%
-% (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 HsSyn ( HsBinds(..), MonoBinds(..), TyClDecl(..),
+ collectLocatedMonoBinders )
+import RdrHsSyn ( RdrNameMonoBinds )
+import RnHsSyn ( RenamedHsBinds, RenamedMonoBinds, RenamedTyClDecl, RenamedHsPred )
+import CmdLineOpts ( DynFlag(..), DynFlags )
import TcMonad
-import Inst ( SYN_IE(InstanceMapper) )
-import TcEnv ( getEnv_TyCons, tcLookupClassByKey )
-import SpecEnv ( SpecEnv )
-import TcKind ( TcKind )
+import TcEnv ( tcSetInstEnv, newDFunName, InstInfo(..), pprInstInfo,
+ tcLookupClass, tcLookupTyCon, tcExtendTyVarEnv
+ )
import TcGenDeriv -- Deriv stuff
-import TcInstUtil ( InstInfo(..), mkInstanceRelatedIds, buildInstanceEnvs )
+import InstEnv ( InstEnv, simpleDFunClassTyCon, extendInstEnv )
+import TcMonoType ( tcHsPred )
import TcSimplify ( tcSimplifyThetas )
-import TcType ( TcIdOcc )
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, emptyBag, isEmptyBag, unionBags, listToBag )
-import Class ( classKey, GenClass, SYN_IE(Class) )
-import ErrUtils ( addErrLoc, SYN_IE(Error) )
-import Id ( dataConArgTys, isNullaryDataCon, mkDictFunId )
+import RnEnv ( bindLocatedLocalsRn )
+import RnMonad ( renameDerivedCode, thenRn, mapRn, returnRn )
+import HscTypes ( DFunId, PersistentRenamerState )
+
+import BasicTypes ( Fixity, NewOrData(..) )
+import Class ( className, classKey, classTyVars, Class )
+import ErrUtils ( dumpIfSet_dyn, Message )
+import MkId ( mkDictFunId )
+import DataCon ( dataConRepArgTys, isNullaryDataCon, isExistentialDataCon )
import PrelInfo ( needsDataDeclCtxtClassKeys )
-import Maybes ( maybeToBool )
-import Name ( isLocallyDefined, getSrcLoc, ExportFlag(..), Provenance,
- Name{--O only-}, SYN_IE(Module)
- )
-import Outputable ( PprStyle(..), Outputable(..){-instances e.g., (,)-} )
-import PprType ( GenType, GenTyVar, GenClass, TyCon )
-import Pretty ( ($$), vcat, hsep, hcat, parens, empty, (<+>),
- ptext, char, hang, Doc )
-import SrcLoc ( mkGeneratedSrcLoc, SrcLoc )
-import TyCon ( tyConTyVars, tyConDataCons, tyConDerivings,
+import Maybes ( maybeToBool, catMaybes )
+import Module ( Module )
+import Name ( Name, getSrcLoc, nameUnique )
+import RdrName ( RdrName )
+
+import TyCon ( tyConTyVars, tyConDataCons, tyConArity, newTyConRep,
tyConTheta, maybeTyConSingleCon, isDataTyCon,
- isEnumerationTyCon, isAlgTyCon, TyCon
- )
-import Type ( GenType(..), SYN_IE(TauType), mkTyVarTys, applyTyCon,
- mkSigmaTy, mkDictTy, isPrimType, instantiateTy,
- getAppDataTyCon, getAppTyCon
- )
-import TysPrim ( voidTy )
-import TyVar ( GenTyVar, SYN_IE(TyVar) )
-import UniqFM ( emptyUFM )
-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-}
-
+ isEnumerationTyCon, TyCon
)
+import TcType ( TcType, ThetaType, mkTyVarTys, mkTyConApp, getClassPredTys_maybe,
+ isUnLiftedType, mkClassPred, tyVarsOfTypes, tcSplitFunTys,
+ tcSplitTyConApp_maybe, tcEqTypes )
+import Var ( TyVar, tyVarKind )
+import VarSet ( mkVarSet, subVarSet )
+import PrelNames
+import Util ( zipWithEqual, sortLt )
+import ListSetOps ( removeDups, assoc )
+import Outputable
+import Maybe ( isJust )
+import List ( nub )
+import FastString ( FastString )
\end{code}
%************************************************************************
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}
%************************************************************************
\begin{code}
-tcDeriving :: Module -- name of module under scrutiny
- -> 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.
