%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcInstDecls]{Typechecking instance declarations}
\begin{code}
-module TcInstDcls (
- tcInstDecls1,
- tcInstDecls2
- ) where
+module TcInstDcls ( tcInstDecls1, tcInstDecls2, tcAddDeclCtxt ) where
#include "HsVersions.h"
-import HsSyn ( HsDecl(..), InstDecl(..),
- HsBinds(..), MonoBinds(..), GRHSsAndBinds(..), GRHS(..),
- HsExpr(..), InPat(..), HsLit(..), Sig(..),
- unguardedRHS,
- collectMonoBinders, andMonoBinds
- )
-import HsBinds ( sigsForMe )
-import RnHsSyn ( RenamedHsBinds, RenamedMonoBinds,
- RenamedInstDecl, RenamedHsExpr,
- RenamedSig, RenamedHsDecl
+
+import CmdLineOpts ( DynFlag(..) )
+
+import HsSyn ( HsDecl(..), InstDecl(..), TyClDecl(..), HsType(..),
+ MonoBinds(..), HsExpr(..), HsLit(..), Sig(..), HsTyVarBndr(..),
+ andMonoBindList, collectMonoBinders,
+ isClassDecl, isIfaceInstDecl, toHsType
)
-import TcHsSyn ( TcMonoBinds, TcIdOcc(..), TcIdBndr,
- maybeBoxedPrimType, tcIdType
+import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedHsDecl,
+ RenamedMonoBinds, RenamedTyClDecl, RenamedHsType,
+ extractHsTyVars, maybeGenericMatch
)
-
-import TcBinds ( tcPragmaSigs )
+import TcHsSyn ( TcMonoBinds, mkHsConApp )
+import TcBinds ( tcSpecSigs )
import TcClassDcl ( tcMethodBind, badMethodErr )
-import TcMonad
-import RnMonad ( RnNameSupply )
-import Inst ( Inst, InstOrigin(..),
- newDicts, LIE, emptyLIE, plusLIE, plusLIEs )
-import TcDeriv ( tcDeriving )
-import TcEnv ( GlobalValueEnv, tcExtendGlobalValEnv, tcAddImportedIdInfo )
-import TcInstUtil ( InstInfo(..), mkInstanceRelatedIds, classDataCon )
-import TcKind ( TcKind, unifyKind )
-import TcMonoType ( tcHsType )
-import TcSimplify ( tcSimplifyAndCheck )
-import TcType ( TcType, TcTyVar, TcTyVarSet,
- zonkSigTyVar, tcInstSigType, tcInstTheta
+import TcMonad
+import TcMType ( tcInstSigType, checkValidTheta, checkValidInstHead, instTypeErr,
+ UserTypeCtxt(..), SourceTyCtxt(..) )
+import TcType ( mkClassPred, mkTyVarTy, mkTyVarTys, tcSplitForAllTys,
+ tcSplitSigmaTy, getClassPredTys, tcSplitPredTy_maybe,
+ TyVarDetails(..)
)
-
-import Bag ( emptyBag, unitBag, unionBags, unionManyBags,
- foldBag, bagToList, Bag
+import Inst ( InstOrigin(..), newDicts, instToId,
+ LIE, mkLIE, emptyLIE, plusLIE, plusLIEs )
+import TcDeriv ( tcDeriving )
+import TcEnv ( TcEnv, tcExtendGlobalValEnv,
+ tcExtendTyVarEnvForMeths, tcLookupId, tcLookupClass,
+ InstInfo(..), pprInstInfo, simpleInstInfoTyCon,
+ simpleInstInfoTy, newDFunName
)
-import CmdLineOpts ( opt_GlasgowExts )
-import Class ( classBigSig, Class )
-import Id ( isNullaryDataCon, dataConArgTys, replaceIdInfo, idName, idType, Id )
-import Maybes ( maybeToBool, seqMaybe, catMaybes, expectJust )
-import Name ( nameOccName, mkLocalName,
- isLocallyDefined, Module,
- NamedThing(..)
+import InstEnv ( InstEnv, extendInstEnv )
+import PprType ( pprClassPred )
+import TcMonoType ( tcHsTyVars, kcHsSigType, tcHsType, tcHsSigType )
+import TcUnify ( checkSigTyVars )
+import TcSimplify ( tcSimplifyCheck )
+import HscTypes ( HomeSymbolTable, DFunId,
+ ModDetails(..), PackageInstEnv, PersistentRenamerState
)
-import PrelVals ( eRROR_ID )
-import PprType ( pprParendType, pprConstraint )
-import SrcLoc ( SrcLoc, noSrcLoc )
-import TyCon ( isSynTyCon, isDataTyCon, tyConDerivings )
-import Type ( Type, ThetaType, isUnpointedType,
- splitSigmaTy, isTyVarTy, mkSigmaTy,
- splitTyConApp_maybe, splitDictTy_maybe,
- splitAlgTyConApp_maybe, splitRhoTy,
- tyVarsOfTypes, mkTyVarTys,
+import Subst ( substTy, substTheta )
+import DataCon ( classDataCon )
+import Class ( Class, classBigSig )
+import Var ( idName, idType )
+import VarSet ( emptyVarSet )
+import Id ( setIdLocalExported )
+import MkId ( mkDictFunId, unsafeCoerceId, eRROR_ID )
+import FunDeps ( checkInstFDs )
+import Generics ( validGenericInstanceType )
+import Module ( Module, foldModuleEnv )
+import Name ( getSrcLoc )
+import NameSet ( unitNameSet, emptyNameSet, nameSetToList )
+import TyCon ( TyCon )
+import Subst ( mkTopTyVarSubst, substTheta )
+import TysWiredIn ( genericTyCons )
+import Name ( Name )
+import SrcLoc ( SrcLoc )
+import Unique ( Uniquable(..) )
+import Util ( lengthExceeds, isSingleton )
+import BasicTypes ( NewOrData(..), Fixity )
+import ErrUtils ( dumpIfSet_dyn )
+import ListSetOps ( Assoc, emptyAssoc, plusAssoc_C, mapAssoc,
+ assocElts, extendAssoc_C, equivClassesByUniq, minusList
)
-import TyVar ( zipTyVarEnv, mkTyVarSet, tyVarSetToList, TyVar )
-import TysPrim ( byteArrayPrimTyCon, mutableByteArrayPrimTyCon )
-import TysWiredIn ( stringTy )
-import Unique ( Unique, cCallableClassKey, cReturnableClassKey, Uniquable(..) )
+import Maybe ( catMaybes )
+import List ( partition )
import Outputable
\end{code}
and $dbinds_super$ bind the superclass dictionaries sd1 \ldots sdm.
