Commit 70918cf4 authored by simonpj@microsoft.com's avatar simonpj@microsoft.com
Browse files

Fixes to datacon wrappers for indexed data types

nominolo@gmail.com pointed out (Trac #1204) that indexed data types
aren't quite right. I investigated and found that the wrapper
functions for indexed data types, generated in MkId, are really very
confusing.  In particular, we'd like these combinations to work
	newtype + indexed data type
	GADT + indexted data type
The wrapper situation gets a bit complicated!  

I did a bit of refactoring, and improved matters, I think.  I am not
certain that I have gotten it right yet, but I think it's better.
I'm committing it now becuase it's been on my non-backed-up laptop for
a month and I want to get it into the repo. I don't think I've broken
anything, but I don't regard it as 'done'.
parent 49079156
......@@ -11,9 +11,9 @@ module DataCon (
mkDataCon,
dataConRepType, dataConSig, dataConFullSig,
dataConName, dataConIdentity, dataConTag, dataConTyCon, dataConUserType,
dataConUnivTyVars, dataConExTyVars, dataConAllTyVars, dataConResTys,
dataConUnivTyVars, dataConExTyVars, dataConAllTyVars,
dataConEqSpec, eqSpecPreds, dataConTheta, dataConStupidTheta,
dataConInstArgTys, dataConOrigArgTys,
dataConInstArgTys, dataConOrigArgTys, dataConOrigResTy,
dataConInstOrigArgTys, dataConRepArgTys,
dataConFieldLabels, dataConFieldType,
dataConStrictMarks, dataConExStricts,
......@@ -233,7 +233,7 @@ data DataCon
-- dcEqSpec = [a:=:(x,y)]
-- dcTheta = [Ord x]
-- dcOrigArgTys = [a,List b]
-- dcTyCon = T
-- dcRepTyCon = T
dcVanilla :: Bool, -- True <=> This is a vanilla Haskell 98 data constructor
-- Its type is of form
......@@ -288,9 +288,11 @@ data DataCon
dcOrigArgTys :: [Type], -- Original argument types
-- (before unboxing and flattening of strict fields)
-- Result type of constructor is T t1..tn
dcTyCon :: TyCon, -- Result tycon, T
dcOrigResTy :: Type, -- Original result type
-- NB: for a data instance, the original user result type may
-- differ from the DataCon's representation TyCon. Example
-- data instance T [a] where MkT :: a -> T [a]
-- The OrigResTy is T [a], but the dcRepTyCon might be :T123
-- Now the strictness annotations and field labels of the constructor
dcStrictMarks :: [StrictnessMark],
......@@ -300,7 +302,7 @@ data DataCon
dcFields :: [FieldLabel],
-- Field labels for this constructor, in the
-- same order as the argument types;
-- same order as the dcOrigArgTys;
-- length = 0 (if not a record) or dataConSourceArity.
-- Constructor representation
......@@ -311,6 +313,9 @@ data DataCon
dcRepStrictness :: [StrictnessMark], -- One for each *representation* argument
-- See also Note [Data-con worker strictness] in MkId.lhs
-- Result type of constructor is T t1..tn
dcRepTyCon :: TyCon, -- Result tycon, T
dcRepType :: Type, -- Type of the constructor
-- forall a x y. (a:=:(x,y), Ord x) => x -> y -> MkT a
-- (this is *not* of the constructor wrapper Id:
......@@ -459,7 +464,8 @@ mkDataCon name declared_infix
dcUnivTyVars = univ_tvs, dcExTyVars = ex_tvs,
dcEqSpec = eq_spec,
dcStupidTheta = stupid_theta, dcTheta = theta,
dcOrigArgTys = orig_arg_tys, dcTyCon = tycon,
dcOrigArgTys = orig_arg_tys, dcOrigResTy = orig_res_ty,
dcRepTyCon = tycon,
dcRepArgTys = rep_arg_tys,
dcStrictMarks = arg_stricts,
dcRepStrictness = rep_arg_stricts,
......@@ -477,6 +483,22 @@ mkDataCon name declared_infix
real_arg_tys = dict_tys ++ orig_arg_tys
real_stricts = map mk_dict_strict_mark theta ++ arg_stricts
-- Example
-- data instance T [a] where
-- TI :: forall b. b -> T [Maybe b]
-- The representation tycon looks like this:
-- data :R7T a where
