X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcInstDcls.lhs;h=2a516618fefbacb3a01a483c53fefa5c85b99f31;hp=8b53e3ec29c9adb61394482a32dd1ecc610b4a16;hb=80c89b80c355b2aaebcd53330e6c6170c3f05aca;hpb=1dfd77341ec56e9d61f2d78cb7ff2b9900385dac diff --git a/compiler/typecheck/TcInstDcls.lhs b/compiler/typecheck/TcInstDcls.lhs index 8b53e3e..2a51661 100644 --- a/compiler/typecheck/TcInstDcls.lhs +++ b/compiler/typecheck/TcInstDcls.lhs @@ -10,26 +10,32 @@ module TcInstDcls ( tcInstDecls1, tcInstDecls2 ) where import HsSyn import TcBinds ( mkPragFun, tcPrags, badBootDeclErr ) +import TcTyClsDecls ( tcIdxTyInstDecl ) import TcClassDcl ( tcMethodBind, mkMethodBind, badMethodErr, tcClassDecl2, getGenericInstances ) import TcRnMonad import TcMType ( tcSkolSigType, checkValidInstance, checkValidInstHead ) -import TcType ( mkClassPred, tcSplitSigmaTy, tcSplitDFunHead, mkTyVarTys, - SkolemInfo(InstSkol), tcSplitDFunTy ) -import Inst ( tcInstClassOp, newDicts, instToId, showLIE, +import TcType ( mkClassPred, tcSplitSigmaTy, tcSplitDFunHead, + SkolemInfo(InstSkol), tcSplitDFunTy, mkFunTy ) +import Inst ( newDictBndr, newDictBndrs, instToId, showLIE, getOverlapFlag, tcExtendLocalInstEnv ) import InstEnv ( mkLocalInstance, instanceDFunId ) import TcDeriv ( tcDeriving ) import TcEnv ( InstInfo(..), InstBindings(..), - newDFunName, tcExtendIdEnv + newDFunName, tcExtendIdEnv, tcExtendGlobalEnv ) import TcHsType ( kcHsSigType, tcHsKindedType ) import TcUnify ( checkSigTyVars ) -import TcSimplify ( tcSimplifyCheck, tcSimplifySuperClasses ) -import Type ( zipOpenTvSubst, substTheta, substTys ) -import DataCon ( classDataCon ) +import TcSimplify ( tcSimplifySuperClasses ) +import Type ( zipOpenTvSubst, substTheta, mkTyConApp, mkTyVarTy, + splitFunTys, TyThing ) +import Coercion ( mkSymCoercion ) +import TyCon ( TyCon, newTyConCo, tyConTyVars ) +import DataCon ( classDataCon, dataConTyCon, dataConInstArgTys ) import Class ( classBigSig ) -import Var ( Id, idName, idType ) +import Var ( TyVar, Id, idName, idType, tyVarKind ) +import Id ( mkSysLocal ) +import UniqSupply ( uniqsFromSupply, splitUniqSupply ) import MkId ( mkDictFunId ) import Name ( Name, getSrcLoc ) import Maybe ( catMaybes ) @@ -38,6 +44,7 @@ import ListSetOps ( minusList ) import Outputable import Bag import BasicTypes ( Activation( AlwaysActive ), InlineSpec(..) ) +import HscTypes ( implicitTyThings ) import FastString \end{code} @@ -51,7 +58,6 @@ pass, when the class-instance envs and GVE contain all the info from all the instance and value decls. Indeed that's the reason we need two passes over the instance decls. - Here is the overall algorithm. Assume that we have an instance declaration @@ -134,35 +140,52 @@ tcInstDecls1 -- Deal with both source-code and imported instance decls tcInstDecls1 tycl_decls inst_decls = checkNoErrs $ - -- Stop if addInstInfos etc discovers any errors - -- (they recover, so that we get more than one error each round) - - -- (1) Do the ordinary instance declarations - mappM tcLocalInstDecl1 inst_decls `thenM` \ local_inst_infos -> - - let - local_inst_info = catMaybes local_inst_infos - clas_decls = filter (isClassDecl.unLoc) tycl_decls - in - -- (2) Instances from generic class declarations - getGenericInstances clas_decls `thenM` \ generic_inst_info -> - - -- Next, construct the instance environment so far, consisting of - -- a) local instance decls - -- b) generic