Data.Bytes.Get

This module generalizes the binary Get and cereal Get monads in an ad hoc fashion to permit code to be written that is compatible across them.

Moreover, this class permits code to be written to be portable over various monad transformers applied to these as base monads.

Documentation

class (Integral (Remaining m), Monad m, Applicative m) => MonadGet m where

Minimal complete definition

lookAhead, lookAheadM, lookAheadE

Associated Types

type Remaining m :: *

An Integral number type used for unchecked skips and counting.

type Bytes m :: *

The underlying ByteString type used by this instance

Methods

skip :: Int -> m ()

Skip ahead n bytes. Fails if fewer than n bytes are available.

ensure :: Int -> m ByteString

If at least n bytes are available return at least that much of the current input. Otherwise fail.

lookAhead :: m a -> m a

Run ga, but return without consuming its input. Fails if ga fails.

lookAheadM :: m (Maybe a) -> m (Maybe a)

Like lookAhead, but consume the input if gma returns 'Just _'. Fails if gma fails.

lookAheadE :: m (Either a b) -> m (Either a b)

Like lookAhead, but consume the input if gea returns 'Right _'. Fails if gea fails.

getBytes :: Int -> m ByteString

Pull n bytes from the input, as a strict ByteString.

remaining :: m (Remaining m)

Get the number of remaining unparsed bytes. Useful for checking whether all input has been consumed. Note that this forces the rest of the input.

isEmpty :: m Bool

Test whether all input has been consumed, i.e. there are no remaining unparsed bytes.

getWord8 :: m Word8

Read a Word8 from the monad state

getByteString :: Int -> m ByteString

An efficient get method for strict ByteStrings. Fails if fewer than n bytes are left in the input.

getLazyByteString :: Int64 -> m ByteString

An efficient get method for lazy ByteStrings. Does not fail if fewer than n bytes are left in the input.

getWord16be :: m Word16

Read a Word16 in big endian format

getWord16le :: m Word16

Read a Word16 in little endian format

getWord16host :: m Word16

O(1). Read a 2 byte Word16 in native host order and host endianness.

getWord32be :: m Word32

Read a Word32 in big endian format

getWord32le :: m Word32

Read a Word32 in little endian format

getWord32host :: m Word32

O(1). Read a Word32 in native host order and host endianness.

getWord64be :: m Word64

Read a Word64 in big endian format

getWord64le :: m Word64

Read a Word64 in little endian format

getWord64host :: m Word64

O(1). Read a Word64 in native host order and host endianess.

getWordhost :: m Word

O(1). Read a single native machine word. The word is read in host order, host endian form, for the machine you're on. On a 64 bit machine the Word is an 8 byte value, on a 32 bit machine, 4 bytes.

Instances

MonadGet Get

MonadGet Get

MonadGet m => MonadGet (ReaderT e m)

MonadGet m => MonadGet (StateT s m)

MonadGet m => MonadGet (StateT s m)

MonadGet m => MonadGet (ExceptT e m)

(MonadGet m, Monoid w) => MonadGet (WriterT w m)

(MonadGet m, Monoid w) => MonadGet (WriterT w m)

(MonadGet m, Monoid w) => MonadGet (RWST r w s m)

(MonadGet m, Monoid w) => MonadGet (RWST r w s m)

runGetL :: Get a -> ByteString -> a

Get something from a lazy ByteString using runGet.

runGetS :: Get a -> ByteString -> Either String a

Get something from a strict ByteString using runGet.