X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FbasicTypes%2FDataCon.lhs;h=312ae943a8ca3c9987060f2fc4f1461142abeb1e;hp=844c69b5551b8f937c384becf11c259bb9ab6f90;hb=c8c2f6bb7d79a2a6aeaa3233363fdf0bbbfad205;hpb=9f703fe41b8300777dc8fcd8da94a3a082fdcfbb diff --git a/compiler/basicTypes/DataCon.lhs b/compiler/basicTypes/DataCon.lhs index 844c69b..312ae94 100644 --- a/compiler/basicTypes/DataCon.lhs +++ b/compiler/basicTypes/DataCon.lhs @@ -6,25 +6,34 @@ \begin{code} module DataCon ( + -- * Main data types DataCon, DataConIds(..), - ConTag, fIRST_TAG, - mkDataCon, + ConTag, + + -- ** Type construction + mkDataCon, fIRST_TAG, + + -- ** Type deconstruction dataConRepType, dataConSig, dataConFullSig, - dataConName, dataConIdentity, dataConTag, dataConTyCon, dataConUserType, + dataConName, dataConIdentity, dataConTag, dataConTyCon, + dataConOrigTyCon, dataConUserType, dataConUnivTyVars, dataConExTyVars, dataConAllTyVars, - dataConEqSpec, eqSpecPreds, dataConEqTheta, dataConDictTheta, dataConStupidTheta, + dataConEqSpec, eqSpecPreds, dataConTheta, + dataConStupidTheta, dataConInstArgTys, dataConOrigArgTys, dataConOrigResTy, - dataConInstOrigArgTys, dataConInstOrigDictsAndArgTys, - dataConRepArgTys, + dataConInstOrigArgTys, dataConRepArgTys, dataConFieldLabels, dataConFieldType, dataConStrictMarks, dataConExStricts, dataConSourceArity, dataConRepArity, dataConIsInfix, dataConWorkId, dataConWrapId, dataConWrapId_maybe, dataConImplicitIds, dataConRepStrictness, + + -- ** Predicates on DataCons isNullarySrcDataCon, isNullaryRepDataCon, isTupleCon, isUnboxedTupleCon, - isVanillaDataCon, classDataCon, + isVanillaDataCon, classDataCon, dataConCannotMatch, + -- * Splitting product types splitProductType_maybe, splitProductType, deepSplitProductType, deepSplitProductType_maybe ) where @@ -32,6 +41,7 @@ module DataCon ( #include "HsVersions.h" import Type +import Unify import Coercion import TyCon import Class @@ -42,13 +52,12 @@ import Outputable import Unique import ListSetOps import Util -import Maybes import FastString import Module +import qualified Data.Data as Data import Data.Char import Data.Word -import Data.List ( partition ) \end{code} @@ -89,12 +98,12 @@ Note [Data Constructor Naming] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Each data constructor C has two, and possibly up to four, Names associated with it: - OccName Name space Name of - --------------------------------------------------------------------------- - * The "data con itself" C DataName DataCon - * The "worker data con" C VarName Id (the worker) - * The "wrapper data con" $WC VarName Id (the wrapper) - * The "newtype coercion" :CoT TcClsName TyCon + OccName Name space Name of Notes + --------------------------------------------------------------------------- + The "data con itself" C DataName DataCon In dom( GlobalRdrEnv ) + The "worker data con" C VarName Id The worker + The "wrapper data con" $WC VarName Id The wrapper + The "newtype coercion" :CoT TcClsName TyCon EVERY data constructor (incl for newtypes) has the former two (the data con itself, and its worker. But only some data constructors have a @@ -119,11 +128,11 @@ The "worker Id", is the actual data constructor. does a cast, e.g. newtype T = MkT Int The worker for MkT has unfolding - \(x:Int). x `cast` sym CoT + \\(x:Int). x `cast` sym CoT Here CoT is the type constructor, witnessing the FC axiom axiom CoT : T = Int -The "wrapper Id", $WC, goes as follows +The "wrapper Id", \$WC, goes as follows * Its type is exactly what it looks like in the source program. @@ -132,7 +141,7 @@ The "wrapper Id", $WC, goes as follows * The wrapper Id isn't generated for a data type if there is nothing for the wrapper to do. That is, if its defn would be - $wC = C + \$wC = C Note [The need for a wrapper] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -140,8 +149,8 @@ Why might the wrapper have anything to do? Two reasons: * Unboxing strict fields (with -funbox-strict-fields) data T = MkT !