%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1994
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
%
\section[TcDeriv]{Deriving}
Handles @deriving@ clauses on @data@ declarations.
\begin{code}
-#include "HsVersions.h"
-
module TcDeriv ( tcDeriving ) where
-import Ubiq
+#include "HsVersions.h"
-import HsSyn ( FixityDecl, Sig, HsBinds(..), Bind(..), MonoBinds(..),
- GRHSsAndBinds, Match, HsExpr, HsLit, InPat,
- ArithSeqInfo, Fake, MonoType )
-import HsPragmas ( InstancePragmas(..) )
-import RnHsSyn ( RenamedHsBinds(..), RenamedFixityDecl(..) )
-import TcHsSyn ( TcIdOcc )
+import HsSyn ( HsBinds(..), MonoBinds(..), collectMonoBinders )
+import RdrHsSyn ( RdrName, RdrNameMonoBinds )
+import RnHsSyn ( RenamedHsBinds, RenamedMonoBinds )
-import TcMonad hiding ( rnMtoTcM )
-import Inst ( InstOrigin(..), InstanceMapper(..) )
-import TcEnv ( getEnv_TyCons )
+import TcMonad
+import Inst ( InstanceMapper )
+import TcEnv ( getEnv_TyCons, tcLookupClassByKey )
import TcKind ( TcKind )
---import TcGenDeriv -- Deriv stuff
+import TcGenDeriv -- Deriv stuff
import TcInstUtil ( InstInfo(..), mkInstanceRelatedIds, buildInstanceEnvs )
import TcSimplify ( tcSimplifyThetas )
-import RnMonad
-import RnUtils ( RnEnv(..) )
-import RnBinds ( rnMethodBinds, rnTopBinds )
-
-import Bag ( emptyBag{-ToDo:rm-}, Bag, isEmptyBag, unionBags, listToBag )
-import Class ( GenClass, classKey )
-import CmdLineOpts ( opt_CompilingPrelude )
-import ErrUtils ( pprBagOfErrors, addErrLoc, Error(..) )
-import Id ( dataConSig, dataConArity )
-import Maybes ( assocMaybe, maybeToBool, Maybe(..) )
-import Outputable
-import PprType ( GenType, GenTyVar, GenClass, TyCon )
-import PprStyle
-import Pretty
-import SrcLoc ( mkGeneratedSrcLoc, mkUnknownSrcLoc, SrcLoc )
+import RnBinds ( rnMethodBinds, rnTopMonoBinds )
+import RnEnv ( newDfunName, bindLocatedLocalsRn )
+import RnMonad ( RnM, RnDown, SDown, RnNameSupply(..),
+ renameSourceCode, thenRn, mapRn, returnRn )
+
+import Bag ( Bag, emptyBag, unionBags, listToBag )
+import Class ( classKey, Class )
+import ErrUtils ( ErrMsg )
+import MkId ( mkDictFunId )
+import Id ( dataConArgTys, isNullaryDataCon )
+import PrelInfo ( needsDataDeclCtxtClassKeys )
+import Maybes ( maybeToBool )
+import Name ( isLocallyDefined, getSrcLoc, Provenance,
+ Name{--O only-}, Module, NamedThing(..),
+ OccName, nameOccName
+ )
+import SrcLoc ( mkGeneratedSrcLoc, SrcLoc )
import TyCon ( tyConTyVars, tyConDataCons, tyConDerivings,
- maybeTyConSingleCon, isEnumerationTyCon, TyCon )
-import Type ( GenType(..), TauType(..), mkTyVarTys, applyTyCon,
- mkSigmaTy, mkDictTy, isPrimType, instantiateTy,
- getAppTyCon, getAppDataTyCon
+ tyConTheta, maybeTyConSingleCon, isDataTyCon,
+ isEnumerationTyCon, isAlgTyCon, TyCon
)
-import TyVar ( GenTyVar )
-import UniqFM ( emptyUFM )
-import Unique -- Keys stuff
-import Util ( zipWithEqual, zipEqual, sortLt, removeDups,
- thenCmp, cmpList, panic, pprPanic, pprPanic#
+import Type ( GenType(..), TauType, mkTyVarTys, mkTyConApp,
+ mkSigmaTy, mkDictTy, isUnboxedType,
+ splitAlgTyConApp
)
+import TysPrim ( voidTy )
+import TyVar ( GenTyVar, TyVar )
+import Unique -- Keys stuff
+import Bag ( bagToList )
+import Util ( zipWithEqual, sortLt, removeDups, assoc, thenCmp )
+import Outputable
\end{code}
%************************************************************************
| C3 (T a a)
deriving (Eq)
+[NOTE: See end of these comments for what to do with
+ data (C a, D b) => T a b = ...
