import HsSyn
import TcBinds ( mkPragFun, tcPrags, badBootDeclErr )
import TcTyClsDecls ( tcIdxTyInstDecl )
-import TcClassDcl ( tcMethodBind, mkMethodBind, badMethodErr,
- tcClassDecl2, getGenericInstances )
+import TcClassDcl ( tcMethodBind, mkMethodBind, badMethodErr, badATErr,
+ omittedATWarn, tcClassDecl2, getGenericInstances )
import TcRnMonad
-import TcMType ( tcSkolSigType, checkValidInstance, checkValidInstHead )
-import TcType ( mkClassPred, tcSplitSigmaTy, tcSplitDFunHead,
- SkolemInfo(InstSkol), tcSplitDFunTy, mkFunTy )
+import TcMType ( tcSkolSigType, checkValidInstance,
+ checkValidInstHead )
+import TcType ( TcType, mkClassPred, tcSplitSigmaTy,
+ tcSplitDFunHead, SkolemInfo(InstSkol),
+ tcSplitDFunTy, mkFunTy )
import Inst ( newDictBndr, newDictBndrs, instToId, showLIE,
getOverlapFlag, tcExtendLocalInstEnv )
import InstEnv ( mkLocalInstance, instanceDFunId )
+import FamInst ( tcExtendLocalFamInstEnv )
+import FamInstEnv ( extractFamInsts )
import TcDeriv ( tcDeriving )
import TcEnv ( InstInfo(..), InstBindings(..),
- newDFunName, tcExtendIdEnv
+ newDFunName, tcExtendIdEnv, tcExtendGlobalEnv
)
import TcHsType ( kcHsSigType, tcHsKindedType )
import TcUnify ( checkSigTyVars )
import TcSimplify ( tcSimplifySuperClasses )
import Type ( zipOpenTvSubst, substTheta, mkTyConApp, mkTyVarTy,
- splitFunTys )
+ splitFunTys, TyThing(ATyCon), isTyVarTy, tcEqType,
+ substTys, emptyTvSubst, extendTvSubst )
import Coercion ( mkSymCoercion )
-import TyCon ( TyCon, newTyConCo, tyConTyVars )
+import TyCon ( TyCon, tyConName, newTyConCo_maybe, tyConTyVars,
+ isTyConAssoc, tyConFamInst_maybe,
+ assocTyConArgPoss_maybe )
import DataCon ( classDataCon, dataConTyCon, dataConInstArgTys )
-import Class ( classBigSig )
-import Var ( TyVar, Id, idName, idType, tyVarKind )
+import Class ( Class, classBigSig, classATs )
+import Var ( TyVar, Id, idName, idType, tyVarKind, tyVarName )
+import VarEnv ( rnBndrs2, mkRnEnv2, emptyInScopeSet )
import Id ( mkSysLocal )
import UniqSupply ( uniqsFromSupply, splitUniqSupply )
import MkId ( mkDictFunId )
-import Name ( Name, getSrcLoc )
-import Maybe ( catMaybes )
-import SrcLoc ( srcLocSpan, unLoc, noLoc, Located(..), srcSpanStart )
+import Name ( Name, getSrcLoc, nameOccName )
+import NameSet ( addListToNameSet, emptyNameSet, minusNameSet,
+ nameSetToList )
+import Maybe ( isNothing, fromJust, catMaybes )
+import Monad ( when )
+import List ( find )
+import DynFlags ( DynFlag(Opt_WarnMissingMethods) )
+import SrcLoc ( srcLocSpan, unLoc, noLoc, Located(..), srcSpanStart,
+ getLoc)
import ListSetOps ( minusList )
import Outputable
import Bag
import BasicTypes ( Activation( AlwaysActive ), InlineSpec(..) )
+import HscTypes ( implicitTyThings )