(Int,Int) - $wMkT :: (Int,Int) -> T - $wMkT (x,y) = MkT x y + \$wMkT :: (Int,Int) -> T + \$wMkT (x,y) = MkT x y Notice that the worker has two fields where the wapper has just one. That is, the worker has type MkT :: Int -> Int -> T @@ -154,10 +163,10 @@ Why might the wrapper have anything to do? Two reasons: MkT :: forall a b. (a=[b]) => b -> T a The wrapper has the programmer-specified type: - $wMkT :: a -> T [a] - $wMkT a x = MkT [a] a [a] x + \$wMkT :: a -> T [a] + \$wMkT a x = MkT [a] a [a] x The third argument is a coerion - [a] :: [a]:=:[a] + [a] :: [a]~[a] INVARIANT: the dictionary constructor for a class never has a wrapper. @@ -223,12 +232,13 @@ Note that (Foo a) might not be an instance of Ord. %************************************************************************ \begin{code} +-- | A data constructor data DataCon = MkData { dcName :: Name, -- This is the name of the *source data con* -- (see "Note [Data Constructor Naming]" above) dcUnique :: Unique, -- Cached from Name - dcTag :: ConTag, + dcTag :: ConTag, -- ^ Tag, used for ordering 'DataCon's -- Running example: -- @@ -238,16 +248,15 @@ data DataCon -- *** As represented internally -- data T a where - -- MkT :: forall a. forall x y. (a:=:(x,y),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)] - -- dcEqTheta = [x~y] - -- dcDictTheta = [Ord x] + -- dcEqSpec = [a~(x,y)] + -- dcOtherTheta = [x~y, Ord x] -- dcOrigArgTys = [a,List b] -- dcRepTyCon = T @@ -255,14 +264,15 @@ data DataCon -- Its type is of form -- forall a1..an . t1 -> ... tm -> T a1..an -- No existentials, no coercions, nothing. - -- That is: dcExTyVars = dcEqSpec = dcEqTheta = dcDictTheta = [] + -- That is: dcExTyVars = dcEqSpec = dcOtherTheta = [] -- 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 + dcUnivTyVars :: [TyVar], -- Universally-quantified type vars [a,b,c] -- INVARIANT: length matches arity of the dcRepTyCon + --- result type of (rep) data con is exactly (T a b c) dcExTyVars :: [TyVar], -- Existentially-quantified type vars -- In general, the dcUnivTyVars are NOT NECESSARILY THE SAME AS THE TYVARS @@ -275,12 +285,12 @@ data DataCon -- Reason: less confusing, and easier to generate IfaceSyn dcEqSpec :: [(TyVar,Type)], -- Equalities derived from the result type, - -- /as written by the programmer/ + -- _as written by the programmer_ -- This field allows us to move conveniently between the two ways -- of representing a GADT constructor's type: - -- MkT :: forall a b. (a :=: [b]) => b -> T a + -- MkT :: forall a b. (a ~ [b]) => b -> T a -- MkT :: forall b. b -> T [b] - -- Each equality is of the form (a :=: ty), where 'a' is one of + -- Each equality is of the form (a ~ ty), where 'a' is one of -- the universally quantified type variables -- The next two fields give the type context of the data constructor @@ -289,8 +299,8 @@ data DataCon -- In GADT form, this is *exactly* what the programmer writes, even if -- the context constrains only universally quantified variables -- 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 + dcOtherTheta :: ThetaType, -- The other constraints in the data con's type + -- other than those in the dcEqSpec dcStupidTheta :: ThetaType, -- The context of the data type declaration -- data Eq a => T a = ... @@ -309,14 +319,14 @@ data DataCon dcOrigArgTys :: [Type], -- Original argument types -- (before unboxing