+]
+
We want to come up with an instance declaration of the form
instance (Ping a, Pong b, ...) => Eq (T a b) where
-- 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}
+
+A note about contexts on data decls
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Consider
+
+ data (RealFloat a) => Complex a = !a :+ !a deriving( Read )
+
+We will need an instance decl like:
+
+ instance (Read a, RealFloat a) => Read (Complex a) where
+ ...
+
+The RealFloat in the context is because the read method for Complex is bound
+to construct a Complex, and doing that requires that the argument type is
+in RealFloat.
+
+But this ain't true for Show, Eq, Ord, etc, since they don't construct
+a Complex; they only take them apart.
+
+Our approach: identify the offending classes, and add the data type
+context to the instance decl. The "offending classes" are
+
+ Read, Enum?
+
+
%************************************************************************
%* *
\subsection[TcDeriv-driver]{Top-level function for \tr{derivings}}
\begin{code}
tcDeriving :: Module -- name of module under scrutiny
- -> RnEnv -- for "renaming" bits of generated code
+ -> RnNameSupply -- for "renaming" bits of generated code
-> Bag InstInfo -- What we already know about instances
- -> [RenamedFixityDecl] -- Fixity info; used by Read and Show
-> TcM s (Bag InstInfo, -- The generated "instance decls".
RenamedHsBinds, -- Extra generated bindings
- PprStyle -> Pretty) -- Printable derived instance decls;
+ SDoc) -- Printable derived instance decls;
-- for debugging via -ddump-derivings.
-tcDeriving modname rn_env inst_decl_infos_in fixities
- = returnTc (trace "tcDeriving:ToDo" (emptyBag, EmptyBinds, \ x -> ppNil))
-{- LATER:
+tcDeriving modname rn_name_supply inst_decl_infos_in
+ = recoverTc (returnTc (emptyBag, EmptyBinds, empty)) $
-tcDeriving modname rn_env inst_decl_infos_in fixities
- = -- Fish the "deriving"-related information out of the TcEnv
+ -- Fish the "deriving"-related information out of the TcEnv
-- and make the necessary "equations".
- makeDerivEqns `thenTc` \ eqns ->
+ makeDerivEqns `thenTc` \ eqns ->
+ if null eqns then
+ returnTc (emptyBag, EmptyBinds, text "No derivings")
+ else
-- Take the equation list and solve it, to deliver a list of
-- solutions, a.k.a. the contexts for the instance decls
-- required for the corresponding equations.
- solveDerivEqns inst_decl_infos_in eqns
- `thenTc` \ new_inst_infos ->
+ solveDerivEqns inst_decl_infos_in eqns `thenTc` \ new_inst_infos ->
-- Now augment the InstInfos, adding in the rather boring
-- actual-code-to-do-the-methods binds. We may also need to
-- "con2tag" and/or "tag2con" functions. We do these
-- separately.
- gen_taggery_Names eqns `thenTc` \ nm_alist_etc ->
- let
- nm_alist = [ (pn, n) | (pn,n,_,_) <- nm_alist_etc ]
-
- -- We have the renamer's final "name funs" in our hands
- -- (they were passed in). So we can handle ProtoNames
- -- that refer to anything "out there". But our generated
- -- code may also mention "con2tag" (etc.). So we need
- -- to augment to "name funs" to include those.
