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 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 )
+import Coercion ( mkAppCoercion, mkAppsCoercion, mkSymCoercion )
+import TyCon ( TyCon, newTyConCo )
+import DataCon ( classDataCon, dataConTyCon, dataConInstArgTys )
import Class ( classBigSig )
-import Var ( Id, idName, idType )
+import Var ( TyVar, Id, idName, idType )
+import Id ( mkSysLocal )
+import UniqSupply ( uniqsFromSupply, splitUniqSupply )
import MkId ( mkDictFunId )
import Name ( Name, getSrcLoc )
import Maybe ( catMaybes )
tcInstDecl2 :: InstInfo -> TcM (LHsBinds Id)
-- Returns a binding for the dfun
---
+------------------------
-- Derived newtype instances
--
-- We need to make a copy of the dictionary we are deriving from
-- 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 :: Tree [a] = T a
+-- axiom CoT a :: T a :=: Tree [a]
--
-- So all need is to generate a binding looking like
--- dfunFooT :: forall a. (Show (T a), Foo Int (Tree [a]) => Foo Int (T a)
+-- 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 (CoT a)) of
+-- case df `cast` (Foo Int (sym (CoT a))) of
-- Foo _ op1 .. opn -> Foo ds op1 .. opn
tcInstDecl2 (InstInfo { iSpec = ispec,
rigid_info = InstSkol dfun_id
origin = SigOrigin rigid_info
inst_ty = idType dfun_id
- maybe_co_con = newTyConCo tycon
+ ; inst_loc <- getInstLoc origin
; (tvs, theta, inst_head) <- tcSkolSigType rigid_info inst_ty
- ; rep_dict <- newDict origin (head theta)
- ; if isSingleton theta then
- return (unitBag (VarBind dfun_id $
- case maybe_co_con of
- Nothing -> rep_dict
- Just co_con -> mkCoerce rep_dict $
- mkAppCoercion (mkAppsCoercion tycon rep_tys)
- (mkTyConApp co_con tvs)))
- else do
- let rep_dict_id = instToId rep_dict
- coerced_dict = case maybe_co_con of
- Nothing -> rep_dict_id
- Just co_con -> mkCoerce rep_dict_id $
- mkAppCoercion (mkAppsCoercion tycon rep_tys)
- (mkTyConApp co_con tvs)
- ; return (unitBag (VarBind dfun_id
- co_fn = CoTyLams tvs <.> CoLams [rep_dict_id] <.> ExprCoFn cast
-
- ; return (unitBag (VarBind dfun_id (HsCoerce co_fn (HsVar rep_dict_id))))
-
-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)
-
+ ; 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)
+
+ coerced_rep_dict = mkHsCoerce (co_fn tvs cls_tycon) (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
- 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')
-
-
+ co_fn :: [TyVar] -> TyCon -> ExprCoFn
+ co_fn tvs cls_tycon | Just co_con <- newTyConCo tycon
+ = ExprCoFn (mkAppCoercion -- (mkAppsCoercion
+ (mkTyConApp cls_tycon [])
+ -- rep_tys)
+ (mkSymCoercion (mkTyConApp co_con (map mkTyVarTy tvs))))
+ | otherwise
+ = idCoercion
+
+------------------------
+-- Ordinary instances
tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = VanillaInst monobinds uprags })
= let
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.
checkSigTyVars inst_tyvars' `thenM_`
-- Deal with 'SPECIALISE instance' pragmas
- tcPrags dfun_id (filter isSpecInstLSig prags) `thenM` \ prags ->
+ tcPrags dfun_id (filter isSpecInstLSig uprags) `thenM` \ prags ->
-- Create the result bindings
let
mapM tc_method_bind meth_infos `thenM` \ meth_binds_s ->
returnM (meth_ids, unionManyBags meth_binds_s)
-v v v v v v v
-*************
-
-
--- Derived newtype instances
-tcMethods origin clas inst_tyvars' dfun_theta' inst_tys'
- avail_insts op_items (NewTypeDerived maybe_co 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}
projects / ghc-hetmet.git / blobdiff