-
-tcDeriving modname rn_name_supply inst_decl_infos_in
- = recoverTc (returnTc (emptyBag, EmptyBinds, \_ -> empty)) $
+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 get_fixity tycl_decls
+ = recoverTc (returnTc ([], EmptyBinds)) $
+ getDOptsTc `thenNF_Tc` \ dflags ->
-- Fish the "deriving"-related information out of the TcEnv
-- and make the necessary "equations".
- makeDerivEqns `thenTc` \ eqns ->
+ makeDerivEqns tycl_decls `thenTc` \ (ordinary_eqns, newtype_inst_info) ->
+ let
+ -- Add the newtype-derived instances to the inst env
+ -- before tacking the "ordinary" ones
+ inst_env1 = extend_inst_env dflags inst_env
+ (map iDFunId newtype_inst_info)
+ in
+ deriveOrdinaryStuff mod prs inst_env1 get_fixity
+ ordinary_eqns `thenTc` \ (ordinary_inst_info, binds) ->
+ let
+ inst_info = newtype_inst_info ++ ordinary_inst_info
+ in
+
+ ioToTc (dumpIfSet_dyn dflags Opt_D_dump_deriv "Derived instances"
+ (ddump_deriving inst_info binds)) `thenTc_`
+
+ returnTc (inst_info, binds)
+
+ where
+ ddump_deriving :: [InstInfo] -> RenamedHsBinds -> SDoc
+ ddump_deriving inst_infos extra_binds
+ = vcat (map pprInstInfo inst_infos) $$ ppr extra_binds
+
+
+-----------------------------------------
+deriveOrdinaryStuff mod prs inst_env_in get_fixity [] -- Short cut
+ = returnTc ([], EmptyBinds)
- -- Take the equation list and solve it, to deliver a list of
+deriveOrdinaryStuff mod prs inst_env_in get_fixity eqns
+ = -- 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
-- generate extra not-one-inst-decl-specific binds, notably
-- "con2tag" and/or "tag2con" functions. We do these
-- separately.
+ gen_taggery_Names new_dfuns `thenTc` \ nm_alist_etc ->
- gen_taggery_Names new_inst_infos `thenTc` \ nm_alist_etc ->
-
-
+ tcGetEnv `thenNF_Tc` \ env ->
+ getDOptsTc `thenNF_Tc` \ 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 new_inst_infos
- mbinders = bagToList (collectMonoBinders extra_mbinds)
+ 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.
- (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_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)
)
- rn_one meth_binds = newDfunName 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
+ new_inst_infos = zipWith gen_inst_info new_dfuns rn_method_binds_s
in
- --pprTrace "derived:\n" (ddump_deriv PprDebug) $
+ returnTc (new_inst_infos, rn_extra_binds)
- returnTc (listToBag really_new_inst_infos,
- rn_extra_binds,
- ddump_deriv)
where
- ddump_deriving :: [InstInfo] -> RenamedHsBinds -> (PprStyle -> Doc)
+ -- 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
- = vcat ((map pp_info inst_infos) ++ [ppr sty 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)
+ rn_meths (cls, meths) = rnMethodBinds cls [] meths `thenRn` \ (meths', _) ->
+ returnRn meths' -- Ignore the free vars returned
\end{code}
all those.
