#include "HsVersions.h"
-import CmdLineOpts ( DynFlag(..), dopt )
+import CmdLineOpts ( DynFlag(..) )
-import HsSyn ( HsDecl(..), InstDecl(..), TyClDecl(..),
- MonoBinds(..), HsExpr(..), HsLit(..), Sig(..),
- andMonoBindList, collectMonoBinders, isClassDecl
+import HsSyn ( HsDecl(..), InstDecl(..), TyClDecl(..), HsType(..),
+ MonoBinds(..), HsExpr(..), HsLit(..), Sig(..), HsTyVarBndr(..),
+ andMonoBindList, collectMonoBinders, isClassDecl, toHsType
)
-import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedHsDecl, RenamedMonoBinds,
- RenamedTyClDecl, RenamedHsType,
+import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedHsDecl,
+ RenamedMonoBinds, RenamedTyClDecl, RenamedHsType,
extractHsTyVars, maybeGenericMatch
)
import TcHsSyn ( TcMonoBinds, mkHsConApp )
import TcBinds ( tcSpecSigs )
import TcClassDcl ( tcMethodBind, badMethodErr )
import TcMonad
+import TcMType ( tcInstSigTyVars, checkValidTheta, checkValidInstHead, instTypeErr,
+ UserTypeCtxt(..), SourceTyCtxt(..) )
+import TcType ( tcSplitDFunTy, mkClassPred, mkTyVarTy, mkTyVarTys,
+ tcSplitSigmaTy, tcSplitPredTy_maybe, getClassPredTys,
+ TyVarDetails(..)
+ )
import Inst ( InstOrigin(..),
- newDicts, newClassDicts,
- LIE, emptyLIE, plusLIE, plusLIEs )
+ newDicts, instToId,
+ LIE, mkLIE, emptyLIE, plusLIE, plusLIEs )
import TcDeriv ( tcDeriving )
import TcEnv ( TcEnv, tcExtendGlobalValEnv,
tcExtendTyVarEnvForMeths,
- tcAddImportedIdInfo, tcInstId, tcLookupClass,
- InstInfo(..), pprInstInfo, simpleInstInfoTyCon, simpleInstInfoTy,
- newDFunName, tcExtendTyVarEnv
+ tcAddImportedIdInfo, tcLookupClass,
+ InstInfo(..), pprInstInfo, simpleInstInfoTyCon,
+ simpleInstInfoTy, newDFunName,
+ isLocalThing,
)
import InstEnv ( InstEnv, extendInstEnv )
-import TcMonoType ( tcTyVars, tcHsSigType, kcHsSigType )
-import TcSimplify ( tcSimplifyAndCheck )
-import TcType ( zonkTcSigTyVars )
+import PprType ( pprClassPred )
+import TcMonoType ( tcHsTyVars, kcHsSigType, tcHsType, tcHsSigType )
+import TcUnify ( checkSigTyVars )
+import TcSimplify ( tcSimplifyCheck )
import HscTypes ( HomeSymbolTable, DFunId,
ModDetails(..), PackageInstEnv, PersistentRenamerState
)
-import Bag ( unionManyBags )
+import Subst ( substTy, substTheta )
import DataCon ( classDataCon )
-import Class ( Class, DefMeth(..), classBigSig )
+import Class ( Class, classBigSig )
import Var ( idName, idType )
-import Maybes ( maybeToBool )
+import VarSet ( emptyVarSet )
+import Id ( setIdLocalExported )
import MkId ( mkDictFunId )
+import FunDeps ( checkInstFDs )
import Generics ( validGenericInstanceType )
import Module ( Module, foldModuleEnv )
import Name ( getSrcLoc )
-import NameSet ( emptyNameSet, nameSetToList )
+import NameSet ( unitNameSet, emptyNameSet, nameSetToList )
import PrelInfo ( eRROR_ID )
-import PprType ( pprConstraint, pprPred )
-import TyCon ( TyCon, isSynTyCon )
-import Type ( splitDFunTy, isTyVarTy,
- splitTyConApp_maybe, splitDictTy,
- splitAlgTyConApp_maybe, splitForAllTys,
- unUsgTy, tyVarsOfTypes, mkClassPred, mkTyVarTy,
- getClassTys_maybe
- )
-import Subst ( mkTopTyVarSubst, substClasses )
-import VarSet ( mkVarSet, varSetElems )
-import TysWiredIn ( genericTyCons, isFFIArgumentTy, isFFIResultTy )
-import PrelNames ( cCallableClassKey, cReturnableClassKey, hasKey )
+import TyCon ( TyCon )
+import Subst ( mkTopTyVarSubst, substTheta )
