Data.ByteString.Strict.Lens

Documentation

packedBytes :: Iso' [Word8] ByteString

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

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

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

unpackedBytes :: Iso' ByteString [Word8]

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

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

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

bytes :: IndexedTraversal' Int ByteString Word8

Traverse each Word8 in a ByteString.

This Traversal walks the ByteString in a tree-like fashion enable zippers to seek to locations in logarithmic time and accelerating 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, setting map can be more efficient.

packedChars :: Iso' String ByteString

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

>>> "hello"^.packedChars.each.re (base 16 . enum).to (\x -> if Prelude.length x == 1 then '0':x else x)
"68656c6c6f"

unpackedChars :: Iso' ByteString String

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

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

chars :: IndexedTraversal' Int ByteString Char

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 the ByteString in a tree-like fashion enable zippers to seek to locations in logarithmic time and accelerating many monoidal queries, but up to associativity (and constant factors) it is equivalent to the much slower:

 chars = unpackedChars . traverse

>>> anyOf chars (== 'h') "hello"
True