and flattening of strict fields) - dcOrigResTy :: Type, -- Original result type + dcOrigResTy :: Type, -- Original result type, as seen by the user -- 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], + dcStrictMarks :: [HsBang], -- Strictness annotations as decided by the compiler. -- Does *not* include the existential dictionaries -- length = dataConSourceArity dataCon @@ -327,18 +337,19 @@ data DataCon -- length = 0 (if not a record) or dataConSourceArity. -- Constructor representation - dcRepArgTys :: [Type], -- Final, representation argument types, - -- after unboxing and flattening, - -- and *including* existential dictionaries + dcRepArgTys :: [Type], -- Final, representation argument types, + -- after unboxing and flattening, + -- and *including* all existential evidence args - dcRepStrictness :: [StrictnessMark], -- One for each *representation* argument + dcRepStrictness :: [StrictnessMark], + -- One for each *representation* *value* 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), x~y, Ord x) => + -- forall a x y. (a~(x,y), x~y, Ord x) => -- x -> y -> T a -- (this is *not* of the constructor wrapper Id: -- see Note [Data con representation] below) @@ -347,7 +358,7 @@ data DataCon -- case (e :: T t) of -- MkT x y co1 co2 (d:Ord x) (v:r) (w:F s) -> ... -- It's convenient to apply the rep-type of MkT to 't', to get - -- forall x y. (t:=:(x,y), x~y, Ord x) => x -> y -> T t + -- forall x y. (t~(x,y), x~y, Ord x) => x -> y -> T t -- and use that to check the pattern. Mind you, this is really only -- used in CoreLint. @@ -364,6 +375,7 @@ data DataCon -- The actual fixity is stored elsewhere } +-- | Contains the Ids of the data constructor functions data DataConIds = DCIds (Maybe Id) Id -- Algebraic data types always have a worker, and -- may or may not have a wrapper, depending on whether @@ -387,10 +399,12 @@ data DataConIds -- but that makes it less likely that rules will match -- when we bring bits of unfoldings together.) +-- | Type of the tags associated with each constructor possibility type ConTag = Int fIRST_TAG :: ConTag -fIRST_TAG = 1 -- Tags allocated from here for real constructors +-- ^ Tags are allocated from here for real constructors +fIRST_TAG = 1 \end{code} Note [Data con representation] @@ -441,6 +455,15 @@ instance Outputable DataCon where instance Show DataCon where showsPrec p con = showsPrecSDoc p (ppr con) + +instance Data.Typeable DataCon where + typeOf _ = Data.mkTyConApp (Data.mkTyCon "DataCon") [] + +instance Data.Data DataCon where + -- don't traverse? + toConstr _ = abstractConstr "DataCon" + gunfold _ _ = error "gunfold" + dataTypeOf _ = mkNoRepType "DataCon" \end{code} @@ -451,13 +474,22 @@ instance Show DataCon where %************************************************************************ \begin{code} +-- | Build a new data constructor mkDataCon :: Name - -> Bool -- Declared infix - -> [StrictnessMark] -> [FieldLabel] - -> [TyVar] -> [TyVar] - -> [(TyVar,Type)] -> ThetaType - -> [Type] -> TyCon - -> ThetaType -> DataConIds + -> Bool -- ^ Is the constructor declared infix? + -> [HsBang] -- ^ Strictness annotations written in the source file + -> [FieldLabel] -- ^ Field labels for the constructor, if it is a record, + -- otherwise empty + -> [TyVar] -- ^ Universally quantified type variables + -> [TyVar] -- ^ Existentially quantified type variables + -> [(TyVar,Type)] -- ^ GADT equalities + -> ThetaType -- ^ Theta-type occuring before the arguments proper + -> [Type] -- ^ Original argument types + -> Type -- ^ Original result type + -> TyCon -- ^ Representation type constructor + -> ThetaType -- ^ The "stupid theta", context of the data declaration + -- e.g. @data Eq a => T a ...