%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1994
+% (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
+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(..), TyClDecl(..),
+ collectLocatedMonoBinders )
+import RdrHsSyn ( RdrNameMonoBinds )
+import RnHsSyn ( RenamedHsBinds, RenamedMonoBinds, RenamedTyClDecl )
+import CmdLineOpts ( DynFlag(..), DynFlags )
import TcMonad
-import Inst ( InstOrigin(..), InstanceMapper(..) )
-import TcEnv ( getEnv_TyCons )
-import TcKind ( TcKind )
---import TcGenDeriv -- Deriv stuff
-import TcInstUtil ( InstInfo(..), mkInstanceRelatedIds, buildInstanceEnvs )
+import TcEnv ( tcSetInstEnv, newDFunName, InstInfo(..), pprInstInfo,
+ tcLookupClass, tcLookupTyCon
+ )
+import TcGenDeriv -- Deriv stuff
+import InstEnv ( InstEnv, simpleDFunClassTyCon, extendInstEnv )
import TcSimplify ( tcSimplifyThetas )
-import RnMonad
-import RnUtils ( RnEnv(..) )
-import RnBinds ( rnMethodBinds, rnTopBinds )
-
-import Bag ( emptyBag{-ToDo:rm-}, Bag, isEmptyBag, unionBags, listToBag )
-import Class ( GenClass, getClassKey )
-import CmdLineOpts ( opt_CompilingPrelude )
-import ErrUtils ( pprBagOfErrors, addErrLoc, Error(..) )
-import Id ( dataConSig, dataConArity )
-import Maybes ( assocMaybe, maybeToBool, Maybe(..) )
+import RnBinds ( rnMethodBinds, rnTopMonoBinds )
+import RnEnv ( bindLocatedLocalsRn )
+import RnMonad ( renameDerivedCode, thenRn, mapRn, returnRn )
+import HscTypes ( DFunId, PersistentRenamerState )
+
+import BasicTypes ( Fixity )
+import Class ( classKey, Class )
+import ErrUtils ( dumpIfSet_dyn, Message )
+import MkId ( mkDictFunId )
+import DataCon ( dataConArgTys, isNullaryDataCon, isExistentialDataCon )
+import PrelInfo ( needsDataDeclCtxtClassKeys )
+import Maybes ( maybeToBool, catMaybes )
+import Module ( Module )
+import Name ( Name, getSrcLoc )
+import RdrName ( RdrName )
+
+import TyCon ( tyConTyVars, tyConDataCons,
+ tyConTheta, maybeTyConSingleCon, isDataTyCon,
+ isEnumerationTyCon, TyCon
+ )
+import Type ( TauType, ThetaType, PredType, mkTyVarTys, mkTyConApp,
+ isUnLiftedType, mkClassPred )
+import Var ( TyVar )
+import PrelNames
+import Util ( zipWithEqual, sortLt )
+import ListSetOps ( removeDups, assoc )
import Outputable
-import PprType ( GenType, GenTyVar, GenClass, TyCon )
-import PprStyle
-import Pretty
-import SrcLoc ( mkGeneratedSrcLoc, mkUnknownSrcLoc, SrcLoc )
-import TyCon ( tyConTyVars, tyConDataCons, tyConDerivings,
- maybeTyConSingleCon, isEnumerationTyCon, TyCon )
-import Type ( GenType(..), TauType(..), mkTyVarTys, applyTyCon,
- mkSigmaTy, mkDictTy, isPrimType, instantiateTy,
- getAppTyCon, getAppDataTyCon )
-import TyVar ( GenTyVar )
-import UniqFM ( emptyUFM )
-import Unique -- Keys stuff
-import Util ( zipWithEqual, zipEqual, sortLt, removeDups,
- thenCmp, cmpList, panic, pprPanic, pprPanic# )
+import List ( nub )
\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
So, here are the synonyms for the ``equation'' structures:
\begin{code}
-type DerivEqn = (Class, TyCon, [TyVar], DerivRhs)
- -- The tyvars bind all the variables in the RHS
- -- NEW: it's convenient to re-use InstInfo
- -- We'll "panic" out some fields...
-
-type DerivRhs = [(Class, TauType)] -- Same as a ThetaType!
