%
-% (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, tcAddDeclCtxt ) where
+
#include "HsVersions.h"
-module TcInstDcls (
- tcInstDecls1,
- tcInstDecls2,
- processInstBinds
- ) where
-
-
-import Ubiq
-
-import HsSyn ( InstDecl(..), FixityDecl, Sig(..),
- SpecInstSig(..), HsBinds(..), Bind(..),
- MonoBinds(..), GRHSsAndBinds, Match,
- InPat(..), OutPat(..), HsExpr(..), HsLit(..),
- Stmt, Qual, ArithSeqInfo, Fake,
- PolyType(..), MonoType )
-import RnHsSyn ( RenamedHsBinds(..), RenamedMonoBinds(..),
- RenamedInstDecl(..), RenamedFixityDecl(..),
- RenamedSig(..), RenamedSpecInstSig(..),
- RnName(..){-incl instance Outputable-}
- )
-import TcHsSyn ( TcIdOcc(..), TcHsBinds(..),
- TcMonoBinds(..), TcExpr(..), tcIdType,
- mkHsTyLam, mkHsTyApp,
- mkHsDictLam, mkHsDictApp )
+import CmdLineOpts ( DynFlag(..), dopt )
-import TcMonad
-import GenSpecEtc ( checkSigTyVars )
-import Inst ( Inst, InstOrigin(..), InstanceMapper(..),
- newDicts, newMethod, LIE(..), emptyLIE, plusLIE )
-import TcBinds ( tcPragmaSigs )
+import HsSyn ( HsDecl(..), InstDecl(..), TyClDecl(..),
+ MonoBinds(..), HsExpr(..), HsLit(..), Sig(..),
+ andMonoBindList, collectMonoBinders, isClassDecl
+ )
+import HsTypes ( HsType (..), HsTyVarBndr(..), toHsTyVar )
+import HsPat ( InPat (..) )
+import HsMatches ( Match (..) )
+import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedHsDecl,
+ extractHsTyVars )
+import TcHsSyn ( TcMonoBinds, mkHsConApp )
+import TcBinds ( tcSpecSigs )
+import TcClassDcl ( tcMethodBind, badMethodErr )
+import TcMonad
+import Inst ( InstOrigin(..),
+ newDicts, newClassDicts,
+ LIE, emptyLIE, plusLIE, plusLIEs )
import TcDeriv ( tcDeriving )
-import TcEnv ( tcLookupClass, tcTyVarScope, newLocalId )
-import TcGRHSs ( tcGRHSsAndBinds )
-import TcInstUtil ( InstInfo(..), mkInstanceRelatedIds, buildInstanceEnvs )
-import TcKind ( TcKind, unifyKind )
-import TcMatches ( tcMatchesFun )
-import TcMonoType ( tcContext, tcMonoTypeKind )
-import TcSimplify ( tcSimplifyAndCheck, tcSimplifyThetas )
-import TcType ( TcType(..), TcTyVar(..),
- tcInstSigTyVars, tcInstType, tcInstTheta
+import TcEnv ( TcEnv, tcExtendGlobalValEnv,
+ tcExtendTyVarEnvForMeths, TyThing (..),
+ tcAddImportedIdInfo, tcInstId, tcLookupClass,
+ newDFunName, tcExtendTyVarEnv
)
-import Unify ( unifyTauTy )
-
+import InstEnv ( InstInfo(..), InstEnv, pprInstInfo, classDataCon,
+ simpleInstInfoTyCon, simpleInstInfoTy, isLocalInst,
+ extendInstEnv )
+import TcMonoType ( tcTyVars, tcHsSigType, tcHsType, kcHsSigType )
+import TcSimplify ( tcSimplifyAndCheck )
+import TcType ( zonkTcSigTyVars )
+import HscTypes ( PersistentCompilerState(..), HomeSymbolTable, DFunId,
+ ModDetails(..) )
import Bag ( emptyBag, unitBag, unionBags, unionManyBags,
- concatBag, foldBag, bagToList )
-import CmdLineOpts ( opt_GlasgowExts, opt_CompilingPrelude,
- opt_OmitDefaultInstanceMethods,
- opt_SpecialiseOverloaded )
-import Class ( GenClass, GenClassOp,
- isCcallishClass, classBigSig,
- classOps, classOpLocalType,
- classOpTagByString
- )
-import Id ( GenId, idType, isDefaultMethodId_maybe )
-import ListSetOps ( minusList )
+ foldBag, Bag, listToBag
+ )
+import Class ( Class, DefMeth(..), classBigSig )
+import Var ( idName, idType )
import Maybes ( maybeToBool, expectJust )
-import Name ( getLocalName, origName, nameOf )
-import PrelVals ( nO_EXPLICIT_METHOD_ERROR_ID )
-import PrelMods ( pRELUDE )
-import PprType ( GenType, GenTyVar, GenClass, GenClassOp, TyCon,
- pprParendGenType
+import MkId ( mkDictFunId )
+import Generics ( validGenericInstanceType )
+import Module ( Module, foldModuleEnv )
+import Name ( isLocallyDefined )
+import NameSet ( emptyNameSet, nameSetToList )
+import PrelInfo ( eRROR_ID )
+import PprType ( pprConstraint, pprPred )
+import TyCon ( TyCon, isSynTyCon, tyConDerivings )
+import Type ( mkTyVarTys, splitDFunTy, isTyVarTy,
+ splitTyConApp_maybe, splitDictTy,
+ splitAlgTyConApp_maybe, classesToPreds, classesOfPreds,
+ unUsgTy, tyVarsOfTypes, mkClassPred, mkTyVarTy,
+ getClassTys_maybe
+ )