\begin{code}
-makeDerivEqns :: TcM s [DerivEqn]
+makeDerivEqns :: [RenamedTyClDecl]
+ -> TcM ([DerivEqn], -- Ordinary derivings
+ [InstInfo]) -- Special newtype derivings
-makeDerivEqns
- = 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
- (derive_these, _) = removeDups cmp_deriv think_about_deriving
- eqns = map mk_eqn derive_these
- in
- mapTc chk_out think_about_deriving `thenTc_`
- returnTc eqns
+makeDerivEqns tycl_decls
+ = mapAndUnzipTc mk_eqn derive_these `thenTc` \ (maybe_ordinaries, maybe_newtypes) ->
+ returnTc (catMaybes maybe_ordinaries, catMaybes maybe_newtypes)
where
------------------------------------------------------------------
- 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 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
- )
- []
- tycons_to_consider
+ derive_these :: [(NewOrData, Name, RenamedHsPred)]
+ -- Find the (nd, TyCon, Pred) pairs that must be `derived'
+ -- NB: only source-language decls have deriving, no imported ones do
+ derive_these = [ (nd, tycon, pred)
+ | TyData {tcdND = nd, tcdName = tycon, tcdDerivs = Just preds} <- tycl_decls,
+ pred <- preds ]
------------------------------------------------------------------
- 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)
+ mk_eqn :: (NewOrData, Name, RenamedHsPred) -> NF_TcM (Maybe DerivEqn, Maybe InstInfo)
+ -- We swizzle the tyvars and datacons out of the tycon
+ -- to make the rest of the equation
- ------------------------------------------------------------------
- cmp_deriv :: (Class, TyCon) -> (Class, TyCon) -> TAG_
- cmp_deriv (c1, t1) (c2, t2)
- = (c1 `cmp` c2) `thenCmp` (t1 `cmp` t2)
+ mk_eqn (new_or_data, tycon_name, pred)
+ = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
+ tcAddSrcLoc (getSrcLoc tycon) $
+ tcAddErrCtxt (derivCtxt tycon) $
+ tcExtendTyVarEnv (tyConTyVars tycon) $ -- Deriving preds may (now) mention
+ -- the type variables for the type constructor
+ tcHsPred pred `thenTc` \ pred' ->
+ case getClassPredTys_maybe pred' of
+ Nothing -> bale_out (malformedPredErr tycon pred)
+ Just (clas, tys) -> mk_eqn_help new_or_data tycon clas tys
------------------------------------------------------------------
- mk_eqn :: (Class, TyCon) -> 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)
+ mk_eqn_help DataType tycon clas tys
+ | Just err <- chk_out clas tycon tys
+ = bale_out (derivingThingErr clas tys tycon tyvars err)
+ | otherwise
+ = new_dfun_name clas tycon `thenNF_Tc` \ dfun_name ->
+ returnNF_Tc (Just (dfun_name, clas, tycon, tyvars, constraints), Nothing)
where
- clas_key = classKey clas
- tyvars = tyConTyVars tycon -- ToDo: Do we need new tyvars ???
- tyvar_tys = mkTyVarTys tyvars
+ tyvars = tyConTyVars tycon
data_cons = tyConDataCons tycon
+ constraints = extra_constraints ++
+ [ mkClassPred clas [arg_ty]
+ | data_con <- tyConDataCons tycon,
+ arg_ty <- dataConRepArgTys data_con,
+ -- Use the same type variables
+ -- as the type constructor,
+ -- hence no need to instantiate
+ not (isUnLiftedType arg_ty) -- No constraints for unlifted types?