@ + -> DataConIds -- ^ The Ids of the actual builder functions -> DataCon -- Can get the tag from the TyCon @@ -466,7 +498,7 @@ mkDataCon name declared_infix fields univ_tvs ex_tvs eq_spec theta - orig_arg_tys tycon + orig_arg_tys orig_res_ty rep_tycon 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: @@ -486,10 +518,10 @@ mkDataCon name declared_infix dcVanilla = is_vanilla, dcInfix = declared_infix, dcUnivTyVars = univ_tvs, dcExTyVars = ex_tvs, dcEqSpec = eq_spec, + dcOtherTheta = theta, dcStupidTheta = stupid_theta, - dcEqTheta = eq_theta, dcDictTheta = dict_theta, dcOrigArgTys = orig_arg_tys, dcOrigResTy = orig_res_ty, - dcRepTyCon = tycon, + dcRepTyCon = rep_tycon, dcRepArgTys = rep_arg_tys, dcStrictMarks = arg_stricts, dcRepStrictness = rep_arg_stricts, @@ -503,177 +535,231 @@ mkDataCon name declared_infix -- The 'arg_stricts' passed to mkDataCon are simply those for the -- source-language arguments. We add extra ones for the -- dictionary arguments right here. - (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) + full_theta = eqSpecPreds eq_spec ++ theta + real_arg_tys = mkPredTys full_theta ++ orig_arg_tys + real_stricts = map mk_dict_strict_mark full_theta ++ arg_stricts -- Representation arguments and demands -- To do: eliminate duplication with MkId (rep_arg_stricts, rep_arg_tys) = computeRep real_stricts real_arg_tys - tag = assoc "mkDataCon" (tyConDataCons tycon `zip` [fIRST_TAG..]) con + tag = assoc "mkDataCon" (tyConDataCons rep_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 mkFunTys rep_arg_tys $ - mkTyConApp tycon (mkTyVarTys univ_tvs) + mkTyConApp rep_tycon (mkTyVarTys univ_tvs) eqSpecPreds :: [(TyVar,Type)] -> ThetaType eqSpecPreds spec = [ mkEqPred (mkTyVarTy tv, ty) | (tv,ty) <- spec ] -mk_dict_strict_mark :: PredType -> StrictnessMark -mk_dict_strict_mark pred | isStrictPred pred = MarkedStrict - | otherwise = NotMarkedStrict +mk_dict_strict_mark :: PredType -> HsBang +mk_dict_strict_mark pred | isStrictPred pred = HsStrict + | otherwise = HsNoBang \end{code} \begin{code} +-- | The 'Name' of the 'DataCon', giving it a unique, rooted identification dataConName :: DataCon -> Name dataConName = dcName +-- | The tag used for ordering 'DataCon's dataConTag :: DataCon -> ConTag dataConTag = dcTag +-- | The type constructor that we are building via this data constructor dataConTyCon :: DataCon -> TyCon dataConTyCon = dcRepTyCon +-- | The original type constructor used in the definition of this data +-- constructor. In case of a data family instance, that will be the family +-- type constructor. +dataConOrigTyCon :: DataCon -> TyCon +dataConOrigTyCon dc + | Just (tc, _) <- tyConFamInst_maybe (dcRepTyCon dc) = tc + | otherwise = dcRepTyCon dc + +-- | The representation type of the data constructor, i.e. the sort +-- type that will represent values of this type at runtime dataConRepType :: DataCon -> Type dataConRepType = dcRepType +-- | Should the 'DataCon' be presented infix? dataConIsInfix :: DataCon -> Bool dataConIsInfix = dcInfix +-- | The universally-quantified type variables of the constructor dataConUnivTyVars :: DataCon -> [TyVar] dataConUnivTyVars = dcUnivTyVars +-- | The existentially-quantified type variables of the constructor dataConExTyVars :: DataCon -> [TyVar] dataConExTyVars = dcExTyVars +-- | Both the universal and existentiatial type variables of the constructor dataConAllTyVars :: DataCon -> [TyVar] dataConAllTyVars (MkData { dcUnivTyVars = univ_tvs, dcExTyVars = ex_tvs }) = univ_tvs ++ ex_tvs +-- | Equalities derived from the result type of the data constructor, as written +-- by the programmer in any GADT declaration