An interpreter and (coming soon) optimising compiler for brainfuck, aptly named after the Oxford Word of the Year 2024.
To run the Brainrot REPL, simply execute cargo run.
To invoke the interpreter on a .b file, pass the file as an argument to the above command, i.e. cargo run file.b.
Brainfuck is an extremely simple Turing-complete language which operates on an array of memory cells. The language uses just eight instructions (and an unofficial debug instruction):
| Instruction | Description |
|---|---|
+ |
Increment the current cell value by 1 |
- |
Decrement the current cell value by 1 |
> |
Move to the next cell to the right |
< |
Move to the previous cell to the left |
[ |
Jump past the corresponding ] if the current cell value is zero |
] |
Jump back to the corresponding [ if the current cell value is non-zero |
. |
Display the current cell value |
, |
Read an input character and set it as the current cell value |
# |
Display the current cell, with DEBUG_RANGE preceding and succeeding cells |
The number of preceding and succeeding cells displayed with the debug instruction can be set with the DEBUG_RANGE environment variable (5 by default).
Here's an example program that echoes your input back:
,[.,]And one that prints Hello world!:
++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.The interpreter performs the below optimisations prior to runtime:
- Folding consecutive increment or decrement instructions
- Folding consecutive move instructions
- Rewriting loops that clear a memory cell (
[-]) into a single instruction - Resolving jump locations
Significant improvement in execution time is seen for the larger programs, with a 24x speed-up for hanoi.b:
| Example | Unoptimised | Optimised |
|---|---|---|
sierpinski.b |
0.0028s | 0.0017s |
numwarp.b |
0.0022s | 0.0021s |
beer.b |
0.0062s | 0.0031s |
golden.b |
0.1758s | 0.1356s |
hanoi.b |
13.5071s | 0.5665s |
bootstrap.b |
20.3662s | 14.8928s |
mandelbrot.b |
21.9095s | 6.2807s |
The example programs can be benchmarked with the bench/bench.sh script. It requires the path to the interpreter or compiler binary as an argument.
This project is licensed under the MIT License. Do whatever you want with it.