\section[DataCon]{@DataCon@: Data Constructors}
\begin{code}
+{-# OPTIONS_GHC -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+-- http://hackage.haskell.org/trac/ghc/wiki/WorkingConventions#Warnings
+-- for details
+
module DataCon (
DataCon, DataConIds(..),
ConTag, fIRST_TAG,
mkDataCon,
dataConRepType, dataConSig, dataConFullSig,
- dataConName, dataConTag, dataConTyCon, dataConUserType,
- dataConUnivTyVars, dataConExTyVars, dataConAllTyVars, dataConResTys,
- dataConEqSpec, eqSpecPreds, dataConTheta, dataConStupidTheta,
- dataConInstArgTys, dataConOrigArgTys,
- dataConInstOrigArgTys, dataConRepArgTys,
+ dataConName, dataConIdentity, dataConTag, dataConTyCon, dataConUserType,
+ dataConUnivTyVars, dataConExTyVars, dataConAllTyVars,
+ dataConEqSpec, eqSpecPreds, dataConEqTheta, dataConDictTheta, dataConStupidTheta,
+ dataConInstArgTys, dataConOrigArgTys, dataConOrigResTy,
+ dataConInstOrigArgTys, dataConInstOrigDictsAndArgTys,
+ dataConRepArgTys,
dataConFieldLabels, dataConFieldType,
dataConStrictMarks, dataConExStricts,
dataConSourceArity, dataConRepArity,
import Util
import Maybes
import FastString
+import PackageConfig
+import Module
+
+import Data.Char
+import Data.Word
+import Data.List ( partition )
\end{code}
--
-- *** As declared by the user
-- data T a where
- -- MkT :: forall x y. (Ord x) => x -> y -> T (x,y)
+ -- MkT :: forall x y. (x~y,Ord x) => x -> y -> T (x,y)
-- *** As represented internally
-- data T a where
- -- MkT :: forall a. forall x y. (a:=:(x,y), Ord x) => x -> y -> T a
+ -- MkT :: forall a. forall x y. (a:=:(x,y),x~y,Ord x) => x -> y -> T a
--
-- The next six fields express the type of the constructor, in pieces
-- e.g.
-- dcUnivTyVars = [a]
-- dcExTyVars = [x,y]
-- dcEqSpec = [a:=:(x,y)]
- -- dcTheta = [Ord x]
+ -- dcEqTheta = [x~y]
+ -- dcDictTheta = [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
-- forall a1..an . t1 -> ... tm -> T a1..an
-- No existentials, no coercions, nothing.
- -- That is: dcExTyVars = dcEqSpec = dcTheta = []
+ -- That is: dcExTyVars = dcEqSpec = dcEqTheta = dcDictTheta = []
-- NB 1: newtypes always have a vanilla data con
-- NB 2: a vanilla constructor can still be declared in GADT-style
-- syntax, provided its type looks like the above.
-- The declaration format is held in the TyCon (algTcGadtSyntax)
dcUnivTyVars :: [TyVar], -- Universally-quantified type vars
+ -- INVARIANT: length matches arity of the dcRepTyCon
+
dcExTyVars :: [TyVar], -- Existentially-quantified type vars
-- In general, the dcUnivTyVars are NOT NECESSARILY THE SAME AS THE TYVARS
-- FOR THE PARENT TyCon. With GADTs the data con might not even have
-- Each equality is of the form (a :=: ty), where 'a' is one of
-- the universally quantified type variables
- dcTheta :: ThetaType, -- The context of the constructor
+ -- The next two fields give the type context of the data constructor
+ -- (aside from the GADT constraints,
+ -- which are given by the dcExpSpec)
-- In GADT form, this is *exactly* what the programmer writes, even if
-- the context constrains only universally quantified variables
- -- MkT :: forall a. Eq a => a -> T a
- -- It may contain user-written equality predicates too
+ -- MkT :: forall a b. (a ~ b, Ord b) => a -> T a b
+ dcEqTheta :: ThetaType, -- The *equational* constraints
+ dcDictTheta :: ThetaType, -- The *type-class and implicit-param* constraints
dcStupidTheta :: ThetaType, -- The context of the data type declaration
-- data Eq a => T a = ...
