Binrep.BLen

Documentation

newtype WithCBLen a

Newtype wrapper for defining BLen instances which are allowed to assume the existence of a valid CBLen family instance.

Constructors

WithCBLen

Fields

• unWithCBLen :: a

Instances

KnownNat (CBLen a + CBLen b) => BLen (WithCBLen (a, b))

Defined in Binrep.BLen

Associated Types

type CBLen (WithCBLen (a, b)) :: Natural

Methods

blen :: WithCBLen (a, b) -> BLenT

KnownNat (CBLen a) => BLen (WithCBLen [a])

Defined in Binrep.BLen

Associated Types

type CBLen (WithCBLen [a]) :: Natural

Methods

blen :: WithCBLen [a] -> BLenT

type CBLen (WithCBLen (a, b))

Defined in Binrep.BLen

type CBLen (WithCBLen (a, b)) = CBLen a + CBLen b

type CBLen (WithCBLen [a])

Defined in Binrep.BLen

type CBLen (WithCBLen [a]) = TypeError ('Text "No CBLen associated family instance defined for " :<>: 'ShowType (WithCBLen [a])) :: Natural

class BLen a where

The length in bytes of a value of the given type can be known on the cheap e.g. by reading a length field, or using compile time information.

Some binary representation building blocks require the notion of length in bytes in order to handle, e.g. null padding. One may always obtain this by serializing the value, then reading out the length of the output bytestring. But in most cases, we can be much more efficient.

• Certain primitives have a size known at compile time, irrelevant of the value. A Word64 is always 8 bytes; some data null-padded to n bytes is exactly n bytes long.
• For simple ADTs, it's often possible to calculate length in bytes via pattern matching and some numeric operations. Very little actual work.

This type class enables each type to implement its own efficient method of byte length calculation. Aim to write something that plainly feels more efficient than full serialization. If that doesn't feel possible, you might be working with a type ill-suited for binary representation.

A thought: Some instances could be improved by reifying CBLen. But it would mess up all the deriving, and it feels like too minor an improvement to be worthwhile supporting, writing a bunch of newtype wrappers, etc.

Minimal complete definition

Nothing

Associated Types

type CBLen a :: Natural

The length in bytes of any value of the given type is constant.

Many binary representation primitives are constant, or may be designed to "store" their size in their type. This is a stronger statement about their length than just blen.

This is now an associated type family of the BLen type class in hopes of simplifying the binrep framework.

type CBLen a = TypeError ('Text "No CBLen associated family instance defined for " :<>: 'ShowType a)

Methods

blen :: a -> BLenT

The length in bytes of the serialized value.

The default implementation reifies the constant length for the type. If a type-wide constant length is not defined, it will fail at compile time.

default blen :: KnownNat (CBLen a) => a -> BLenT

Instances

BLen Void

Impossible to put a byte length to Void.

