import TysWiredIn ( charTy, mkListTy )
import PrelRules ( primOpRules )
import Type ( TyThing(..), mkForAllTy, tyVarsOfTypes,
- newTyConInstRhs, mkTopTvSubst, substTyVar )
+ newTyConInstRhs, mkTopTvSubst, substTyVar,
+ substTys, zipTopTvSubst )
import TcGadt ( gadtRefine, refineType, emptyRefinement )
-import HsBinds ( ExprCoFn(..), isIdCoercion )
+import HsBinds ( HsWrapper(..), isIdHsWrapper )
import Coercion ( mkSymCoercion, mkUnsafeCoercion, isEqPred )
import TcType ( Type, ThetaType, mkDictTy, mkPredTys, mkPredTy,
mkTyConApp, mkTyVarTys, mkClassPred, isPredTy,
isUnLiftedType, mkForAllTys, mkTyVarTy, tyVarsOfType,
tcSplitFunTys, tcSplitForAllTys, dataConsStupidTheta
)
-import CoreUtils ( exprType, dataConOrigInstPat )
+import CoreUtils ( exprType, dataConOrigInstPat, mkCoerce )
import CoreUnfold ( mkTopUnfolding, mkCompulsoryUnfolding )
import Literal ( nullAddrLit, mkStringLit )
-import TyCon ( TyCon, isNewTyCon, tyConDataCons, FieldLabel,
- tyConStupidTheta, isProductTyCon, isDataTyCon, isRecursiveTyCon,
- newTyConCo )
+import TyCon ( TyCon, isNewTyCon, tyConTyVars, tyConDataCons,
+ FieldLabel,
+ tyConStupidTheta, isProductTyCon, isDataTyCon,
+ isRecursiveTyCon, isFamInstTyCon,
+ tyConFamInst_maybe, tyConFamilyCoercion_maybe,
+ newTyConCo_maybe )
import Class ( Class, classTyCon, classSelIds )
import Var ( Id, TyVar, Var, setIdType )
import VarSet ( isEmptyVarSet, subVarSet, varSetElems )
import OccName ( mkOccNameFS, varName )
import PrimOp ( PrimOp, primOpSig, primOpOcc, primOpTag )
import ForeignCall ( ForeignCall )
-import DataCon ( DataCon, DataConIds(..), dataConTyCon, dataConUnivTyVars,
+import DataCon ( DataCon, DataConIds(..), dataConTyCon,
+ dataConUnivTyVars,
dataConFieldLabels, dataConRepArity, dataConResTys,
dataConRepArgTys, dataConRepType, dataConFullSig,
dataConStrictMarks, dataConExStricts,
splitProductType, isVanillaDataCon, dataConFieldType,
- deepSplitProductType
+ deepSplitProductType,
)
import Id ( idType, mkGlobalId, mkVanillaGlobal, mkSysLocal,
mkTemplateLocals, mkTemplateLocalsNum, mkExportedLocalId,
Making an explicit case expression allows the simplifier to eliminate
it in the (common) case where the constructor arg is already evaluated.
+[Wrappers for data instance tycons]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+In the case of data instances, the wrapper also applies the coercion turning
+the representation type into the family instance type to cast the result of
+the wrapper. For example, consider the declarations
+
+ data family Map k :: * -> *
+ data instance Map (a, b) v = MapPair (Map a (Pair b v))
+
+The tycon to which the datacon MapPair belongs gets a unique internal name of
+the form :R123Map, and we call it the representation tycon. In contrast, Map
+is the family tycon (accessible via tyConFamInst_maybe). The wrapper and work
+of MapPair get the types
+
+ $WMapPair :: forall a b v. Map a (Map a b v) -> Map (a, b) v
+ $wMapPair :: forall a b v. Map a (Map a b v) -> :R123Map a b v
+
+which implies that the wrapper code will have to apply the coercion moving
+between representation and family type. It is accessible via
+tyConFamilyCoercion_maybe and has kind
+
+ Co123Map a b v :: {Map (a, b) v :=: :R123Map a b v}
+
+This coercion is conditionally applied by wrapFamInstBody.