dataConEqSpec :: DataCon -> [(TyVar,Type)] dataConEqSpec = dcEqSpec -dataConEqTheta :: DataCon -> ThetaType -dataConEqTheta = dcEqTheta - -dataConDictTheta :: DataCon -> ThetaType -dataConDictTheta = dcDictTheta +-- | The *full* constraints on the constructor type +dataConTheta :: DataCon -> ThetaType +dataConTheta (MkData { dcEqSpec = eq_spec, dcOtherTheta = theta }) + = eqSpecPreds eq_spec ++ theta +-- | Get the Id of the 'DataCon' worker: a function that is the "actual" +-- constructor and has no top level binding in the program. The type may +-- be different from the obvious one written in the source program. Panics +-- if there is no such 'Id' for this 'DataCon' dataConWorkId :: DataCon -> Id dataConWorkId dc = case dcIds dc of DCIds _ wrk_id -> wrk_id +-- | Get the Id of the 'DataCon' wrapper: a function that wraps the "actual" +-- constructor so it has the type visible in the source program: c.f. 'dataConWorkId'. +-- Returns Nothing if there is no wrapper, which occurs for an algebraic data constructor +-- and also for a newtype (whose constructor is inlined compulsorily) dataConWrapId_maybe :: DataCon -> Maybe Id --- Returns Nothing if there is no wrapper for an algebraic data con --- and also for a newtype (whose constructor is inlined compulsorily) dataConWrapId_maybe dc = case dcIds dc of DCIds mb_wrap _ -> mb_wrap +-- | Returns an Id which looks like the Haskell-source constructor by using +-- the wrapper if it exists (see 'dataConWrapId_maybe') and failing over to +-- the worker (see 'dataConWorkId') dataConWrapId :: DataCon -> Id --- Returns an Id which looks like the Haskell-source constructor dataConWrapId dc = case dcIds dc of DCIds (Just wrap) _ -> wrap DCIds Nothing wrk -> wrk -- worker=wrapper +-- | Find all the 'Id's implicitly brought into scope by the data constructor. Currently, +-- the union of the 'dataConWorkId' and the 'dataConWrapId' dataConImplicitIds :: DataCon -> [Id] dataConImplicitIds dc = case dcIds dc of DCIds (Just wrap) work -> [wrap,work] DCIds Nothing work -> [work] +-- | The labels for the fields of this particular 'DataCon' dataConFieldLabels :: DataCon -> [FieldLabel] dataConFieldLabels = dcFields +-- | Extract the type for any given labelled field of the 'DataCon' dataConFieldType :: DataCon -> FieldLabel -> Type -dataConFieldType con label = expectJust "unexpected label" $ - lookup label (dcFields con `zip` dcOrigArgTys con) - -dataConStrictMarks :: DataCon -> [StrictnessMark] +dataConFieldType con label + = case lookup label (dcFields con `zip` dcOrigArgTys con) of + Just ty -> ty + Nothing -> pprPanic "dataConFieldType" (ppr con <+> ppr label) + +-- | The strictness markings decided on by the compiler. Does not include those for +-- existential dictionaries. The list is in one-to-one correspondence with the arity of the 'DataCon' +dataConStrictMarks :: DataCon -> [HsBang] dataConStrictMarks = dcStrictMarks -dataConExStricts :: DataCon -> [StrictnessMark] --- Strictness of *existential* arguments only +-- | Strictness of evidence arguments to the wrapper function +dataConExStricts :: DataCon -> [HsBang] -- Usually empty, so we don't bother to cache this -dataConExStricts dc = map mk_dict_strict_mark $ dcDictTheta dc +dataConExStricts dc = map mk_dict_strict_mark $ (dataConTheta dc) +-- | Source-level arity of the data constructor dataConSourceArity :: DataCon -> Arity - -- Source-level arity of the data constructor dataConSourceArity dc = length (dcOrigArgTys dc) --- dataConRepArity gives the number of actual fields in the --- {\em representation} of the data constructor. This may be more than appear --- in the source code; the extra ones are the