Data.Array.Byte

Lifted wrapper for ByteArray#.

Since ByteArray# is an unlifted type and not a member of kind Type, things like [ByteArray#] or IO ByteArray# are ill-typed. To work around this inconvenience this module provides a standard lifted wrapper, inhabiting Type. Clients are expected to use ByteArray in higher-level APIs, but wrap and unwrap ByteArray internally as they please and use functions from GHC.Exts.

The memory representation of a ByteArray is:

╭─────────────┬───╮  ╭────────┬──────┬─────────╮
│ Constructor │ * ┼─►│ Header │ Size │ Payload │
╰─────────────┴───╯  ╰────────┴──────┴─────────╯

And its overhead is the following:

• ByteArray constructor: 1 word

• Pointer to ByteArray#: 1 word

• ByteArray# Header: 1 word

• ByteArray# Size: 1 word

Where a word is the unit of heap allocation, measuring 8 bytes on 64-bit systems, and 4 bytes on 32-bit systems.

Lifted wrapper for MutableByteArray#.

Since MutableByteArray# is an unlifted type and not a member of kind Type, things like [MutableByteArray#] or IO MutableByteArray# are ill-typed. To work around this inconvenience this module provides a standard lifted wrapper, inhabiting Type. Clients are expected to use MutableByteArray in higher-level APIs, but wrap and unwrap MutableByteArray internally as they please and use functions from GHC.Exts.