+import TysWiredIn ( genericTyCons )
import Name ( Name )
import SrcLoc ( SrcLoc )
-import VarSet ( varSetElems )
import Unique ( Uniquable(..) )
+import Util ( lengthExceeds )
import BasicTypes ( NewOrData(..), Fixity )
import ErrUtils ( dumpIfSet_dyn )
import ListSetOps ( Assoc, emptyAssoc, plusAssoc_C, mapAssoc,
-> TcEnv -- Contains IdInfo for dfun ids
-> (Name -> Maybe Fixity) -- for deriving Show and Read
-> Module -- Module for deriving
- -> [TyCon]
-> [RenamedHsDecl]
-> TcM (PackageInstEnv, InstEnv, [InstInfo], RenamedHsBinds)
-tcInstDecls1 inst_env0 prs hst unf_env get_fixity mod tycons decls
+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
in
-- (1) Do the ordinary instance declarations
- mapNF_Tc (tcInstDecl1 mod unf_env) inst_decls `thenNF_Tc` \ inst_infos ->
+ mapNF_Tc tcInstDecl1 inst_decls `thenNF_Tc` \ inst_infos ->
-- (2) Instances from generic class declarations
- getGenericInstances mod clas_decls `thenTc` \ generic_inst_info ->
+ 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
-- e) generic instances inst_env4
-- The result of (b) replaces the cached InstEnv in the PCS
let
- (local_inst_info, imported_inst_info) = partition iLocal (concat inst_infos)
+ (local_inst_info, imported_inst_info)
+ = partition (isLocalThing this_mod . iDFunId) (concat inst_infos)
imported_dfuns = map (tcAddImportedIdInfo unf_env . iDFunId)
imported_inst_info
hst_dfuns = foldModuleEnv ((++) . md_insts) [] hst
- in
+ 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 ->
-- 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; hecne inst_env4
- tcDeriving prs mod inst_env4 get_fixity tycl_decls `thenTc` \ (deriv_inst_info, deriv_binds) ->
+ 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,
addInstInfos inst_env infos = addInstDFuns inst_env (map iDFunId infos)
addInstDFuns :: InstEnv -> [DFunId] -> NF_TcM InstEnv
-addInstDFuns dfuns infos
+addInstDFuns inst_env dfuns
= getDOptsTc `thenTc` \ dflags ->
- extendInstEnv dflags dfuns infos `bind` \ (inst_env', errs) ->
+ let
+ (inst_env', errs) = extendInstEnv dflags inst_env dfuns
+ in
addErrsTc errs `thenNF_Tc_`
+ traceTc (text "Adding instances:" <+> vcat (map pp dfuns)) `thenTc_`
returnTc inst_env'
where
- bind x f = f x
-
+ pp dfun = ppr dfun <+> dcolon <+> ppr (idType dfun)
\end{code}
\begin{code}
-tcInstDecl1 :: Module -> TcEnv -> RenamedInstDecl -> NF_TcM [InstInfo]
+tcInstDecl1 :: RenamedInstDecl -> NF_TcM [InstInfo]
-- Deal with a single instance declaration
-tcInstDecl1 mod unf_env (InstDecl poly_ty binds uprags maybe_dfun_name src_loc)
+-- Type-check all the stuff before the "where"
+tcInstDecl1 decl@(InstDecl poly_ty binds uprags maybe_dfun_name src_loc)
= -- Prime error recovery, set source location
recoverNF_Tc (returnNF_Tc []) $
tcAddSrcLoc src_loc $
+ tcAddErrCtxt (instDeclCtxt poly_ty) $
- -- Type-check all the stuff before the "where"
- tcHsSigType poly_ty `thenTc` \ 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
- (tyvars, theta, clas, inst_tys) = splitDFunTy poly_ty'
+ (tyvars, theta, tau) = tcSplitSigmaTy poly_ty'
+ (clas,inst_tys) = case tcSplitPredTy_maybe tau of { Just st -> getClassPredTys st }
+ -- The checkValidInstHead makes sure these splits succeed
in
-
(case maybe_dfun_name of
Nothing -> -- A source-file instance declaration
-
