg_ty)
+ = [ (clas, [arg_ty])
| arg_ty <- instd_arg_tys,
- not (isPrimType arg_ty) -- No constraints for primitive types
+ not (isUnboxedType arg_ty) -- No constraints for unboxed types?
]
where
instd_arg_tys = dataConArgTys data_con tyvar_tys
+
+ ------------------------------------------------------------------
+ chk_out :: Class -> TyCon -> Maybe Message
+ chk_out clas tycon
+ | clas_key == enumClassKey && not is_enumeration = bog_out nullary_why
+ | clas_key == boundedClassKey && not is_enumeration_or_single = bog_out single_nullary_why
+ | clas_key == ixClassKey && not is_enumeration_or_single = bog_out single_nullary_why
+ | any isExistentialDataCon (tyConDataCons tycon) = Just (existentialErr clas tycon)
+ | otherwise = Nothing
+ where
+ clas_key = classKey clas
+
+ 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}
%************************************************************************
initial_solutions :: [DerivSoln]
initial_solutions = [ [] | _ <- orig_eqns ]
+ ------------------------------------------------------------------
-- iterateDeriv calculates the next batch of solutions,
-- compares it with the current one; finishes if they are the
-- same, otherwise recurses with the new solutions.
-
+ -- It fails if any iteration fails
iterateDeriv :: [DerivSoln] ->TcM s [InstInfo]
-
iterateDeriv current_solns
+ = checkNoErrsTc (iterateOnce current_solns) `thenTc` \ (new_inst_infos, new_solns) ->
+ if (current_solns == new_solns) then
+ returnTc new_inst_infos
+ else
+ iterateDeriv new_solns
+
+ ------------------------------------------------------------------
+ iterateOnce current_solns
= -- Extend the inst info from the explicit instance decls
-- with the current set of solutions, giving a
add_solns inst_decl_infos_in orig_eqns current_solns
- `thenTc` \ (new_inst_infos, inst_mapper) ->
+ `thenNF_Tc` \ (new_inst_infos, inst_mapper) ->
let
- class_to_inst_env cls = fst (inst_mapper cls)
+ class_to_inst_env cls = inst_mapper cls
in
-- Simplify each RHS
- listTc [ tcSimplifyThetas class_to_inst_env [{-Nothing "given"-}] deriv_rhs
- | (_,_,_,deriv_rhs) <- orig_eqns ] `thenTc` \ next_solns ->
+ listTc [ tcAddErrCtxt (derivCtxt tc) $
+ tcSimplifyThetas class_to_inst_env deriv_rhs
+ | (_,tc,_,deriv_rhs) <- orig_eqns ] `thenTc` \ next_solns ->
-- Canonicalise the solutions, so they compare nicely
let canonicalised_next_solns
- = [ sortLt lt_rhs next_soln | next_soln <- next_solns ] in
-
- if (current_solns `eq_solns` canonicalised_next_solns) then
- returnTc new_inst_infos
- else
- iterateDeriv canonicalised_next_solns
-
- where
- ------------------------------------------------------------------
- lt_rhs r1 r2 = case cmp_rhs r1 r2 of { LT_ -> True; _ -> False }
- eq_solns s1 s2 = case cmp_solns s1 s2 of { EQ_ -> True; _ -> False }
- cmp_solns s1 s2 = cmpList (cmpList cmp_rhs) s1 s2
- cmp_rhs (c1, TyVarTy tv1) (c2, TyVarTy tv2)
- = (tv1 `cmp` tv2) `thenCmp` (c1 `cmp` c2)
-#ifdef DEBUG
- cmp_rhs other_1 other_2
- = panic# "tcDeriv:cmp_rhs:" --(hsep [ppr PprDebug other_1, ppr PprDebug other_2])
-#endif
-
+ = [ sortLt (<) next_soln | next_soln <- next_solns ]
+ in
+ returnTc (new_inst_infos, canonicalised_next_solns)
\end{code}
\begin{code}
add_solns :: Bag InstInfo -- The global, non-derived ones
-> [DerivEqn] -> [DerivSoln]
- -> TcM s ([InstInfo], -- The new, derived ones
- InstanceMapper)
+ -> NF_TcM s ([InstInfo], -- The new, derived ones
+ InstanceMapper)
-- the eqns and solns move "in lockstep"; we have the eqns
-- because we need the LHS info for addClassInstance.
add_solns inst_infos_in eqns solns
- = buildInstanceEnvs all_inst_infos `thenTc` \ inst_mapper ->
- returnTc (new_inst_infos, inst_mapper)
+
+ = discardErrsTc (buildInstanceEnvs all_inst_infos) `thenNF_Tc` \ inst_mapper ->
+ -- We do the discard-errs so that we don't get repeated error messages
+ -- about duplicate instances.