\begin{code}
mkDataConIds :: Name -> Name -> DataCon -> DataConIds
mkDataConIds wrap_name wkr_name data_con
| isNewTyCon tycon
- = NewDC nt_wrap_id
+ = DCIds Nothing nt_work_id -- Newtype, only has a worker
- | any isMarkedStrict all_strict_marks -- Algebraic, needs wrapper
- || not (null eq_spec)
- = AlgDC (Just alg_wrap_id) wrk_id
+ | any isMarkedStrict all_strict_marks -- Algebraic, needs wrapper
+ || not (null eq_spec) -- NB: LoadIface.ifaceDeclSubBndrs
+ || isFamInstTyCon tycon -- depends on this test
+ = DCIds (Just alg_wrap_id) wrk_id
- | otherwise -- Algebraic, no wrapper
- = AlgDC Nothing wrk_id
+ | otherwise -- Algebraic, no wrapper
+ = DCIds Nothing wrk_id
where
- (univ_tvs, ex_tvs, eq_spec, theta, orig_arg_tys) = dataConFullSig data_con
- tycon = dataConTyCon data_con
+ (univ_tvs, ex_tvs, eq_spec,
+ theta, orig_arg_tys) = dataConFullSig data_con
+ tycon = dataConTyCon data_con
----------- Wrapper --------------
-- We used to include the stupid theta in the wrapper's args
-- extra constraints where necessary.
wrap_tvs = (univ_tvs `minusList` map fst eq_spec) ++ ex_tvs
subst = mkTopTvSubst eq_spec
+ famSubst = ASSERT( length (tyConTyVars tycon ) ==
+ length (mkTyVarTys univ_tvs) )
+ zipTopTvSubst (tyConTyVars tycon) (mkTyVarTys univ_tvs)
+ -- substitution mapping the type constructor's type
+ -- arguments to the universals of the data constructor
+ -- (crucial when type checking interfaces)
dict_tys = mkPredTys theta
result_ty_args = map (substTyVar subst) univ_tvs
- result_ty = mkTyConApp tycon result_ty_args
+ result_ty = case tyConFamInst_maybe tycon of
+ -- ordinary constructor
+ Nothing -> mkTyConApp tycon result_ty_args
+ -- family instance constructor
+ Just (familyTyCon,
+ instTys) ->
+ mkTyConApp familyTyCon ( substTys subst
+ . substTys famSubst
+ $ instTys)
wrap_ty = mkForAllTys wrap_tvs $ mkFunTys dict_tys $
mkFunTys orig_arg_tys $ result_ty
-- NB: watch out here if you allow user-written equality
-- RetCPR is only true for products that are real data types;
-- that is, not unboxed tuples or [non-recursive] newtypes
- ----------- Wrappers for newtypes --------------
- nt_wrap_id = mkGlobalId (DataConWrapId data_con) wrap_name wrap_ty nt_wrap_info
- nt_wrap_info = noCafIdInfo -- The NoCaf-ness is set by noCafIdInfo
+ ----------- Workers for newtypes --------------
+ nt_work_id = mkGlobalId (DataConWrapId data_con) wkr_name wrap_ty nt_work_info
+ nt_work_info = noCafIdInfo -- The NoCaf-ness is set by noCafIdInfo
`setArityInfo` 1 -- Arity 1
`setUnfoldingInfo` newtype_unf
newtype_unf = ASSERT( isVanillaDataCon data_con &&
(zip (dict_args ++ id_args) all_strict_marks)
i3 []
- con_app _ rep_ids = Var wrk_id `mkTyApps` result_ty_args
- `mkVarApps` ex_tvs
- `mkTyApps` map snd eq_spec
- `mkVarApps` reverse rep_ids
+ con_app _ rep_ids = wrapFamInstBody tycon result_ty_args $
+ Var wrk_id `mkTyApps` result_ty_args
+ `mkVarApps` ex_tvs
+ `mkTyApps` map snd eq_spec
+ `mkVarApps` reverse rep_ids
(dict_args,i2) = mkLocals 1 dict_tys
(id_args,i3) = mkLocals i2 orig_arg_tys
mkLocals i tys = (zipWith mkTemplateLocal [i..i+n-1] tys, i+n)
where
n = length tys
+
+-- If the type constructor is a representation type of a data instance, wrap
+-- the expression into a cast adjusting the expression type, which is an
+-- instance of the representation type, to the corresponding instance of the
+-- family instance type.