-- 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]
- scrutiniseInstanceHead clas inst_tys `thenNF_Tc_`
- mapNF_Tc scrutiniseInstanceConstraint theta `thenNF_Tc_`
-
- -- Make the dfun id and return it
- newDFunName mod clas inst_tys src_loc `thenNF_Tc` \ dfun_name ->
- returnNF_Tc (True, dfun_name)
+ checkValidTheta InstThetaCtxt theta `thenTc_`
+ checkValidInstHead tau `thenTc_`
+ checkTc (checkInstFDs theta clas inst_tys)
+ (instTypeErr (pprClassPred clas inst_tys) msg) `thenTc_`
+ newDFunName clas inst_tys src_loc
Just dfun_name -> -- An interface-file instance declaration
- -- Make the dfun id
- returnNF_Tc (False, dfun_name)
- ) `thenNF_Tc` \ (is_local, dfun_name) ->
-
+ returnNF_Tc dfun_name
+ ) `thenNF_Tc` \ dfun_name ->
let
dfun_id = mkDictFunId dfun_name clas tyvars inst_tys theta
in
- returnTc [InstInfo { iLocal = is_local, iDFunId = dfun_id,
- iBinds = binds, iPrags = uprags }]
+ returnTc [InstInfo { iDFunId = dfun_id, iBinds = binds, iPrags = uprags }]
+ where
+ msg = parens (ptext SLIT("the instance types do not agree with the functional dependencies of the class"))
\end{code}
\begin{code}
-getGenericInstances :: Module -> [RenamedTyClDecl] -> TcM [InstInfo]
-getGenericInstances mod class_decls
- = mapTc (get_generics mod) class_decls `thenTc` \ gen_inst_infos ->
+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 `thenTc` \ 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 mod decl@(ClassDecl context class_name tyvar_names
- fundeps class_sigs def_methods
- name_list loc)
+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, or
- -- its an imported class decl (=> has no methods at all)
+ = returnTc [] -- The comon case: no generic default methods
- | otherwise -- A local class decl with 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 mod clas loc) groups `thenTc` \ inst_infos ->
+ 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
tc_inst_infos = [(simpleInstInfoTyCon i, i) | i <- inst_infos]
bad_groups = [group | group <- equivClassesByUniq get_uniq tc_inst_infos,
- length group > 1]
+ group `lengthExceeds` 1]
get_uniq (tc,_) = getUnique tc
in
mapTc (addErrTc . dupGenericInsts) bad_groups `thenTc_`
= plusAssoc_C AndMonoBinds (getGenericBinds m1) (getGenericBinds m2)
getGenericBinds (FunMonoBind id infixop matches loc)
- = mapAssoc wrap (foldr add emptyAssoc matches)
+ = mapAssoc wrap (foldl add emptyAssoc matches)
+ -- Using foldl not foldr is vital, else
+ -- we reverse the order of the bindings!
where
- add match env = case maybeGenericMatch match of
+ 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 :: Module -> Class -> SrcLoc
+mkGenericInstance :: Class -> SrcLoc
-> (RenamedHsType, RenamedMonoBinds)
-> TcM InstInfo
-mkGenericInstance mod clas loc (hs_ty, binds)
+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
- tcTyVars (nameSetToList (extractHsTyVars hs_ty))
- (kcHsSigType hs_ty) `thenTc` \ tyvars ->
- tcExtendTyVarEnv tyvars $
+ let
+ sig_tvs = map UserTyVar (nameSetToList (extractHsTyVars hs_ty))
+ in
+ tcHsTyVars sig_tvs (kcHsSigType hs_ty) $ \ tyvars ->
-- Type-check the instance type, and check its form
- tcHsSigType hs_ty `thenTc` \ inst_ty ->
+ tcHsSigType GenPatCtxt hs_ty `thenTc` \ inst_ty ->
checkTc (validGenericInstanceType inst_ty)
(badGenericInstanceType binds) `thenTc_`
-- Make the dictionary function.