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],
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
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:
-- The 'Nothing' case of DCIds is important
-- Not only is this efficient,
-- but it also ensures that the wrapper is replaced
- -- by the worker (becuase it *is* the wroker)
+ -- by the worker (becuase it *is* the worker)
-- even when there are no args. E.g. in
-- f (:) x
-- the (:) *is* the worker.
-- so the error is detected properly... it's just that asaertions here
-- are a little dodgy.
- = ASSERT( not (any isEqPred theta) )
+ = -- 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
dcVanilla = is_vanilla, dcInfix = declared_infix,
dcUnivTyVars = univ_tvs, dcExTyVars = ex_tvs,
dcEqSpec = eq_spec,
- dcStupidTheta = stupid_theta, dcTheta = theta,
- dcOrigArgTys = orig_arg_tys, dcTyCon = tycon,
+ dcStupidTheta = stupid_theta,
+ dcEqTheta = eq_theta, dcDictTheta = dict_theta,
+ dcOrigArgTys = orig_arg_tys, dcOrigResTy = orig_res_ty,
+ dcRepTyCon = tycon,
dcRepArgTys = rep_arg_tys,
dcStrictMarks = arg_stricts,
dcRepStrictness = rep_arg_stricts,
-- The 'arg_stricts' passed to mkDataCon are simply those for the
-- source-language arguments. We add extra ones for the
-- dictionary arguments right here.
- dict_tys = mkPredTys theta
- real_arg_tys = dict_tys ++ orig_arg_tys
- real_stricts = map mk_dict_strict_mark theta ++ arg_stricts
+ (eq_theta,dict_theta) = partition isEqPred theta
+ dict_tys = mkPredTys dict_theta
+ real_arg_tys = dict_tys ++ orig_arg_tys
+ real_stricts = map mk_dict_strict_mark dict_theta ++ arg_stricts
+
+ -- Example
+ -- data instance T (b,c) where
+ -- TI :: forall e. e -> T (e,e)
+ --
+ -- The representation tycon looks like this:
+ -- data :R7T b c where
+ -- TI :: forall b1 c1. (b1 ~ c1) => b1 -> :R7T b1 c1
+ -- In this case orig_res_ty = T (e,e)
+ orig_res_ty = mkFamilyTyConApp tycon (substTyVars (mkTopTvSubst eq_spec) univ_tvs)
-- Representation arguments and demands
-- To do: eliminate duplication with MkId
tag = assoc "mkDataCon" (tyConDataCons tycon `zip` [fIRST_TAG..]) con
ty = mkForAllTys univ_tvs $ mkForAllTys ex_tvs $
mkFunTys (mkPredTys (eqSpecPreds eq_spec)) $
+ mkFunTys (mkPredTys eq_theta) $
-- NB: the dict args are already in rep_arg_tys
-- because they might be flattened..