+--
+wrapFamInstBody :: TyCon -> [Type] -> CoreExpr -> CoreExpr
+wrapFamInstBody tycon args result_expr
+ | Just co_con <- tyConFamilyCoercion_maybe tycon
+ = mkCoerce (mkSymCoercion (mkTyConApp co_con args)) result_expr
+ | otherwise
+ = result_expr
\end{code}
-- and apply to (Maybe b'), to get (Maybe b)
rhs = case co_fn of
- ExprCoFn co -> Cast (Var the_arg_id) co
- id_co -> ASSERT(isIdCoercion id_co) Var the_arg_id
+ WpCo co -> Cast (Var the_arg_id) co
+ id_co -> ASSERT(isIdHsWrapper id_co) Var the_arg_id
field_vs = filter (not . isPredTy . idType) arg_vs
the_arg_id = assoc "mkRecordSelId:mk_alt" (field_lbls `zip` field_vs) field_label
-- If we have e = MkT (MkS (PairInt 0 1)) and some body expecting a list of
-- ids, we get (modulo int passing)
--
--- case (e `cast` (sym CoT)) `cast` (sym CoS) of
+-- case (e `cast` CoT) `cast` CoS of
-- PairInt a b -> body [a,b]
--
-- The Ints passed around are just for creating fresh locals
-- The wrapper for the data constructor for a newtype looks like this:
-- newtype T a = MkT (a,Int)
-- MkT :: forall a. (a,Int) -> T a
--- MkT = /\a. \(x:(a,Int)). x `cast` CoT a
+-- MkT = /\a. \(x:(a,Int)). x `cast` sym (CoT a)
-- where CoT is the coercion TyCon assoicated with the newtype
--
-- The call (wrapNewTypeBody T [a] e) returns the
-- body of the wrapper, namely
--- e `cast` CoT [a]
+-- e `cast` (CoT [a])
--
-- If a coercion constructor is prodivided in the newtype, then we use
-- it, otherwise the wrap/unwrap are both no-ops
--
+-- If the we are dealing with a newtype instance, we have a second coercion
+-- identifying the family instance with the constructor of the newtype
+-- instance. This coercion is applied in any case (ie, composed with the
+-- coercion constructor of the newtype or applied by itself).
+--
wrapNewTypeBody tycon args result_expr
- | Just co_con <- newTyConCo tycon
- = Cast result_expr (mkTyConApp co_con args)
- | otherwise
- = result_expr
+ = wrapFamInstBody tycon args inner
+ where
+ inner
+ | Just co_con <- newTyConCo_maybe tycon
+ = mkCoerce (mkSymCoercion (mkTyConApp co_con args)) result_expr
+ | otherwise
+ = result_expr
+-- When unwrapping, we do *not* apply any family coercion, because this will
+-- be done via a CoPat by the type checker. We have to do it this way as
+-- computing the right type arguments for the coercion requires more than just
+-- a spliting operation (cf, TcPat.tcConPat).
+--
unwrapNewTypeBody :: TyCon -> [Type] -> CoreExpr -> CoreExpr
unwrapNewTypeBody tycon args result_expr
- | Just co_con <- newTyConCo tycon
- = Cast result_expr (mkSymCoercion (mkTyConApp co_con args))
+ | Just co_con <- newTyConCo_maybe tycon
+ = mkCoerce (mkTyConApp co_con args) result_expr
| otherwise
= result_expr
ty = mkForAllTys tyvars (mkFunTys arg_tys res_ty)
name = mkWiredInName gHC_PRIM (primOpOcc prim_op)
(mkPrimOpIdUnique (primOpTag prim_op))
- Nothing (AnId id) UserSyntax
+ (AnId id) UserSyntax
id = mkGlobalId (PrimOpId prim_op) name ty info
info = noCafIdInfo
\begin{code}
mkWiredInIdName mod fs uniq id
- = mkWiredInName mod (mkOccNameFS varName fs) uniq Nothing (AnId id) UserSyntax
+ = mkWiredInName mod (mkOccNameFS varName fs) uniq (AnId id) UserSyntax
unsafeCoerceName = mkWiredInIdName gHC_PRIM FSLIT("unsafeCoerce#") unsafeCoerceIdKey unsafeCoerceId
nullAddrName = mkWiredInIdName gHC_PRIM FSLIT("nullAddr#") nullAddrIdKey nullAddrId
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