Brainfuck

A minimal Brainfuck Interpreter (<30 lines) running Hello World!

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let run (program:string) =
    let b = Array.create 30000 0uy
    let p, pc = ref 0, ref 0
    let rec execute () =
        match program.[!pc] with
        | '>' -> incr p; incr pc
        | '<' -> decr p; incr pc
        | '+' -> b.[!p] <- b.[!p]+1uy; incr pc
        | '-' -> b.[!p] <- b.[!p]-1uy; incr pc
        | '.' -> b.[!p] |> char |> printf "%O"; incr pc
        | ',' -> b.[!p] <- System.Console.ReadKey().KeyChar |> byte; incr pc
        | '[' -> if b.[!p] = 0uy then findend -1 else incr pc
        | ']' -> if b.[!p] <> 0uy then findstart -1 else incr pc        
        | _ -> incr pc
    and findend count =
        match program.[!pc] with
        | ']' -> if count > 0 then incr pc; findend (count-1)        
        | '[' -> incr pc; findend (count+1)
        | _ -> incr pc; findend count          
    and findstart count =
        match program.[!pc] with
        | '[' -> if count > 0 then decr pc; findstart (count-1)        
        | ']' -> decr pc; findstart (count+1)
        | _ -> decr pc; findstart count      
    while !pc < program.Length do execute ()

run "++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>."

val run : program:string -> unit

Full name: Script.run

val program : string

Multiple items
val string : value:'T -> string

Full name: Microsoft.FSharp.Core.Operators.string

--------------------
type string = System.String

Full name: Microsoft.FSharp.Core.string

val b : byte []

module Array

from Microsoft.FSharp.Collections

val create : count:int -> value:'T -> 'T []

Full name: Microsoft.FSharp.Collections.Array.create

val p : int ref

val pc : int ref

Multiple items
val ref : value:'T -> 'T ref

Full name: Microsoft.FSharp.Core.Operators.ref

--------------------
type 'T ref = Ref<'T>

Full name: Microsoft.FSharp.Core.ref<_>

val execute : (unit -> unit)

val incr : cell:int ref -> unit

Full name: Microsoft.FSharp.Core.Operators.incr

val decr : cell:int ref -> unit

Full name: Microsoft.FSharp.Core.Operators.decr

Multiple items
val char : value:'T -> char (requires member op_Explicit)

Full name: Microsoft.FSharp.Core.Operators.char

--------------------
type char = System.Char

Full name: Microsoft.FSharp.Core.char

val printf : format:Printf.TextWriterFormat<'T> -> 'T

Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.printf

namespace System

type Console =
  static member BackgroundColor : ConsoleColor with get, set
  static member Beep : unit -> unit + 1 overload
  static member BufferHeight : int with get, set
  static member BufferWidth : int with get, set
  static member CapsLock : bool
  static member Clear : unit -> unit
  static member CursorLeft : int with get, set
  static member CursorSize : int with get, set
  static member CursorTop : int with get, set
  static member CursorVisible : bool with get, set
  ...

Full name: System.Console

System.Console.ReadKey() : System.ConsoleKeyInfo
System.Console.ReadKey(intercept: bool) : System.ConsoleKeyInfo

Multiple items
val byte : value:'T -> byte (requires member op_Explicit)

Full name: Microsoft.FSharp.Core.Operators.byte

--------------------
type byte = System.Byte

Full name: Microsoft.FSharp.Core.byte

val findend : (int -> unit)

val findstart : (int -> unit)

val count : int

property System.String.Length: int

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More information

Link:	http://fssnip.net/ci
Posted:	12 years ago
Author:	Phillip Trelford
Tags:	interpreter