\end{enumerate}
+
+%************************************************************************
+%* *
+\subsection{Extracting instance decls}
+%* *
+%************************************************************************
+
+Gather up the instance declarations from their various sources
+
\begin{code}
-tcInstDecls1 :: GlobalValueEnv -- Contains IdInfo for dfun ids
+tcInstDecls1 :: PackageInstEnv
+ -> PersistentRenamerState
+ -> HomeSymbolTable -- Contains instances
+ -> TcEnv -- Contains IdInfo for dfun ids
+ -> (Name -> Maybe Fixity) -- for deriving Show and Read
+ -> Module -- Module for deriving
-> [RenamedHsDecl]
- -> Module -- module name for deriving
- -> RnNameSupply -- for renaming derivings
- -> TcM s (Bag InstInfo,
- RenamedHsBinds,
- SDoc)
-
-tcInstDecls1 unf_env decls mod_name rn_name_supply
- = -- Do the ordinary instance declarations
- mapNF_Tc (tcInstDecl1 unf_env mod_name)
- [inst_decl | InstD inst_decl <- decls] `thenNF_Tc` \ inst_info_bags ->
+ -> TcM (PackageInstEnv, InstEnv, [InstInfo], RenamedHsBinds)
+
+tcInstDecls1 inst_env0 prs hst unf_env get_fixity this_mod decls
+ = let
+ inst_decls = [inst_decl | InstD inst_decl <- decls]
+ tycl_decls = [decl | TyClD decl <- decls]
+ clas_decls = filter isClassDecl tycl_decls
+ (imported_inst_ds, local_inst_ds) = partition isIfaceInstDecl inst_decls
+ in
+ -- (1) Do the ordinary instance declarations
+ mapNF_Tc tcLocalInstDecl1 local_inst_ds `thenNF_Tc` \ local_inst_infos ->
+ mapNF_Tc tcImportedInstDecl1 imported_inst_ds `thenNF_Tc` \ imported_dfuns ->
+
+ -- (2) Instances from generic class declarations
+ getGenericInstances clas_decls `thenTc` \ generic_inst_info ->
+
+ -- Next, construct the instance environment so far, consisting of
+ -- a) cached non-home-package InstEnv (gotten from pcs) pcs_insts pcs
+ -- b) imported instance decls (not in the home package) inst_env1
+ -- c) other modules in this package (gotten from hst) inst_env2
+ -- d) local instance decls inst_env3
+ -- e) generic instances inst_env4
+ -- The result of (b) replaces the cached InstEnv in the PCS
+ let
+ local_inst_info = catMaybes local_inst_infos
+ hst_dfuns = foldModuleEnv ((++) . md_insts) [] hst
+ in
+
+-- pprTrace "tcInstDecls" (vcat [ppr imported_dfuns, ppr hst_dfuns]) $
+
+ addInstDFuns inst_env0 imported_dfuns `thenNF_Tc` \ inst_env1 ->
+ addInstDFuns inst_env1 hst_dfuns `thenNF_Tc` \ inst_env2 ->
+ addInstInfos inst_env2 local_inst_info `thenNF_Tc` \ inst_env3 ->
+ addInstInfos inst_env3 generic_inst_info `thenNF_Tc` \ inst_env4 ->
+
+ -- (3) Compute instances from "deriving" clauses;
+ -- note that we only do derivings for things in this module;
+ -- we ignore deriving decls from interfaces!
+ -- This stuff computes a context for the derived instance decl, so it
+ -- needs to know about all the instances possible; hence inst_env4
+ tcDeriving prs this_mod inst_env4 get_fixity tycl_decls
+ `thenTc` \ (deriv_inst_info, deriv_binds) ->
+ addInstInfos inst_env4 deriv_inst_info `thenNF_Tc` \ final_inst_env ->
+
+ returnTc (inst_env1,
+ final_inst_env,
+ generic_inst_info ++ deriv_inst_info ++ local_inst_info,
+ deriv_binds)
+
+addInstInfos :: InstEnv -> [InstInfo] -> NF_TcM InstEnv
+addInstInfos inst_env infos = addInstDFuns inst_env (map iDFunId infos)
+
+addInstDFuns :: InstEnv -> [DFunId] -> NF_TcM InstEnv
+addInstDFuns inst_env dfuns
+ = getDOptsTc `thenNF_Tc` \ dflags ->
let
- decl_inst_info = unionManyBags inst_info_bags
+ (inst_env', errs) = extendInstEnv dflags inst_env dfuns
in
- -- Handle "derived" instances; note that we only do derivings
- -- for things in this module; we ignore deriving decls from
- -- interfaces!
- tcDeriving mod_name rn_name_supply decl_inst_info
- `thenTc` \ (deriv_inst_info, deriv_binds, ddump_deriv) ->
+ addErrsTc errs `thenNF_Tc_`
+ traceTc (text "Adding instances:" <+> vcat (map pp dfuns)) `thenTc_`
+ returnTc inst_env'
+ where
+ pp dfun = ppr dfun <+> dcolon <+> ppr (idType dfun)
+\end{code}
+
+\begin{code}
+tcImportedInstDecl1 :: RenamedInstDecl -> NF_TcM DFunId
+ -- An interface-file instance declaration
+ -- Should be in scope by now, because we should
+ -- have sucked in its interface-file definition
+ -- So it will be replete with its unfolding etc
+tcImportedInstDecl1 decl@(InstDecl poly_ty binds uprags (Just dfun_name) src_loc)
+ = tcLookupId dfun_name
+
+
+tcLocalInstDecl1 :: RenamedInstDecl
+ -> NF_TcM (Maybe InstInfo) -- Nothing if there was an error
+ -- A source-file instance declaration
+ -- Type-check all the stuff before the "where"
+ --
+ -- We check for respectable instance type, and context
+ -- but only do this for non-imported instance decls.