+import Subst ( mkTopTyVarSubst, substClasses, substTheta )
+import VarSet ( mkVarSet, varSetElems )
+import TysWiredIn ( genericTyCons, isFFIArgumentTy, isFFIResultTy )
+import PrelNames ( cCallableClassKey, cReturnableClassKey, hasKey )
+import Name ( Name, NameEnv, extendNameEnv_C, emptyNameEnv,
+ plusNameEnv_C, nameEnvElts )
+import FiniteMap ( mapFM )
+import SrcLoc ( SrcLoc )
+import RnHsSyn -- ( RenamedMonoBinds )
+import VarSet ( varSetElems )
+import UniqFM ( mapUFM )
+import Unique ( Uniquable(..) )
+import BasicTypes ( NewOrData(..) )
+import ErrUtils ( dumpIfSet_dyn )
+import ListSetOps ( Assoc, emptyAssoc, plusAssoc_C, mapAssoc,
+ assocElts, extendAssoc_C,
+ equivClassesByUniq, minusList
)
-import PprStyle
-import Pretty
-import RnUtils ( RnEnv(..) )
-import TyCon ( derivedFor )
-import Type ( GenType(..), ThetaType(..), mkTyVarTys,
- splitSigmaTy, splitAppTy, isTyVarTy, matchTy, mkSigmaTy,
- getTyCon_maybe, maybeBoxedPrimType )
-import TyVar ( GenTyVar, mkTyVarSet )
-import TysWiredIn ( stringTy )
-import Unique ( Unique )
-import Util ( panic )
+import List ( intersect, (\\), partition )
+import Outputable
\end{code}
Typechecking instance declarations is done in two passes. The first
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 :: Bag RenamedInstDecl
- -> [RenamedSpecInstSig]
- -> Module -- module name for deriving
- -> RnEnv -- for renaming derivings
- -> [RenamedFixityDecl] -- fixities for deriving
- -> TcM s (Bag InstInfo,
- RenamedHsBinds,
- PprStyle -> Pretty)
-
-tcInstDecls1 inst_decls specinst_sigs mod_name rn_env fixities
- = -- Do the ordinary instance declarations
- mapBagNF_Tc (tcInstDecl1 mod_name) inst_decls
- `thenNF_Tc` \ inst_info_bags ->
+tcInstDecls1 :: PersistentCompilerState
+ -> HomeSymbolTable -- Contains instances
+ -> TcEnv -- Contains IdInfo for dfun ids
+ -> (Name -> Maybe Fixity) -- for deriving Show and Read
+ -> Module -- Module for deriving
+ -> [TyCon]
+ -> [RenamedHsDecl]
+ -> TcM (PersistentCompilerState, InstEnv, [InstInfo], RenamedHsBinds)
+
+tcInstDecls1 pcs hst unf_env get_fixity mod local_tycons decls
+ = let
+ inst_decls = [inst_decl | InstD inst_decl <- decls]
+ clas_decls = [clas_decl | TyClD clas_decl <- decls, isClassDecl clas_decl]
+ in
+ -- (1) Do the ordinary instance declarations
+ mapNF_Tc (tcInstDecl1 mod unf_env) inst_decls `thenNF_Tc` \ inst_infos ->
+
+ -- (2) Instances from generic class declarations
+ getGenericInstances mod 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, imported_inst_info)
+ = partition isLocalInst (concat inst_infos)
+
+ imported_dfuns = map (tcAddImportedIdInfo unf_env . iDFunId)
+ imported_inst_info
+ hst_dfuns = foldModuleEnv ((++) . md_insts) [] hst
+ in
+ addInstDFuns (pcs_insts pcs) 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; hecne inst_env4
+ tcDeriving (pcs_PRS pcs) mod inst_env4 get_fixity local_tycons
+ `thenTc` \ (deriv_inst_info, deriv_binds) ->
+ addInstInfos inst_env4 deriv_inst_info
+ `thenNF_Tc` \ final_inst_env ->
+
+ returnTc (pcs { pcs_insts = 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 dfuns infos
+ = getDOptsTc `thenTc` \ dflags ->
+ extendInstEnv dflags dfuns infos `bind` \ (inst_env', errs) ->
+ addErrsTc errs `thenNF_Tc_`
+ returnTc inst_env'
+ where
+ bind x f = f x
+
+\end{code}
+
+\begin{code}
+tcInstDecl1 :: Module -> TcEnv -> RenamedInstDecl -> NF_TcM [InstInfo]
+-- Deal with a single instance declaration
+tcInstDecl1 mod unf_env (InstDecl poly_ty binds uprags maybe_dfun_name src_loc)
+ = -- Prime error recovery, set source location
+ recoverNF_Tc (returnNF_Tc []) $
+ tcAddSrcLoc src_loc $
+
+ -- Type-check all the stuff before the "where"
+ tcHsSigType poly_ty `thenTc` \ poly_ty' ->
let
- decl_inst_info = concatBag inst_info_bags
+ (tyvars, theta, clas, inst_tys) = splitDFunTy poly_ty'
in
- -- Handle "derived" instances; note that we only do derivings
- -- for things in this module; we ignore deriving decls from
- -- interfaces! We pass fixities, because they may be used
- -- in deriving Read and Show.