-- but the equality predicates are not
dataConTag = dcTag
dataConTyCon :: DataCon -> TyCon
-dataConTyCon = dcTyCon
+dataConTyCon = dcRepTyCon
dataConRepType :: DataCon -> Type
dataConRepType = dcRepType
dataConEqSpec :: DataCon -> [(TyVar,Type)]
dataConEqSpec = dcEqSpec
-dataConTheta :: DataCon -> ThetaType
-dataConTheta = dcTheta
+dataConEqTheta :: DataCon -> ThetaType
+dataConEqTheta = dcEqTheta
+
+dataConDictTheta :: DataCon -> ThetaType
+dataConDictTheta = dcDictTheta
dataConWorkId :: DataCon -> Id
dataConWorkId dc = case dcIds dc of
dataConExStricts :: DataCon -> [StrictnessMark]
-- Strictness of *existential* arguments only
-- Usually empty, so we don't bother to cache this
-dataConExStricts dc = map mk_dict_strict_mark (dcTheta dc)
+dataConExStricts dc = map mk_dict_strict_mark $ dcDictTheta dc
dataConSourceArity :: DataCon -> Arity
-- Source-level arity of the data constructor
-- 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)
+ dcEqTheta = eq_theta, dcDictTheta = dict_theta, dcOrigArgTys = arg_tys, dcOrigResTy = res_ty})
+ = (univ_tvs ++ ex_tvs, eqSpecPreds eq_spec ++ eq_theta ++ dict_theta, arg_tys, res_ty)
dataConFullSig :: DataCon
- -> ([TyVar], [TyVar], [(TyVar,Type)], ThetaType, [Type])
+ -> ([TyVar], [TyVar], [(TyVar,Type)], ThetaType, 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)
+ dcEqTheta = eq_theta, dcDictTheta = dict_theta, dcOrigArgTys = arg_tys, dcOrigResTy = res_ty})
+ = (univ_tvs, ex_tvs, eq_spec, eq_theta, dict_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
--- T :: forall a. a -> T [a]
+-- T :: forall a b. a -> b -> T [a]
-- rather than
--- T :: forall b. forall a. (a=[b]) => a -> T b
+-- T :: forall a c. forall b. (c=[a]) => a -> b -> T c
-- NB: If the constructor is part of a data instance, the result type
-- mentions the family tycon, not the internal one.
dataConUserType (MkData { dcUnivTyVars = univ_tvs,
dcExTyVars = ex_tvs, dcEqSpec = eq_spec,
- dcTheta = theta, dcOrigArgTys = arg_tys,
- dcTyCon = tycon })
+ dcEqTheta = eq_theta, dcDictTheta = dict_theta, dcOrigArgTys = arg_tys,
+ dcOrigResTy = res_ty })
= mkForAllTys ((univ_tvs `minusList` map fst eq_spec) ++ ex_tvs) $
- mkFunTys (mkPredTys theta) $
+ mkFunTys (mkPredTys eq_theta) $
+ mkFunTys (mkPredTys dict_theta) $
mkFunTys arg_tys $
- case tyConFamInst_maybe tycon of
- Nothing -> mkTyConApp tycon (map (substTyVar subst) univ_tvs)
- Just (ftc, insttys) -> mkTyConApp ftc insttys -- data instance
- where
- subst = mkTopTvSubst eq_spec
+ res_ty
-dataConInstArgTys :: DataCon
+dataConInstArgTys :: DataCon -- A datacon with no existentials or equality constraints
+ -- However, it can have a dcTheta (notably it can be a
+ -- class dictionary, with superclasses)
-> [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
+ -- NB: these INCLUDE any dict args
-- but EXCLUDE the data-decl context which is discarded
-- It's all post-flattening etc; this is a representation type
-dataConInstArgTys (MkData {dcRepArgTys = arg_tys,
- dcUnivTyVars = univ_tvs,
- dcExTyVars = ex_tvs}) inst_tys
- = ASSERT( length tyvars == length inst_tys )
- map (substTyWith tyvars inst_tys) arg_tys
- where
- tyvars = univ_tvs ++ ex_tvs
-
-
--- And the same deal for the original arg tys
-dataConInstOrigArgTys :: DataCon -> [Type] -> [Type]
+dataConInstArgTys dc@(MkData {dcRepArgTys = rep_arg_tys,
+ dcUnivTyVars = univ_tvs, dcEqSpec = eq_spec,
+ dcExTyVars = ex_tvs}) inst_tys
+ = ASSERT2 ( length univ_tvs == length inst_tys
+ , ptext SLIT("dataConInstArgTys") <+> ppr dc $$ ppr univ_tvs $$ ppr inst_tys)