+ -- Imported ones should have been checked already, and may indeed
+ -- contain something illegal in normal Haskell, notably
+ -- instance CCallable [Char]
+tcLocalInstDecl1 decl@(InstDecl poly_ty binds uprags Nothing src_loc)
+ = -- Prime error recovery, set source location
+ recoverNF_Tc (returnNF_Tc Nothing) $
+ tcAddSrcLoc src_loc $
+ tcAddErrCtxt (instDeclCtxt poly_ty) $
+ -- Typecheck the instance type itself. We can't use
+ -- tcHsSigType, because it's not a valid user type.
+ kcHsSigType poly_ty `thenTc_`
+ tcHsType poly_ty `thenTc` \ poly_ty' ->
let
- full_inst_info = deriv_inst_info `unionBags` decl_inst_info
+ (tyvars, theta, tau) = tcSplitSigmaTy poly_ty'
in
- returnTc (full_inst_info, deriv_binds, ddump_deriv)
+ checkValidTheta InstThetaCtxt theta `thenTc_`
+ checkValidInstHead tau `thenTc` \ (clas,inst_tys) ->
+ checkTc (checkInstFDs theta clas inst_tys)
+ (instTypeErr (pprClassPred clas inst_tys) msg) `thenTc_`
+ newDFunName clas inst_tys src_loc `thenNF_Tc` \ dfun_name ->
+ returnTc (Just (InstInfo { iDFunId = mkDictFunId dfun_name clas tyvars inst_tys theta,
+ iBinds = binds, iPrags = uprags }))
+ where
+ msg = parens (ptext SLIT("the instance types do not agree with the functional dependencies of the class"))
+\end{code}
-tcInstDecl1 :: GlobalValueEnv -> Module -> RenamedInstDecl -> NF_TcM s (Bag InstInfo)
+%************************************************************************
+%* *
+\subsection{Extracting generic instance declaration from class declarations}
+%* *
+%************************************************************************
-tcInstDecl1 unf_env mod_name (InstDecl poly_ty binds uprags (Just dfun_name) src_loc)
- = -- Prime error recovery, set source location
- recoverNF_Tc (returnNF_Tc emptyBag) $
- tcAddSrcLoc src_loc $
+@getGenericInstances@ extracts the generic instance declarations from a class
+declaration. For exmaple
- -- Type-check all the stuff before the "where"
- tcHsType poly_ty `thenTc` \ poly_ty' ->
+ class C a where
+ op :: a -> a
+
+ op{ x+y } (Inl v) = ...
+ op{ x+y } (Inr v) = ...
+ op{ x*y } (v :*: w) = ...
+ op{ 1 } Unit = ...
+
+gives rise to the instance declarations
+
+ instance C (x+y) where
+ op (Inl v) = ...
+ op (Inr v) = ...
+
+ instance C (x*y) where
+ op (v :*: w) = ...
+
+ instance C 1 where
+ op Unit = ...
+
+
+\begin{code}
+getGenericInstances :: [RenamedTyClDecl] -> TcM [InstInfo]
+getGenericInstances class_decls
+ = mapTc get_generics class_decls `thenTc` \ gen_inst_infos ->
+ let
+ gen_inst_info = concat gen_inst_infos
+ in
+ if null gen_inst_info then
+ returnTc []
+ else
+ getDOptsTc `thenNF_Tc` \ dflags ->
+ ioToTc (dumpIfSet_dyn dflags Opt_D_dump_deriv "Generic instances"
+ (vcat (map pprInstInfo gen_inst_info)))
+ `thenNF_Tc_`
+ returnTc gen_inst_info
+
+get_generics decl@(ClassDecl {tcdMeths = Nothing})
+ = returnTc [] -- Imported class decls
+
+get_generics decl@(ClassDecl {tcdName = class_name, tcdMeths = Just def_methods, tcdLoc = loc})
+ | null groups
+ = returnTc [] -- The comon case: no generic default methods
+
+ | otherwise -- A source class decl with generic default methods
+ = recoverNF_Tc (returnNF_Tc []) $
+ tcAddDeclCtxt decl $
+ tcLookupClass class_name `thenTc` \ clas ->
+
+ -- Make an InstInfo out of each group
+ mapTc (mkGenericInstance clas loc) groups `thenTc` \ inst_infos ->
+
+ -- Check that there is only one InstInfo for each type constructor
+ -- The main way this can fail is if you write
+ -- f {| a+b |} ... = ...
+ -- f {| x+y |} ... = ...
+ -- Then at this point we'll have an InstInfo for each
+ let
+ tc_inst_infos :: [(TyCon, InstInfo)]
+ tc_inst_infos = [(simpleInstInfoTyCon i, i) | i <- inst_infos]
+
+ bad_groups = [group | group <- equivClassesByUniq get_uniq tc_inst_infos,
+ group `lengthExceeds` 1]
+ get_uniq (tc,_) = getUnique tc
+ in
+ mapTc (addErrTc . dupGenericInsts) bad_groups `thenTc_`
+
+ -- Check that there is an InstInfo for each generic type constructor
+ let
+ missing = genericTyCons `minusList` [tc | (tc,_) <- tc_inst_infos]
+ in
+ checkTc (null missing) (missingGenericInstances missing) `thenTc_`
+
+ returnTc inst_infos
+
+ where
+ -- Group the declarations by type pattern
+ groups :: [(RenamedHsType, RenamedMonoBinds)]
+ groups = assocElts (getGenericBinds def_methods)
+
+
+---------------------------------
+getGenericBinds :: RenamedMonoBinds -> Assoc RenamedHsType RenamedMonoBinds
+ -- Takes a group of method bindings, finds the generic ones, and returns
+ -- them in finite map indexed by the type parameter in the definition.
