bf interpreter written in Rust (https://github.com/rust-lang/rust)

main.rs

fn main() {
  let prog = ">+++++++++[<++++++++>-]<.>+++++++[<++++>-]<+.+++++++..+++.[-]>++++++++[<++
++>-]<.>+++++++++++[<+++++>-]<.>++++++++[<+++>-]<.+++.------.--------.[-]>
++++++++[<++++>-]<+.[-]++++++++++.";
  let mut inst = 0;

  let mut tape = [0; 30000];
  let mut ptr = 0;

  while inst < prog.len() {
    let command = prog.as_bytes()[inst];
    match command as char {
      '>' => ptr += 1,
      '<' => ptr -= 1,
      '+' => tape[ptr] += 1,
      '-' => tape[ptr] -= 1,
      '.' => print!("{}", tape[ptr] as u8 as char),
      ',' => {}, // TODO:
      '[' => {
               if tape[ptr] == 0 {
                 let mut cnt = 0;
                 inst += 1;
                 loop {
                   match prog.as_bytes()[inst] as char {
                     '[' => cnt += 1,
                     ']' => match cnt {
                              0 => break,
                              _ => cnt -= 1,
                            },
                     _ => {},
                   }
                   inst += 1;
                 }
               }
             },
      ']' => {
               let mut cnt = 0;
               inst -= 1;
               loop {
                 match prog.as_bytes()[inst] as char {
                   '[' => match cnt {
                            0 => break,
                            _ => cnt -= 1,
                          },
                   ']' => cnt += 1,
                   _ => {},
                 }
                 inst -= 1;
               }
               continue;
             },
      _ => {},
    }

    inst = inst + 1;
  }
}