-- TI :: forall b c. (c :=: Maybe b) b -> :R7T c
orig_res_ty
| Just (fam_tc, fam_tys) <- tyConFamInst_maybe tycon
, let fam_subst = zipTopTvSubst (tyConTyVars fam_tc) res_tys
= mkTyConApp fam_tc (substTys fam_subst fam_tys)
| otherwise
= mkTyConApp tycon res_tys
where
res_tys = substTyVars (mkTopTvSubst eq_spec) univ_tvs
-- In the example above, res_tys is a singleton, (Maybe b)
-- Representation arguments and demands
-- To do: eliminate duplication with MkId
(rep_arg_stricts, rep_arg_tys) = computeRep real_stricts real_arg_tys
......@@ -518,7 +540,7 @@ dataConTag :: DataCon -> ConTag
dataConTag = dcTag
dataConTyCon :: DataCon -> TyCon
dataConTyCon = dcTyCon
dataConTyCon = dcRepTyCon
dataConRepType :: DataCon -> Type
dataConRepType = dcRepType
......@@ -597,25 +619,23 @@ dataConRepStrictness :: DataCon -> [StrictnessMark]
-- Core constructor application (Con dc args)
dataConRepStrictness dc = dcRepStrictness dc
dataConSig :: DataCon -> ([TyVar], ThetaType, [Type])
dataConSig :: DataCon -> ([TyVar], ThetaType, [Type], Type)
dataConSig (MkData {dcUnivTyVars = univ_tvs, dcExTyVars = ex_tvs, dcEqSpec = eq_spec,
dcTheta = theta, dcOrigArgTys = arg_tys, dcTyCon = tycon})
= (univ_tvs ++ ex_tvs, eqSpecPreds eq_spec ++ theta, arg_tys)
dcTheta = theta, dcOrigArgTys = arg_tys, dcOrigResTy = res_ty})
= (univ_tvs ++ ex_tvs, eqSpecPreds eq_spec ++ theta, arg_tys, res_ty)
dataConFullSig :: DataCon
-> ([TyVar], [TyVar], [(TyVar,Type)], ThetaType, [Type])
-> ([TyVar], [TyVar], [(TyVar,Type)], ThetaType, [Type], Type)
dataConFullSig (MkData {dcUnivTyVars = univ_tvs, dcExTyVars = ex_tvs, dcEqSpec = eq_spec,
dcTheta = theta, dcOrigArgTys = arg_tys, dcTyCon = tycon})
= (univ_tvs, ex_tvs, eq_spec, theta, arg_tys)
dcTheta = theta, dcOrigArgTys = arg_tys, dcOrigResTy = res_ty})
= (univ_tvs, ex_tvs, eq_spec, theta, arg_tys, res_ty)
dataConOrigResTy :: DataCon -> Type
dataConOrigResTy dc = dcOrigResTy dc
dataConStupidTheta :: DataCon -> ThetaType
dataConStupidTheta dc = dcStupidTheta dc
dataConResTys :: DataCon -> [Type]
dataConResTys dc = [substTyVar env tv | tv <- dcUnivTyVars dc]
where
env = mkTopTvSubst (dcEqSpec dc)
dataConUserType :: DataCon -> Type
-- The user-declared type of the data constructor
-- in the nice-to-read form
......@@ -627,15 +647,11 @@ dataConUserType :: DataCon -> Type
dataConUserType (MkData { dcUnivTyVars = univ_tvs,
dcExTyVars = ex_tvs, dcEqSpec = eq_spec,
dcTheta = theta, dcOrigArgTys = arg_tys,
dcTyCon = tycon })
dcOrigResTy = res_ty })
= mkForAllTys ((univ_tvs `minusList` map fst eq_spec) ++ ex_tvs) $
mkFunTys (mkPredTys theta) $
mkFunTys arg_tys $
case tyConFamInst_maybe tycon of
Nothing -> mkTyConApp tycon (substTyVars subst univ_tvs)
Just (ftc, insttys) -> mkTyConApp ftc insttys -- data instance
where
subst = mkTopTvSubst eq_spec
res_ty
dataConInstArgTys :: DataCon
-> [Type] -- Instantiated at these types
......@@ -686,10 +702,10 @@ dataConRepArgTys dc = dcRepArgTys dc
\begin{code}
isTupleCon :: DataCon -> Bool
isTupleCon (MkData {dcTyCon = tc}) = isTupleTyCon tc
isTupleCon (MkData {dcRepTyCon = tc}) = isTupleTyCon tc
isUnboxedTupleCon :: DataCon -> Bool
isUnboxedTupleCon (MkData {dcTyCon = tc}) = isUnboxedTupleTyCon tc
isUnboxedTupleCon (MkData {dcRepTyCon = tc}) = isUnboxedTupleTyCon tc
isVanillaDataCon :: DataCon -> Bool
isVanillaDataCon dc = dcVanilla dc
......@@ -700,6 +716,7 @@ isVanillaDataCon dc = dcVanilla dc
classDataCon :: Class -> DataCon
classDataCon clas = case tyConDataCons (classTyCon clas) of
(dict_constr:no_more) -> ASSERT( null no_more ) dict_constr
[] -> panic "classDataCon"
\end{code}
%************************************************************************
......