+ ]
- if_not_Eval cs = if clas_key == evalClassKey then [] else cs
+
+ -- "extra_constraints": see notes above about contexts on data decls
+ extra_constraints | offensive_class = tyConTheta tycon
+ | otherwise = []
+
+ offensive_class = classKey clas `elem` needsDataDeclCtxtClassKeys
- 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_eqn_help NewType tycon clas tys
+ = doptsTc Opt_GlasgowExts `thenTc` \ gla_exts ->
+ if can_derive_via_isomorphism && (gla_exts || standard_instance) then
+ -- Go ahead and use the isomorphism
+ new_dfun_name clas tycon `thenNF_Tc` \ dfun_name ->
+ returnTc (Nothing, Just (NewTypeDerived (mk_dfun dfun_name)))
+ else
+ if standard_instance then
+ mk_eqn_help DataType tycon clas [] -- Go via bale-out route
+ else
+ bale_out cant_derive_err
+ where
+ -- Here is the plan for newtype derivings. We see
+ -- newtype T a1...an = T (t ak...an) deriving (C1...Cm)
+ -- where aj...an do not occur free in t, and the Ci are *partial applications* of
+ -- classes with the last parameter missing
+ --
+ -- We generate the instances
+ -- instance Ci (t ak...aj) => Ci (T a1...aj)
+ -- where T a1...aj is the partial application of the LHS of the correct kind
+ --
+ -- Running example: newtype T s a = MkT (ST s a) deriving( Monad )
+
+ kind = tyVarKind (last (classTyVars clas))
+ -- Kind of the thing we want to instance
+ -- e.g. argument kind of Monad, *->*
+
+ (arg_kinds, _) = tcSplitFunTys kind
+ n_args_to_drop = length arg_kinds
+ -- Want to drop 1 arg from (T s a) and (ST s a)
+ -- to get instance Monad (ST s) => Monad (T s)
+
+ (tyvars, rep_ty) = newTyConRep tycon
+ maybe_rep_app = tcSplitTyConApp_maybe rep_ty
+ Just (rep_tc, rep_ty_args) = maybe_rep_app
+
+ n_tyvars_to_keep = tyConArity tycon - n_args_to_drop
+ tyvars_to_drop = drop n_tyvars_to_keep tyvars
+ tyvars_to_keep = take n_tyvars_to_keep tyvars
+
+ n_args_to_keep = tyConArity rep_tc - n_args_to_drop
+ args_to_drop = drop n_args_to_keep rep_ty_args
+ args_to_keep = take n_args_to_keep rep_ty_args
+
+ ctxt_pred = mkClassPred clas (tys ++ [mkTyConApp rep_tc args_to_keep])
+
+ mk_dfun dfun_name = mkDictFunId dfun_name clas tyvars
+ (tys ++ [mkTyConApp tycon (mkTyVarTys tyvars_to_keep)] )
+ [ctxt_pred]
+
+ -- We can only do this newtype deriving thing if:
+ standard_instance = null tys && classKey clas `elem` derivableClassKeys
+
+ can_derive_via_isomorphism
+ = not (clas `hasKey` readClassKey) -- Never derive Read,Show this way
+ && not (clas `hasKey` showClassKey)
+ && n_tyvars_to_keep >= 0 -- Well kinded;
+ -- eg not: newtype T = T Int deriving( Monad )
+ && isJust maybe_rep_app -- The rep type is a type constructor app
+ && n_args_to_keep >= 0 -- Well kinded:
+ -- eg not: newtype T a = T Int deriving( Monad )
+ && eta_ok -- Eta reduction works
+
+ -- Check that eta reduction is OK
+ -- (a) the dropped-off args are identical
+ -- (b) the remaining type args mention
+ -- only the remaining type variables
+ eta_ok = (args_to_drop `tcEqTypes` mkTyVarTys tyvars_to_drop)
+ && (tyVarsOfTypes args_to_keep `subVarSet` mkVarSet tyvars_to_keep)
+
+ cant_derive_err = derivingThingErr clas tys tycon tyvars_to_keep
