ConTag, fIRST_TAG,
mkDataCon,
dataConRepType, dataConSig, dataConName, dataConTag, dataConTyCon,
- dataConTyVars, dataConStupidTheta,
- dataConArgTys, dataConOrigArgTys, dataConResTy,
+ dataConTyVars, dataConResTys,
+ dataConStupidTheta,
+ dataConInstArgTys, dataConOrigArgTys, dataConInstResTy,
dataConInstOrigArgTys, dataConRepArgTys,
dataConFieldLabels, dataConFieldType,
dataConStrictMarks, dataConExStricts,
#include "HsVersions.h"
-import Type ( Type, ThetaType, substTyWith, substTy, zipTopTvSubst,
+import Type ( Type, ThetaType, substTyWith, substTy, zipOpenTvSubst,
mkForAllTys, mkFunTys, mkTyConApp,
splitTyConApp_maybe,
mkPredTys, isStrictPred, pprType
)
-import TyCon ( TyCon, FieldLabel, tyConDataCons, tyConDataCons,
+import TyCon ( TyCon, FieldLabel, tyConDataCons,
isProductTyCon, isTupleTyCon, isUnboxedTupleTyCon )
import Class ( Class, classTyCon )
import Name ( Name, NamedThing(..), nameUnique )
-- Its type is of form
-- forall a1..an . t1 -> ... tm -> T a1..an
-- No existentials, no GADTs, nothing.
+ --
+ -- NB1: the order of the forall'd variables does matter;
+ -- for a vanilla constructor, we assume that if the result
+ -- type is (T t1 ... tn) then we can instantiate the constr
+ -- at types [t1, ..., tn]
+ --
+ -- NB2: a vanilla constructor can still be declared in GADT-style
+ -- syntax, provided its type looks like the above.
dcTyVars :: [TyVar], -- Universally-quantified type vars
-- for the data constructor.
- -- dcVanilla = True <=> The [TyVar] are identical to those of the parent tycon
- -- False <=> The [TyVar] are NOT NECESSARILY THE SAME AS THE TYVARS
- -- FOR THE PARENT TyCon. (With GADTs the data
- -- con might not even have the same number of
- -- type variables.)
+ -- See NB1 on dcVanilla for the conneciton between dcTyVars and dcResTys
+ --
+ -- In general, the dcTyVars are NOT NECESSARILY THE SAME AS THE TYVARS
+ -- FOR THE PARENT TyCon. With GADTs the data con might not even have
+ -- the same number of type variables.
+ -- [This is a change (Oct05): previously, vanilla datacons guaranteed to
+ -- have the same type variables as their parent TyCon, but that seems ugly.]
dcStupidTheta :: ThetaType, -- This is a "thinned" version of
-- the context of the data decl.
-- longer in the type of the wrapper Id, because
-- that makes it harder to use the wrap-id to rebuild
-- values after record selection or in generics.
+ --
+ -- Fact: the free tyvars of dcStupidTheta are a subset of
+ -- the free tyvars of dcResTys
+ -- Reason: dcStupidTeta is gotten by instantiating the
+ -- stupid theta from the tycon (see BuildTyCl.mkDataConStupidTheta)
dcTheta :: ThetaType, -- The existentially quantified stuff
dcOrigArgTys = arg_tys, dcTyCon = tycon, dcResTys = res_tys})
= (tyvars, theta, arg_tys, tycon, res_tys)
-dataConArgTys :: DataCon
- -> [Type] -- Instantiated at these types
- -- NB: these INCLUDE the existentially quantified arg types
- -> [Type] -- Needs arguments of these types
+dataConStupidTheta :: DataCon -> ThetaType
+dataConStupidTheta dc = dcStupidTheta dc
+
+dataConResTys :: DataCon -> [Type]
+dataConResTys dc = dcResTys dc
+
+dataConInstArgTys :: DataCon
+ -> [Type] -- Instantiated at these types
+ -- NB: these INCLUDE the existentially quantified arg types
+ -> [Type] -- Needs arguments of these types
-- NB: these INCLUDE the existentially quantified dict args
-- but EXCLUDE the data-decl context which is discarded
-- It's all post-flattening etc; this is a representation type
-dataConArgTys (MkData {dcRepArgTys = arg_tys, dcTyVars = tyvars}) inst_tys
+dataConInstArgTys (MkData {dcRepArgTys = arg_tys, dcTyVars = tyvars}) inst_tys
= ASSERT( length tyvars == length inst_tys )
map (substTyWith tyvars inst_tys) arg_tys
-dataConResTy :: DataCon -> [Type] -> Type
-dataConResTy (MkData {dcTyVars = tyvars, dcTyCon = tc, dcResTys = res_tys}) inst_tys
+dataConInstResTy :: DataCon -> [Type] -> Type
+dataConInstResTy (MkData {dcTyVars = tyvars, dcTyCon = tc, dcResTys = res_tys}) inst_tys
= ASSERT( length tyvars == length inst_tys )
- substTy (zipTopTvSubst tyvars inst_tys) (mkTyConApp tc res_tys)
- -- zipTopTvSubst because the res_tys can't contain any foralls
+ substTy (zipOpenTvSubst tyvars inst_tys) (mkTyConApp tc res_tys)
+ -- res_tys can't currently contain any foralls,
+ -- but might in future; hence zipOpenTvSubst
-- And the same deal for the original arg tys
--- This one only works for vanilla DataCons
dataConInstOrigArgTys :: DataCon -> [Type] -> [Type]
-dataConInstOrigArgTys (MkData {dcOrigArgTys = arg_tys, dcTyVars = tyvars, dcVanilla = is_vanilla}) inst_tys
- = ASSERT( is_vanilla )
- ASSERT( length tyvars == length inst_tys )
+dataConInstOrigArgTys (MkData {dcOrigArgTys = arg_tys, dcTyVars = tyvars}) inst_tys
+ = ASSERT( length tyvars == length inst_tys )
map (substTyWith tyvars inst_tys) arg_tys
-
-dataConStupidTheta :: DataCon -> ThetaType
-dataConStupidTheta dc = dcStupidTheta dc
\end{code}
These two functions get the real argument types of the constructor,
Just (tycon,ty_args)
| isProductTyCon tycon -- Includes check for non-existential,
-- and for constructors visible
- -> Just (tycon, ty_args, data_con, dataConArgTys data_con ty_args)
+ -> Just (tycon, ty_args, data_con, dataConInstArgTys data_con ty_args)
where
data_con = head (tyConDataCons tycon)
other -> Nothing
projects / ghc-hetmet.git / blobdiff