+type DerivEqn = (Name, Class, TyCon, [TyVar], DerivRhs)
+ -- The Name is the name for the DFun we'll build
+ -- The tyvars bind all the variables in the RHS
+type DerivRhs = 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
- -> 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;
- -- 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_env inst_decl_infos_in fixities
- = -- Fish the "deriving"-related information out of the TcEnv
+tcDeriving :: PersistentRenamerState
+ -> Module -- name of module under scrutiny
+ -> InstEnv -- What we already know about instances
+ -> (Name -> Maybe Fixity) -- used in deriving Show and Read
+ -> [RenamedTyClDecl] -- All type constructors
+ -> TcM ([InstInfo], -- The generated "instance decls".
+ RenamedHsBinds) -- Extra generated bindings
+
+tcDeriving prs mod inst_env_in get_fixity tycl_decls
+ = recoverTc (returnTc ([], EmptyBinds)) $
+
+ -- Fish the "deriving"-related information out of the TcEnv
-- and make the necessary "equations".
- makeDerivEqns `thenTc` \ eqns ->
+ makeDerivEqns tycl_decls `thenTc` \ eqns ->
+ if null eqns then
+ returnTc ([], EmptyBinds)
+ 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_env_in eqns `thenTc` \ new_dfuns ->
-- 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_dfuns `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
+ tcGetEnv `thenNF_Tc` \ env ->
+ getDOptsTc `thenTc` \ dflags ->
+ 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 get_fixity) new_dfuns
+ mbinders = collectLocatedMonoBinders extra_mbinds
+
+ -- Rename to get RenamedBinds.
+ -- The only tricky bit is that the extra_binds must scope over the
+ -- method bindings for the instances.
+ (rn_method_binds_s, rn_extra_binds)
+ = renameDerivedCode dflags mod prs (
+ bindLocatedLocalsRn (ptext (SLIT("deriving"))) mbinders $ \ _ ->
+ rnTopMonoBinds extra_mbinds [] `thenRn` \ (rn_extra_binds, _) ->
+ mapRn rn_meths method_binds_s `thenRn` \ rn_method_binds_s ->
+ returnRn (rn_method_binds_s, rn_extra_binds)
+ )
+
+ new_inst_infos = zipWith gen_inst_info new_dfuns rn_method_binds_s
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 ->
+ ioToTc (dumpIfSet_dyn dflags Opt_D_dump_deriv "Derived instances"
+ (ddump_deriving new_inst_infos rn_extra_binds)) `thenTc_`
- returnTc (listToBag really_new_inst_infos,
- extra_binds,
- ddump_deriving really_new_inst_infos extra_binds)
+ returnTc (new_inst_infos, rn_extra_binds)
where
- maybe_mod = if opt_CompilingPrelude then Nothing else Just mod_name
+ ddump_deriving :: [InstInfo] -> RenamedHsBinds -> SDoc
+ ddump_deriving inst_infos extra_binds
+ = vcat (map pprInstInfo inst_infos) $$ ppr extra_binds
+ where
- ddump_deriving :: [InstInfo] -> RenamedHsBinds -> (PprStyle -> Pretty)
+ -- 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 = binds, iPrags = [] }
- ddump_deriving inst_infos extra_binds sty
- = ppAboves ((map pp_info inst_infos) ++ [ppr sty 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)
+ rn_meths meths = rnMethodBinds [] meths `thenRn` \ (meths', _) -> returnRn meths'
+ -- Ignore the free vars returned
\end{code}
all those.
\begin{code}
-makeDerivEqns :: TcM s [DerivEqn]
+makeDerivEqns :: [RenamedTyClDecl] -> TcM [DerivEqn]
-makeDerivEqns
- = tcGetEnv `thenNF_Tc` \ env ->
- let
- tycons = getEnv_TyCons env
- think_about_deriving = need_deriving tycons
- in
- mapTc (chk_out think_about_deriving) think_about_deriving `thenTc_`
- let
- (derive_these, _) = removeDups cmp_deriv think_about_deriving
- eqns = map mk_eqn derive_these
- in
- returnTc eqns
+makeDerivEqns tycl_decls
+ = mapTc mk_eqn derive_these `thenTc` \ maybe_eqns ->
+ returnTc (catMaybes maybe_eqns)
where
------------------------------------------------------------------
- need_deriving :: [TyCon] -> [(Class, TyCon)]
- -- find the tycons that have `deriving' clauses
-
- need_deriving tycons_to_consider
- = foldr ( \ tycon acc ->
- case (tyConDerivings tycon) of
- [] -> acc
- cs -> [ (clas,tycon) | clas <- cs ] ++ acc
- )
- []
- tycons_to_consider
+ derive_these :: [(Name, Name)]
+ -- Find the (Class,TyCon) pairs that must be `derived'
+ -- NB: only source-language decls have deriving, no imported ones do
+ derive_these = [ (clas,tycon)
+ | TyData {tcdName = tycon, tcdDerivs = Just classes} <- tycl_decls,
+ clas <- nub classes ]
------------------------------------------------------------------
- chk_out :: [(Class, TyCon)] -> (Class, TyCon) -> TcM s ()
- chk_out whole_deriving_list this_one@(clas, tycon)
- = let
- clas_key = getClassKey clas
- in
-
- -- Are things OK for deriving Enum (if appropriate)?