+ SLIT("too hard for cunning newtype deriving")
+
+
+ bale_out err = addErrTc err `thenNF_Tc_` returnNF_Tc (Nothing, Nothing)
- mk_constraints data_con
- = [ (clas, arg_ty)
- | arg_ty <- instd_arg_tys,
- not (isPrimType arg_ty) -- No constraints for primitive types
- ]
- where
- instd_arg_tys = dataConArgTys data_con tyvar_tys
+ ------------------------------------------------------------------
+ chk_out :: Class -> TyCon -> [TcType] -> Maybe FastString
+ chk_out clas tycon tys
+ | not (null tys) = Just non_std_why
+ | not (getUnique clas `elem` derivableClassKeys) = Just non_std_why
+ | clas `hasKey` enumClassKey && not is_enumeration = Just nullary_why
+ | clas `hasKey` boundedClassKey && not is_enumeration_or_single = Just single_nullary_why
+ | clas `hasKey` ixClassKey && not is_enumeration_or_single = Just single_nullary_why
+ | null data_cons = Just no_cons_why
+ | any isExistentialDataCon data_cons = Just existential_why
+ | otherwise = Nothing
+ where
+ data_cons = tyConDataCons tycon
+ 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")
+ no_cons_why = SLIT("type has no data constructors")
+ non_std_why = SLIT("not a derivable class")
+ existential_why = SLIT("it has existentially-quantified constructor(s)")
+
+new_dfun_name clas tycon -- Just a simple wrapper
+ = newDFunName clas [mkTyConApp tycon []] (getSrcLoc tycon)
+ -- The type passed to newDFunName is only used to generate
+ -- a suitable string; hence the empty type arg list
\end{code}
%************************************************************************
\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
-- 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 :: [DerivSoln] ->TcM [DFunId]
iterateDeriv current_solns
- = checkNoErrsTc (iterateOnce current_solns) `thenTc` \ (new_inst_infos, new_solns) ->
- if (current_solns `eq_solns` new_solns) then
- returnTc new_inst_infos
+ = 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) ->
- let
- class_to_inst_env cls = inst_mapper cls
- in
+ getDOptsTc `thenNF_Tc` \ dflags ->
+ let
+ new_dfuns = zipWithEqual "add_solns" mk_deriv_dfun orig_eqns current_solns
+ inst_env = extend_inst_env dflags inst_env_in new_dfuns
+ -- the eqns and solns move "in lockstep"; we have the eqns
+ -- because we need the LHS info for addClassInstance.
+ in
-- Simplify each RHS
-
- listTc [ tcAddErrCtxt (derivCtxt tc) $
- tcSimplifyThetas class_to_inst_env [{-Nothing "given"-}] deriv_rhs
- | (_,tc,_,deriv_rhs) <- orig_eqns ] `thenTc` \ next_solns ->
+ 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 ]
+ let canonicalised_next_solns = [ sortLt (<) next_soln | next_soln <- next_solns ]
in
- returnTc (new_inst_infos, canonicalised_next_solns)
-
- ------------------------------------------------------------------
- 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
-
+ returnTc (new_dfuns, 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)
- -- 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
-
--- ------------------
--- OLD: checkErrsTc above now deals with this
--- = discardErrsTc (buildInstanceEnvs all_inst_infos `thenTc` \ 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.
