Data.ByteString.Lazy.Optics

pack (or unpack) a list of bytes into a ByteString.

packedBytes ≡ re unpackedBytes
pack x ≡  x ^. packedBytes
unpack x ≡ x ^. re packedBytes

>>> [104,101,108,108,111] ^. packedBytes == Char8.pack "hello"True

unpack (or pack) a ByteString into a list of bytes.

unpackedBytes ≡ re packedBytes
unpack x ≡ x ^. unpackedBytes
pack x ≡  x ^. re unpackedBytes

>>> "hello" ^. packedChars % unpackedBytes[104,101,108,108,111]

Traverse the individual bytes in a ByteString.

This Traversal walks each strict ByteString chunk in a tree-like fashion enable zippers to seek to locations more quickly and accelerate many monoidal queries, but up to associativity (and constant factors) it is equivalent to the much slower:

bytes ≡ unpackedBytes % traversed

>>> anyOf bytes (== 0x80) (Char8.pack "hello")False

Note that when just using this as a Setter, sets map can be more efficient.

pack (or unpack) a list of characters into a ByteString.

When writing back to the ByteString it is assumed that every Char lies between 'x00' and 'xff'.

packedChars ≡ re unpackedChars
pack x ≡ x ^. packedChars
unpack x ≡ x ^. re packedChars

>>> foldOf (packedChars % each % to (\w -> let x = showHex w "" in if Prelude.length x == 1 then '0':x else x)) "hello""68656c6c6f"

unpack (or pack) a list of characters into a ByteString

When writing back to the ByteString it is assumed that every Char lies between 'x00' and 'xff'.

unpackedChars ≡ re packedChars
unpack x ≡ x ^. unpackedChars
pack x ≡ x ^. re unpackedChars

>>> [104,101,108,108,111] ^. packedBytes % unpackedChars"hello"

Traverse the individual bytes in a ByteString as characters.

When writing back to the ByteString it is assumed that every Char lies between 'x00' and 'xff'.

This Traversal walks each strict ByteString chunk in a tree-like fashion enable zippers to seek to locations more quickly and accelerate many monoidal queries, but up to associativity (and constant factors) it is equivalent to:

chars = unpackedChars % traversed

>>> anyOf chars (== 'h') $ Char8.pack "hello"True