bf interpreter

main.fs

open System
open System.IO
open System.Collections.Generic
 
let args = Environment.GetCommandLineArgs()
if args.Length <> 2 then Environment.Exit(1)
 
let bf = File.ReadAllText(args.[1])
let loop = Array.zeroCreate<int>(bf.Length)
let stack = Stack<int>()
for i = 0 to bf.Length - 1 do
    match bf.[i] with
    | '[' -> stack.Push(i)
    | ']' -> let start = stack.Pop()
             loop.[start] <- i
             loop.[i] <- start
    | _   -> ()
 
let mem = Array.zeroCreate<byte>(30000)
let mutable pc, ptr = 0, 0
 
while pc < bf.Length do
    match bf.[pc] with
    | '+' -> mem.[ptr] <- mem.[ptr] + byte(1)
    | '-' -> mem.[ptr] <- mem.[ptr] - byte(1)
    | '<' -> ptr <- ptr - 1
    | '>' -> ptr <- ptr + 1
    | '.' -> Console.Write(char(mem.[ptr]))
    | ',' -> mem.[ptr] <- byte(Console.Read())
    | '[' -> if mem.[ptr] = byte(0) then pc <- loop.[pc]
    | ']' -> pc <- loop.[pc] - 1
    | _   -> ()
    pc <- pc + 1