Data.Finitary.PackBytes

If a type a is Finitary, each inhabitant of a has an index, which can be represented as a byte string of a fixed length (as the number of indexes is finite). Essentially, we can represent any value of a as a fixed-length string over an alphabet of cardinality \(256\). Based on this, we can derive a Unbox instance, representing a Vector as a large byte string. This also allows us to provide a Storable instance for a.

This encoding is fairly tight in terms of space use, especially for types whose cardinalities are large. Additionally, byte-access is considerably faster than bit-access on most architectures. If your types have large cardinalities, and minimal space use isn't a concern, this encoding is good.

Some architectures prefer whole-word access - on these, there can be some overheads using this encoding. Additionally, the encoding and decoding step for this encoding is longer than the one for Data.Finitary.PackWords. If Cardinality a < Cardinality Word, you should consider a different encoding - in particular, check Data.Finitary.PackInto, which is more flexible and faster, with greater control over space usage.

Documentation

data PackBytes (a :: Type)

An opaque wrapper around a, representing each value as a byte string.

Instances

(Finitary a, 1 <= Cardinality a) => Vector Vector (PackBytes a)

Defined in Data.Finitary.PackBytes

Methods

basicUnsafeFreeze :: PrimMonad m => Mutable Vector (PrimState m) (PackBytes a) -> m (Vector (PackBytes a))

basicUnsafeThaw :: PrimMonad m => Vector (PackBytes a) -> m (Mutable Vector (PrimState m) (PackBytes a))

basicLength :: Vector (PackBytes a) -> Int

basicUnsafeSlice :: Int -> Int -> Vector (PackBytes a) -> Vector (PackBytes a)

basicUnsafeIndexM :: Monad m => Vector (PackBytes a) -> Int -> m (PackBytes a)

basicUnsafeCopy :: PrimMonad m => Mutable Vector (PrimState m) (PackBytes a) -> Vector (PackBytes a) -> m ()

elemseq :: Vector (PackBytes a) -> PackBytes a -> b -> b

(Finitary a, 1 <= Cardinality a) => MVector MVector (PackBytes a)

Defined in Data.Finitary.PackBytes

Methods

basicLength :: MVector s (PackBytes a) -> Int

basicUnsafeSlice :: Int -> Int -> MVector s (PackBytes a) -> MVector s (PackBytes a)

basicOverlaps :: MVector s (PackBytes a) -> MVector s (PackBytes a) -> Bool

basicUnsafeNew :: PrimMonad m => Int -> m (MVector (PrimState m) (PackBytes a))

basicInitialize :: PrimMonad m => MVector (PrimState m) (PackBytes a) -> m ()

basicUnsafeReplicate :: PrimMonad m => Int -> PackBytes a -> m (MVector (PrimState m) (PackBytes a))

basicUnsafeRead :: PrimMonad m => MVector (PrimState m) (PackBytes a) -> Int -> m (PackBytes a)

basicUnsafeWrite :: PrimMonad m => MVector (PrimState m) (PackBytes a) -> Int -> PackBytes a -> m ()

basicClear :: PrimMonad m => MVector (PrimState m) (PackBytes a) -> m ()

basicSet :: PrimMonad m => MVector (PrimState m) (PackBytes a) -> PackBytes a -> m ()

basicUnsafeCopy :: PrimMonad m => MVector (PrimState m) (PackBytes a) -> MVector (PrimState m) (PackBytes a) -> m ()

basicUnsafeMove :: PrimMonad m => MVector (PrimState m) (PackBytes a) -> MVector (PrimState m) (PackBytes a) -> m ()

basicUnsafeGrow :: PrimMonad m => MVector (PrimState m) (PackBytes a) -> Int -> m (MVector (PrimState m) (PackBytes a))

(Finitary a, 1 <= Cardinality a) => Bounded (PackBytes a)

Defined in Data.Finitary.PackBytes

Methods

minBound :: PackBytes a

maxBound :: PackBytes a

Eq (PackBytes a)