Defined in Binrep.BLen

Associated Types

type CBLen Void :: Natural

Methods

blen :: Void -> BLenT

BLen Int16

Defined in Binrep.BLen

Associated Types

type CBLen Int16 :: Natural

Methods

blen :: Int16 -> BLenT

BLen Int32

Defined in Binrep.BLen

Associated Types

type CBLen Int32 :: Natural

Methods

blen :: Int32 -> BLenT

BLen Int64

Defined in Binrep.BLen

Associated Types

type CBLen Int64 :: Natural

Methods

blen :: Int64 -> BLenT

BLen Int8

Defined in Binrep.BLen

Associated Types

type CBLen Int8 :: Natural

Methods

blen :: Int8 -> BLenT

BLen Word16

Defined in Binrep.BLen

Associated Types

type CBLen Word16 :: Natural

Methods

blen :: Word16 -> BLenT

BLen Word32

Defined in Binrep.BLen

Associated Types

type CBLen Word32 :: Natural

Methods

blen :: Word32 -> BLenT

BLen Word64

Defined in Binrep.BLen

Associated Types

type CBLen Word64 :: Natural

Methods

blen :: Word64 -> BLenT

BLen Word8

Defined in Binrep.BLen

Associated Types

type CBLen Word8 :: Natural

Methods

blen :: Word8 -> BLenT

BLen DCS

Defined in Binrep.Example

Associated Types

type CBLen DCS :: Natural

Methods

blen :: DCS -> BLenT

BLen DSS

Defined in Binrep.Example

Associated Types

type CBLen DSS :: Natural

Methods

blen :: DSS -> BLenT

BLen DU

Defined in Binrep.Example

Associated Types

type CBLen DU :: Natural

Methods

blen :: DU -> BLenT

BLen DX

Defined in Binrep.Example

Associated Types

type CBLen DX :: Natural

Methods

blen :: DX -> BLenT

BLen Tar

Defined in Binrep.Example.Tar

Associated Types

type CBLen Tar :: Natural

Methods

blen :: Tar -> BLenT

BLen Tiff

Defined in Binrep.Example.Tiff

Associated Types

type CBLen Tiff :: Natural

Methods

blen :: Tiff -> BLenT

BLen WavHeader

Defined in Binrep.Example.Wav

Associated Types

type CBLen WavHeader :: Natural

Methods

blen :: WavHeader -> BLenT

BLen ByteString

Defined in Binrep.BLen

Associated Types

type CBLen ByteString :: Natural

Methods

blen :: ByteString -> BLenT

KnownNat (CBLen a + CBLen b) => BLen (WithCBLen (a, b))

Defined in Binrep.BLen

Associated Types

type CBLen (WithCBLen (a, b)) :: Natural

Methods

blen :: WithCBLen (a, b) -> BLenT

KnownNat (CBLen a) => BLen (WithCBLen [a])

Defined in Binrep.BLen

Associated Types

type CBLen (WithCBLen [a]) :: Natural

Methods

blen :: WithCBLen [a] -> BLenT

(bs ~ MagicBytes (TiffMagic end), KnownNat (Length bs)) => BLen (TiffBody end)

Defined in Binrep.Example.Tiff

Associated Types

type CBLen (TiffBody end) :: Natural

Methods

blen :: TiffBody end -> BLenT

KnownNat base => BLen (AsciiNat base)

The bytelength of an AsciiNat is the number of digits in the number in the given base. We can calculate this generically with great efficiency using GHC primitives.

Defined in Binrep.Type.AsciiNat

Associated Types

type CBLen (AsciiNat base) :: Natural

Methods

blen :: AsciiNat base -> BLenT

BLen (AsByteString 'C)

Defined in Binrep.Type.ByteString

Associated Types

type CBLen (AsByteString 'C) :: Natural

Methods

blen :: AsByteString 'C -> BLenT

(itype ~ I 'U size end, irep ~ IRep 'U size, KnownNat (CBLen irep)) => BLen (AsByteString ('Pascal size end))

Defined in Binrep.Type.ByteString

Associated Types

type CBLen (AsByteString ('Pascal size end)) :: Natural

Methods

blen :: AsByteString ('Pascal size end) -> BLenT

KnownSymbol str => BLen (MagicUTF8 str)

Defined in Binrep.Type.Magic.UTF8

Associated Types

type CBLen (MagicUTF8 str) :: Natural

Methods

blen :: MagicUTF8 str -> BLenT

BLen a => BLen [a]

O(n)

Defined in Binrep.BLen

Associated Types

type CBLen [a] :: Natural

Methods

blen :: [a] -> BLenT

KnownNat n => BLen (TarNat n)

Defined in Binrep.Example.Tar

Associated Types

type CBLen (TarNat n) :: Natural

Methods

blen :: TarNat n -> BLenT

KnownNat (Length (MagicBytes a)) => BLen (Magic a)

Defined in Binrep.Type.Magic

Associated Types

type CBLen (Magic a) :: Natural

Methods

blen :: Magic a -> BLenT

KnownNat n => BLen (NullPadded n a)

Defined in Binrep.Type.NullPadded

Associated Types

type CBLen (NullPadded n a) :: Natural

Methods

blen :: NullPadded n a -> BLenT

KnownNat n => BLen (Sized n a)

Defined in Binrep.Type.Sized

Associated Types

type CBLen (Sized n a) :: Natural

Methods

blen :: Sized n a -> BLenT

BLen a => BLen (Vector n a)

Defined in Binrep.Type.Vector

Associated Types

type CBLen (Vector n a) :: Natural

Methods

blen :: Vector n a -> BLenT

(BLen a, BLen b) => BLen (a, b)

Defined in Binrep.BLen

Associated Types

type CBLen (a, b) :: Natural

Methods

blen :: (a, b) -> BLenT

KnownNat (CBLen (I sign size end)) => BLen (I sign size end)

Defined in Binrep.Type.Int

Associated Types

type CBLen (I sign size end) :: Natural

Methods

blen :: I sign size end -> BLenT

(BLen a, itype ~ I 'U size end, KnownNat (CBLen itype)) => BLen (LenPfx size end a)

Defined in Binrep.Type.LenPfx

Associated Types

type CBLen (LenPfx size end a) :: Natural

Methods

blen :: LenPfx size end a -> BLenT

type BLenT = Int

typeNatToBLen :: forall n. KnownNat n => BLenT

cblen :: forall a n. (n ~ CBLen a, KnownNat n) => BLenT

Reify a type's constant byte length to the term level.

module Binrep.BLen.Internal.AsBLen