- checkTc (clas_key == enumClassKey && not (isEnumerationTyCon tycon))
- (derivingEnumErr tycon) `thenTc_`
-
- -- Are things OK for deriving Ix (if appropriate)?
- checkTc (clas_key == ixClassKey
- && not (isEnumerationTyCon tycon
- || maybeToBool (maybeTyConSingleCon tycon)))
- (derivingIxErr tycon)
-
- ------------------------------------------------------------------
- cmp_deriv :: (Class, TyCon) -> (Class, TyCon) -> TAG_
- cmp_deriv (c1, t1) (c2, t2)
- = (c1 `cmp` c2) `thenCmp` (t1 `cmp` t2)
-
- ------------------------------------------------------------------
- mk_eqn :: (Class, TyCon) -> DerivEqn
+ mk_eqn :: (Name, Name) -> NF_TcM (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)
- where
- tyvars = tyConTyVars tycon -- ToDo: Do we need new tyvars ???
- tyvar_tys = mkTyVarTys tyvars
- data_cons = tyConDataCons tycon
- constraints = concat (map mk_constraints data_cons)
-
- mk_constraints data_con
- = [ (clas, instantiateTy inst_env arg_ty)
- | arg_ty <- arg_tys,
- not (isPrimType arg_ty) -- No constraints for primitive types
- ]
- where
- (con_tyvars, _, arg_tys, _) = dataConSig data_con
- inst_env = con_tyvars `zipEqual` tyvar_tys
- -- same number of tyvars in data constr and type constr!
+ mk_eqn (clas_name, tycon_name)
+ = tcLookupClass clas_name `thenNF_Tc` \ clas ->
+ tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
+ let
+ clas_key = classKey clas
+ tyvars = tyConTyVars tycon
+ tyvar_tys = mkTyVarTys tyvars
+ ty = mkTyConApp tycon tyvar_tys
+ data_cons = tyConDataCons tycon
+ locn = getSrcLoc tycon
+ 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 = []
+
+ offensive_class = clas_key `elem` needsDataDeclCtxtClassKeys
+
+ mk_constraints data_con
+ = [ mkClassPred clas [arg_ty]
+ | arg_ty <- dataConArgTys data_con tyvar_tys,
+ not (isUnLiftedType arg_ty) -- No constraints for unlifted types?
+ ]
+ in
+ case chk_out clas tycon of
+ Just err -> addErrTc err `thenNF_Tc_`
+ returnNF_Tc Nothing
+ Nothing -> newDFunName clas [ty] locn `thenNF_Tc` \ dfun_name ->
+ returnNF_Tc (Just (dfun_name, clas, tycon, tyvars, constraints))
+
+
+
+ ------------------------------------------------------------------
+ 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}
%************************************************************************
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}
\begin{code}
-solveDerivEqns :: Bag InstInfo
+solveDerivEqns :: InstEnv
-> [DerivEqn]
- -> TcM s [InstInfo] -- Solns in same order as eqns.
- -- This bunch is Absolutely minimal...
+ -> TcM [DFunId] -- Solns in same order as eqns.
+ -- This bunch is Absolutely minimal...
-solveDerivEqns inst_decl_infos_in orig_eqns
+solveDerivEqns inst_env_in orig_eqns
= iterateDeriv initial_solutions
where
-- The initial solutions for the equations claim that each
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.
