%
+% (c) The University of Glasgow 2006
% (c) The GRASP/AQUA Project, Glasgow University, 1998
%
\section[DataCon]{@DataCon@: Data Constructors}
dataConRepType, dataConSig, dataConFullSig,
dataConName, dataConTag, dataConTyCon, dataConUserType,
dataConUnivTyVars, dataConExTyVars, dataConAllTyVars, dataConResTys,
- dataConInstTys,
dataConEqSpec, eqSpecPreds, dataConTheta, dataConStupidTheta,
dataConInstArgTys, dataConOrigArgTys,
dataConInstOrigArgTys, dataConRepArgTys,
#include "HsVersions.h"
-import Type ( Type, ThetaType,
- substTyWith, substTyVar, mkTopTvSubst,
- mkForAllTys, mkFunTys, mkTyConApp, mkTyVarTy, mkTyVarTys,
- splitTyConApp_maybe, newTyConInstRhs,
- mkPredTys, isStrictPred, pprType, mkPredTy
- )
-import Coercion ( isEqPred, mkEqPred )
-import TyCon ( TyCon, FieldLabel, tyConDataCons,
- isProductTyCon, isTupleTyCon, isUnboxedTupleTyCon,
- isNewTyCon, isRecursiveTyCon, tyConFamily_maybe )
-import Class ( Class, classTyCon )
-import Name ( Name, NamedThing(..), nameUnique, mkSysTvName, mkSystemName )
-import Var ( TyVar, CoVar, Id, mkTyVar, tyVarKind, setVarUnique,
- mkCoVar )
-import BasicTypes ( Arity, StrictnessMark(..) )
+import Type
+import Coercion
+import TyCon
+import Class
+import Name
+import Var
+import BasicTypes
import Outputable
-import Unique ( Unique, Uniquable(..) )
-import ListSetOps ( assoc, minusList )
-import Util ( zipEqual, zipWithEqual )
-import List ( partition )
-import Maybes ( expectJust )
+import Unique
+import ListSetOps
+import Util
+import Maybes
import FastString
\end{code}
-- [This is a change (Oct05): previously, vanilla datacons guaranteed to
-- have the same type variables as their parent TyCon, but that seems ugly.]
+ -- INVARIANT: the UnivTyVars and ExTyVars all have distinct OccNames
+ -- Reason: less confusing, and easier to generate IfaceSyn
+
dcEqSpec :: [(TyVar,Type)], -- Equalities derived from the result type,
-- *as written by the programmer*
-- This field allows us to move conveniently between the two ways
-- and *including* existential dictionaries
dcRepStrictness :: [StrictnessMark], -- One for each *representation* argument
+ -- See also Note [Data-con worker strictness] in MkId.lhs
dcRepType :: Type, -- Type of the constructor
-- forall a x y. (a:=:(x,y), Ord x) => x -> y -> MkT a
-- An entirely separate wrapper function is built in TcTyDecls
dcIds :: DataConIds,
- dcInfix :: Bool, -- True <=> declared infix
+ dcInfix :: Bool -- True <=> declared infix
-- Used for Template Haskell and 'deriving' only
-- The actual fixity is stored elsewhere
-
- dcInstTys :: Maybe [Type] -- If this data constructor is part of a
- -- data instance, then these are the type
- -- patterns of the instance.
}
data DataConIds
-> [TyVar] -> [TyVar]
-> [(TyVar,Type)] -> ThetaType
-> [Type] -> TyCon
- -> Maybe [Type]
-> ThetaType -> DataConIds
-> DataCon
-- Can get the tag from the TyCon
univ_tvs ex_tvs
eq_spec theta
orig_arg_tys tycon
- mb_typats
stupid_theta ids
+-- Warning: mkDataCon is not a good place to check invariants.
+-- If the programmer writes the wrong result type in the decl, thus:
+-- data T a where { MkT :: S }
+-- then it's possible that the univ_tvs may hit an assertion failure
+-- if you pull on univ_tvs. This case is checked by checkValidDataCon,
+-- so the error is detected properly... it's just that asaertions here
+-- are a little dodgy.
+
= ASSERT( not (any isEqPred theta) )
-- We don't currently allow any equality predicates on
-- a data constructor (apart from the GADT ones in eq_spec)
con
where
is_vanilla = null ex_tvs && null eq_spec && null theta
- con = ASSERT( is_vanilla || not (isNewTyCon tycon) )
- -- Invariant: newtypes have a vanilla data-con
- MkData {dcName = name, dcUnique = nameUnique name,
+ con = MkData {dcName = name, dcUnique = nameUnique name,
dcVanilla = is_vanilla, dcInfix = declared_infix,
dcUnivTyVars = univ_tvs, dcExTyVars = ex_tvs,
dcEqSpec = eq_spec,
dcStrictMarks = arg_stricts,
dcRepStrictness = rep_arg_stricts,
dcFields = fields, dcTag = tag, dcRepType = ty,
- dcIds = ids,
- dcInstTys = mb_typats }
+ dcIds = ids }
-- Strictness marks for source-args
-- *after unboxing choices*,
where
env = mkTopTvSubst (dcEqSpec dc)
-dataConInstTys :: DataCon -> Maybe [Type]
-dataConInstTys = dcInstTys
-
dataConUserType :: DataCon -> Type
-- The user-declared type of the data constructor
-- in the nice-to-read form
dataConUserType (MkData { dcUnivTyVars = univ_tvs,
dcExTyVars = ex_tvs, dcEqSpec = eq_spec,
dcTheta = theta, dcOrigArgTys = arg_tys,
- dcTyCon = tycon, dcInstTys = mb_insttys })
+ dcTyCon = tycon })
= mkForAllTys ((univ_tvs `minusList` map fst eq_spec) ++ ex_tvs) $
mkFunTys (mkPredTys theta) $
mkFunTys arg_tys $
- case mb_insttys of
- Nothing -> mkTyConApp tycon (map (substTyVar subst) univ_tvs)
- Just insttys -> mkTyConApp ftycon insttys -- data instance
- where
- ftycon = case tyConFamily_maybe tycon of
- Just ftycon -> ftycon
- Nothing -> panic err
- err = "dataConUserType: type patterns without family tycon"
+ 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
deepSplitProductType_maybe ty
= do { (res@(tycon, tycon_args, _, _)) <- splitProductType_maybe ty
; let {result
- | isNewTyCon tycon && not (isRecursiveTyCon tycon)
+ | isClosedNewTyCon tycon && not (isRecursiveTyCon tycon)
= deepSplitProductType_maybe (newTyConInstRhs tycon tycon_args)
- | isNewTyCon tycon = Nothing -- cannot unbox through recursive newtypes
+ | isNewTyCon tycon = Nothing -- cannot unbox through recursive
+ -- newtypes nor through families
| otherwise = Just res}
; result
}
unbox MarkedStrict ty = [(MarkedStrict, ty)]
unbox MarkedUnboxed ty = zipEqual "computeRep" (dataConRepStrictness arg_dc) arg_tys
where
- (tycon, tycon_args, arg_dc, arg_tys)
+ (_tycon, _tycon_args, arg_dc, arg_tys)
= deepSplitProductType "unbox_strict_arg_ty" ty
\end{code}
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