import FastString
\end{code}
-- (they recover, so that we get more than one error each
-- round)
- -- (1) Do the ordinary instance declarations and instances of
- -- indexed types
+ -- (1) Do class instance declarations and instances of indexed
+ -- types
; let { idxty_decls = filter (isIdxTyDecl . unLoc) tycl_decls }
- ; local_inst_infos <- mappM tcLocalInstDecl1 inst_decls
- ; idxty_inst_infos <- mappM tcIdxTyInstDecl idxty_decls
-
- ; let { local_inst_info = concat local_inst_infos ++
- catMaybes idxty_inst_infos
- ; clas_decls = filter (isClassDecl.unLoc) tycl_decls }
-
- -- (2) Instances from generic class declarations
+ ; local_info_tycons <- mappM tcLocalInstDecl1 inst_decls
+ ; idx_tycons <- mappM tcIdxTyInstDeclTL idxty_decls
+
+ ; let { (local_infos,
+ at_tycons) = unzip local_info_tycons
+ ; local_info = concat local_infos
+ ; at_idx_tycon = concat at_tycons ++ catMaybes idx_tycons
+ ; clas_decls = filter (isClassDecl.unLoc) tycl_decls
+ ; implicit_things = concatMap implicitTyThings at_idx_tycon
+ }
+
+ -- (2) Add the tycons of indexed types and their implicit
+ -- tythings to the global environment
+ ; tcExtendGlobalEnv (at_idx_tycon ++ implicit_things) $ do {
+
+ -- (3) Instances from generic class declarations
; generic_inst_info <- getGenericInstances clas_decls
-- Next, construct the instance environment so far, consisting
-- of
-- a) local instance decls
-- b) generic instances
- ; addInsts local_inst_info $ do {
- ; addInsts generic_inst_info $ do {
+ -- c) local family instance decls
+ ; addInsts local_info $ do {
+ ; addInsts generic_inst_info $ do {
+ ; addFamInsts at_idx_tycon $ do {
- -- (3) Compute instances from "deriving" clauses;
+ -- (4) Compute instances from "deriving" clauses;
-- This stuff computes a context for the derived instance
-- decl, so it needs to know about all the instances possible
; (deriv_inst_info, deriv_binds) <- tcDeriving tycl_decls
; gbl_env <- getGblEnv
; returnM (gbl_env,
- generic_inst_info ++ deriv_inst_info ++ local_inst_info,
+ generic_inst_info ++ deriv_inst_info ++ local_info,
deriv_binds)
- }}}}
+ }}}}}}
+ where
+ -- Make sure that toplevel type instance are not for associated types.
+ -- !!!TODO: Need to perform this check for the TyThing of type functions,
+ -- too.
+ tcIdxTyInstDeclTL ldecl@(L loc decl) =
+ do { tything <- tcIdxTyInstDecl ldecl
+ ; setSrcSpan loc $
+ when (isAssocFamily tything) $
+ addErr $ assocInClassErr (tcdName decl)
+ ; return tything
+ }
+ isAssocFamily (Just (ATyCon tycon)) =
+ case tyConFamInst_maybe tycon of
+ Nothing -> panic "isAssocFamily: no family?!?"
+ Just (fam, _) -> isTyConAssoc fam
+ isAssocFamily (Just _ ) = panic "isAssocFamily: no tycon?!?"