+
+getGenericBinds EmptyMonoBinds = emptyAssoc
+getGenericBinds (AndMonoBinds m1 m2)
+ = plusAssoc_C AndMonoBinds (getGenericBinds m1) (getGenericBinds m2)
+
+getGenericBinds (FunMonoBind id infixop matches loc)
+ = mapAssoc wrap (foldl add emptyAssoc matches)
+ -- Using foldl not foldr is vital, else
+ -- we reverse the order of the bindings!
+ where
+ add env match = case maybeGenericMatch match of
+ Nothing -> env
+ Just (ty, match') -> extendAssoc_C (++) env (ty, [match'])
+
+ wrap ms = FunMonoBind id infixop ms loc
+
+---------------------------------
+mkGenericInstance :: Class -> SrcLoc
+ -> (RenamedHsType, RenamedMonoBinds)
+ -> TcM InstInfo
+
+mkGenericInstance clas loc (hs_ty, binds)
+ -- Make a generic instance declaration
+ -- For example: instance (C a, C b) => C (a+b) where { binds }
+
+ = -- Extract the universally quantified type variables
let
- (tyvars, theta, dict_ty) = splitSigmaTy poly_ty'
- (clas, inst_tys) = case splitDictTy_maybe dict_ty of
- Nothing -> pprPanic "tcInstDecl1" (ppr poly_ty)
- Just pair -> pair
+ sig_tvs = map UserTyVar (nameSetToList (extractHsTyVars hs_ty))
in
+ tcHsTyVars sig_tvs (kcHsSigType hs_ty) $ \ tyvars ->
- -- Check for respectable instance type, and context
- scrutiniseInstanceHead clas inst_tys `thenNF_Tc_`
- mapNF_Tc scrutiniseInstanceConstraint theta `thenNF_Tc_`
+ -- Type-check the instance type, and check its form
+ tcHsSigType GenPatCtxt hs_ty `thenTc` \ inst_ty ->
+ checkTc (validGenericInstanceType inst_ty)
+ (badGenericInstanceType binds) `thenTc_`
- -- Make the dfun id and constant-method ids
+ -- Make the dictionary function.
+ newDFunName clas [inst_ty] loc `thenNF_Tc` \ dfun_name ->
let
- (dfun_id, dfun_theta) = mkInstanceRelatedIds dfun_name
- clas tyvars inst_tys theta
- -- Add info from interface file
- final_dfun_id = tcAddImportedIdInfo unf_env dfun_id
+ inst_theta = [mkClassPred clas [mkTyVarTy tv] | tv <- tyvars]
+ dfun_id = mkDictFunId dfun_name clas tyvars [inst_ty] inst_theta
in
- returnTc (unitBag (InstInfo clas tyvars inst_tys theta
- dfun_theta final_dfun_id
- binds src_loc uprags))
+
+ returnTc (InstInfo { iDFunId = dfun_id, iBinds = binds, iPrags = [] })
\end{code}
%************************************************************************
\begin{code}
-tcInstDecls2 :: Bag InstInfo
- -> NF_TcM s (LIE s, TcMonoBinds s)
+tcInstDecls2 :: [InstInfo]
+ -> NF_TcM (LIE, TcMonoBinds)
tcInstDecls2 inst_decls
- = foldBag combine tcInstDecl2 (returnNF_Tc (emptyLIE, EmptyMonoBinds)) inst_decls
+-- = foldBag combine tcInstDecl2 (returnNF_Tc (emptyLIE, EmptyMonoBinds)) inst_decls
+ = foldr combine (returnNF_Tc (emptyLIE, EmptyMonoBinds))
+ (map tcInstDecl2 inst_decls)
where
combine tc1 tc2 = tc1 `thenNF_Tc` \ (lie1, binds1) ->
tc2 `thenNF_Tc` \ (lie2, binds2) ->
binds1 `AndMonoBinds` binds2)
\end{code}
-
======= New documentation starts here (Sept 92) ==============
The main purpose of @tcInstDecl2@ is to return a @HsBinds@ which defines
First comes the easy case of a non-local instance decl.
+
\begin{code}
-tcInstDecl2 :: InstInfo -> NF_TcM s (LIE s, TcMonoBinds s)
-
-tcInstDecl2 (InstInfo clas inst_tyvars inst_tys
- inst_decl_theta dfun_theta
- dfun_id monobinds
- locn uprags)
- | not (isLocallyDefined dfun_id)
- = returnNF_Tc (emptyLIE, EmptyMonoBinds)
-
-{-
- -- I deleted this "optimisation" because when importing these
- -- instance decls the renamer would look for the dfun bindings and they weren't there.
- -- This would be fixable, but it seems simpler just to produce a tiny void binding instead,
- -- even though it's never used.
-
- -- This case deals with CCallable etc, which don't need any bindings
- | isNoDictClass clas
- = returnNF_Tc (emptyLIE, EmptyBinds)
--}
-
- | otherwise
+tcInstDecl2 :: InstInfo -> TcM (LIE, TcMonoBinds)
+
+tcInstDecl2 (NewTypeDerived { iDFunId = dfun_id })
+ = tcInstSigType InstTv (idType dfun_id) `thenNF_Tc` \ (inst_tyvars', dfun_theta', inst_head') ->
+ newDicts InstanceDeclOrigin dfun_theta' `thenNF_Tc` \ rep_dicts ->
+ let
+ rep_dict_id = ASSERT( isSingleton rep_dicts )
+ instToId (head rep_dicts) -- Derived newtypes have just one dict arg
+
+ body = TyLam inst_tyvars' $
+ DictLam [rep_dict_id] $
+ (HsVar unsafeCoerceId `TyApp` [idType rep_dict_id, inst_head'])
+ `HsApp`
+ (HsVar rep_dict_id)
+ -- You might wonder why we have the 'coerce'. It's because the
+ -- type equality mechanism isn't clever enough; see comments with Type.eqType.