- (rn_val_gnf, rn_tc_gnf) = renamer_name_funs
-
- deriv_val_gnf pname = case (assoc_maybe nm_alist pname) of
- Just xx -> Just xx
- Nothing -> rn_val_gnf pname
+ gen_taggery_Names new_inst_infos `thenTc` \ nm_alist_etc ->
- deriver_name_funs = (deriv_val_gnf, rn_tc_gnf)
- assoc_maybe [] _ = Nothing
- assoc_maybe ((k,v) : vs) key
- = if k `eqProtoName` key then Just v else assoc_maybe vs key
+ 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
+ mbinders = bagToList (collectMonoBinders extra_mbinds)
+
+ -- Rename to get RenamedBinds.
+ -- The only tricky bit is that the extra_binds must scope over the
+ -- method bindings for the instances.
+ (dfun_names_w_method_binds, rn_extra_binds)
+ = renameSourceCode modname rn_name_supply (
+ 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 (cl_nm, tycon_nm, meth_binds)
+ = newDfunName cl_nm tycon_nm
+ Nothing 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)
+
+ ddump_deriv = ddump_deriving really_new_inst_infos rn_extra_binds
in
- gen_tag_n_con_binds deriver_rn_env nm_alist_etc `thenTc` \ extra_binds ->
-
- mapTc (gen_inst_info maybe_mod fixities deriver_rn_env) new_inst_infos
- `thenTc` \ really_new_inst_infos ->
+ --pprTrace "derived:\n" (ddump_deriv) $
returnTc (listToBag really_new_inst_infos,
- extra_binds,
- ddump_deriving really_new_inst_infos extra_binds)
+ rn_extra_binds,
+ ddump_deriv)
where
- maybe_mod = if opt_CompilingPrelude then Nothing else Just mod_name
-
- ddump_deriving :: [InstInfo] -> RenamedHsBinds -> (PprStyle -> Pretty)
+ ddump_deriving :: [InstInfo] -> RenamedHsBinds -> SDoc
- ddump_deriving inst_infos extra_binds sty
- = ppAboves ((map pp_info inst_infos) ++ [ppr sty extra_binds])
+ 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 _ _ _ _)
- = ppAbove (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)
\end{code}
makeDerivEqns :: TcM s [DerivEqn]
makeDerivEqns
- = tcGetEnv `thenNF_Tc` \ env ->
+ = tcGetEnv `thenNF_Tc` \ env ->
let
- tycons = getEnv_TyCons env
- think_about_deriving = need_deriving tycons
+ local_data_tycons = filter (\tc -> isLocallyDefined tc && isAlgTyCon tc)
+ (getEnv_TyCons env)
in
- mapTc (chk_out think_about_deriving) think_about_deriving `thenTc_`
+ 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
- (derive_these, _) = removeDups cmp_deriv think_about_deriving
- eqns = map mk_eqn derive_these
+ think_about_deriving = need_deriving eval_clas 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
where
------------------------------------------------------------------
- need_deriving :: [TyCon] -> [(Class, TyCon)]
- -- find the tycons that have `deriving' clauses
+ need_deriving :: Class -> [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 tycons_to_consider
+ 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
- cs -> [ (clas,tycon) | clas <- cs ] ++ acc
+ [] -> acc_plus
+ cs -> [ (clas,tycon) | clas <- cs ] ++ acc_plus
)
[]
tycons_to_consider
------------------------------------------------------------------
- chk_out :: [(Class, TyCon)] -> (Class, TyCon) -> TcM s ()
- chk_out whole_deriving_list this_one@(clas, tycon)
+ chk_out :: (Class, TyCon) -> TcM s ()
+ chk_out this_one@(clas, tycon)
= let
clas_key = classKey clas
- in
+ 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)?