- tcDeriving mod_name rn_env decl_inst_info fixities
- `thenTc` \ (deriv_inst_info, deriv_binds, ddump_deriv) ->
+ (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, mkDictFunId dfun_name clas tyvars inst_tys theta)
+
+ Just dfun_name -> -- An interface-file instance declaration
+ -- Make the dfun id
+ returnNF_Tc (False, mkDictFunId dfun_name clas tyvars inst_tys theta)
+ ) `thenNF_Tc` \ (is_local, dfun_id) ->
+
+ returnTc [InstInfo { iLocal = is_local,
+ iClass = clas, iTyVars = tyvars, iTys = inst_tys,
+ iTheta = theta, iDFunId = dfun_id,
+ iBinds = binds, iLoc = src_loc, iPrags = uprags }]
+\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{Extracting generic instance declaration from class declarations}
+%* *
+%************************************************************************
+
+@getGenericInstances@ extracts the generic instance declarations from a class
+declaration. For exmaple
+
+ 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 :: Module -> [RenamedTyClDecl] -> TcM [InstInfo]
+getGenericInstances mod class_decls
+ = mapTc (get_generics mod) class_decls `thenTc` \ gen_inst_infos ->
let
- inst_info = deriv_inst_info `unionBags` decl_inst_info
+ gen_inst_info = concat gen_inst_infos
in
-{- LATER
- -- Handle specialise instance pragmas
- tcSpecInstSigs inst_info specinst_sigs
- `thenTc` \ spec_inst_info ->
--}
+ 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)
+ | null groups
+ = returnTc [] -- The comon case:
+ -- no generic default methods, or
+ -- its an imported class decl (=> has no methods at all)
+
+ | otherwise -- A local 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 ->
+
+ -- 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
- spec_inst_info = emptyBag -- For now
+ bad_groups = [group | group <- equivClassesByUniq get_uniq inst_infos,
+ length group > 1]
+ get_uniq inst = getUnique (simpleInstInfoTyCon inst)
+ in
+ mapTc (addErrTc . dupGenericInsts) bad_groups `thenTc_`
- full_inst_info = inst_info `unionBags` spec_inst_info
+ -- Check that there is an InstInfo for each generic type constructor
+ let
+ missing = genericTyCons `minusList` map simpleInstInfoTyCon inst_infos
in
- returnTc (full_inst_info, deriv_binds, ddump_deriv)
+ checkTc (null missing) (missingGenericInstances missing) `thenTc_`
+ returnTc inst_infos
-tcInstDecl1 :: FAST_STRING -> RenamedInstDecl -> NF_TcM s (Bag InstInfo)
+ where
+ -- Group the declarations by type pattern
+ groups :: [(RenamedHsType, RenamedMonoBinds)]
+ groups = assocElts (getGenericBinds def_methods)
-tcInstDecl1 mod_name
- (InstDecl class_name
- poly_ty@(HsForAllTy tyvar_names context inst_ty)
- binds
- from_here inst_mod uprags pragmas src_loc)
- = -- Prime error recovery, set source location
- recoverNF_Tc (returnNF_Tc emptyBag) $
- tcAddSrcLoc src_loc $
- -- Look things up
- tcLookupClass class_name `thenNF_Tc` \ (clas_kind, clas) ->
+---------------------------------
+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 (foldr add emptyAssoc matches)
+ where
+ add match env = 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
+ -> (RenamedHsType, RenamedMonoBinds)
+ -> TcM InstInfo
+
+mkGenericInstance mod 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 $
+
+ -- Type-check the instance type, and check its form
+ tcHsSigType 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 ->
let
- de_rn (RnName n) = n
+ inst_theta = [mkClassPred clas [mkTyVarTy tv] | tv <- tyvars]
+ inst_tys = [inst_ty]
+ dfun_id = mkDictFunId dfun_name clas tyvars inst_tys inst_theta
in
- -- Typecheck the context and instance type
- tcTyVarScope (map de_rn tyvar_names) (\ tyvars ->
- tcContext context `thenTc` \ theta ->
- tcMonoTypeKind inst_ty `thenTc` \ (tau_kind, tau) ->
- unifyKind clas_kind tau_kind `thenTc_`
- returnTc (tyvars, theta, tau)
- ) `thenTc` \ (inst_tyvars, inst_theta, inst_tau) ->
-
- -- Check for respectable instance type
- scrutiniseInstanceType from_here clas inst_tau
- `thenTc` \ (inst_tycon,arg_tys) ->
-
- -- Deal with the case where we are deriving
- -- and importing the same instance
- if (not from_here && (clas `derivedFor` inst_tycon)
- && all isTyVarTy arg_tys)
- then
- if not opt_CompilingPrelude && maybeToBool inst_mod &&
- mod_name == expectJust "inst_mod" inst_mod
- then
- -- Imported instance came from this module;
- -- discard and derive fresh instance
- returnTc emptyBag
- else
- -- Imported instance declared in another module;
- -- report duplicate instance error
- failTc (derivingWhenInstanceImportedErr inst_mod clas inst_tycon)
- else
-
- -- Make the dfun id and constant-method ids
- mkInstanceRelatedIds from_here inst_mod pragmas
- clas inst_tyvars inst_tau inst_theta uprags
- `thenTc` \ (dfun_id, dfun_theta, const_meth_ids) ->
-
- returnTc (unitBag (InstInfo clas inst_tyvars inst_tau inst_theta
- dfun_theta dfun_id const_meth_ids
- binds from_here inst_mod src_loc uprags))
+
+ returnTc (InstInfo { iLocal = True,
+ iClass = clas, iTyVars = tyvars, iTys = inst_tys,
+ iTheta = inst_theta, iDFunId = dfun_id, iBinds = binds,
+ iLoc = loc, iPrags = [] })
\end{code}
%************************************************************************
\begin{code}
-tcInstDecls2 :: Bag InstInfo
- -> NF_TcM s (LIE s, TcHsBinds s)
+tcInstDecls2 :: [InstInfo]
+ -> NF_TcM (LIE, TcMonoBinds)
tcInstDecls2 inst_decls
- = foldBag combine tcInstDecl2 (returnNF_Tc (emptyLIE, EmptyBinds)) 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) ->
returnNF_Tc (lie1 `plusLIE` lie2,
- binds1 `ThenBinds` 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, TcHsBinds s)
+tcInstDecl2 :: InstInfo -> NF_TcM (LIE, TcMonoBinds)
-tcInstDecl2 (InstInfo _ _ _ _ _ _ _ _ False{-import-} _ _ _)
- = returnNF_Tc (emptyLIE, EmptyBinds)
+tcInstDecl2 (InstInfo { iClass = clas, iTyVars = inst_tyvars, iTys = inst_tys,
+ iTheta = inst_decl_theta, iDFunId = dfun_id,
+ iBinds = monobinds, iLoc = locn, iPrags = uprags })
+ | not (isLocallyDefined dfun_id)
+ = returnNF_Tc (emptyLIE, EmptyMonoBinds)
-tcInstDecl2 (InstInfo clas inst_tyvars inst_ty