+ ASSERT2 ( null ex_tvs && null eq_spec, ppr dc )
+ map (substTyWith univ_tvs inst_tys) rep_arg_tys
+
+dataConInstOrigArgTys
+ :: DataCon -- Works for any DataCon
+ -> [Type] -- Includes existential tyvar args, but NOT
+ -- equality constraints or dicts
+ -> [Type] -- Returns just the instsantiated *value* arguments
+-- For vanilla datacons, it's all quite straightforward
+-- But for the call in MatchCon, we really do want just the value args
dataConInstOrigArgTys dc@(MkData {dcOrigArgTys = arg_tys,
- dcUnivTyVars = univ_tvs,
- dcExTyVars = ex_tvs}) inst_tys
- = ASSERT2( length tyvars == length inst_tys, ptext SLIT("dataConInstOrigArgTys") <+> ppr dc <+> ppr inst_tys )
- map (substTyWith tyvars inst_tys) arg_tys
- where
- tyvars = univ_tvs ++ ex_tvs
+ dcUnivTyVars = univ_tvs,
+ dcExTyVars = ex_tvs}) inst_tys
+ = ASSERT2( length tyvars == length inst_tys
+ , ptext SLIT("dataConInstOrigArgTys") <+> ppr dc $$ ppr tyvars $$ ppr inst_tys )
+ map (substTyWith tyvars inst_tys) arg_tys
+ where
+ tyvars = univ_tvs ++ ex_tvs
+
+dataConInstOrigDictsAndArgTys
+ :: DataCon -- Works for any DataCon
+ -> [Type] -- Includes existential tyvar args, but NOT
+ -- equality constraints or dicts
+ -> [Type] -- Returns just the instsantiated dicts and *value* arguments
+dataConInstOrigDictsAndArgTys dc@(MkData {dcOrigArgTys = arg_tys,
+ dcDictTheta = dicts,
+ dcUnivTyVars = univ_tvs,
+ dcExTyVars = ex_tvs}) inst_tys
+ = ASSERT2( length tyvars == length inst_tys
+ , ptext SLIT("dataConInstOrigDictsAndArgTys") <+> ppr dc $$ ppr tyvars $$ ppr inst_tys )
+ map (substTyWith tyvars inst_tys) (mkPredTys dicts ++ arg_tys)
+ where
+ tyvars = univ_tvs ++ ex_tvs
\end{code}
These two functions get the real argument types of the constructor,
dataConRepArgTys dc = dcRepArgTys dc
\end{code}
+The string <package>:<module>.<name> identifying a constructor, which is attached
+to its info table and used by the GHCi debugger and the heap profiler. We want
+this string to be UTF-8, so we get the bytes directly from the FastStrings.
+
+\begin{code}
+dataConIdentity :: DataCon -> [Word8]
+dataConIdentity dc = bytesFS (packageIdFS (modulePackageId mod)) ++
+ fromIntegral (ord ':') : bytesFS (moduleNameFS (moduleName mod)) ++
+ fromIntegral (ord '.') : bytesFS (occNameFS (nameOccName name))
+ where name = dataConName dc
+ mod = nameModule name
+\end{code}
+
\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
classDataCon :: Class -> DataCon
classDataCon clas = case tyConDataCons (classTyCon clas) of
(dict_constr:no_more) -> ASSERT( null no_more ) dict_constr
+ [] -> panic "classDataCon"
\end{code}
%************************************************************************
-- and for constructors visible
-> Just (tycon, ty_args, data_con, dataConInstArgTys data_con ty_args)
where
- data_con = head (tyConDataCons tycon)
+ data_con = ASSERT( not (null (tyConDataCons tycon)) )
+ head (tyConDataCons tycon)
other -> Nothing
splitProductType str ty
deepSplitProductType_maybe ty
= do { (res@(tycon, tycon_args, _, _)) <- splitProductType_maybe ty
; let {result
- | isClosedNewTyCon tycon && not (isRecursiveTyCon tycon)
- = deepSplitProductType_maybe (newTyConInstRhs tycon tycon_args)
+ | Just (ty', _co) <- instNewTyCon_maybe tycon tycon_args
+ , not (isRecursiveTyCon tycon)
+ = deepSplitProductType_maybe ty' -- Ignore the coercion?
| isNewTyCon tycon = Nothing -- cannot unbox through recursive
-- newtypes nor through families
| otherwise = Just res}
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