--- ------------------
-
- = buildInstanceEnvs all_inst_infos `thenTc` \ inst_mapper ->
- returnTc (new_inst_infos, inst_mapper)
+extend_inst_env dflags inst_env new_dfuns
+ = new_inst_env
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))
- theta
- (my_panic "dfun_theta")
-
- dummy_dfun_id
-
- (my_panic "binds") (getSrcLoc tycon)
- (my_panic "upragmas")
- where
- 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 PprDebug clas, ppr PprDebug tycon])
+ (new_inst_env, _errs) = extendInstEnv dflags inst_env 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}
%************************************************************************
\begin{code}
-- Generate the method bindings for the required instance
-gen_bind :: InstInfo -> RdrNameMonoBinds
-gen_bind (InstInfo clas _ ty _ _ _ _ _ _)
- | not from_here
- = EmptyMonoBinds
- | 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
+-- (paired with class name, as we need that when renaming
+-- the method binds)
+gen_bind :: (Name -> Maybe Fixity) -> DFunId -> (Name, RdrNameMonoBinds)
+gen_bind get_fixity dfun
+ = (cls_nm, binds)
where
- from_here = isLocallyDefined tycon
- (tycon,_,_) = getAppDataTyCon 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 ty inst_decl_theta _ _ _ locn _, (dfun_name, meth_binds))
- =
- -- Generate the various instance-related Ids
- InstInfo clas tyvars ty inst_decl_theta
- dfun_theta dfun_id
- meth_binds
- locn []
- where
- (dfun_id, dfun_theta) = mkInstanceRelatedIds
- dfun_name
- clas tyvars ty
- inst_decl_theta
-
- from_here = isLocallyDefined tycon
- (tycon,_,_) = getAppDataTyCon ty
+ cls_nm = className clas
+ (clas, tycon) = simpleDFunClassTyCon dfun
+
+ binds = assoc "gen_bind:bad derived class" gen_list
+ (nameUnique cls_nm) tycon
+
+ gen_list = [(eqClassKey, gen_Eq_binds)
+ ,(ordClassKey, gen_Ord_binds)
+ ,(enumClassKey, gen_Enum_binds)
+ ,(boundedClassKey, gen_Bounded_binds)
+ ,(ixClassKey, gen_Ix_binds)
+ ,(showClassKey, gen_Show_binds get_fixity)
+ ,(readClassKey, gen_Read_binds get_fixity)
+ ]
\end{code}
con2tag_Foo :: Foo ... -> Int#
tag2con_Foo :: Int -> Foo ... -- easier if Int, not Int#
-maxtag_Foo :: Int -- ditto (NB: not unboxed)
+maxtag_Foo :: Int -- ditto (NB: not unlifted)
We have a @con2tag@ function for a tycon if:
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
- TyCon, -- related tycon
- TagThingWanted)]
-
-gen_taggery_Names inst_infos
- = --pprTrace "gen_taggery:\n" (vcat [hsep [ppr PprDebug c, ppr PprDebug t] | (c,t) <- all_CTs]) $
- foldlTc do_con2tag [] tycons_of_interest `thenTc` \ names_so_far ->
+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 = [ mk_CT c ty | (InstInfo c _ ty _ _ _ _ _ _) <- inst_infos ]
-
- mk_CT c ty = (c, fst (getAppTyCon ty))
-
- all_tycons = map snd all_CTs
- (tycons_of_interest, _) = removeDups cmp all_tycons
+ all_CTs = map simpleDFunClassTyCon dfuns
+ all_tycons = map snd all_CTs
+ (tycons_of_interest, _) = removeDups compare all_tycons
do_con2tag acc_Names tycon
| isDataTyCon tycon &&
- (we_are_deriving eqClassKey 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)
+ || (we_are_deriving ixClassKey tycon))
= returnTc ((con2tag_RDR tycon, tycon, GenCon2Tag)
: acc_Names)
= 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
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}
-derivingThingErr :: FAST_STRING -> FAST_STRING -> TyCon -> Error
+derivingThingErr clas tys tycon tyvars why
+ = sep [hsep [ptext SLIT("Can't make a derived instance of"), quotes (ppr pred)],
+ parens (ptext why)]
+ where
+ pred = mkClassPred clas (tys ++ [mkTyConApp tycon (mkTyVarTys tyvars)])
-derivingThingErr thing why tycon sty
- = hang (hsep [ptext SLIT("Can't make a derived instance of"), ptext thing])
- 0 (hang (hsep [ptext SLIT("for the type"), ppr sty tycon])
- 0 (parens (ptext why)))
+malformedPredErr tycon pred = ptext SLIT("Illegal deriving item") <+> ppr pred
-derivCtxt tycon sty
- = ptext SLIT("When deriving classes for") <+> ppr sty tycon
+derivCtxt tycon
+ = ptext SLIT("When deriving classes for") <+> quotes (ppr tycon)
\end{code}
+
projects / ghc-hetmet.git / blobdiff