existentially quantified --- dictionaries +-- | Gives the number of actual fields in the /representation/ of the +-- data constructor. This may be more than appear in the source code; +-- the extra ones are the existentially quantified dictionaries dataConRepArity :: DataCon -> Int dataConRepArity (MkData {dcRepArgTys = arg_tys}) = length arg_tys -isNullarySrcDataCon, isNullaryRepDataCon :: DataCon -> Bool +-- | Return whether there are any argument types for this 'DataCon's original source type +isNullarySrcDataCon :: DataCon -> Bool isNullarySrcDataCon dc = null (dcOrigArgTys dc) + +-- | Return whether there are any argument types for this 'DataCon's runtime representation type +isNullaryRepDataCon :: DataCon -> Bool isNullaryRepDataCon dc = null (dcRepArgTys dc) dataConRepStrictness :: DataCon -> [StrictnessMark] - -- Give the demands on the arguments of a - -- Core constructor application (Con dc args) +-- ^ Give the demands on the arguments of a +-- Core constructor application (Con dc args) dataConRepStrictness dc = dcRepStrictness dc +-- | The \"signature\" of the 'DataCon' returns, in order: +-- +-- 1) The result of 'dataConAllTyVars', +-- +-- 2) All the 'ThetaType's relating to the 'DataCon' (coercion, dictionary, implicit +-- parameter - whatever) +-- +-- 3) The type arguments to the constructor +-- +-- 4) The /original/ result type of the 'DataCon' dataConSig :: DataCon -> ([TyVar], ThetaType, [Type], Type) -dataConSig (MkData {dcUnivTyVars = univ_tvs, dcExTyVars = ex_tvs, dcEqSpec = eq_spec, - 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) - +dataConSig (MkData {dcUnivTyVars = univ_tvs, dcExTyVars = ex_tvs, + dcEqSpec = eq_spec, dcOtherTheta = theta, + dcOrigArgTys = arg_tys, dcOrigResTy = res_ty}) + = (univ_tvs ++ ex_tvs, eqSpecPreds eq_spec ++ theta, arg_tys, res_ty) + +-- | The \"full signature\" of the 'DataCon' returns, in order: +-- +-- 1) The result of 'dataConUnivTyVars' +-- +-- 2) The result of 'dataConExTyVars' +-- +-- 3) The result of 'dataConEqSpec' +-- +-- 4) The result of 'dataConDictTheta' +-- +-- 5) The original argument types to the 'DataCon' (i.e. before +-- any change of the representation of the type) +-- +-- 6) The original result type of the 'DataCon' dataConFullSig :: DataCon - -> ([TyVar], [TyVar], [(TyVar,Type)], ThetaType, ThetaType, [Type], Type) -dataConFullSig (MkData {dcUnivTyVars = univ_tvs, dcExTyVars = ex_tvs, dcEqSpec = eq_spec, - 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) + -> ([TyVar], [TyVar], [(TyVar,Type)], ThetaType, [Type], Type) +dataConFullSig (MkData {dcUnivTyVars = univ_tvs, dcExTyVars = ex_tvs, + dcEqSpec = eq_spec, dcOtherTheta = 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 +-- | The \"stupid theta\" of the 'DataCon', such as @data Eq a@ in: +-- +-- > data Eq a => T a = ... dataConStupidTheta :: DataCon -> ThetaType dataConStupidTheta dc = dcStupidTheta dc dataConUserType :: DataCon -> Type --- The user-declared type of the data constructor --- in the nice-to-read form --- T :: forall a b. a -> b -> T [a] --- rather than --- T :: forall a c. forall b. (c=[a]) => a -> b -> T c +-- ^ The user-declared type of the data constructor +-- in the nice-to-read form: +-- +-- > T :: forall a b. a -> b -> T [a] +-- +-- rather than: +-- +-- > 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, - dcEqTheta = eq_theta, dcDictTheta = dict_theta, dcOrigArgTys = arg_tys, + dcOtherTheta = theta, dcOrigArgTys = arg_tys, dcOrigResTy = res_ty }) = mkForAllTys ((univ_tvs `minusList` map fst eq_spec) ++ ex_tvs) $ - mkFunTys (mkPredTys eq_theta) $ - mkFunTys (mkPredTys dict_theta) $ + mkFunTys (mkPredTys theta) $ mkFunTys arg_tys $ res_ty -dataConInstArgTys :: DataCon -- A datacon with no existentials or equality constraints +-- | Finds the instantiated types of the arguments required to construct a 'DataCon' representation +-- NB: these INCLUDE any dictionary args +-- but EXCLUDE the data-declaration context, which is discarded +-- It's all post-flattening etc; this is a representation type +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 - -> [Type] -- Needs arguments of these types - -- 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 + -> [Type] -- ^ Instantiated at these types + -> [Type] dataConInstArgTys dc@(MkData {dcRepArgTys = rep_arg_tys, dcUnivTyVars = univ_tvs, dcEqSpec = eq_spec, dcExTyVars = ex_tvs}) inst_tys @@ -682,11 +768,13 @@ dataConInstArgTys dc@(MkData {dcRepArgTys = rep_arg_tys, ASSERT2 ( null ex_tvs && null eq_spec, ppr dc ) map (substTyWith univ_tvs inst_tys) rep_arg_tys +-- | Returns just the instantiated /value/ argument types of a 'DataCon', +-- (excluding dictionary args) dataConInstOrigArgTys :: DataCon -- Works for any DataCon -> [Type] -- Includes existential tyvar args, but NOT -- equality constraints or dicts - -> [Type] -- Returns just the instsantiated *value* arguments + -> [Type] -- 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, @@ -697,53 +785,32 @@ dataConInstOrigArgTys dc@(MkData {dcOrigArgTys = arg_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, -without substituting for any type variables. - -dataConOrigArgTys returns the arg types of the wrapper, excluding all dictionary args. - -dataConRepArgTys retuns the arg types of the worker, including all dictionaries, and -after any flattening has been done. - \begin{code} +-- | Returns the argument types of the wrapper, excluding all dictionary arguments +-- and without substituting for any type variables dataConOrigArgTys :: DataCon -> [Type] dataConOrigArgTys dc = dcOrigArgTys dc +-- | Returns the arg types of the worker, including all dictionaries, after any +-- flattening has been done and without substituting for any type variables dataConRepArgTys :: DataCon -> [Type] dataConRepArgTys dc = dcRepArgTys dc \end{code} -The string :. 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} +-- | 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 dataConIdentity :: DataCon -> [Word8] +-- We want this string to be UTF-8, so we get the bytes directly from the FastStrings. 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 + mod = ASSERT( isExternalName name ) nameModule name \end{code} - \begin{code} isTupleCon :: DataCon -> Bool isTupleCon (MkData {dcRepTyCon = tc}) = isTupleTyCon tc @@ -751,11 +818,11 @@ isTupleCon (MkData {dcRepTyCon = tc}) = isTupleTyCon tc isUnboxedTupleCon :: DataCon -> Bool isUnboxedTupleCon (MkData {dcRepTyCon = tc}) = isUnboxedTupleTyCon tc +-- | Vanilla 'DataCon's are those that are nice boring Haskell 98 constructors isVanillaDataCon :: DataCon -> Bool isVanillaDataCon dc = dcVanilla dc \end{code} - \begin{code} classDataCon :: Class -> DataCon classDataCon clas = case tyConDataCons (classTyCon clas) of @@ -763,6 +830,25 @@ classDataCon clas = case tyConDataCons (classTyCon clas) of [] -> panic "classDataCon" \end{code} +\begin{code} +dataConCannotMatch :: [Type] -> DataCon -> Bool +-- Returns True iff the data con *definitely cannot* match a +-- scrutinee of type (T tys) +-- where T is the type constructor for the data con +-- NB: look at *all* equality constraints, not only those +-- in dataConEqSpec; see Trac #5168 +dataConCannotMatch tys con + | null theta = False -- Common + | all isTyVarTy tys = False -- Also common + | otherwise + = typesCantMatch [(Type.substTy subst