+ -- So Lint complains if we don't have this.
+ in
+ returnTc (emptyLIE, VarMonoBind dfun_id body)
+
+tcInstDecl2 (InstInfo { iDFunId = dfun_id, iBinds = monobinds, iPrags = uprags })
= -- Prime error recovery
- recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $
- tcAddSrcLoc locn $
+ recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $
+ tcAddSrcLoc (getSrcLoc dfun_id) $
+ tcAddErrCtxt (instDeclCtxt (toHsType (idType dfun_id))) $
-- Instantiate the instance decl with tc-style type variables
- tcInstSigType (idType dfun_id) `thenNF_Tc` \ dfun_ty' ->
+ tcInstSigType InstTv (idType dfun_id) `thenNF_Tc` \ (inst_tyvars', dfun_theta', inst_head') ->
let
- (inst_tyvars',
- dfun_theta', dict_ty') = splitSigmaTy dfun_ty'
+ Just pred = tcSplitPredTy_maybe inst_head'
+ (clas, inst_tys') = getClassPredTys pred
+ (class_tyvars, sc_theta, _, op_items) = classBigSig clas
- (clas, inst_tys') = expectJust "tcInstDecl2" (splitDictTy_maybe dict_ty')
+ sel_names = [idName sel_id | (sel_id, _) <- op_items]
- (class_tyvars,
- sc_theta, sc_sel_ids,
- op_sel_ids, defm_ids) = classBigSig clas
+ -- Instantiate the super-class context with inst_tys
+ sc_theta' = substTheta (mkTopTyVarSubst class_tyvars inst_tys') sc_theta
- origin = InstanceDeclOrigin
+ -- Find any definitions in monobinds that aren't from the class
+ bad_bndrs = collectMonoBinders monobinds `minusList` sel_names
+ (inst_tyvars, _) = tcSplitForAllTys (idType dfun_id)
+ origin = InstanceDeclOrigin
in
- -- Instantiate the theta found in the original instance decl
- tcInstTheta (zipTyVarEnv inst_tyvars (mkTyVarTys inst_tyvars'))
- inst_decl_theta `thenNF_Tc` \ inst_decl_theta' ->
-
- -- Instantiate the super-class context with the instance types
- tcInstTheta (zipTyVarEnv class_tyvars inst_tys') sc_theta `thenNF_Tc` \ sc_theta' ->
-
- -- Create dictionary Ids from the specified instance contexts.
- newDicts origin sc_theta' `thenNF_Tc` \ (sc_dicts, sc_dict_ids) ->
- newDicts origin dfun_theta' `thenNF_Tc` \ (dfun_arg_dicts, dfun_arg_dicts_ids) ->
- newDicts origin inst_decl_theta' `thenNF_Tc` \ (inst_decl_dicts, _) ->
- newDicts origin [(clas,inst_tys')] `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
-
-- Check that all the method bindings come from this class
- let
- check_from_this_class (bndr, loc)
- | nameOccName bndr `elem` sel_names = returnNF_Tc ()
- | otherwise = tcAddSrcLoc loc $
- addErrTc (badMethodErr bndr clas)
- sel_names = map getOccName op_sel_ids
- bndrs = bagToList (collectMonoBinders monobinds)
- in
- mapNF_Tc check_from_this_class bndrs `thenNF_Tc_`
-
- tcExtendGlobalValEnv (catMaybes defm_ids) (
-
- -- Default-method Ids may be mentioned in synthesised RHSs
- mapAndUnzip3Tc (tcMethodBind clas origin inst_tys' inst_tyvars' monobinds uprags True)
- (op_sel_ids `zip` defm_ids)
- ) `thenTc` \ (method_binds_s, insts_needed_s, meth_lies_w_ids) ->
+ mapTc (addErrTc . badMethodErr clas) bad_bndrs `thenNF_Tc_`
- -- Deal with SPECIALISE instance pragmas
+ -- Create dictionary Ids from the specified instance contexts.
+ newDicts origin sc_theta' `thenNF_Tc` \ sc_dicts ->
+ newDicts origin dfun_theta' `thenNF_Tc` \ dfun_arg_dicts ->
+ newDicts origin [mkClassPred clas inst_tys'] `thenNF_Tc` \ [this_dict] ->
+
+ tcExtendTyVarEnvForMeths inst_tyvars inst_tyvars' (
+ -- The type variable from the dict fun actually scope
+ -- over the bindings. They were gotten from
+ -- the original instance declaration
+
+ -- Default-method Ids may be mentioned in synthesised RHSs,
+ -- but they'll already be in the environment.
+
+ mapAndUnzip3Tc (tcMethodBind clas origin inst_tyvars' inst_tys'
+ dfun_theta'
+ monobinds uprags True)
+ op_items
+ ) `thenTc` \ (method_binds_s, insts_needed_s, meth_insts) ->
+
+ -- Deal with SPECIALISE instance pragmas by making them
+ -- look like SPECIALISE pragmas for the dfun
let
- dfun_prags = [Sig (idName dfun_id) ty loc | SpecInstSig ty loc <- uprags]
+ dfun_prags = [SpecSig (idName dfun_id) ty loc | SpecInstSig ty loc <- uprags]
in
tcExtendGlobalValEnv [dfun_id] (
- tcPragmaSigs dfun_prags
- ) `thenTc` \ (prag_info_fn, prag_binds, prag_lie) ->
+ tcSpecSigs dfun_prags
+ ) `thenTc` \ (prag_binds, prag_lie) ->
-- Check the overloading constraints of the methods and superclasses
- mapNF_Tc zonkSigTyVar inst_tyvars' `thenNF_Tc` \ zonked_inst_tyvars ->
-
let
- inst_tyvars_set = mkTyVarSet zonked_inst_tyvars
-
- (meth_lies, meth_ids) = unzip meth_lies_w_ids
-
-- These insts are in scope; quite a few, eh?