- newDFunName mod clas [inst_ty] loc `thenNF_Tc` \ dfun_name ->
+ newDFunName clas [inst_ty] loc `thenNF_Tc` \ dfun_name ->
let
inst_theta = [mkClassPred clas [mkTyVarTy tv] | tv <- tyvars]
inst_tys = [inst_ty]
dfun_id = mkDictFunId dfun_name clas tyvars inst_tys inst_theta
in
- returnTc (InstInfo { iLocal = True, iDFunId = dfun_id,
+ returnTc (InstInfo { iDFunId = dfun_id,
iBinds = binds, iPrags = [] })
\end{code}
First comes the easy case of a non-local instance decl.
+
\begin{code}
tcInstDecl2 :: InstInfo -> NF_TcM (LIE, TcMonoBinds)
+-- tcInstDecl2 is called *only* on InstInfos
-tcInstDecl2 (InstInfo { iLocal = is_local, iDFunId = dfun_id,
+tcInstDecl2 (InstInfo { iDFunId = dfun_id,
iBinds = monobinds, iPrags = uprags })
- | not is_local
- = returnNF_Tc (emptyLIE, EmptyMonoBinds)
-
- | otherwise
= -- Prime error recovery
- recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $
- tcAddSrcLoc (getSrcLoc dfun_id) $
+ 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
- tcInstId dfun_id `thenNF_Tc` \ (inst_tyvars', dfun_theta', dict_ty') ->
let
- (clas, inst_tys') = splitDictTy dict_ty'
- origin = InstanceDeclOrigin
+ (inst_tyvars, dfun_theta, clas, inst_tys) = tcSplitDFunTy (idType dfun_id)
+ in
+ tcInstSigTyVars InstTv inst_tyvars `thenNF_Tc` \ inst_tyvars' ->
+ let
+ tenv = mkTopTyVarSubst inst_tyvars (mkTyVarTys inst_tyvars')
+ inst_tys' = map (substTy tenv) inst_tys
+ dfun_theta' = substTheta tenv dfun_theta
+ origin = InstanceDeclOrigin
(class_tyvars, sc_theta, _, op_items) = classBigSig clas
- dm_ids = [dm_id | (_, DefMeth dm_id) <- op_items]
sel_names = [idName sel_id | (sel_id, _) <- op_items]
-- Instantiate the super-class context with inst_tys
- sc_theta' = substClasses (mkTopTyVarSubst class_tyvars inst_tys') sc_theta
+ sc_theta' = substTheta (mkTopTyVarSubst class_tyvars inst_tys') sc_theta
-- Find any definitions in monobinds that aren't from the class
bad_bndrs = collectMonoBinders monobinds `minusList` sel_names
-
- -- The type variable from the dict fun actually scope
- -- over the bindings. They were gotten from
- -- the original instance declaration
- (inst_tyvars, _) = splitForAllTys (idType dfun_id)
in
-- Check that all the method bindings come from this class
mapTc (addErrTc . badMethodErr clas) bad_bndrs `thenNF_Tc_`
-- Create dictionary Ids from the specified instance contexts.