- inst_decl_theta dfun_theta
- dfun_id const_meth_ids monobinds
- True{-here-} inst_mod locn uprags)
+ | otherwise
= -- Prime error recovery
- recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyBinds)) $
- tcAddSrcLoc locn $
-
- -- Get the class signature
- tcInstSigTyVars inst_tyvars `thenNF_Tc` \ (inst_tyvars', _, tenv) ->
- let
- (class_tyvar,
- super_classes, sc_sel_ids,
- class_ops, op_sel_ids, defm_ids) = classBigSig clas
- in
- tcInstType tenv inst_ty `thenNF_Tc` \ inst_ty' ->
- tcInstTheta tenv dfun_theta `thenNF_Tc` \ dfun_theta' ->
- tcInstTheta tenv inst_decl_theta `thenNF_Tc` \ inst_decl_theta' ->
+ recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $
+ tcAddSrcLoc locn $
+
+ -- Instantiate the instance decl with tc-style type variables
+ tcInstId dfun_id `thenNF_Tc` \ (inst_tyvars', dfun_theta', dict_ty') ->
let
- sc_theta' = super_classes `zip` (repeat inst_ty')
- origin = InstanceDeclOrigin
- mk_method sel_id = newMethodId sel_id inst_ty' origin locn
- in
- -- 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_ty')] `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
+ (clas, inst_tys') = splitDictTy dict_ty'
+ 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]
- -- Create method variables
- mapAndUnzipNF_Tc mk_method op_sel_ids `thenNF_Tc` \ (meth_insts_s, meth_ids) ->
+ -- Instantiate the theta found in the original instance decl
+ inst_decl_theta' = substTheta (mkTopTyVarSubst inst_tyvars (mkTyVarTys inst_tyvars'))
+ inst_decl_theta
+
+ -- Instantiate the super-class context with inst_tys
+ sc_theta' = substClasses (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
+ in
+ -- Check that all the method bindings come from this class
+ mapTc (addErrTc . badMethodErr clas) bad_bndrs `thenNF_Tc_`
- -- Collect available Insts
+ -- 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) ->
+ newDicts origin inst_decl_theta' `thenNF_Tc` \ (inst_decl_dicts, _) ->
+ newClassDicts origin [(clas,inst_tys')] `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
+
+ tcExtendTyVarEnvForMeths inst_tyvars inst_tyvars' (
+ tcExtendGlobalValEnv dm_ids (
+ -- Default-method Ids may be mentioned in synthesised RHSs
+
+ mapAndUnzip3Tc (tcMethodBind clas origin inst_tyvars' inst_tys'
+ inst_decl_theta'
+ monobinds uprags True)
+ op_items
+ )) `thenTc` \ (method_binds_s, insts_needed_s, meth_lies_w_ids) ->
+
+ -- Deal with SPECIALISE instance pragmas by making them
+ -- look like SPECIALISE pragmas for the dfun
let
- avail_insts -- These insts are in scope; quite a few, eh?
- = unionManyBags (this_dict : dfun_arg_dicts : meth_insts_s)
-
- mk_method_expr
- = if opt_OmitDefaultInstanceMethods then
- makeInstanceDeclNoDefaultExpr origin meth_ids defm_ids inst_ty' clas inst_mod
- else
- makeInstanceDeclDefaultMethodExpr origin meth_ids defm_ids inst_ty' this_dict_id
+ dfun_prags = [SpecSig (idName dfun_id) ty loc | SpecInstSig ty loc <- uprags]
in
- processInstBinds clas mk_method_expr inst_tyvars' avail_insts meth_ids monobinds
- `thenTc` \ (insts_needed, method_mbinds) ->
+ tcExtendGlobalValEnv [dfun_id] (
+ tcSpecSigs dfun_prags
+ ) `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
- -- Create the dict and method binds
- dict_bind
- = VarMonoBind this_dict_id (Dictionary sc_dict_ids meth_ids)
+ inst_tyvars_set = mkVarSet zonked_inst_tyvars
+
+ (meth_lies, meth_ids) = unzip meth_lies_w_ids
- dict_and_method_binds
- = dict_bind `AndMonoBinds` method_mbinds
+ -- These insts are in scope; quite a few, eh?
+ avail_insts = this_dict `plusLIE`
+ dfun_arg_dicts `plusLIE`
+ sc_dicts `plusLIE`
+ unionManyBags meth_lies
- inst_tyvars_set' = mkTyVarSet inst_tyvars'
+ methods_lie = plusLIEs insts_needed_s
in
- -- Check the overloading constraints of the methods and superclasses
- tcAddErrCtxt (bindSigCtxt meth_ids) (
- tcSimplifyAndCheck
- inst_tyvars_set' -- Local tyvars
- avail_insts
- (sc_dicts `unionBags` insts_needed) -- Need to get defns for all these
- ) `thenTc` \ (const_lie, super_binds) ->
+ -- Ditto method bindings
+ tcAddErrCtxt methodCtxt (
+ tcSimplifyAndCheck
+ (ptext SLIT("instance declaration context"))
+ inst_tyvars_set -- Local 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.
- tcAddErrCtxt superClassSigCtxt (
- tcSimplifyAndCheck
- inst_tyvars_set' -- Local tyvars
+ -- the check ensures that the caller will never have
+ --a problem building them.
+ 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
+ ) `thenTc` \ _ ->
+ -- Ignore the result; we're only doing
-- this to make sure it can be done.
- -- Now process any SPECIALIZE pragmas for the methods
- let
- spec_sigs = [ s | s@(SpecSig _ _ _ _) <- uprags ]
- in
- tcPragmaSigs spec_sigs `thenTc` \ (_, spec_binds, spec_lie) ->
+ -- 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
+ (ptext SLIT("instance declaration context"))
+ inst_tyvars_set
+ 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) ->
+
+
+ -- Create the result bindings
let
- -- Complete the binding group, adding any spec_binds
- inst_binds
+ dict_constr = classDataCon clas
+ scs_and_meths = sc_dict_ids ++ meth_ids
+
+ dict_rhs
+ | null scs_and_meths
+ = -- Blatant special case for CCallable, CReturnable
+ -- If the dictionary is empty then we should never
+ -- select anything from it, so we make its RHS just
+ -- 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])
+ (HsLit (HsString msg))
+
+ | otherwise -- The common case
+ = mkHsConApp dict_constr inst_tys' (map HsVar (sc_dict_ids ++ meth_ids))
+ -- 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
+ -- 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 = andMonoBindList method_binds_s
+
+ main_bind
= AbsBinds
- inst_tyvars'
+ zonked_inst_tyvars
dfun_arg_dicts_ids
- ((this_dict_id, RealId dfun_id)
- : (meth_ids `zip` (map RealId const_meth_ids)))
- -- const_meth_ids will often be empty
- super_binds
- (RecBind dict_and_method_binds)
-
- `ThenBinds`
- spec_binds
- in
-
- returnTc (const_lie `plusLIE` spec_lie, inst_binds)
-\end{code}
-
-@mkMethodId@ manufactures an id for a local method.