instances - addInsts local_inst_info $ - addInsts generic_inst_info $ - - -- (3) 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; hence inst_env4 - tcDeriving tycl_decls `thenM` \ (deriv_inst_info, deriv_binds) -> - addInsts deriv_inst_info $ - - getGblEnv `thenM` \ gbl_env -> - returnM (gbl_env, - generic_inst_info ++ deriv_inst_info ++ local_inst_info, - deriv_binds) + do { -- Stop if addInstInfos etc discovers any errors + -- (they recover, so that we get more than one error each + -- round) + + -- (1) Do the ordinary instance declarations and instances of + -- indexed types + ; let { idxty_decls = filter (isIdxTyDecl . unLoc) tycl_decls } + ; local_info_tycons <- mappM tcLocalInstDecl1 inst_decls + ; idxty_info_tycons <- mappM tcIdxTyInstDecl idxty_decls + + ; let { (local_infos, + local_tycons) = unzip local_info_tycons + ; (idxty_infos, + idxty_tycons) = unzip idxty_info_tycons + ; local_idxty_info = concat local_infos ++ catMaybes idxty_infos + ; local_idxty_tycon = concat local_tycons ++ + catMaybes idxty_tycons + ; clas_decls = filter (isClassDecl.unLoc) tycl_decls + ; implicit_things = concatMap implicitTyThings local_idxty_tycon + } + + -- (2) Add the tycons of associated types and their implicit + -- tythings to the global environment + ; tcExtendGlobalEnv (local_idxty_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_idxty_info $ do { + ; addInsts generic_inst_info $ do { + + -- (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 + ; addInsts deriv_inst_info $ do { + + ; gbl_env <- getGblEnv + ; returnM (gbl_env, + generic_inst_info ++ deriv_inst_info ++ local_idxty_info, + deriv_binds) + }}}}} addInsts :: [InstInfo] -> TcM a -> TcM a addInsts infos thing_inside @@ -171,14 +194,14 @@ addInsts infos thing_inside \begin{code} tcLocalInstDecl1 :: LInstDecl Name - -> TcM (Maybe InstInfo) -- Nothing 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)) +tcLocalInstDecl1 decl@(L loc (InstDecl poly_ty binds uprags ats)) = -- Prime error recovery, set source location - recoverM (returnM Nothing) $ + recoverM (returnM ([], [])) $ setSrcSpan loc $ addErrCtxt (instDeclCtxt1 poly_ty) $ @@ -192,15 +215,27 @@ tcLocalInstDecl1 decl@(L loc (InstDecl poly_ty binds uprags)) ; poly_ty' <- tcHsKindedType kinded_ty ; let (tyvars, theta, tau) = tcSplitSigmaTy poly_ty' + -- Now, check the validity of the instance. ; (clas, inst_tys) <- checkValidInstHead tau ; checkValidInstance tyvars theta clas inst_tys + -- Next, process any associated types. + ; idxty_info_tycons <- mappM tcIdxTyInstDecl ats + + -- 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 - - ; return (Just (InstInfo { iSpec = ispec, iBinds = VanillaInst binds uprags })) } + ; let dfun = mkDictFunId dfun_name tyvars theta clas inst_tys + ispec = mkLocalInstance dfun overlap_flag + (idxty_infos, + idxty_tycons) = unzip idxty_info_tycons + + ; return ([InstInfo { iSpec = ispec, + iBinds = VanillaInst binds uprags }] ++ + catMaybes idxty_infos, + catMaybes idxty_tycons) + } \end{code} @@ -303,8 +338,100 @@ First comes the easy case of a non-local instance decl. \begin{code} tcInstDecl2 :: InstInfo -> TcM (LHsBinds Id) +-- Returns a binding for the dfun -tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = binds }) +------------------------ +-- Derived newtype instances +-- +-- We need to make a copy of the dictionary we are deriving from +-- because we may need to