......@@ -44,7 +44,6 @@ import TysWiredIn
import PrelRules
import Type
import TcGadt
import HsBinds
import Coercion
import TcType
import CoreUtils
......@@ -162,8 +161,8 @@ Notice that
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]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Note [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
......@@ -171,27 +170,45 @@ 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
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). A coercion allows you to move between
representation and family type. It is accessible from :R123Map via
tyConFamilyCoercion_maybe and has kind
Co123Map a b v :: {Map (a, b) v :=: :R123Map a b v}
The wrapper and worker of MapPair get the types
$WMapPair :: forall a b v. Map a (Map a b v) -> Map (a, b) v
$WMapPair a b v = $wMapPair a b v `cast` sym (Co123Map 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
This coercion is conditionally applied by wrapFamInstBody.
Co123Map a b v :: {Map (a, b) v :=: :R123Map a b v}
It's a bit more complicated if the data instance is a GADT as well!
This coercion is conditionally applied by wrapFamInstBody.
data instance T [a] where
T1 :: forall b. b -> T [Maybe b]
Hence
Co7T a :: T [a] ~ :R7T a
Now we want
$WT1 :: forall b. b -> T [Maybe b]
$WT1 a b v = $wT1 b (Maybe b) (Maybe b)
`cast` sym (Co7T (Maybe b))
$wT1 :: forall b c. (b ~ Maybe c) => b -> :R7T c
\begin{code}
mkDataConIds :: Name -> Name -> DataCon -> DataConIds
mkDataConIds wrap_name wkr_name data_con
| isNewTyCon tycon
= DCIds Nothing nt_work_id -- Newtype, only has a worker
| isNewTyCon tycon -- Newtype, only has a worker
, not (isFamInstTyCon tycon) -- unless it's a family instancex
= DCIds Nothing nt_work_id
| any isMarkedStrict all_strict_marks -- Algebraic, needs wrapper
|| not (null eq_spec) -- NB: LoadIface.ifaceDeclSubBndrs
......@@ -202,34 +219,18 @@ mkDataConIds wrap_name wkr_name data_con
= DCIds Nothing wrk_id
where
(univ_tvs, ex_tvs, eq_spec,
theta, orig_arg_tys) = dataConFullSig data_con
tycon = dataConTyCon data_con
theta, orig_arg_tys, res_ty) = dataConFullSig data_con
res_ty_args = tyConAppArgs res_ty
tycon = dataConTyCon data_con
----------- Wrapper --------------
-- We used to include the stupid theta in the wrapper's args
-- but now we don't. Instead the type checker just injects these
-- 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 = substTyVars subst univ_tvs
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
dict_tys = mkPredTys theta
wrap_ty = mkForAllTys wrap_tvs $ mkFunTys dict_tys $
mkFunTys orig_arg_tys $ res_ty
-- NB: watch out here if you allow user-written equality
-- constraints in data constructor signatures
......@@ -283,7 +284,7 @@ mkDataConIds wrap_name wkr_name data_con
-- e.g. newtype Eq a => T a = MkT (...)