- avail_insts = this_dict `plusLIE`
- dfun_arg_dicts `plusLIE`
- sc_dicts `plusLIE`
- unionManyBags meth_lies
+ avail_insts = [this_dict] ++
+ dfun_arg_dicts ++
+ sc_dicts ++
+ meth_insts
- methods_lie = plusLIEs insts_needed_s
+ methods_lie = plusLIEs insts_needed_s
in
- -- Ditto method bindings
+ -- Simplify the constraints from methods
tcAddErrCtxt methodCtxt (
- tcSimplifyAndCheck
+ tcSimplifyCheck
(ptext SLIT("instance declaration context"))
- inst_tyvars_set -- Local tyvars
+ inst_tyvars'
avail_insts
methods_lie
) `thenTc` \ (const_lie1, lie_binds1) ->
- -- Check that we *could* construct the superclass dictionaries,
- -- even though we are *actually* going to pass the superclass dicts in;
- -- the check ensures that the caller will never have
- --a problem building them.
+ -- Figure out bindings for the superclass context
tcAddErrCtxt superClassCtxt (
- tcSimplifyAndCheck
- (ptext SLIT("instance declaration context"))
- inst_tyvars_set -- Local tyvars
- inst_decl_dicts -- The instance dictionaries available
- sc_dicts -- The superclass dicationaries reqd
- ) `thenTc_`
- -- Ignore the result; we're only doing
- -- this to make sure it can be done.
-
- -- Now do the simplification again, this time to get the
- -- bindings; this time we use an enhanced "avails"
- -- Ignore errors because they come from the *previous* tcSimplify
- discardErrsTc (
- tcSimplifyAndCheck
+ tcSimplifyCheck
(ptext SLIT("instance declaration context"))
- inst_tyvars_set
+ inst_tyvars'
dfun_arg_dicts -- NB! Don't include this_dict here, else the sc_dicts
-- get bound by just selecting from this_dict!!
- sc_dicts
- ) `thenTc` \ (const_lie2, lie_binds2) ->
-
+ (mkLIE sc_dicts)
+ ) `thenTc` \ (const_lie2, lie_binds2) ->
+
+ checkSigTyVars inst_tyvars' emptyVarSet `thenNF_Tc` \ zonked_inst_tyvars ->
-- Create the result bindings
let
+ local_dfun_id = setIdLocalExported dfun_id
+ -- Reason for setIdLocalExported: see notes with MkId.mkDictFunId
+
dict_constr = classDataCon clas
- scs_and_meths = sc_dict_ids ++ meth_ids
+ scs_and_meths = map instToId (sc_dicts ++ meth_insts)
+ this_dict_id = instToId this_dict
+ inlines | null dfun_arg_dicts = emptyNameSet
+ | otherwise = unitNameSet (idName dfun_id)
+ -- Always inline the dfun; this is an experimental decision
+ -- because it makes a big performance difference sometimes.
+ -- Often it means we can do the method selection, and then
+ -- inline the method as well. Marcin's idea; see comments below.
+ --
+ -- BUT: don't inline it if it's a constant dictionary;
+ -- we'll get all the benefit without inlining, and we get
+ -- a **lot** of code duplication if we inline it
dict_rhs
| null scs_and_meths
-- emit an error message. This in turn means that we don't
-- mention the constructor, which doesn't exist for CCallable, CReturnable
-- Hardly beautiful, but only three extra lines.
- HsApp (TyApp (HsVar (RealId eRROR_ID)) [tcIdType this_dict_id])
- (HsLitOut (HsString msg) stringTy)
+ HsApp (TyApp (HsVar eRROR_ID) [idType this_dict_id])
+ (HsLit (HsString msg))
| otherwise -- The common case
- = HsCon dict_constr inst_tys' (map HsVar (sc_dict_ids ++ meth_ids))
+ = mkHsConApp dict_constr inst_tys' (map HsVar scs_and_meths)
-- We don't produce a binding for the dict_constr; instead we
- -- just generate the saturated constructor directly
+ -- rely on the simplifier to unfold this saturated application
+ -- We do this rather than generate an HsCon directly, because
+ -- it means that the special cases (e.g. dictionary with only one
+ -- member) are dealt with by the common MkId.mkDataConWrapId code rather
+ -- than needing to be repeated here.
+
where
msg = _PK_ ("Compiler error: bad dictionary " ++ showSDoc (ppr clas))
dict_bind = VarMonoBind this_dict_id dict_rhs
- method_binds = andMonoBinds method_binds_s
+ method_binds = andMonoBindList method_binds_s
- final_dfun_id = replaceIdInfo dfun_id (prag_info_fn (idName dfun_id))
- -- Pretty truesome
main_bind
= AbsBinds
zonked_inst_tyvars
- dfun_arg_dicts_ids
- [(inst_tyvars', RealId final_dfun_id, this_dict_id)]
+ (map instToId dfun_arg_dicts)
+ [(inst_tyvars', local_dfun_id, this_dict_id)]
+ inlines
(lie_binds1 `AndMonoBinds`
lie_binds2 `AndMonoBinds`
method_binds `AndMonoBinds`
main_bind `AndMonoBinds` prag_binds)
\end{code}
+ ------------------------------
+ Inlining dfuns unconditionally
+ ------------------------------
+
+The code above unconditionally inlines dict funs. Here's why.
+Consider this program:
+
+ test :: Int -> Int -> Bool
+ test x y = (x,y) == (y,x) || test y x
+ -- Recursive to avoid making it inline.
