I'm sorry, they never should have legalized it.

For Arithmetic Encoding, it is made clear how the "infinite floating point number" calculations can be implement with a finite sliding window. There's a particular tricky part which handlings the problem of the window underflowing in precision.

For Burrows-Wheeler, the key insight is the transform makes it possible to exploit all the "2 letter" repeated codes in the message.

In both cases, explanations I've read before cover the "gee-whiz" mathematical part, but doesn't explain the actual practical _algorithm_ required.

Correction: I'm a _talented_ asshole

Looking forward to a Daring Fireball review of the latest Lumon release.