ekmett/lens — pull request #479 by sordina (2014-09-22 09:09:24+00:00)
Title: Added xorish operators to Data.Bits.Lens

Inspired by http://en.wikipedia.org/wiki/Rijndael_S-box#Implementations

```haskell
affineX' :: Word8 -> Word8 -> Word8
affineX' c b = b &~ forM_ [0..7] twiddle
where
twiddle j = do bitAt j .= getBit b 4
bitAt j .^|.= getBit b 5
bitAt j .^|.= getBit b 6
bitAt j .^|.= getBit b 7
bitAt j .^|.= getBit c 0
where
getBit n o = n ^. bitAt (mod (o + j) 8)
```