-It's rather turgid stuff, because there are two cases:
-
- (a) For methods with no local polymorphism, we can make an Inst of the
- class-op selector function and a corresp InstId;
- which is good because then other methods which call
- this one will do so directly.
-
- (b) For methods with local polymorphism, we can't do this. For example,
-
- class Foo a where
- op :: (Num b) => a -> b -> a
-
- Here the type of the class-op-selector is
-
- forall a b. (Foo a, Num b) => a -> b -> a
-
- The locally defined method at (say) type Float will have type
-
- forall b. (Num b) => Float -> b -> Float
-
- and the one is not an instance of the other.
-
- So for these we just make a local (non-Inst) id with a suitable type.
-
-How disgusting.
-
-\begin{code}
-newMethodId sel_id inst_ty origin loc
- = let (sel_tyvars,sel_theta,sel_tau) = splitSigmaTy (idType sel_id)
- (_:meth_theta) = sel_theta -- The local theta is all except the
- -- first element of the context
- in
- case sel_tyvars of
- -- Ah! a selector for a class op with no local polymorphism
- -- Build an Inst for this
- [clas_tyvar] -> newMethod origin (RealId sel_id) [inst_ty]
-
- -- Ho! a selector for a class op with local polymorphism.
- -- Just make a suitably typed local id for this
- (clas_tyvar:local_tyvars) ->
- tcInstType [(clas_tyvar,inst_ty)]
- (mkSigmaTy local_tyvars meth_theta sel_tau)
- `thenNF_Tc` \ method_ty ->
- newLocalId (getLocalName sel_id) method_ty `thenNF_Tc` \ meth_id ->
- returnNF_Tc (emptyLIE, meth_id)
-\end{code}
-
-The next function makes a default method which calls the global default method, at
-the appropriate instance type.
-
-See the notes under default decls in TcClassDcl.lhs.
-
-\begin{code}
-makeInstanceDeclDefaultMethodExpr
- :: InstOrigin s
- -> [TcIdOcc s]
- -> [Id]
- -> TcType s
- -> TcIdOcc s
- -> Int
- -> NF_TcM s (TcExpr s)
-
-makeInstanceDeclDefaultMethodExpr origin meth_ids defm_ids inst_ty this_dict tag
- = newDicts origin op_theta `thenNF_Tc` \ (op_lie,op_dicts) ->
-
- -- def_op_id = /\ op_tyvars -> \ op_dicts ->
- -- defm_id inst_ty op_tyvars this_dict op_dicts
- returnNF_Tc (
- mkHsTyLam op_tyvars (
- mkHsDictLam op_dicts (
- mkHsDictApp (mkHsTyApp (HsVar (RealId defm_id))
- (inst_ty : mkTyVarTys op_tyvars))
- (this_dict : op_dicts)
- )))
- where
- idx = tag - 1
- meth_id = meth_ids !! idx
- defm_id = defm_ids !! idx
- (op_tyvars, op_theta, op_tau) = splitSigmaTy (tcIdType meth_id)
-
-makeInstanceDeclNoDefaultExpr
- :: InstOrigin s
- -> [TcIdOcc s]
- -> [Id]
- -> TcType s
- -> Class
- -> Maybe Module
- -> Int
- -> NF_TcM s (TcExpr s)
-
-makeInstanceDeclNoDefaultExpr origin meth_ids defm_ids inst_ty clas inst_mod tag
- = newDicts origin op_theta `thenNF_Tc` \ (op_lie, op_dicts) ->
-
- -- Produce a warning if the default instance method
- -- has been omitted when one exists in the class
- warnTc (not err_defm_ok)
- (omitDefaultMethodWarn clas_op clas_name inst_ty)
- `thenNF_Tc_`
- returnNF_Tc (mkHsTyLam op_tyvars (
- mkHsDictLam op_dicts (
- HsApp (mkHsTyApp (HsVar (RealId nO_EXPLICIT_METHOD_ERROR_ID)) [op_tau])
- (HsLitOut (HsString (_PK_ error_msg)) stringTy))))
- where
- idx = tag - 1
- meth_id = meth_ids !! idx
- clas_op = (classOps clas) !! idx
- defm_id = defm_ids !! idx
- (op_tyvars,op_theta,op_tau) = splitSigmaTy (tcIdType meth_id)
-
- Just (_, _, err_defm_ok) = isDefaultMethodId_maybe defm_id
-
- mod_str = case inst_mod of { Nothing -> pRELUDE; Just m -> m }
-
- error_msg = _UNPK_ mod_str ++ "." ++ _UNPK_ clas_name ++ "."
- ++ (ppShow 80 (ppr PprForUser inst_ty)) ++ "."
- ++ (ppShow 80 (ppr PprForUser clas_op)) ++ "\""
-
- clas_name = nameOf (origName clas)
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection{Processing each method}
-%* *
-%************************************************************************
-
-@processInstBinds@ returns a @MonoBinds@ which binds
-all the method ids (which are passed in). It is used
- - both for instance decls,
- - and to compile the default-method declarations in a class decl.
-
-Any method ids which don't have a binding have a suitable default
-binding created for them. The actual right-hand side used is
-created using a function which is passed in, because the right thing to
-do differs between instance and class decls.