- checkTc (clas_key == enumClassKey && not (isEnumerationTyCon tycon))
- (derivingEnumErr tycon) `thenTc_`
+ 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)?
- checkTc (clas_key == ixClassKey
- && not (isEnumerationTyCon tycon
- || maybeToBool (maybeTyConSingleCon tycon)))
- (derivingIxErr tycon)
+ chk_clas ixClassKey (SLIT("Ix.Ix")) single_nullary_why
+ (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
-- to make the rest of the equation
mk_eqn (clas, tycon)
- = (clas, tycon, tyvars, constraints)
+ = (clas, tycon, tyvars, if_not_Eval constraints)
where
+ clas_key = classKey clas
tyvars = tyConTyVars tycon -- ToDo: Do we need new tyvars ???
tyvar_tys = mkTyVarTys tyvars
data_cons = tyConDataCons tycon
- constraints = concat (map mk_constraints data_cons)
+
+ 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
+ extra_constraints
+ | offensive_class = tyConTheta tycon
+ | otherwise = []
+ where
+ offensive_class = clas_key `elem` needsDataDeclCtxtClassKeys
mk_constraints data_con
- = [ (clas, instantiateTy inst_env arg_ty)
- | arg_ty <- arg_tys,
- not (isPrimType arg_ty) -- No constraints for primitive types
+ = [ (clas, [arg_ty])
+ | arg_ty <- instd_arg_tys,
+ not (isUnboxedType arg_ty) -- No constraints for unboxed types?
]
where
- (con_tyvars, _, arg_tys, _) = dataConSig data_con
- inst_env = zipEqual "mk_eqn" con_tyvars tyvar_tys
- -- same number of tyvars in data constr and type constr!
+ instd_arg_tys = dataConArgTys data_con tyvar_tys
\end{code}
%************************************************************************
equation.
\begin{itemize}
\item
-Each (k,UniTyVarTemplate tv) in a solution constrains only a type
+Each (k,TyVarTy tv) in a solution constrains only a type
variable, tv.
\item
-The (k,UniTyVarTemplate tv) pairs in a solution are canonically
+The (k,TyVarTy tv) pairs in a solution are canonically
ordered by sorting on type varible, tv, (major key) and then class, k,
(minor key)
\end{itemize}
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) ->
-
- -- Simplify each RHS, using a DerivingOrigin containing an
- -- inst_mapper reflecting the previous solution
+ `thenNF_Tc` \ (new_inst_infos, inst_mapper) ->
let
- mk_deriv_origin clas ty
- = DerivingOrigin inst_mapper clas tycon
- where
- (tycon,_) = getAppTyCon ty
+ class_to_inst_env cls = inst_mapper cls
in
- listTc [ tcSimplifyThetas mk_deriv_origin rhs
- | (_, _, _, rhs) <- orig_eqns
- ] `thenTc` \ next_solns ->
+ -- Simplify each RHS
+
+ 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
- = pprPanic# "tcDeriv:cmp_rhs:" (ppCat [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 :: FAST_STRING
- -> Bag InstInfo -- The global, non-derived ones
+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
- theta -- Blarg. This is the dfun_theta slot,
- -- which is needed by buildInstanceEnv;
- -- This works ok for solving the eqns, and
- -- gen_eqns sets it to its final value
- -- (incl super class dicts) before we
- -- finally return it.
-#ifdef DEBUG
- (panic "add_soln:dfun_id") (panic "add_soln:const_meth_ids")
- (panic "add_soln:binds") (panic "add_soln:from_here")
- (panic "add_soln:modname") mkGeneratedSrcLoc
- (panic "add_soln:upragmas")
-#else
- bottom bottom bottom bottom bottom mkGeneratedSrcLoc bottom
+ (my_panic "dfun_theta")
+
+ dummy_dfun_id
+
+ (my_panic "binds") (getSrcLoc tycon)
+ (my_panic "upragmas")
where
- bottom = panic "add_soln"
-#endif
+ dummy_dfun_id
+ = mkDictFunId (getName tycon) dummy_dfun_ty bottom bottom
+ -- The name is getSrcLoc'd in an error message
+ where
+ bottom = panic "dummy_dfun_id"
+
+ 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,
+ -- but that'll be added after the equations are solved. For now,
+ -- it's enough just to make a dummy dfun with the simple theta part.