ty1, Type.substTy subst ty2) + | EqPred ty1 ty2 <- theta ] + where + dc_tvs = dataConUnivTyVars con + theta = dataConTheta con + subst = zipTopTvSubst dc_tvs tys +\end{code} + %************************************************************************ %* * \subsection{Splitting products} @@ -770,19 +856,25 @@ classDataCon clas = case tyConDataCons (classTyCon clas) of %************************************************************************ \begin{code} +-- | Extract the type constructor, type argument, data constructor and it's +-- /representation/ argument types from a type if it is a product type. +-- +-- Precisely, we return @Just@ for any type that is all of: +-- +-- * Concrete (i.e. constructors visible) +-- +-- * Single-constructor +-- +-- * Not existentially quantified +-- +-- Whether the type is a @data@ type or a @newtype@ splitProductType_maybe - :: Type -- A product type, perhaps + :: Type -- ^ A product type, perhaps -> Maybe (TyCon, -- The type constructor [Type], -- Type args of the tycon DataCon, -- The data constructor - [Type]) -- Its *representation* arg types + [Type]) -- Its /representation/ arg types - -- Returns (Just ...) for any - -- concrete (i.e. constructors visible) - -- single-constructor - -- not existentially quantified - -- type whether a data type or a new type - -- -- Rejecing existentials is conservative. Maybe some things -- could be made to work with them, but I'm not going to sweat -- it through till someone finds it's important. @@ -798,6 +890,7 @@ splitProductType_maybe ty head (tyConDataCons tycon) _other -> Nothing +-- | As 'splitProductType_maybe', but panics if the 'Type' is not a product type splitProductType :: String -> Type -> (TyCon, [Type], DataCon, [Type]) splitProductType str ty = case splitProductType_maybe ty of @@ -805,6 +898,8 @@ splitProductType str ty Nothing -> pprPanic (str ++ ": not a product") (pprType ty) +-- | As 'splitProductType_maybe', but in turn instantiates the 'TyCon' returned +-- and hence recursively tries to unpack it as far as it able to deepSplitProductType_maybe :: Type -> Maybe (TyCon, [Type], DataCon, [Type]) deepSplitProductType_maybe ty = do { (res@(tycon, tycon_args, _, _)) <- splitProductType_maybe ty @@ -817,25 +912,28 @@ deepSplitProductType_maybe ty | otherwise = Just res} ; result } - + +-- | As 'deepSplitProductType_maybe', but panics if the 'Type' is not a product type deepSplitProductType :: String -> Type -> (TyCon, [Type], DataCon, [Type]) deepSplitProductType str ty = case deepSplitProductType_maybe ty of Just stuff -> stuff Nothing -> pprPanic (str ++ ": not a product") (pprType ty) -computeRep :: [StrictnessMark] -- Original arg strictness - -> [Type] -- and types +-- | Compute the representation type strictness and type suitable for a 'DataCon' +computeRep :: [HsBang] -- ^ Original argument strictness + -> [Type] -- ^ Original argument types -> ([StrictnessMark], -- Representation arg strictness [Type]) -- And type computeRep stricts tys = unzip $ concat $ zipWithEqual "computeRep" unbox stricts tys where - unbox NotMarkedStrict ty = [(NotMarkedStrict, ty)] - unbox MarkedStrict ty = [(MarkedStrict, ty)] - unbox MarkedUnboxed ty = zipEqual "computeRep" (dataConRepStrictness arg_dc) arg_tys - where - (_tycon, _tycon_args, arg_dc, arg_tys) - = deepSplitProductType "unbox_strict_arg_ty" ty + unbox HsNoBang ty = [(NotMarkedStrict, ty)] + unbox HsStrict ty = [(MarkedStrict, ty)] + unbox HsUnpackFailed ty = [(MarkedStrict, ty)] + unbox HsUnpack ty = zipEqual "computeRep" (dataConRepStrictness arg_dc) arg_tys + where + (_tycon, _tycon_args, arg_dc, arg_tys) + = deepSplitProductType "unbox_strict_arg_ty" ty \end{code}