X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FbasicTypes%2FDataCon.lhs;h=5a67ffe77b6283ac4a1a64b50ea1a928cd11f5e7;hp=851bf661da52d639a68ea60a66e7ed5d89aedf6b;hb=66579ff945831c5fc9a17c58c722ff01f2268d76;hpb=5862b2c52a1d678ef54ddbbdbcec93999bc247cc diff --git a/compiler/basicTypes/DataCon.lhs b/compiler/basicTypes/DataCon.lhs index 851bf66..5a67ffe 100644 --- a/compiler/basicTypes/DataCon.lhs +++ b/compiler/basicTypes/DataCon.lhs @@ -6,25 +6,32 @@ \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, dataConUnivTyVars, dataConExTyVars, dataConAllTyVars, dataConEqSpec, eqSpecPreds, dataConEqTheta, dataConDictTheta, 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, + -- * Splitting product types splitProductType_maybe, splitProductType, deepSplitProductType, deepSplitProductType_maybe ) where @@ -87,15 +94,20 @@ differently, as follows. Note [Data Constructor Naming] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -Each data constructor C has two, and possibly three, Names associated with it: +Each data constructor C has two, and possibly up to four, Names associated with it: - OccName Name space Used for + OccName Name space Name of --------------------------------------------------------------------------- - * The "source data con" C DataName The DataCon itself - * The "real data con" C VarName Its worker Id - * The "wrapper data con" $WC VarName Wrapper Id (optional) - -Each of these three has a distinct Unique. The "source data con" name + * 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 + +EVERY data constructor (incl for newtypes) has the former two (the +data con itself, and its worker. But only some data constructors have a +wrapper (see Note [The need for a wrapper]). + +Each of these three has a distinct Unique. The "data con itself" name appears in the output of the renamer, and names the Haskell-source data constructor. The type checker translates it into either the wrapper Id (if it exists) or worker Id (otherwise). @@ -114,11 +126,11 @@ 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. @@ -127,14 +139,16 @@ 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] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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 @@ -147,11 +161,13 @@ 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] +INVARIANT: the dictionary constructor for a class + never has a wrapper. A note about the stupid context @@ -214,12 +230,13 @@ 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: -- @@ -266,7 +283,7 @@ 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 @@ -329,19 +346,21 @@ data DataCon dcRepTyCon :: TyCon, -- Result tycon, T dcRepType :: Type, -- Type of the constructor - -- forall a x y. (a:=:(x,y), Ord x) => x -> y -> MkT a + -- 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) -- Notice that the existential type parameters come *second*. -- Reason: in a case expression we may find: - -- case (e :: T t) of { MkT b (d:Ord b) (x:t) (xs:[b]) -> ... } + -- 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 b. Ord b => ... + -- 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 - -- use in CoreLint. + -- used in CoreLint. - -- Finally, the curried worker function that corresponds to the constructor + -- The curried worker function that corresponds to the constructor: -- It doesn't have an unfolding; the code generator saturates these Ids -- and allocates a real constructor when it finds one. -- @@ -353,6 +372,7 @@ 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 @@ -367,7 +387,7 @@ data DataConIds -- 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 worker) + -- by the worker (because it *is* the worker) -- even when there are no args. E.g. in -- f (:) x -- the (:) *is* the worker. @@ -376,10 +396,12 @@ 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] @@ -440,13 +462,19 @@ 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? + -> [StrictnessMark] -- ^ 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] -- ^ Argument types + -> TyCon -- ^ Type constructor we are for + -> 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 @@ -530,101 +558,154 @@ mk_dict_strict_mark pred | isStrictPred pred = MarkedStrict \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 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 +-- | The equational constraints on the data constructor type dataConEqTheta :: DataCon -> ThetaType dataConEqTheta = dcEqTheta +-- | The type class and implicit parameter contsraints on the data constructor type dataConDictTheta :: DataCon -> ThetaType dataConDictTheta = dcDictTheta +-- | 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) +-- | 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 -> [StrictnessMark] dataConStrictMarks = dcStrictMarks +-- | Strictness of /existential/ arguments only 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 $ dcDictTheta 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) +-- | 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, @@ -634,15 +715,22 @@ dataConFullSig (MkData {dcUnivTyVars = univ_tvs, dcExTyVars = ex_tvs, dcEqSpec = 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, @@ -655,84 +743,66 @@ dataConUserType (MkData { dcUnivTyVars = univ_tvs, 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 = ASSERT2 ( length univ_tvs == length inst_tys - , ptext SLIT("dataConInstArgTys") <+> ppr dc $$ ppr univ_tvs $$ ppr 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 +-- | 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, dcUnivTyVars = univ_tvs, dcExTyVars = ex_tvs}) inst_tys = ASSERT2( length tyvars == length inst_tys - , ptext SLIT("dataConInstOrigArgTys") <+> ppr dc $$ ppr tyvars $$ ppr 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, -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 @@ -740,11 +810,11 @@ 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 @@ -759,19 +829,25 @@ 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. @@ -787,6 +863,7 @@ 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 @@ -794,6 +871,8 @@ 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 @@ -806,15 +885,17 @@ 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 :: [StrictnessMark] -- ^ Original argument strictness + -> [Type] -- ^ Original argument types -> ([StrictnessMark], -- Representation arg strictness [Type]) -- And type