+ --
+ -- The part after the theta is dummied here as voidTy; actually it's
+ -- (C (T a b)), but it doesn't seem worth constructing it.
+ -- 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 clas, ppr tycon])
\end{code}
%************************************************************************
``you-couldn't-do-better-by-hand'' efficient.
\item
-Deriving @Text@---also pretty common, usually just for
-@show@---should also be reasonable good code.
+Deriving @Show@---also pretty common--- should also be reasonable good code.
\item
Deriving for the other classes isn't that common or that big a deal.
\begin{itemize}
\item
-Deriving @Ord@ is done mostly with our non-standard @tagCmp@ method.
+Deriving @Ord@ is done mostly with the 1.3 @compare@ method.
\item
-Deriving @Eq@ also uses @tagCmp@, if we're deriving @Ord@, too.
+Deriving @Eq@ also uses @compare@, if we're deriving @Ord@, too.
\item
-We {\em normally} generated code only for the non-defaulted methods;
+We {\em normally} generate code only for the non-defaulted methods;
there are some exceptions for @Eq@ and (especially) @Ord@...
\item
@gen_tag_n_con_binds@, and the heuristic for deciding if one of
these is around is given by @hasCon2TagFun@.
-
The examples under the different sections below will make this
clearer.
@_tag2con_<tycon>@ function. See the examples.
\item
-We use Pass~4 of the renamer!!! Reason: we're supposed to be
+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
possible (the @TcM@ monad has a @UniqueSupply@), but it is painful.
-So, instead, we produce @ProtoNameMonoBinds@ then heave 'em through
+So, instead, we produce @RdrNameMonoBinds@ then heave 'em through
the renamer. What a great hack!
\end{itemize}
\begin{code}
-gen_inst_info :: Maybe Module -- Module name; Nothing => Prelude
- -> [RenamedFixityDecl] -- all known fixities;
- -- may be needed for Text
- -> RnEnv -- lookup stuff for names we may use
- -> InstInfo -- the main stuff to work on
- -> TcM s InstInfo -- the gen'd (filled-in) "instance decl"
-
-gen_inst_info modname fixities deriver_rn_env
- info@(InstInfo clas tyvars ty inst_decl_theta _ _ _ _ _ _ locn _)
+-- Generate the method bindings for the required instance
+-- (paired with class name, as we need that when generating dict
+-- names.)