+ isAssocFamily Nothing = False
+
+assocInClassErr name =
+ ptext SLIT("Associated type") <+> quotes (ppr name) <+>
+ ptext SLIT("must be inside a class instance")
addInsts :: [InstInfo] -> TcM a -> TcM a
addInsts infos thing_inside
= tcExtendLocalInstEnv (map iSpec infos) thing_inside
+
+addFamInsts :: [TyThing] -> TcM a -> TcM a
+addFamInsts tycons thing_inside
+ = tcExtendLocalFamInstEnv (extractFamInsts tycons) thing_inside
\end{code}
\begin{code}
tcLocalInstDecl1 :: LInstDecl Name
- -> TcM [InstInfo] -- [] if there was an error
+ -> TcM ([InstInfo], [TyThing]) -- [] 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
tcLocalInstDecl1 decl@(L loc (InstDecl poly_ty binds uprags ats))
= -- Prime error recovery, set source location
- recoverM (returnM []) $
+ recoverM (returnM ([], [])) $
setSrcSpan loc $
addErrCtxt (instDeclCtxt1 poly_ty) $
; poly_ty' <- tcHsKindedType kinded_ty
; let (tyvars, theta, tau) = tcSplitSigmaTy poly_ty'
+ -- Next, process any associated types.
+ ; idx_tycons <- mappM tcIdxTyInstDecl ats
+
-- Now, check the validity of the instance.
; (clas, inst_tys) <- checkValidInstHead tau
; checkValidInstance tyvars theta clas inst_tys
-
- -- Next, process any associated types.
- ; idxty_inst_info <- mappM tcIdxTyInstDecl ats
+ ; checkValidAndMissingATs clas (tyvars, inst_tys)
+ (zip ats idx_tycons)
-- Finally, construct the Core representation of the instance.
-- (This no longer includes the associated types.)
; dfun_name <- newDFunName clas inst_tys (srcSpanStart loc)
; overlap_flag <- getOverlapFlag
- ; let dfun = mkDictFunId dfun_name tyvars theta clas inst_tys
- ispec = mkLocalInstance dfun overlap_flag
+ ; let dfun = mkDictFunId dfun_name tyvars theta clas inst_tys
+ ispec = mkLocalInstance dfun overlap_flag
- ; return $ [InstInfo { iSpec = ispec,
- iBinds = VanillaInst binds uprags }] ++
- catMaybes idxty_inst_info }
+ ; return ([InstInfo { iSpec = ispec,
+ iBinds = VanillaInst binds uprags }],
+ catMaybes idx_tycons)
+ }
+ where
+ -- We pass in the source form and the type checked form of the ATs. We
+ -- really need the source form only to be able to produce more informative
+ -- error messages.
+ checkValidAndMissingATs :: Class
+ -> ([TyVar], [TcType]) -- instance types
+ -> [(LTyClDecl Name, -- source form of AT
+ Maybe TyThing)] -- Core form of AT
+ -> TcM ()
+ checkValidAndMissingATs clas inst_tys ats
+ = do { -- Issue a warning for each class AT that is not defined in this
+ -- instance.
+ ; let classDefATs = listToNameSet . map tyConName . classATs $ clas
+ definedATs = listToNameSet . map (tcdName.unLoc.fst) $ ats
+ omitted = classDefATs `minusNameSet` definedATs
+ ; warn <- doptM Opt_WarnMissingMethods
+ ; mapM_ (warnTc warn . omittedATWarn) (nameSetToList omitted)
+
+ -- Ensure that all AT indexes that correspond to class parameters
+ -- coincide with the types in the instance head. All remaining
+ -- AT arguments must be variables. Also raise an error for any
+ -- type instances that are not associated with this class.
+ ; mapM_ (checkIndexes clas inst_tys) ats
+ }
+
+ checkIndexes _ _ (hsAT, Nothing) =
+ return () -- skip, we already had an error here
+ checkIndexes clas inst_tys (hsAT, Just (ATyCon tycon)) =
+-- !!!TODO: check that this does the Right Thing for indexed synonyms, too!
+ checkIndexes' clas inst_tys hsAT
+ (tyConTyVars tycon,
+ snd . fromJust . tyConFamInst_maybe $ tycon)
+ checkIndexes _ _ _ = panic "checkIndexes"
+
+ checkIndexes' clas (instTvs, instTys) hsAT (atTvs, atTys)
+ = let atName = tcdName . unLoc $ hsAT
+ in
+ setSrcSpan (getLoc hsAT) $
+ addErrCtxt (atInstCtxt atName) $
+ case find ((atName ==) . tyConName) (classATs clas) of
+ Nothing -> addErrTc $ badATErr clas atName -- not in this class
+ Just atDecl ->
+ case assocTyConArgPoss_maybe atDecl of
+ Nothing -> panic "checkIndexes': AT has no args poss?!?"
