Awesome

Brainfuck

This is a project where I try to formalize brainfuck in Coq.

Goal

The goal is to prove properties about brainfuck. I have implemented a compiler from simple arithmetic expressions (addition, subtraction and multiplication) to brainfuck. This is done by compiling to a stack machine subset of brainfuck.

Arithmetic expression compiler

A compiler from simple arithmetic expressions with addition, subtraction and multiplication to brainfuck is included in ae_compiler.v. The correctness of the compiler is proven as well. The idea in the proof is to develop a number of stack primitives and show their correctness, and then compile down to those stack primitives.

The hello world example

A "Hello World!" example is included in bf_theorems.v. It proves that the given "Hello World!" program does output the string Hello World! (or rather the ASCII values corresponding to said string - you have to verify that yourself!). The proof is largely automated. Unfortunately it takes a while to finish so it is recommended to comment out the theorem.

The time it takes to compile with the hello_world theorem:

real    0m14.674s
user    0m14.340s
sys     0m0.230s

And when hello_world is commented out:

real    0m2.485s
user    0m2.313s
sys     0m0.113s

The project's Github page.