-
-\begin{code}
-processInstBinds
- :: Class
- -> (Int -> NF_TcM s (TcExpr s)) -- Function to make default method
- -> [TcTyVar s] -- Tyvars for this instance decl
- -> LIE s -- available Insts
- -> [TcIdOcc s] -- Local method ids in tag order
- -- (instance tyvars are free in their types)
- -> RenamedMonoBinds
- -> TcM s (LIE s, -- These are required
- TcMonoBinds s)
-
-processInstBinds clas mk_default_method_rhs inst_tyvars avail_insts method_ids monobinds
- =
- -- Process the explicitly-given method bindings
- processInstBinds1 clas inst_tyvars avail_insts method_ids monobinds
- `thenTc` \ (tags, insts_needed_in_methods, method_binds) ->
-
- -- Find the methods not handled, and make default method bindings for them.
- let
- unmentioned_tags = [1.. length method_ids] `minusList` tags
- in
- mapNF_Tc mk_default_method unmentioned_tags
- `thenNF_Tc` \ default_bind_list ->
-
- returnTc (insts_needed_in_methods,
- foldr AndMonoBinds method_binds default_bind_list)
- where
- -- From a tag construct us the passed-in function to construct
- -- the binding for the default method
- mk_default_method tag = mk_default_method_rhs tag `thenNF_Tc` \ rhs ->
- returnNF_Tc (VarMonoBind (method_ids !! (tag-1)) rhs)
-\end{code}
-
-\begin{code}
-processInstBinds1
- :: Class
- -> [TcTyVar s] -- Tyvars for this instance decl
- -> LIE s -- available Insts
- -> [TcIdOcc s] -- Local method ids in tag order (instance tyvars are free),
- -> RenamedMonoBinds
- -> TcM s ([Int], -- Class-op tags accounted for
- LIE s, -- These are required
- TcMonoBinds s)
-
-processInstBinds1 clas inst_tyvars avail_insts method_ids EmptyMonoBinds
- = returnTc ([], emptyLIE, EmptyMonoBinds)
-
-processInstBinds1 clas inst_tyvars avail_insts method_ids (AndMonoBinds mb1 mb2)
- = processInstBinds1 clas inst_tyvars avail_insts method_ids mb1
- `thenTc` \ (op_tags1,dicts1,method_binds1) ->
- processInstBinds1 clas inst_tyvars avail_insts method_ids mb2
- `thenTc` \ (op_tags2,dicts2,method_binds2) ->
- returnTc (op_tags1 ++ op_tags2,
- dicts1 `unionBags` dicts2,
- AndMonoBinds method_binds1 method_binds2)
-\end{code}
-
-\begin{code}
-processInstBinds1 clas inst_tyvars avail_insts method_ids mbind
- =
- -- Find what class op is being defined here. The complication is
- -- that we could have a PatMonoBind or a FunMonoBind. If the
- -- former, it should only bind a single variable, or else we're in
- -- trouble (I'm not sure what the static semantics of methods
- -- defined in a pattern binding with multiple patterns is!)
- -- Renamer has reduced us to these two cases.
- let
- (op,locn) = case mbind of
- FunMonoBind op _ _ locn -> (op, locn)
- PatMonoBind (VarPatIn op) _ locn -> (op, locn)
-
- occ = getLocalName op
- origin = InstanceDeclOrigin
+ [(inst_tyvars', dfun_id, this_dict_id)]
+ emptyNameSet -- No inlines (yet)
+ (lie_binds1 `AndMonoBinds`
+ lie_binds2 `AndMonoBinds`
+ method_binds `AndMonoBinds`
+ dict_bind)
in
- tcAddSrcLoc locn $
-
- -- Make a method id for the method
- let
- tag = classOpTagByString clas occ
- method_id = method_ids !! (tag-1)
-
- method_ty = tcIdType method_id
- (method_tyvars, method_theta, method_tau) = splitSigmaTy method_ty
- in
- newDicts origin method_theta `thenNF_Tc` \ (method_dicts,method_dict_ids) ->
-
- case (method_tyvars, method_dict_ids) of
-
- ([],[]) -> -- The simple case; no local polymorphism or overloading in the method
-
- -- Type check the method itself
- tcMethodBind method_id method_tau mbind `thenTc` \ (mbind', lieIop) ->
- returnTc ([tag], lieIop, mbind')
-
- other -> -- It's a locally-polymorphic and/or overloaded method; UGH!
-
- -- Make a new id for (a) the local, non-overloaded method
- -- and (b) the locally-overloaded method
- -- The latter is needed just so we can return an AbsBinds wrapped
- -- up inside a MonoBinds.
-
- newLocalId occ method_tau `thenNF_Tc` \ local_id ->
- newLocalId occ method_ty `thenNF_Tc` \ copy_id ->
- let
- inst_method_tyvars = inst_tyvars ++ method_tyvars
- in
- -- Typecheck the method
- tcMethodBind local_id method_tau mbind `thenTc` \ (mbind', lieIop) ->
-
- -- Check the overloading part of the signature.
- -- Simplify everything fully, even though some
- -- constraints could "really" be left to the next
- -- level out. The case which forces this is
- --
- -- class Foo a where { op :: Bar a => a -> a }
- --
- -- Here we must simplify constraints on "a" to catch all
- -- the Bar-ish things.