mkCompulsoryUnfolding $
mkLams wrap_tvs $ Lam id_arg1 $
wrapNewTypeBody tycon result_ty_args
wrapNewTypeBody tycon res_ty_args
(Var id_arg1)
id_arg1 = mkTemplateLocal 1 (head orig_arg_tys)
......@@ -318,10 +319,10 @@ mkDataConIds wrap_name wkr_name data_con
(zip (dict_args ++ id_args) all_strict_marks)
i3 []
con_app _ rep_ids = wrapFamInstBody tycon result_ty_args $
Var wrk_id `mkTyApps` result_ty_args
`mkVarApps` ex_tvs
`mkTyApps` map snd eq_spec
con_app _ rep_ids = wrapFamInstBody tycon res_ty_args $
Var wrk_id `mkTyApps` res_ty_args
`mkVarApps` ex_tvs
`mkTyApps` map snd eq_spec -- Equality evidence
`mkVarApps` reverse rep_ids
(dict_args,i2) = mkLocals 1 dict_tys
......@@ -340,7 +341,7 @@ mkDataConIds wrap_name wkr_name data_con
MarkedStrict
| isUnLiftedType (idType arg) -> body i (arg:rep_args)
| otherwise ->
Case (Var arg) arg result_ty [(DEFAULT,[], body i (arg:rep_args))]
Case (Var arg) arg res_ty [(DEFAULT,[], body i (arg:rep_args))]
MarkedUnboxed
-> unboxProduct i (Var arg) (idType arg) the_body
......@@ -361,18 +362,6 @@ mAX_CPR_SIZE = 10
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}
......@@ -453,23 +442,41 @@ Note the forall'd tyvars of the selector are just the free tyvars
of the result type; there may be other tyvars in the constructor's
type (e.g. 'b' in T2).
\begin{code}
Note [Selector running example]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It's OK to combine GADTs and type families. Here's a running example:
data instance T [a] where
T1 { fld :: b } :: T [Maybe b]
The representation type looks like this
data :R7T a where
T1 { fld :: b } :: :R7T (Maybe b)
-- Steps for handling "naughty" vs "non-naughty" selectors:
-- 1. Determine naughtiness by comparing field type vs result type
-- 2. Install naughty ones with selector_ty of type _|_ and fill in mzero for info
-- 3. If it's not naughty, do the normal plan.
and there's coercion from the family type to the representation type
:CoR7T a :: T [a] ~ :R7T a
The selector we want for fld looks like this:
fld :: forall b. T [Maybe b] -> b
fld = /\b. \(d::T [Maybe b]).
case d `cast` :CoR7T (Maybe b) of
T1 (x::b) -> x
The scrutinee of the case has type :R7T (Maybe b), which can be
gotten by appying the eq_spec to the univ_tvs of the data con.
\begin{code}
mkRecordSelId :: TyCon -> FieldLabel -> Id
mkRecordSelId tycon field_label
-- Assumes that all fields with the same field label have the same type
| is_naughty = naughty_id
| otherwise = sel_id
where
is_naughty = not (tyVarsOfType field_ty `subVarSet` res_tv_set)
is_naughty = not (tyVarsOfType field_ty `subVarSet` data_tv_set)
sel_id_details = RecordSelId tycon field_label is_naughty
-- Escapist case here for naughty construcotrs
-- Escapist case here for naughty constructors
-- We give it no IdInfo, and a type of forall a.a (never looked at)
naughty_id = mkGlobalId sel_id_details field_label forall_a_a noCafIdInfo
forall_a_a = mkForAllTy alphaTyVar (mkTyVarTy alphaTyVar)
......@@ -481,10 +488,9 @@ mkRecordSelId tycon field_label
has_field con = field_label `elem` dataConFieldLabels con
con1 = head data_cons_w_field
res_tys = dataConResTys con1
res_tv_set = tyVarsOfTypes res_tys
res_tvs = varSetElems res_tv_set
data_ty = mkTyConApp tycon res_tys
(univ_tvs, _, eq_spec, _, _, data_ty) = dataConFullSig con1
data_tv_set = tyVarsOfType data_ty
data_tvs = varSetElems data_tv_set