+ Just poss ->
+
+ -- The following is tricky! We need to deal with three
+ -- complications: (1) The AT possibly only uses a subset of
+ -- the class parameters as indexes and those it uses may be in
+ -- a different order; (2) the AT may have extra arguments,
+ -- which must be type variables; and (3) variables in AT and
+ -- instance head will be different `Name's even if their
+ -- source lexemes are identical.
+ --
+ -- Re (1), `poss' contains a permutation vector to extract the
+ -- class parameters in the right order.
+ --
+ -- Re (2), we wrap the (permuted) class parameters in a Maybe
+ -- type and use Nothing for any extra AT arguments. (First
+ -- equation of `checkIndex' below.)
+ --
+ -- Re (3), we replace any type variable in the AT parameters
+ -- that has the same source lexeme as some variable in the
+ -- instance types with the instance type variable sharing its
+ -- source lexeme.
+ --
+ let relevantInstTys = map (instTys !!) poss
+ instArgs = map Just relevantInstTys ++
+ repeat Nothing -- extra arguments
+ renaming = substSameTyVar atTvs instTvs
+ in
+ zipWithM_ checkIndex (substTys renaming atTys) instArgs
+
+ checkIndex ty Nothing
+ | isTyVarTy ty = return ()
+ | otherwise = addErrTc $ mustBeVarArgErr ty
+ checkIndex ty (Just instTy)
+ | ty `tcEqType` instTy = return ()
+ | otherwise = addErrTc $ wrongATArgErr ty instTy
+
+ listToNameSet = addListToNameSet emptyNameSet
+
+ substSameTyVar [] _ = emptyTvSubst
+ substSameTyVar (tv:tvs) replacingTvs =
+ let replacement = case find (tv `sameLexeme`) replacingTvs of
+ Nothing -> mkTyVarTy tv
+ Just rtv -> mkTyVarTy rtv
+ --
+ tv1 `sameLexeme` tv2 =
+ nameOccName (tyVarName tv1) == nameOccName (tyVarName tv2)
+ in
+ extendTvSubst (substSameTyVar tvs replacingTvs) tv replacement
\end{code}
where
-- For newtype T a = MkT <ty>
-- The returned coercion has kind :: C (T a):=:C <ty>
- co_fn tvs cls_tycon cls_inst_tys | Just co_con <- newTyConCo tycon
+ co_fn tvs cls_tycon cls_inst_tys | Just co_con <- newTyConCo_maybe tycon
= ExprCoFn (mkTyConApp cls_tycon (drop_tail 1 cls_inst_tys ++
[mkSymCoercion (mkTyConApp co_con (map mkTyVarTy tvs))]))
| otherwise
inst_decl_ctxt doc = ptext SLIT("In the instance declaration for") <+> quotes doc
superClassCtxt = ptext SLIT("When checking the super-classes of an instance declaration")
+
+atInstCtxt name = ptext SLIT("In the associated type instance for") <+>
+ quotes (ppr name)
+
+mustBeVarArgErr ty =
+ sep [ ptext SLIT("Arguments that do not correspond to a class parameter") <+>
+ ptext SLIT("must be variables")
+ , ptext SLIT("Instead of a variable, found") <+> ppr ty
+ ]
+
+wrongATArgErr ty instTy =
+ sep [ ptext SLIT("Type indexes must match class instance head")
+ , ptext SLIT("Found") <+> ppr ty <+> ptext SLIT("but expected") <+>
+ ppr instTy
+ ]
\end{code}
projects / ghc-hetmet.git / blobdiff