- tcAddErrCtxt (methodSigCtxt op method_ty) (
- tcSimplifyAndCheck
- (mkTyVarSet inst_method_tyvars)
- (method_dicts `plusLIE` avail_insts)
- lieIop
- ) `thenTc` \ (f_dicts, dict_binds) ->
-
- returnTc ([tag],
- f_dicts,
- VarMonoBind method_id
- (HsLet
- (AbsBinds
- method_tyvars
- method_dict_ids
- [(local_id, copy_id)]
- dict_binds
- (NonRecBind mbind'))
- (HsVar copy_id)))
-\end{code}
-
-\begin{code}
-tcMethodBind :: TcIdOcc s -> TcType s -> RenamedMonoBinds
- -> TcM s (TcMonoBinds s, LIE s)
-
-tcMethodBind meth_id meth_ty (FunMonoBind name inf matches locn)
- = tcMatchesFun name meth_ty matches `thenTc` \ (rhs', lie) ->
- returnTc (FunMonoBind meth_id inf rhs' locn, lie)
-
-tcMethodBind meth_id meth_ty pbind@(PatMonoBind pat grhss_and_binds locn)
- -- pat is sure to be a (VarPatIn op)
- = tcAddErrCtxt (patMonoBindsCtxt pbind) $
- tcGRHSsAndBinds grhss_and_binds `thenTc` \ (grhss_and_binds', lie, rhs_ty) ->
- unifyTauTy meth_ty rhs_ty `thenTc_`
- returnTc (PatMonoBind (VarPat meth_id) grhss_and_binds' locn, lie)
+ returnTc (const_lie1 `plusLIE` const_lie2 `plusLIE` prag_lie,
+ main_bind `AndMonoBinds` prag_binds)
\end{code}
%************************************************************************
%* *
-\subsection{Type-checking specialise instance pragmas}
+\subsection{Checking for a decent instance type}
%* *
%************************************************************************
-\begin{code}
-{- LATER
-tcSpecInstSigs :: E -> CE -> TCE
- -> Bag InstInfo -- inst decls seen (declared and derived)
- -> [RenamedSpecInstSig] -- specialise instance upragmas
- -> TcM (Bag InstInfo) -- new, overlapped, inst decls
-
-tcSpecInstSigs e ce tce inst_infos []
- = returnTc emptyBag
-
-tcSpecInstSigs e ce tce inst_infos sigs
- = buildInstanceEnvs inst_infos `thenTc` \ inst_mapper ->
- tc_inst_spec_sigs inst_mapper sigs `thenNF_Tc` \ spec_inst_infos ->
- returnTc spec_inst_infos
- where
- tc_inst_spec_sigs inst_mapper []
- = returnNF_Tc emptyBag
- tc_inst_spec_sigs inst_mapper (sig:sigs)
- = tcSpecInstSig e ce tce inst_infos inst_mapper sig `thenNF_Tc` \ info_sig ->
- tc_inst_spec_sigs inst_mapper sigs `thenNF_Tc` \ info_sigs ->
- returnNF_Tc (info_sig `unionBags` info_sigs)
-
-tcSpecInstSig :: E -> CE -> TCE
- -> Bag InstInfo
- -> InstanceMapper
- -> RenamedSpecInstSig
- -> NF_TcM (Bag InstInfo)
-
-tcSpecInstSig e ce tce inst_infos inst_mapper (SpecInstSig class_name ty src_loc)
- = recoverTc emptyBag (
- tcAddSrcLoc src_loc (
- let
- clas = lookupCE ce class_name -- Renamer ensures this can't fail
-
- -- Make some new type variables, named as in the specialised instance type
- ty_names = extractMonoTyNames ???is_tyvarish_name??? ty
- (tmpl_e,inst_tmpls,inst_tmpl_tys) = mkTVE ty_names
- in
- babyTcMtoTcM (tcInstanceType ce tce tmpl_e True src_loc ty)
- `thenTc` \ inst_ty ->
- let
- maybe_tycon = case maybeAppDataTyCon inst_ty of
- Just (tc,_,_) -> Just tc
- Nothing -> Nothing
-
- maybe_unspec_inst = lookup_unspec_inst clas maybe_tycon inst_infos
- in
- -- Check that we have a local instance declaration to specialise
- checkMaybeTc maybe_unspec_inst
- (specInstUnspecInstNotFoundErr clas inst_ty src_loc) `thenTc_`
-
- -- Create tvs to substitute for tmpls while simplifying the context
- copyTyVars inst_tmpls `thenNF_Tc` \ (tv_e, inst_tvs, inst_tv_tys) ->
- let
- Just (InstInfo _ unspec_tyvars unspec_inst_ty unspec_theta
- _ _ _ binds True{-from here-} mod _ uprag) = maybe_unspec_inst
-
- subst = case matchTy unspec_inst_ty inst_ty of
- Just subst -> subst
- Nothing -> panic "tcSpecInstSig:matchTy"
-
- subst_theta = instantiateThetaTy subst unspec_theta
- subst_tv_theta = instantiateThetaTy tv_e subst_theta
-
- mk_spec_origin clas ty
- = InstanceSpecOrigin inst_mapper clas ty src_loc
- in
- tcSimplifyThetas mk_spec_origin subst_tv_theta
- `thenTc` \ simpl_tv_theta ->
- let
- simpl_theta = [ (clas, tv_to_tmpl tv) | (clas, tv) <- simpl_tv_theta ]
-
- tv_tmpl_map = inst_tv_tys `zipEqual` inst_tmpl_tys
- tv_to_tmpl tv = assoc "tcSpecInstSig" tv_tmpl_map tv
- in
- mkInstanceRelatedIds e True{-from here-} mod NoInstancePragmas src_loc
- clas inst_tmpls inst_ty simpl_theta uprag
- `thenTc` \ (dfun_id, dfun_theta, const_meth_ids) ->
-
- getSwitchCheckerTc `thenNF_Tc` \ sw_chkr ->
- (if sw_chkr SpecialiseTrace then
- pprTrace "Specialised Instance: "
- (ppAboves [ppCat [if null simpl_theta then ppNil else ppr PprDebug simpl_theta,
- if null simpl_theta then ppNil else ppStr "=>",
- ppr PprDebug clas,
- pprParendGenType PprDebug inst_ty],
- ppCat [ppStr " derived from:",
- if null unspec_theta then ppNil else ppr PprDebug unspec_theta,
- if null unspec_theta then ppNil else ppStr "=>",
- ppr PprDebug clas,
- pprParendGenType PprDebug unspec_inst_ty]])
- else id) (
-
- returnTc (unitBag (InstInfo clas inst_tmpls inst_ty simpl_theta
- dfun_theta dfun_id const_meth_ids
- binds True{-from here-} mod src_loc uprag))
- )))
-
-
-lookup_unspec_inst clas maybe_tycon inst_infos
- = case filter (match_info match_inst_ty) (bagToList inst_infos) of
- [] -> Nothing
- (info:_) -> Just info
- where
- match_info match_ty (InstInfo inst_clas _ inst_ty _ _ _ _ _ from_here _ _ _)
- = from_here && clas == inst_clas &&
- match_ty inst_ty && is_plain_instance inst_ty
-
- match_inst_ty = case maybe_tycon of
- Just tycon -> match_tycon tycon
- Nothing -> match_fun
-
- match_tycon tycon inst_ty = case (maybeAppDataTyCon inst_ty) of
- Just (inst_tc,_,_) -> tycon == inst_tc
- Nothing -> False
-
- match_fun inst_ty = isFunType inst_ty
-
-
-is_plain_instance inst_ty
- = case (maybeAppDataTyCon inst_ty) of
- Just (_,tys,_) -> all isTyVarTemplateTy tys
- Nothing -> case maybeUnpackFunTy inst_ty of
- Just (arg, res) -> isTyVarTemplateTy arg && isTyVarTemplateTy res
- Nothing -> error "TcInstDecls:is_plain_instance"
--}
-\end{code}
-
-
-Checking for a decent instance type
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-@scrutiniseInstanceType@ checks the type {\em and} its syntactic constraints:
+@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@
We can also have instances for functions: @instance Foo (a -> b) ...@.
