Impractical Macros

by Alex Burka

Alex Burka

Alex is a robotics graduate student at the University of Pennsylvania. He got into Rust by writing his research software (a hardware controller and web interface for a sensor suite), and continues to spend too much of his free time writing macros.
A whirlwind tour through a (macro_rules 1.0!) macro that interprets everyone’s favorite Turing tarpit, Brainfuck, completely at compile time. I’ll highlight various components such as number encoding, arithmetic, input/output and explain how they work.

This is not a macro tutorial. I’ll cover a few techniques that you might possibly be able to use in real code, such as how to set up a recursive macro with an accumulator, but I’ll be breezing through them to get to the fun stuff, like memory zippers and “Zermelo numbers” (a term I may have invented).