-
- iterateDeriv :: [DerivSoln] ->TcM s [InstInfo]
-
+ -- It fails if any iteration fails
+ iterateDeriv :: [DerivSoln] ->TcM [DFunId]
iterateDeriv current_solns
+ = checkNoErrsTc (iterateOnce current_solns)
+ `thenTc` \ (new_dfuns, new_solns) ->
+ if (current_solns == new_solns) then
+ returnTc new_dfuns
+ 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
- let
- mk_deriv_origin clas ty
- = DerivingOrigin inst_mapper clas tycon
- where
- (tycon,_) = getAppTyCon ty
- in
- listTc [ tcSimplifyThetas mk_deriv_origin rhs
- | (_, _, _, rhs) <- orig_eqns
- ] `thenTc` \ next_solns ->
+ getDOptsTc `thenTc` \ dflags ->
+ let (new_dfuns, inst_env) =
+ add_solns dflags inst_env_in orig_eqns current_solns
+ in
+ -- Simplify each RHS
+ tcSetInstEnv inst_env (
+ listTc [ tcAddSrcLoc (getSrcLoc tc) $
+ tcAddErrCtxt (derivCtxt tc) $
+ tcSimplifyThetas 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
-
+ let canonicalised_next_solns = [ sortLt (<) next_soln | next_soln <- next_solns ]
+ in
+ returnTc (new_dfuns, canonicalised_next_solns)
\end{code}
\begin{code}
-add_solns :: FAST_STRING
- -> Bag InstInfo -- The global, non-derived ones
+add_solns :: DynFlags
+ -> InstEnv -- The global, non-derived ones
-> [DerivEqn] -> [DerivSoln]
- -> TcM s ([InstInfo], -- The new, derived ones
- InstanceMapper)
+ -> ([DFunId], InstEnv)
-- 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)
- where
- new_inst_infos = zipWithEqual 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))
- 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
- where
- bottom = panic "add_soln"
-#endif
+add_solns dflags inst_env_in eqns solns
+ = (new_dfuns, inst_env)
+ where
+ new_dfuns = zipWithEqual "add_solns" mk_deriv_dfun eqns solns
+ (inst_env, _) = extendInstEnv dflags inst_env_in new_dfuns
+ -- Ignore the errors about duplicate instances.
+ -- We don't want repeated error messages
+ -- They'll appear later, when we do the top-level extendInstEnvs
+
+ mk_deriv_dfun (dfun_name, clas, tycon, tyvars, _) theta
+ = mkDictFunId dfun_name clas tyvars
+ [mkTyConApp tycon (mkTyVarTys tyvars)]
+ theta
\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 various instance-related Ids
- mkInstanceRelatedIds
- True {-from_here-} 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 [])
+-- Generate the method bindings for the required instance
+-- (paired with class name, as we need that when generating dict
+-- names.)
+gen_bind :: (Name -> Maybe Fixity) -> DFunId -> RdrNameMonoBinds
+gen_bind get_fixity dfun
+ | clas `hasKey` showClassKey = gen_Show_binds get_fixity tycon
+ | clas `hasKey` readClassKey = gen_Read_binds get_fixity tycon
+ | otherwise
+ = 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)
+ ]
+ (classKey clas)
+ tycon
where
- clas_key = getClassKey clas
- clas_Name
- = let (mod, nm) = moduleNamePair clas in
- ClassName clas_key (mkPreludeCoreName mod nm) []
+ (clas, tycon) = simpleDFunClassTyCon dfun
\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) ->
+maxtag_Foo :: Int -- ditto (NB: not unlifted)
- 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
- 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 :: [DFunId]
+ -> TcM [(RdrName, -- for an assoc list
+ TyCon, -- related tycon
+ TagThingWanted)]
+
+gen_taggery_Names dfuns
+ = foldlTc do_con2tag [] tycons_of_interest `thenTc` \ names_so_far ->
+ foldlTc do_tag2con names_so_far tycons_of_interest
where
+ all_CTs = map simpleDFunClassTyCon dfuns
+ 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)
- : 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 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)
- = (clas_key == getClassKey c && tycon == t)
- || is_in_eqns clas_key tycon eqns
-
+ is_in_eqns clas_key tycon ((c,t):cts)
+ = (clas_key == classKey c && tycon == t)
+ || 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 :: 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)")]
+
+derivCtxt tycon
+ = ptext SLIT("When deriving classes for") <+> quotes (ppr tycon)
\end{code}
projects / ghc-hetmet.git / blobdiff