change some of the superclass dictionaries +-- see Note [Newtype deriving superclasses] in TcDeriv.lhs +-- +-- In the case of a newtype, things are rather easy +-- class Show a => Foo a b where ... +-- newtype T a = MkT (Tree [a]) deriving( Foo Int ) +-- The newtype gives an FC axiom looking like +-- axiom CoT a :: T a :=: Tree [a] +-- +-- So all need is to generate a binding looking like +-- dfunFooT :: forall a. (Foo Int (Tree [a], Show (T a)) => Foo Int (T a) +-- dfunFooT = /\a. \(ds:Show (T a)) (df:Foo (Tree [a])). +-- case df `cast` (Foo Int (sym (CoT a))) of +-- Foo _ op1 .. opn -> Foo ds op1 .. opn + +tcInstDecl2 (InstInfo { iSpec = ispec, + iBinds = NewTypeDerived tycon rep_tys }) + = do { let dfun_id = instanceDFunId ispec + rigid_info = InstSkol dfun_id + origin = SigOrigin rigid_info + inst_ty = idType dfun_id + ; inst_loc <- getInstLoc origin + ; (tvs, theta, inst_head) <- tcSkolSigType rigid_info inst_ty + ; dicts <- newDictBndrs inst_loc theta + ; uniqs <- newUniqueSupply + ; let (cls, cls_inst_tys) = tcSplitDFunHead inst_head + ; this_dict <- newDictBndr inst_loc (mkClassPred cls rep_tys) + ; let (rep_dict_id:sc_dict_ids) + | null dicts = [instToId this_dict] + | otherwise = map instToId dicts + + -- (Here, we are relying on the order of dictionary + -- arguments built by NewTypeDerived in TcDeriv.) + + wrap_fn = mkCoTyLams tvs <.> mkCoLams (rep_dict_id:sc_dict_ids) + + -- we need to find the kind that this class applies to + -- and drop trailing tvs appropriately + cls_kind = tyVarKind (head (reverse (tyConTyVars cls_tycon))) + the_tvs = drop_tail (length (fst (splitFunTys cls_kind))) tvs + + coerced_rep_dict = mkHsCoerce (co_fn the_tvs cls_tycon cls_inst_tys) (HsVar rep_dict_id) + + body | null sc_dict_ids = coerced_rep_dict + | otherwise = HsCase (noLoc coerced_rep_dict) $ + MatchGroup [the_match] (mkFunTy in_dict_ty inst_head) + in_dict_ty = mkTyConApp cls_tycon cls_inst_tys + + the_match = mkSimpleMatch [noLoc the_pat] the_rhs + the_rhs = mkHsConApp cls_data_con cls_inst_tys (map HsVar (sc_dict_ids ++ op_ids)) + + (uniqs1, uniqs2) = splitUniqSupply uniqs + + op_ids = zipWith (mkSysLocal FSLIT("op")) + (uniqsFromSupply uniqs1) op_tys + + dict_ids = zipWith (mkSysLocal FSLIT("dict")) + (uniqsFromSupply uniqs2) (map idType sc_dict_ids) + + the_pat = ConPatOut { pat_con = noLoc cls_data_con, pat_tvs = [], + pat_dicts = dict_ids, + pat_binds = emptyLHsBinds, + pat_args = PrefixCon (map nlVarPat op_ids), + pat_ty = in_dict_ty} + + cls_data_con = classDataCon cls + cls_tycon = dataConTyCon cls_data_con + cls_arg_tys = dataConInstArgTys cls_data_con cls_inst_tys + + n_dict_args = if length dicts == 0 then 0 else length dicts - 1 + op_tys = drop n_dict_args cls_arg_tys + + dict = mkHsCoerce wrap_fn body + ; return (unitBag (noLoc $ VarBind dfun_id (noLoc dict))) } + where + -- For newtype T a = MkT + -- The returned coercion has kind :: C (T a):=:C + co_fn tvs cls_tycon cls_inst_tys | Just co_con <- newTyConCo tycon + = ExprCoFn (mkTyConApp cls_tycon (drop_tail 1 cls_inst_tys ++ + [mkSymCoercion (mkTyConApp co_con (map mkTyVarTy tvs))])) + | otherwise + = idCoercion + drop_tail n l = take (length l - n) l + +------------------------ +-- Ordinary instances + +tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = VanillaInst monobinds uprags }) = let dfun_id = instanceDFunId ispec rigid_info = InstSkol dfun_id @@ -329,9 +456,11 @@ tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = binds }) origin = SigOrigin rigid_info in -- Create dictionary Ids from the specified instance contexts. - newDicts InstScOrigin sc_theta' `thenM` \ sc_dicts -> - newDicts origin dfun_theta' `thenM` \ dfun_arg_dicts -> - newDicts origin [mkClassPred clas inst_tys'] `thenM` \ [this_dict] -> + getInstLoc InstScOrigin `thenM` \ sc_loc -> + newDictBndrs sc_loc sc_theta' `thenM` \ sc_dicts -> + getInstLoc origin `thenM` \ inst_loc -> + newDictBndrs inst_loc dfun_theta' `thenM` \ dfun_arg_dicts -> + newDictBndr inst_loc (mkClassPred clas inst_tys') `thenM` \ this_dict -> -- Default-method Ids may be mentioned in synthesised RHSs, -- but they'll already be in the environment. @@ -341,7 +470,7 @@ tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = binds }) in tcMethods origin clas inst_tyvars' dfun_theta' inst_tys' avail_insts - op_items binds `thenM` \ (meth_ids, meth_binds) -> + op_items monobinds uprags `thenM` \ (meth_ids, meth_binds) -> -- Figure out bindings for the superclass context -- Don't include this_dict in the 'givens', else @@ -356,12 +485,7 @@ tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = binds }) checkSigTyVars inst_tyvars' `thenM_` -- Deal with 'SPECIALISE instance' pragmas - let - specs = case binds of - VanillaInst _ prags -> filter isSpecInstLSig prags - other -> [] - in - tcPrags dfun_id specs `thenM` \ prags -> + tcPrags dfun_id (filter isSpecInstLSig uprags) `thenM` \ prags -> -- Create the result bindings let @@ -405,7 +529,7 @@ tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = binds }) tcMethods origin clas inst_tyvars' dfun_theta' inst_tys' - avail_insts op_items (VanillaInst monobinds uprags) + avail_insts op_items monobinds uprags = -- Check that all the method bindings come from this class let sel_names = [idName sel_id | (sel_id, _) <- op_items] @@ -461,41 +585,6 @@ tcMethods origin clas inst_tyvars' dfun_theta' inst_tys' mapM tc_method_bind meth_infos `thenM` \ meth_binds_s -> returnM (meth_ids, unionManyBags meth_binds_s) - - --- Derived newtype instances -tcMethods origin clas inst_tyvars' dfun_theta' inst_tys' - avail_insts op_items (NewTypeDerived rep_tys) - = getInstLoc origin `thenM` \ inst_loc -> - mapAndUnzip3M (do_one inst_loc) op_items `thenM` \ (meth_ids, meth_binds, rhs_insts) -> - - tcSimplifyCheck - (ptext SLIT("newtype derived instance")) - inst_tyvars' avail_insts rhs_insts `thenM` \ lie_binds -> - - -- I don't think we have to do the checkSigTyVars thing - - returnM (meth_ids, lie_binds `unionBags` listToBag meth_binds) - - where - do_one inst_loc (sel_id, _) - = -- The binding is like "op @ NewTy = op @ RepTy" - -- Make the *binder*, like in mkMethodBind - tcInstClassOp inst_loc sel_id inst_tys' `thenM` \ meth_inst -> - - -- Make the *occurrence on the rhs* - tcInstClassOp inst_loc sel_id rep_tys' `thenM` \ rhs_inst -> - let - meth_id = instToId meth_inst - in - return (meth_id, noLoc (VarBind meth_id (nlHsVar (instToId rhs_inst))), rhs_inst) - - -- Instantiate rep_tys with the relevant type variables - -- This looks a bit odd, because inst_tyvars' are the skolemised version - -- of the type variables in the instance declaration; but rep_tys doesn't - -- have the skolemised version, so we substitute them in here - rep_tys' = substTys subst rep_tys - subst = zipOpenTvSubst inst_tyvars' (mkTyVarTys inst_tyvars') \end{code}