\begin{code}
-scrutiniseInstanceType from_here clas inst_tau
- -- TYCON CHECK
- | not (maybeToBool inst_tycon_maybe)
- = failTc (instTypeErr inst_tau)
-
- -- IMPORTED INSTANCES ARE OK (but see tcInstDecl1)
- | from_here
- = returnTc (inst_tycon,arg_tys)
-
- -- TYVARS CHECK
- | not (all isTyVarTy arg_tys ||
- not from_here ||
- opt_GlasgowExts)
- = failTc (instTypeErr inst_tau)
+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)
-- DERIVING CHECK
-- It is obviously illegal to have an explicit instance
-- for something that we are also planning to `derive'
- -- Though we can have an explicit instance which is more
- -- specific than the derived instance
- | clas `derivedFor` inst_tycon
- && all isTyVarTy arg_tys
- = failTc (derivingWhenInstanceExistsErr clas inst_tycon)
-
- | -- CCALL CHECK
- -- A user declaration of a CCallable/CReturnable instance
- -- must be for a "boxed primitive" type.
- isCcallishClass clas
- && not opt_CompilingPrelude -- which allows anything
- && maybeToBool (maybeBoxedPrimType inst_tau)
- = failTc (nonBoxedPrimCCallErr clas inst_tau)
-
- | otherwise
- = returnTc (inst_tycon,arg_tys)
+ | 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
+
+ -- 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
- (possible_tycon, arg_tys) = splitAppTy inst_tau
- inst_tycon_maybe = getTyCon_maybe possible_tycon
- inst_tycon = expectJust "tcInstDecls1:inst_tycon" inst_tycon_maybe
+ (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}
-\begin{code}
-
-instTypeErr ty sty
- = case ty of
- SynTy tc _ _ -> ppBesides [ppStr "The type synonym `", ppr sty tc, rest_of_msg]
- TyVarTy tv -> ppBesides [ppStr "The type variable `", ppr sty tv, rest_of_msg]
- other -> ppBesides [ppStr "The type `", ppr sty ty, rest_of_msg]
- where
- rest_of_msg = ppStr "' cannot be used as an instance type."
-derivingWhenInstanceExistsErr clas tycon sty
- = ppHang (ppBesides [ppStr "Deriving class `", ppr sty clas, ppStr "' type `", ppr sty tycon, ppStr "'"])
- 4 (ppStr "when an explicit instance exists")
+%************************************************************************
+%* *
+\subsection{Error messages}
+%* *
+%************************************************************************
-derivingWhenInstanceImportedErr inst_mod clas tycon sty
- = ppHang (ppBesides [ppStr "Deriving class `", ppr sty clas, ppStr "' type `", ppr sty tycon, ppStr "'"])
- 4 (ppBesides [ppStr "when an instance declared in module `", pp_mod, ppStr "' has been imported"])
+\begin{code}
+tcAddDeclCtxt decl thing_inside
+ = tcAddSrcLoc loc $
+ tcAddErrCtxt ctxt $
+ thing_inside
where
- pp_mod = case inst_mod of
- Nothing -> ppPStr SLIT("the standard Prelude")
- Just m -> ppBesides [ppStr "module `", ppPStr m, ppStr "'"]
-
-nonBoxedPrimCCallErr clas inst_ty sty
- = ppHang (ppStr "Instance isn't for a `boxed-primitive' type")
- 4 (ppBesides [ ppStr "class `", ppr sty clas, ppStr "' type `",
- ppr sty inst_ty, ppStr "'"])
-
-omitDefaultMethodWarn clas_op clas_name inst_ty sty
- = ppCat [ppStr "Warning: Omitted default method for",
- ppr sty clas_op, ppStr "in instance",
- ppPStr clas_name, pprParendGenType sty inst_ty]
-
-
-patMonoBindsCtxt pbind sty
- = ppHang (ppStr "In a pattern binding:")
- 4 (ppr sty pbind)
-
-methodSigCtxt name ty sty
- = ppHang (ppBesides [ppStr "When matching the definition of class method `",
- ppr sty name, ppStr "' to its signature :" ])
- 4 (ppr sty ty)
-
-bindSigCtxt method_ids sty
- = ppHang (ppStr "When checking type signatures for: ")
- 4 (ppInterleave (ppStr ", ") (map (ppr sty) method_ids))
-
-superClassSigCtxt sty
- = ppStr "When checking superclass constraints on instance declaration"
+ (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")
+
+ ctxt = hsep [ptext SLIT("In the"), text thing,
+ ptext SLIT("declaration for"), quotes (ppr name)]
+\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 inst_infos
+ = vcat [ptext SLIT("More than one type pattern for a single generic type constructor:"),
+ nest 4 (vcat (map (ppr . simpleInstInfoTy) inst_infos)),
+ ptext SLIT("All the type patterns for a generic type constructor must be identical")
+ ]
+
+instTypeErr clas tys msg
+ = sep [ptext SLIT("Illegal instance declaration for") <+> quotes (pprConstraint clas tys),
+ nest 4 (parens msg)
+ ]
+
+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])
+
+methodCtxt = ptext SLIT("When checking the methods of an instance declaration")
+superClassCtxt = ptext SLIT("When checking the superclasses of an instance declaration")
\end{code}
projects / ghc-hetmet.git / blobdiff