+
+This needs the (Eq (Int,Int)) instance. If we inline that dfun
+the code we end up with is good:
+
+ Test.$wtest =
+ \r -> case ==# [ww ww1] of wild {
+ PrelBase.False -> Test.$wtest ww1 ww;
+ PrelBase.True ->
+ case ==# [ww1 ww] of wild1 {
+ PrelBase.False -> Test.$wtest ww1 ww;
+ PrelBase.True -> PrelBase.True [];
+ };
+ };
+ Test.test = \r [w w1]
+ case w of w2 {
+ PrelBase.I# ww ->
+ case w1 of w3 { PrelBase.I# ww1 -> Test.$wtest ww ww1; };
+ };
+
+If we don't inline the dfun, the code is not nearly as good:
+
+ (==) = case PrelTup.$fEq(,) PrelBase.$fEqInt PrelBase.$fEqInt of tpl {
+ PrelBase.:DEq tpl1 tpl2 -> tpl2;
+ };
+
+ Test.$wtest =
+ \r [ww ww1]
+ let { y = PrelBase.I#! [ww1]; } in
+ let { x = PrelBase.I#! [ww]; } in
+ let { sat_slx = PrelTup.(,)! [y x]; } in
+ let { sat_sly = PrelTup.(,)! [x y];
+ } in
+ case == sat_sly sat_slx of wild {
+ PrelBase.False -> Test.$wtest ww1 ww;
+ PrelBase.True -> PrelBase.True [];
+ };
+
+ Test.test =
+ \r [w w1]
+ case w of w2 {
+ PrelBase.I# ww ->
+ case w1 of w3 { PrelBase.I# ww1 -> Test.$wtest ww ww1; };
+ };
+
+Why doesn't GHC inline $fEq? Because it looks big:
+
+ PrelTup.zdfEqZ1T{-rcX-}
+ = \ @ a{-reT-} :: * @ b{-reS-} :: *
+ zddEq{-rf6-} _Ks :: {PrelBase.Eq{-23-} a{-reT-}}
+ zddEq1{-rf7-} _Ks :: {PrelBase.Eq{-23-} b{-reS-}} ->
+ let {
+ zeze{-rf0-} _Kl :: (b{-reS-} -> b{-reS-} -> PrelBase.Bool{-3c-})
+ zeze{-rf0-} = PrelBase.zeze{-01L-}@ b{-reS-} zddEq1{-rf7-} } in
+ let {
+ zeze1{-rf3-} _Kl :: (a{-reT-} -> a{-reT-} -> PrelBase.Bool{-3c-})
+ zeze1{-rf3-} = PrelBase.zeze{-01L-} @ a{-reT-} zddEq{-rf6-} } in
+ let {
+ zeze2{-reN-} :: ((a{-reT-}, b{-reS-}) -> (a{-reT-}, b{-reS-})-> PrelBase.Bool{-3c-})
+ zeze2{-reN-} = \ ds{-rf5-} _Ks :: (a{-reT-}, b{-reS-})
+ ds1{-rf4-} _Ks :: (a{-reT-}, b{-reS-}) ->
+ case ds{-rf5-}
+ of wild{-reW-} _Kd { (a1{-rf2-} _Ks, a2{-reZ-} _Ks) ->
+ case ds1{-rf4-}
+ of wild1{-reX-} _Kd { (b1{-rf1-} _Ks, b2{-reY-} _Ks) ->
+ PrelBase.zaza{-r4e-}
+ (zeze1{-rf3-} a1{-rf2-} b1{-rf1-})
+ (zeze{-rf0-} a2{-reZ-} b2{-reY-})
+ }
+ } } in
+ let {
+ a1{-reR-} :: ((a{-reT-}, b{-reS-})-> (a{-reT-}, b{-reS-})-> PrelBase.Bool{-3c-})
+ a1{-reR-} = \ a2{-reV-} _Ks :: (a{-reT-}, b{-reS-})
+ b1{-reU-} _Ks :: (a{-reT-}, b{-reS-}) ->
+ PrelBase.not{-r6I-} (zeze2{-reN-} a2{-reV-} b1{-reU-})
+ } in
+ PrelBase.zdwZCDEq{-r8J-} @ (a{-reT-}, b{-reS-}) a1{-reR-} zeze2{-reN-})
+
+and it's not as bad as it seems, because it's further dramatically
+simplified: only zeze2 is extracted and its body is simplified.
+
%************************************************************************
%* *
-\subsection{Checking for a decent instance type}
+\subsection{Error messages}
%* *
%************************************************************************
-@scrutiniseInstanceHead@ checks the type {\em and} its syntactic constraints:
-it must normally look like: @instance Foo (Tycon a b c ...) ...@
-
-The exceptions to this syntactic checking: (1)~if the @GlasgowExts@
-flag is on, or (2)~the instance is imported (they must have been
-compiled elsewhere). In these cases, we let them go through anyway.
-
-We can also have instances for functions: @instance Foo (a -> b) ...@.
-
\begin{code}
-scrutiniseInstanceConstraint (clas, tys)
- | all isTyVarTy tys = returnNF_Tc ()
- | otherwise = addErrTc (instConstraintErr clas tys)
-
-scrutiniseInstanceHead clas inst_taus
- | -- CCALL CHECK (a).... urgh!
- -- To verify that a user declaration of a CCallable/CReturnable
- -- instance is OK, we must be able to see the constructor(s)
- -- of the instance type (see next guard.)
- --
- -- We flag this separately to give a more precise error msg.
- --
- (uniqueOf clas == cCallableClassKey || uniqueOf clas == cReturnableClassKey)
- && is_alg_tycon_app && not constructors_visible
- = addErrTc (invisibleDataConPrimCCallErr clas first_inst_tau)
-
- | -- CCALL CHECK (b)
- -- A user declaration of a CCallable/CReturnable instance
- -- must be for a "boxed primitive" type.