Defined in Data.Finitary.PackBytes

Methods

(==) :: PackBytes a -> PackBytes a -> Bool

(/=) :: PackBytes a -> PackBytes a -> Bool

Ord (PackBytes a)

Defined in Data.Finitary.PackBytes

Methods

compare :: PackBytes a -> PackBytes a -> Ordering

(<) :: PackBytes a -> PackBytes a -> Bool

(<=) :: PackBytes a -> PackBytes a -> Bool

(>) :: PackBytes a -> PackBytes a -> Bool

(>=) :: PackBytes a -> PackBytes a -> Bool

max :: PackBytes a -> PackBytes a -> PackBytes a

min :: PackBytes a -> PackBytes a -> PackBytes a

Show (PackBytes a)

Defined in Data.Finitary.PackBytes

Methods

showsPrec :: Int -> PackBytes a -> ShowS

show :: PackBytes a -> String

showList :: [PackBytes a] -> ShowS

(Finitary a, 1 <= Cardinality a) => Finitary (PackBytes a)

Defined in Data.Finitary.PackBytes

Associated Types

type Cardinality (PackBytes a) :: Nat

Methods

fromFinite :: Finite (Cardinality (PackBytes a)) -> PackBytes a

toFinite :: PackBytes a -> Finite (Cardinality (PackBytes a))

start :: PackBytes a

end :: PackBytes a

previous :: PackBytes a -> Maybe (PackBytes a)

next :: PackBytes a -> Maybe (PackBytes a)

Hashable (PackBytes a)

Defined in Data.Finitary.PackBytes

Methods

hashWithSalt :: Int -> PackBytes a -> Int

hash :: PackBytes a -> Int

(Finitary a, 1 <= Cardinality a) => Storable (PackBytes a)

Defined in Data.Finitary.PackBytes

Methods

sizeOf :: PackBytes a -> Int

alignment :: PackBytes a -> Int

peekElemOff :: Ptr (PackBytes a) -> Int -> IO (PackBytes a)

pokeElemOff :: Ptr (PackBytes a) -> Int -> PackBytes a -> IO ()

peekByteOff :: Ptr b -> Int -> IO (PackBytes a)

pokeByteOff :: Ptr b -> Int -> PackBytes a -> IO ()

peek :: Ptr (PackBytes a) -> IO (PackBytes a)

poke :: Ptr (PackBytes a) -> PackBytes a -> IO ()

(Finitary a, 1 <= Cardinality a) => Unbox (PackBytes a)

Defined in Data.Finitary.PackBytes

NFData (PackBytes a)

Defined in Data.Finitary.PackBytes

Methods

rnf :: PackBytes a -> ()

Binary (PackBytes a)

Defined in Data.Finitary.PackBytes

Methods

put :: PackBytes a -> Put

get :: Get (PackBytes a)

putList :: [PackBytes a] -> Put

newtype MVector s (PackBytes a)

Defined in Data.Finitary.PackBytes

newtype MVector s (PackBytes a) = MV_PackBytes (MVector s Word8)

newtype Vector (PackBytes a)

Defined in Data.Finitary.PackBytes

newtype Vector (PackBytes a) = V_PackBytes (Vector Word8)

type Cardinality (PackBytes a)

Defined in Data.Finitary.PackBytes

type Cardinality (PackBytes a) = Cardinality a

pattern Packed :: forall (a :: Type). (Finitary a, 1 <= Cardinality a) => a -> PackBytes a

To provide (something that resembles a) data constructor for PackBytes, we provide the following pattern. It can be used like any other data constructor:

import Data.Finitary.PackBytes

anInt :: PackBytes Int
anInt = Packed 10

isPackedEven :: PackBytes Int -> Bool
isPackedEven (Packed x) = even x

Every pattern match, and data constructor call, performs a \(\Theta(\log_{256}(\texttt{Cardinality a}))\) encoding or decoding of a. Use with this in mind.