+ -- They'll appear later, when we do the top-level buildInstanceEnvs.
+
+ returnNF_Tc (new_inst_infos, inst_mapper)
where
new_inst_infos = zipWithEqual "add_solns" mk_deriv_inst_info eqns solns
all_inst_infos = inst_infos_in `unionBags` listToBag new_inst_infos
mk_deriv_inst_info (clas, tycon, tyvars, _) theta
- = InstInfo clas tyvars (applyTyCon tycon (mkTyVarTys tyvars))
+ = InstInfo clas tyvars [mkTyConApp tycon (mkTyVarTys tyvars)]
theta
- (my_panic "dfun_theta")
-
dummy_dfun_id
-
(my_panic "binds") (getSrcLoc tycon)
(my_panic "upragmas")
where
dummy_dfun_id
- = mkDictFunId bottom dummy_dfun_ty bottom bottom
- where
- bottom = panic "dummy_dfun_id"
+ = 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,
-- We can't leave it as a panic because to get the theta part we
-- have to run down the type!
- my_panic str = panic "add_soln" -- pprPanic ("add_soln:"++str) (hsep [char ':', ppr PprDebug clas, ppr PprDebug tycon])
+ my_panic str = panic "add_soln" -- pprPanic ("add_soln:"++str) (hsep [char ':', ppr clas, ppr tycon])
\end{code}
%************************************************************************
\begin{code}
-- Generate the method bindings for the required instance
-gen_bind :: InstInfo -> RdrNameMonoBinds
-gen_bind (InstInfo clas _ ty _ _ _ _ _ _)
+-- (paired with class name, as we need that when generating dict
+-- names.)
+gen_bind :: Fixities -> InstInfo -> ({-class-}OccName, {-tyCon-}OccName, RdrNameMonoBinds)
+gen_bind fixities (InstInfo clas _ [ty] _ _ _ _ _)
| not from_here
- = EmptyMonoBinds
+ = (clas_nm, tycon_nm, EmptyMonoBinds)
+ | ckey == showClassKey
+ = (clas_nm, tycon_nm, gen_Show_binds fixities tycon)
+ | ckey == readClassKey
+ = (clas_nm, tycon_nm, gen_Read_binds fixities tycon)
| otherwise
- = assoc "gen_inst_info:bad derived class"
- [(eqClassKey, gen_Eq_binds)
- ,(ordClassKey, gen_Ord_binds)
- ,(enumClassKey, gen_Enum_binds)
- ,(evalClassKey, gen_Eval_binds)
- ,(boundedClassKey, gen_Bounded_binds)
- ,(showClassKey, gen_Show_binds)
- ,(readClassKey, gen_Read_binds)
- ,(ixClassKey, gen_Ix_binds)
- ]
- (classKey clas)
- tycon
+ = (clas_nm, tycon_nm,
+ assoc "gen_bind:bad derived class"
+ [(eqClassKey, gen_Eq_binds)
+ ,(ordClassKey, gen_Ord_binds)
+ ,(enumClassKey, gen_Enum_binds)
+ ,(boundedClassKey, gen_Bounded_binds)
+ ,(ixClassKey, gen_Ix_binds)
+ ]
+ ckey
+ tycon)
where
+ clas_nm = nameOccName (getName clas)
+ tycon_nm = nameOccName (getName tycon)
from_here = isLocallyDefined tycon
- (tycon,_,_) = getAppDataTyCon ty
+ (tycon,_,_) = splitAlgTyConApp ty
+ ckey = classKey clas
-gen_inst_info :: Module -- Module name
- -> (InstInfo, (Name, RenamedMonoBinds)) -- the main stuff to work on
- -> TcM s InstInfo -- the gen'd (filled-in) "instance decl"
+gen_inst_info :: InstInfo
+ -> (Name, RenamedMonoBinds)
+ -> InstInfo -- the gen'd (filled-in) "instance decl"
-gen_inst_info modname
- (InstInfo clas tyvars 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