- (uniqueOf clas == cCallableClassKey && not (ccallable_type first_inst_tau)) ||
- (uniqueOf clas == cReturnableClassKey && not (creturnable_type first_inst_tau))
- = addErrTc (nonBoxedPrimCCallErr clas first_inst_tau)
-
- -- DERIVING CHECK
- -- It is obviously illegal to have an explicit instance
- -- for something that we are also planning to `derive'
- | maybeToBool alg_tycon_app_maybe && clas `elem` (tyConDerivings alg_tycon)
- = addErrTc (derivingWhenInstanceExistsErr clas first_inst_tau)
- -- Kind check will have ensured inst_taus is of length 1
-
- -- WITH HASKELL 1.4, MUST HAVE C (T a b c)
- | not opt_GlasgowExts
- && not (length inst_taus == 1 &&
- maybeToBool maybe_tycon_app && -- Yes, there's a type constuctor
- not (isSynTyCon tycon) && -- ...but not a synonym
- all isTyVarTy arg_tys && -- Applied to type variables
- length (tyVarSetToList (tyVarsOfTypes arg_tys)) == length arg_tys
- -- This last condition checks that all the type variables are distinct
- )
- = addErrTc (instTypeErr clas inst_taus
- (text "the instance type must be of form (T a b c)" $$
- text "where T is not a synonym, and a,b,c are distinct type variables")
- )
-
- | otherwise
- = returnNF_Tc ()
-
- where
- (first_inst_tau : _) = inst_taus
-
- -- Stuff for algebraic or -> type
- maybe_tycon_app = splitTyConApp_maybe first_inst_tau
- Just (tycon, arg_tys) = maybe_tycon_app
-
- -- Stuff for an *algebraic* data type
- alg_tycon_app_maybe = splitAlgTyConApp_maybe first_inst_tau
- -- The "Alg" part looks through synonyms
- is_alg_tycon_app = maybeToBool alg_tycon_app_maybe
- Just (alg_tycon, _, data_cons) = alg_tycon_app_maybe
-
- constructors_visible = not (null data_cons)
-
-
--- These conditions come directly from what the DsCCall is capable of.
--- Totally grotesque. Green card should solve this.
-
-ccallable_type ty = isUnpointedType ty || -- Allow CCallable Int# etc
- maybeToBool (maybeBoxedPrimType ty) || -- Ditto Int etc
- ty == stringTy ||
- byte_arr_thing
+tcAddDeclCtxt decl thing_inside
+ = tcAddSrcLoc (tcdLoc decl) $
+ tcAddErrCtxt ctxt $
+ thing_inside
where
- byte_arr_thing = case splitAlgTyConApp_maybe ty of
- Just (tycon, ty_args, [data_con]) | isDataTyCon tycon ->
- length data_con_arg_tys == 2 &&
- maybeToBool maybe_arg2_tycon &&
- (arg2_tycon == byteArrayPrimTyCon ||
- arg2_tycon == mutableByteArrayPrimTyCon)
- where
- data_con_arg_tys = dataConArgTys data_con ty_args
- (data_con_arg_ty1 : data_con_arg_ty2 : _) = data_con_arg_tys
- maybe_arg2_tycon = splitTyConApp_maybe data_con_arg_ty2
- Just (arg2_tycon,_) = maybe_arg2_tycon
-
- other -> False
-
-creturnable_type ty = maybeToBool (maybeBoxedPrimType ty) ||
- -- Or, a data type with a single nullary constructor
- case (splitAlgTyConApp_maybe ty) of
- Just (tycon, tys_applied, [data_con])
- -> isNullaryDataCon data_con
- other -> False
+ thing = case decl of
+ ClassDecl {} -> "class"
+ TySynonym {} -> "type synonym"
+ TyData {tcdND = NewType} -> "newtype"
+ TyData {tcdND = DataType} -> "data type"
+
+ ctxt = hsep [ptext SLIT("In the"), text thing,
+ ptext SLIT("declaration for"), quotes (ppr (tcdName decl))]
+
+instDeclCtxt inst_ty = ptext SLIT("In the instance declaration for") <+> quotes doc
+ where
+ doc = case inst_ty of
+ HsForAllTy _ _ (HsPredTy pred) -> ppr pred
+ HsPredTy pred -> ppr pred
+ other -> ppr inst_ty -- Don't expect this
\end{code}
\begin{code}
-instConstraintErr clas tys
- = hang (ptext SLIT("Illegal constaint") <+>
- quotes (pprConstraint clas tys) <+>
- ptext SLIT("in instance context"))
- 4 (ptext SLIT("(Instance contexts must constrain only type variables)"))
-
-instTypeErr clas tys msg
- = sep [ptext SLIT("Illegal instance declaration for") <+> quotes (pprConstraint clas tys),
- nest 4 (parens msg)
+badGenericInstanceType binds
+ = vcat [ptext SLIT("Illegal type pattern in the generic bindings"),
+ nest 4 (ppr binds)]
+
+missingGenericInstances missing
+ = ptext SLIT("Missing type patterns for") <+> pprQuotedList missing
+
+dupGenericInsts tc_inst_infos
+ = vcat [ptext SLIT("More than one type pattern for a single generic type constructor:"),
+ nest 4 (vcat (map ppr_inst_ty tc_inst_infos)),
+ ptext SLIT("All the type patterns for a generic type constructor must be identical")
]
-
-derivingWhenInstanceExistsErr clas tycon
- = hang (hsep [ptext SLIT("Deriving class"),
- quotes (ppr clas),
- ptext SLIT("type"), quotes (ppr tycon)])
- 4 (ptext SLIT("when an explicit instance exists"))
-
-nonBoxedPrimCCallErr clas inst_ty
- = hang (ptext SLIT("Unacceptable instance type for ccall-ish class"))
- 4 (hsep [ ptext SLIT("class"), ppr clas, ptext SLIT("type"),
- ppr inst_ty])
-
-{-
- Declaring CCallable & CReturnable instances in a module different
- from where the type was defined. Caused by importing data type
- abstractly (either programmatically or by the renamer being over-eager
- in its pruning.)
--}
-invisibleDataConPrimCCallErr clas inst_ty
- = hang (hsep [ptext SLIT("Constructors for"), quotes (ppr inst_ty),
- ptext SLIT("not visible when checking"),
- quotes (ppr clas), ptext SLIT("instance")])
- 4 (hsep [text "(Try either importing", ppr inst_ty,
- text "non-abstractly or compile using -fno-prune-tydecls ..)"])
+ where
+ ppr_inst_ty (tc,inst) = ppr (simpleInstInfoTy inst)
methodCtxt = ptext SLIT("When checking the methods of an instance declaration")
-superClassCtxt = ptext SLIT("When checking the superclasses of an instance declaration")
+superClassCtxt = ptext SLIT("When checking the super-classes of an instance declaration")
\end{code}
projects / ghc-hetmet.git / blobdiff