field_ty = dataConFieldType con1 field_label
-- *Very* tiresomely, the selectors are (unnecessarily!) overloaded over
......@@ -499,10 +505,9 @@ mkRecordSelId tycon field_label
n_stupid_dicts = length stupid_dict_tys
(field_tyvars,pre_field_theta,field_tau) = tcSplitSigmaTy field_ty
field_theta = filter (not . isEqPred) pre_field_theta
field_dict_tys = mkPredTys field_theta
n_field_dict_tys = length field_dict_tys
field_theta = filter (not . isEqPred) pre_field_theta
field_dict_tys = mkPredTys field_theta
n_field_dict_tys = length field_dict_tys
-- If the field has a universally quantified type we have to
-- be a bit careful. Suppose we have
-- data R = R { op :: forall a. Foo a => a -> a }
......@@ -519,7 +524,7 @@ mkRecordSelId tycon field_label
-- op (R op) = op
selector_ty :: Type
selector_ty = mkForAllTys res_tvs $ mkForAllTys field_tyvars $
selector_ty = mkForAllTys data_tvs $ mkForAllTys field_tyvars $
mkFunTys stupid_dict_tys $ mkFunTys field_dict_tys $
mkFunTy data_ty field_tau
......@@ -546,7 +551,8 @@ mkRecordSelId tycon field_label
field_dict_ids = mkTemplateLocalsNum field_dict_base field_dict_tys
dict_id_base = field_dict_base + n_field_dict_tys
data_id = mkTemplateLocal dict_id_base data_ty
arg_base = dict_id_base + 1
scrut_id = mkTemplateLocal (dict_id_base+1) scrut_ty
arg_base = dict_id_base + 2
the_alts :: [CoreAlt]
the_alts = map mk_alt data_cons_w_field -- Already sorted by data-con
......@@ -559,14 +565,19 @@ mkRecordSelId tycon field_label
caf_info | no_default = NoCafRefs
| otherwise = MayHaveCafRefs
sel_rhs = mkLams res_tvs $ mkLams field_tyvars $
sel_rhs = mkLams data_tvs $ mkLams field_tyvars $
mkLams stupid_dict_ids $ mkLams field_dict_ids $
Lam data_id $ mk_result sel_body
Lam data_id $ mk_result sel_body
scrut_ty_args = substTyVars (mkTopTvSubst eq_spec) univ_tvs
scrut_ty = mkTyConApp tycon scrut_ty_args
scrut = unwrapFamInstScrut tycon scrut_ty_args (Var data_id)
-- First coerce from the type family to the representation type
-- NB: A newtype always has a vanilla DataCon; no existentials etc
-- res_tys will simply be the dataConUnivTyVars
sel_body | isNewTyCon tycon = unwrapNewTypeBody tycon res_tys (Var data_id)
| otherwise = Case (Var data_id) data_id field_ty (default_alt ++ the_alts)
-- data_tys will simply be the dataConUnivTyVars
sel_body | isNewTyCon tycon = unwrapNewTypeBody tycon scrut_ty_args scrut
| otherwise = Case scrut scrut_id field_ty (default_alt ++ the_alts)
mk_result poly_result = mkVarApps (mkVarApps poly_result field_tyvars) field_dict_ids
-- We pull the field lambdas to the top, so we need to
......@@ -577,12 +588,12 @@ mkRecordSelId tycon field_label
-- foo = /\a. \t:T. case t of { MkT f -> f a }
mk_alt data_con
= ASSERT2( res_ty `tcEqType` field_ty, ppr data_con $$ ppr res_ty $$ ppr field_ty )
= ASSERT2( data_ty `tcEqType` field_ty, ppr data_con $$ ppr data_ty $$ ppr field_ty )
mkReboxingAlt rebox_uniqs data_con (ex_tvs ++ co_tvs ++ arg_vs) rhs
where
-- get pattern binders with types appropriately instantiated
arg_uniqs = map mkBuiltinUnique [arg_base..]
(ex_tvs, co_tvs, arg_vs) = dataConOrigInstPat arg_uniqs data_con res_tys
(ex_tvs, co_tvs, arg_vs) = dataConOrigInstPat arg_uniqs data_con scrut_ty_args
rebox_base = arg_base + length ex_tvs + length co_tvs + length arg_vs
rebox_uniqs = map mkBuiltinUnique [rebox_base..]