- mkInstanceRelatedIds
- dfun_name
- clas tyvars ty
- inst_decl_theta
- `thenNF_Tc` \ (dfun_id, dfun_theta) ->
-
- returnTc (InstInfo clas tyvars ty inst_decl_theta
- dfun_theta dfun_id
- meth_binds
- locn [])
+ InstInfo clas tyvars tys inst_decl_theta
+ dfun_id
+ meth_binds
+ locn []
where
- from_here = isLocallyDefined tycon
- (tycon,_,_) = getAppDataTyCon ty
+ dfun_id = mkDictFunId dfun_name clas tyvars tys inst_decl_theta
+
+ from_here = isLocallyDefined tycon
+ (tycon,_,_) = splitAlgTyConApp ty
\end{code}
TagThingWanted)]
gen_taggery_Names inst_infos
- = --pprTrace "gen_taggery:\n" (vcat [hsep [ppr PprDebug c, ppr PprDebug t] | (c,t) <- all_CTs]) $
+ = --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_tag2con names_so_far tycons_of_interest
where
- all_CTs = [ mk_CT c ty | (InstInfo c _ ty _ _ _ _ _ _) <- inst_infos ]
+ all_CTs = [ (c, get_tycon ty) | (InstInfo c _ [ty] _ _ _ _ _) <- inst_infos ]
- mk_CT c ty = (c, fst (getAppTyCon ty))
+ get_tycon ty = case splitAlgTyConApp ty of { (tc, _, _) -> tc }
all_tycons = map snd all_CTs
- (tycons_of_interest, _) = removeDups cmp all_tycons
+ (tycons_of_interest, _) = removeDups compare all_tycons
do_con2tag acc_Names tycon
- = if (we_are_deriving eqClassKey tycon
+ | isDataTyCon tycon &&
+ ((we_are_deriving eqClassKey tycon
&& any isNullaryDataCon (tyConDataCons tycon))
- || (we_are_deriving ordClassKey tycon
+ || (we_are_deriving ordClassKey tycon
&& not (maybeToBool (maybeTyConSingleCon tycon)))
- || (we_are_deriving enumClassKey tycon)
- || (we_are_deriving ixClassKey tycon)
- then
- returnTc ((con2tag_RDR tycon, tycon, GenCon2Tag)
+ || (we_are_deriving enumClassKey tycon)
+ || (we_are_deriving ixClassKey tycon))
+
+ = returnTc ((con2tag_RDR tycon, tycon, GenCon2Tag)
: acc_Names)
- else
- returnTc acc_Names
+ | otherwise
+ = returnTc acc_Names
do_tag2con acc_Names tycon
- = if (we_are_deriving enumClassKey tycon)
- || (we_are_deriving ixClassKey tycon)
- then
- returnTc ( (tag2con_RDR tycon, tycon, GenTag2Con)
- : (maxtag_RDR tycon, tycon, GenMaxTag)
- : acc_Names)
- else
- returnTc acc_Names
+ | isDataTyCon tycon &&
+ (we_are_deriving enumClassKey tycon ||
+ we_are_deriving ixClassKey tycon
+ && isEnumerationTyCon tycon)
+ = returnTc ( (tag2con_RDR tycon, tycon, GenTag2Con)
+ : (maxtag_RDR tycon, tycon, GenMaxTag)
+ : acc_Names)
+ | otherwise
+ = returnTc acc_Names
we_are_deriving clas_key tycon
= is_in_eqns clas_key tycon all_CTs
\end{code}
\begin{code}
-derivingThingErr :: String -> TyCon -> Error
+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)]
+
+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)")]
-derivingThingErr thing tycon sty
- = hang (hsep [ptext SLIT("Can't make a derived instance of"), text thing])
- 4 (hsep [ptext SLIT("for the type"), ppr sty tycon])
+derivCtxt tycon
+ = ptext SLIT("When deriving classes for") <+> quotes (ppr tycon)
\end{code}
projects / ghc-hetmet.git / blobdiff