+gen_bind :: InstInfo -> ({-class-}OccName, {-tyCon-}OccName, RdrNameMonoBinds)
+gen_bind (InstInfo clas _ [ty] _ _ _ _ _ _)
+ | not from_here
+ = (clas_nm, tycon_nm, EmptyMonoBinds)
+ | otherwise
+ = (clas_nm, tycon_nm,
+ assoc "gen_bind: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)
+ where
+ clas_nm = nameOccName (getName clas)
+ tycon_nm = nameOccName (getName tycon)
+ from_here = isLocallyDefined tycon
+ (tycon,_,_) = splitAlgTyConApp ty
+
+
+gen_inst_info :: Module -- Module name
+ -> (InstInfo, (Name, RenamedMonoBinds)) -- the main stuff to work on
+ -> 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))
=
-- Generate the various instance-related Ids
- mkInstanceRelatedIds
- True {-from_here-} locn modname
- NoInstancePragmas
- clas tyvars ty
- inst_decl_theta
- [{-no user pragmas-}]
- `thenTc` \ (dfun_id, dfun_theta, const_meth_ids) ->
-
- -- Generate the bindings for the new instance declaration,
- -- rename it, and check for errors
- let
- (tycon,_,_) = getAppDataTyCon ty
-
- proto_mbinds
- | clas_key == eqClassKey = gen_Eq_binds tycon
- | clas_key == showClassKey = gen_Show_binds fixities tycon
- | clas_key == ordClassKey = gen_Ord_binds tycon
- | clas_key == enumClassKey = gen_Enum_binds tycon
- | clas_key == ixClassKey = gen_Ix_binds tycon
- | clas_key == readClassKey = gen_Read_binds fixities tycon
- | clas_key == binaryClassKey = gen_Binary_binds tycon
- | otherwise = panic "gen_inst_info:bad derived class"
- in
- rnMtoTcM deriver_rn_env (
- setExtraRn emptyUFM{-no fixities-} $
- rnMethodBinds clas_Name proto_mbinds
- ) `thenNF_Tc` \ (mbinds, errs) ->
-
- if not (isEmptyBag errs) then
- pprPanic "gen_inst_info:renamer errs!\n"
- (ppAbove (pprBagOfErrors PprDebug errs) (ppr PprDebug proto_mbinds))
- else
- --pprTrace "derived binds:" (ppr PprDebug proto_mbinds) $
-
- -- All done
- let
- from_here = isLocallyDefined tycon -- If so, then from here
- in
- returnTc (InstInfo clas tyvars ty inst_decl_theta
- dfun_theta dfun_id const_meth_ids
- (if from_here then mbinds else EmptyMonoBinds)
- from_here modname locn [])
+ InstInfo clas tyvars tys inst_decl_theta
+ dfun_theta dfun_id
+ meth_binds
+ locn []
where
- clas_key = classKey clas
- clas_Name
- = let (mod, nm) = moduleNamePair clas in
- ClassName clas_key (mkPreludeCoreName mod nm) []
+ (dfun_id, dfun_theta) = mkInstanceRelatedIds
+ dfun_name
+ clas tyvars tys
+ inst_decl_theta
+
+ from_here = isLocallyDefined tycon
+ (tycon,_,_) = splitAlgTyConApp ty
\end{code}
+
%************************************************************************
%* *
-\subsection[TcGenDeriv-con2tag-tag2con]{Generating extra binds (@con2tag@ and @tag2con@)}
+\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)
-\begin{code}
-gen_tag_n_con_binds :: RnEnv
- -> [(RdrName, RnName, TyCon, TagThingWanted)]
- -> TcM s RenamedHsBinds
-
-gen_tag_n_con_binds deriver_rn_env nm_alist_etc
- = let
- proto_mbind_list = map gen_tag_n_con_monobind nm_alist_etc
- proto_mbinds = foldr AndMonoBinds EmptyMonoBinds proto_mbind_list
- in
-
- rnMtoTcM deriver_rn_env (
- setExtraRn emptyUFM{-no fixities-} $
- rnTopBinds (SingleBind (RecBind proto_mbinds))
- ) `thenNF_Tc` \ (binds, errs) ->
-
- if not (isEmptyBag errs) then
- panic "gen_inst_info:renamer errs (2)!"
- else
- returnTc binds
-\end{code}
-
-%************************************************************************
-%* *
-\subsection[TcDeriv-taggery-Names]{What con2tag/tag2con functions are available?}
-%* *
-%************************************************************************
We have a @con2tag@ function for a tycon if:
\begin{itemize}
If we have a @tag2con@ function, we also generate a @maxtag@ constant.