......@@ -599,9 +610,9 @@ mkRecordSelId tycon field_label
-- and apply to (Maybe b'), to get (Maybe b)
Succeeded refinement = gadtRefine emptyRefinement ex_tvs co_tvs
the_arg_id_ty = idType the_arg_id
(rhs, res_ty) = case refineType refinement the_arg_id_ty of
Just (co, res_ty) -> (Cast (Var the_arg_id) co, res_ty)
Nothing -> (Var the_arg_id, the_arg_id_ty)
(rhs, data_ty) = case refineType refinement the_arg_id_ty of
Just (co, data_ty) -> (Cast (Var the_arg_id) co, data_ty)
Nothing -> (Var the_arg_id, the_arg_id_ty)
field_vs = filter (not . isPredTy . idType) arg_vs
the_arg_id = assoc "mkRecordSelId:mk_alt" (field_lbls `zip` field_vs) field_label
......@@ -806,7 +817,16 @@ mkDictSelId name clas
rhs_body | isNewTyCon tycon = unwrapNewTypeBody tycon (map mkTyVarTy tyvars) (Var dict_id)
| otherwise = Case (Var dict_id) dict_id (idType the_arg_id)
[(DataAlt data_con, arg_ids, Var the_arg_id)]
\end{code}
%************************************************************************
%* *
Wrapping and unwrapping newtypes and type families
%* *
%************************************************************************
\begin{code}
wrapNewTypeBody :: TyCon -> [Type] -> CoreExpr -> CoreExpr
-- The wrapper for the data constructor for a newtype looks like this:
-- newtype T a = MkT (a,Int)
......@@ -818,14 +838,14 @@ wrapNewTypeBody :: TyCon -> [Type] -> CoreExpr -> CoreExpr
-- body of the wrapper, namely
-- e `cast` (CoT [a])
--
-- If a coercion constructor is prodivided in the newtype, then we use
-- If a coercion constructor is provided 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
-- 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
= wrapFamInstBody tycon args inner
where
......@@ -839,7 +859,7 @@ wrapNewTypeBody tycon args result_expr
-- 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_maybe tycon
......@@ -847,7 +867,24 @@ unwrapNewTypeBody tycon args result_expr
| otherwise
= result_expr
-- 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.
-- See Note [Wrappers for data instance tycons]
wrapFamInstBody :: TyCon -> [Type] -> CoreExpr -> CoreExpr
wrapFamInstBody tycon args body
| Just co_con <- tyConFamilyCoercion_maybe tycon
= mkCoerce (mkSymCoercion (mkTyConApp co_con args)) body
| otherwise
= body
unwrapFamInstScrut :: TyCon -> [Type] -> CoreExpr -> CoreExpr
unwrapFamInstScrut tycon args scrut
| Just co_con <- tyConFamilyCoercion_maybe tycon
= mkCoerce (mkTyConApp co_con args) scrut
| otherwise
= scrut
\end{code}
......
......@@ -18,8 +18,9 @@ module PprTyThing (
import qualified GHC
import GHC ( TyThing(..), SrcLoc )
import DataCon ( dataConResTys )
import TyCon ( tyConFamInst_maybe )
import Type ( pprTypeApp )
import GHC ( TyThing(..), SrcLoc )
import Outputable
-- -----------------------------------------------------------------------------
......@@ -66,8 +67,11 @@ pprTyThingHdr exts (ADataCon dataCon) = pprDataConSig exts dataCon
pprTyThingHdr exts (ATyCon tyCon) = pprTyConHdr exts tyCon
pprTyThingHdr exts (AClass cls) = pprClassHdr exts cls
pprTyConHdr exts tyCon =
addFamily (ptext keyword) <+> ppr_bndr tyCon <+> hsep (map ppr vars)
pprTyConHdr exts tyCon
| Just (fam_tc, tys) <- tyConFamInst_maybe tyCon
= ptext keyword <+> ptext SLIT("instance") <+> pprTypeApp (ppr_bndr tyCon) tys
| otherwise