- newClassDicts origin sc_theta' `thenNF_Tc` \ (sc_dicts, sc_dict_ids) ->
- newDicts origin dfun_theta' `thenNF_Tc` \ (dfun_arg_dicts, dfun_arg_dicts_ids) ->
- newClassDicts origin [(clas,inst_tys')] `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
+ 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' (
- tcExtendGlobalValEnv dm_ids (
- -- Default-method Ids may be mentioned in synthesised RHSs
+ -- 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_lies_w_ids) ->
+ ) `thenTc` \ (method_binds_s, insts_needed_s, meth_insts) ->
-- Deal with SPECIALISE instance pragmas by making them
-- look like SPECIALISE pragmas for the dfun
) `thenTc` \ (prag_binds, prag_lie) ->
-- Check the overloading constraints of the methods and superclasses
-
- -- tcMethodBind has checked that the class_tyvars havn't
- -- been unified with each other or another type, but we must
- -- still zonk them before passing them to tcSimplifyAndCheck
- zonkTcSigTyVars inst_tyvars' `thenNF_Tc` \ zonked_inst_tyvars ->
let
- inst_tyvars_set = mkVarSet 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) ->
- -- 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
+ -- Figure out bindings for the superclass context
+ tcAddErrCtxt superClassCtxt (
+ 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 eRROR_ID) [(unUsgTy . idType) this_dict_id])
+ HsApp (TyApp (HsVar eRROR_ID) [idType this_dict_id])
(HsLit (HsString msg))
| otherwise -- The common case
- = mkHsConApp 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
-- rely on the simplifier to unfold this saturated application
-- We do this rather than generate an HsCon directly, because
main_bind
= AbsBinds
zonked_inst_tyvars
- dfun_arg_dicts_ids
- [(inst_tyvars', dfun_id, this_dict_id)]
- emptyNameSet -- No inlines (yet)
+ (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}
-
-%************************************************************************
-%* *
-\subsection{Checking for a decent instance type}
-%* *
-%************************************************************************
-
-@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 pred
- = getDOptsTc `thenTc` \ dflags -> case () of
- ()
- | dopt Opt_AllowUndecidableInstances dflags
- -> returnNF_Tc ()
-
- | Just (clas,tys) <- getClassTys_maybe pred,
- all isTyVarTy tys
- -> returnNF_Tc ()
-
- | otherwise
- -> addErrTc (instConstraintErr pred)
-
-scrutiniseInstanceHead clas inst_taus
- = getDOptsTc `thenTc` \ dflags -> case () of
- ()
- | -- CCALL CHECK
- -- A user declaration of a CCallable/CReturnable instance
- -- must be for a "boxed primitive" type.
- (clas `hasKey` cCallableClassKey
- && not (ccallable_type dflags first_inst_tau))
- ||
- (clas `hasKey` cReturnableClassKey
- && not (creturnable_type first_inst_tau))
- -> addErrTc (nonBoxedPrimCCallErr clas first_inst_tau)
-
- -- Allow anything for AllowUndecidableInstances
- | dopt Opt_AllowUndecidableInstances dflags
- -> returnNF_Tc ()
-
- -- If GlasgowExts then check at least one isn't a type variable
- | dopt Opt_GlasgowExts dflags
- -> if all isTyVarTy inst_taus
- then addErrTc (instTypeErr clas inst_taus
- (text "There must be at least one non-type-variable in the instance head"))
- else returnNF_Tc ()
-
- -- WITH HASKELL 1.4, MUST HAVE C (T a b c)
- | 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 (varSetElems (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
- Just (alg_tycon, _, _) = alg_tycon_app_maybe
-
- ccallable_type dflags ty = isFFIArgumentTy dflags False {- Not safe call -} ty
- creturnable_type ty = isFFIResultTy ty
-\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.
%************************************************************************
\begin{code}
tcAddDeclCtxt decl thing_inside
- = tcAddSrcLoc loc $
+ = tcAddSrcLoc (tcdLoc decl) $
tcAddErrCtxt ctxt $
thing_inside
where
- (name, loc, thing)
- = case decl of
- (ClassDecl _ name _ _ _ _ _ loc) -> (name, loc, "class")
- (TySynonym name _ _ loc) -> (name, loc, "type synonym")
- (TyData NewType _ name _ _ _ _ loc _ _) -> (name, loc, "newtype")
- (TyData DataType _ name _ _ _ _ loc _ _) -> (name, loc, "data type")
+ 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 name)]
+ 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 pred
- = hang (ptext SLIT("Illegal constraint") <+>
- quotes (pprPred pred) <+>
- ptext SLIT("in instance context"))
- 4 (ptext SLIT("(Instance contexts must constrain only type variables)"))
-
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)),
where
ppr_inst_ty (tc,inst) = ppr (simpleInstInfoTy inst)
-instTypeErr clas tys msg
- = sep [ptext SLIT("Illegal instance declaration for") <+> quotes (pprConstraint clas tys),
- nest 4 (parens msg)
- ]
-
-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])
-
methodCtxt = ptext SLIT("When checking the methods of an instance declaration")
+superClassCtxt = ptext SLIT("When checking the super-classes of an instance declaration")
\end{code}
-
-