Safe Haskell	None
Language	Haskell2010

Haskus.Binary.Union

Description

Union (as in C)

Unions are storable and can contain any storable data.

Use fromUnion to read an alternative:

{--}

getUnion :: IO (Union '[Word16, Word32, Word64])
getUnion = ...

test = do
   u <- getUnion

   -- to get one of the member
   let v = fromUnion u :: Word16
   let v = fromUnion u :: Word32
   let v = fromUnion u :: Word64

   -- This won't compile (Word8 is not a member of the union)
   let v = fromUnion u :: Word8

Use toUnion to create a new union:

let
   u2 :: Union '[Word32, Vector 4 Word8]
   u2 = toUnion (0x12345678 :: Word32)

Synopsis

data Union (x :: [*])
fromUnion :: (Storable a, Member a l) => Union l -> a
toUnion :: forall a l. (Storable (Union l), Storable a, Member a l) => a -> Union l
toUnionZero :: forall a l. (Storable (Union l), Storable a, Member a l) => a -> Union l

Documentation

data Union (x :: [*]) Source #

An union

We use a list of types as a parameter.

The union is just a pointer to a buffer containing the value(s). The size of the buffer is implicitly known from the types in the list.

Instances

Show (Union x) Source #
Instance details Defined in Haskus.Binary.Union Methods showsPrec :: Int -> Union x -> ShowS # show :: Union x -> String # showList :: [Union x] -> ShowS #
(HFoldr' FoldSizeOf Word l Word, HFoldr' FoldAlignment Word l Word) => Storable (Union l) Source #
Instance details Defined in Haskus.Binary.Union Methods sizeOf :: Union l -> Int # alignment :: Union l -> Int # peekElemOff :: Ptr (Union l) -> Int -> IO (Union l) # pokeElemOff :: Ptr (Union l) -> Int -> Union l -> IO () # peekByteOff :: Ptr b -> Int -> IO (Union l) # pokeByteOff :: Ptr b -> Int -> Union l -> IO () # peek :: Ptr (Union l) -> IO (Union l) # poke :: Ptr (Union l) -> Union l -> IO () #
(HFoldr' FoldSizeOf Word l Word, HFoldr' FoldAlignment Word l Word) => Storable (Union l) Source #
Instance details Defined in Haskus.Binary.Union Methods peekIO :: Ptr (Union l) -> IO (Union l) Source # pokeIO :: Ptr (Union l) -> Union l -> IO () Source # alignment :: Union l -> Word Source # sizeOf :: Union l -> Word Source #
(KnownNat (ListMax (MapSizeOf fs)), KnownNat (ListMax (MapAlignment fs))) => StaticStorable (Union fs) Source #
Instance details Defined in Haskus.Binary.Union Associated Types type SizeOf (Union fs) :: Nat Source # type Alignment (Union fs) :: Nat Source # Methods staticPeekIO :: Ptr (Union fs) -> IO (Union fs) Source # staticPokeIO :: Ptr (Union fs) -> Union fs -> IO () Source #
type SizeOf (Union fs) Source #
Instance details Defined in Haskus.Binary.Union type SizeOf (Union fs)
type Alignment (Union fs) Source #
Instance details Defined in Haskus.Binary.Union type Alignment (Union fs)

fromUnion :: (Storable a, Member a l) => Union l -> a Source #

Retrieve a union member from its type

toUnion :: forall a l. (Storable (Union l), Storable a, Member a l) => a -> Union l Source #

Create a new union from one of the union types

toUnionZero :: forall a l. (Storable (Union l), Storable a, Member a l) => a -> Union l Source #

Like toUnion but set the remaining bytes to 0