= ptext keyword <+> opt_family <+> ppr_bndr tyCon <+> hsep (map ppr vars)
where
vars | GHC.isPrimTyCon tyCon ||
GHC.isFunTyCon tyCon = take (GHC.tyConArity tyCon) GHC.alphaTyVars
......@@ -77,9 +81,9 @@ pprTyConHdr exts tyCon =
| GHC.isNewTyCon tyCon = SLIT("newtype")
| otherwise = SLIT("data")
addFamily keytext
| GHC.isOpenTyCon tyCon = keytext <> ptext SLIT(" family")
| otherwise = keytext
opt_family
| GHC.isOpenTyCon tyCon = ptext SLIT("family")
| otherwise = empty
pprDataConSig exts dataCon =
ppr_bndr dataCon <+> dcolon <+> pprType exts (GHC.dataConType dataCon)
......@@ -143,10 +147,9 @@ pprDataConDecl exts gadt_style show_label dataCon
| otherwise = ppr_bndr dataCon <+> dcolon <+>
sep [ ppr_tvs, GHC.pprThetaArrow theta, pp_tau ]
where
(tyvars, theta, argTypes) = GHC.dataConSig dataCon
(tyvars, theta, argTypes, res_ty) = GHC.dataConSig dataCon
tyCon = GHC.dataConTyCon dataCon
labels = GHC.dataConFieldLabels dataCon
res_tys = dataConResTys dataCon
qualVars = filter (flip notElem (GHC.tyConTyVars tyCon)) tyvars
stricts = GHC.dataConStrictMarks dataCon
tys_w_strs = zip stricts argTypes
......@@ -157,8 +160,7 @@ pprDataConDecl exts gadt_style show_label dataCon
hsep (map ppr qualVars) <> dot
-- printing out the dataCon as a type signature, in GADT style
pp_tau = foldr add pp_res_ty tys_w_strs
pp_res_ty = GHC.pprTypeApp (ppr_bndr tyCon) res_tys
pp_tau = foldr add (ppr res_ty) tys_w_strs
add (str,ty) pp_ty = pprBangTy str ty <+> arrow <+> pp_ty
pprParendBangTy (strict,ty)
......
......@@ -546,7 +546,7 @@ tcConPat :: PatState -> SrcSpan -> DataCon -> TyCon
-> HsConDetails Name (LPat Name) -> (PatState -> TcM a)
-> TcM (Pat TcId, [TcTyVar], a)
tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside
= do { let (univ_tvs, ex_tvs, eq_spec, theta, arg_tys) = dataConFullSig data_con
= do { let (univ_tvs, ex_tvs, eq_spec, theta, arg_tys, _) = dataConFullSig data_con
skol_info = PatSkol data_con
origin = SigOrigin skol_info
......@@ -583,8 +583,8 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside
ex_tvs' ++ inner_tvs, res)
}
where
-- Split against the family tycon if the pattern constructor belongs to a
-- representation tycon.
-- Split against the family tycon if the pattern constructor
-- belongs to a representation tycon.
--
boxySplitTyConAppWithFamily tycon pat_ty =
traceTc traceMsg >>
......
......@@ -960,23 +960,23 @@ checkValidTyCon tc
-- NB: this check assumes that all the constructors of a given
-- data type use the same type variables
where
tvs1 = mkVarSet (dataConAllTyVars con1)
res1 = dataConResTys con1
(tvs1, _, _, res1) = dataConSig con1
ts1 = mkVarSet tvs1
fty1 = dataConFieldType con1 label
checkOne (_, con2) -- Do it bothways to ensure they are structurally identical
= do { checkFieldCompat label con1 con2 tvs1 res1 res2 fty1 fty2
; checkFieldCompat label con2 con1 tvs2 res2 res1 fty2 fty1 }
= do { checkFieldCompat label con1 con2 ts1 res1 res2 fty1 fty2
; checkFieldCompat label con2 con1 ts2 res2 res1 fty2 fty1 }
where
tvs2 = mkVarSet (dataConAllTyVars con2)
res2 = dataConResTys con2
(tvs2, _, _, res2) = dataConSig con2
ts2 = mkVarSet tvs2
fty2 = dataConFieldType con2 label
checkFieldCompat fld con1 con2 tvs1 res1 res2 fty1 fty2
= do { checkTc (isJust mb_subst1) (resultTypeMisMatch fld con1 con2)
; checkTc (isJust mb_subst2) (fieldTypeMisMatch fld con1 con2) }
where