\begin{code}
-gen_taggery_Names :: [DerivEqn]
- -> TcM s [(RdrName, RnName, -- for an assoc list
- TyCon, -- related tycon
+gen_taggery_Names :: [InstInfo]
+ -> TcM s [(RdrName, -- for an assoc list
+ TyCon, -- related tycon
TagThingWanted)]
-gen_taggery_Names eqns
- = let
- all_tycons = [ tc | (_, tc, _, _) <- eqns ]
- (tycons_of_interest, _) = removeDups cmp all_tycons
- in
- foldlTc do_con2tag [] tycons_of_interest `thenTc` \ names_so_far ->
- foldlTc do_tag2con names_so_far tycons_of_interest
+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_tag2con names_so_far tycons_of_interest
where
+ all_CTs = [ (c, get_tycon ty) | (InstInfo c _ [ty] _ _ _ _ _ _) <- inst_infos ]
+
+ get_tycon ty = case splitAlgTyConApp ty of { (tc, _, _) -> tc }
+
+ all_tycons = map snd all_CTs
+ (tycons_of_interest, _) = removeDups compare all_tycons
+
do_con2tag acc_Names tycon
- = if (we_are_deriving eqClassKey tycon
- && any ( (== 0).dataConArity ) (tyConDataCons tycon))
- || (we_are_deriving ordClassKey tycon
+ | isDataTyCon tycon &&
+ (we_are_deriving eqClassKey tycon
+ && any isNullaryDataCon (tyConDataCons tycon))
+ || (we_are_deriving ordClassKey tycon
&& not (maybeToBool (maybeTyConSingleCon tycon)))
- || (we_are_deriving enumClassKey tycon)
- || (we_are_deriving ixClassKey tycon)
- then
- tcGetUnique `thenNF_Tc` ( \ u ->
- returnTc ((con2tag_PN tycon, ValName u (con2tag_FN tycon), tycon, GenCon2Tag)
- : acc_Names) )
- else
- returnTc acc_Names
+ || (we_are_deriving enumClassKey tycon)
+ || (we_are_deriving ixClassKey tycon)
+
+ = returnTc ((con2tag_RDR tycon, tycon, GenCon2Tag)
+ : acc_Names)
+ | otherwise
+ = returnTc acc_Names
do_tag2con acc_Names tycon
= if (we_are_deriving enumClassKey tycon)
|| (we_are_deriving ixClassKey tycon)
then
- tcGetUnique `thenNF_Tc` \ u1 ->
- tcGetUnique `thenNF_Tc` \ u2 ->
- returnTc ( (tag2con_PN tycon, ValName u1 (tag2con_FN tycon), tycon, GenTag2Con)
- : (maxtag_PN tycon, ValName u2 (maxtag_FN tycon), tycon, GenMaxTag)
+ returnTc ( (tag2con_RDR tycon, tycon, GenTag2Con)
+ : (maxtag_RDR tycon, tycon, GenMaxTag)
: acc_Names)
else
returnTc acc_Names
we_are_deriving clas_key tycon
- = is_in_eqns clas_key tycon eqns
+ = is_in_eqns clas_key tycon all_CTs
where
is_in_eqns clas_key tycon [] = False
- is_in_eqns clas_key tycon ((c,t,_,_):eqns)
+ is_in_eqns clas_key tycon ((c,t):cts)
= (clas_key == classKey c && tycon == t)
- || is_in_eqns clas_key tycon eqns
+ || is_in_eqns clas_key tycon cts
\end{code}
\begin{code}
-derivingEnumErr :: TyCon -> Error
-derivingEnumErr tycon
- = addErrLoc (getSrcLoc tycon) "Can't derive an instance of `Enum'" ( \ sty ->
- ppBesides [ppStr "type `", ppr sty tycon, ppStr "'"] )
-
-derivingIxErr :: TyCon -> Error
-derivingIxErr tycon
- = addErrLoc (getSrcLoc tycon) "Can't derive an instance of `Ix'" ( \ sty ->
- ppBesides [ppStr "type `", ppr sty tycon, ppStr "'"] )
--}
+derivingThingErr :: FAST_STRING -> FAST_STRING -> TyCon -> ErrMsg
+
+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)))
+
+derivCtxt tycon
+ = ptext SLIT("When deriving classes for") <+> quotes (ppr tycon)
\end{code}