F#中的BF解释器问题

以下是一个简单的F#中的BF解释器的实现示例：

let runBF (program: string) (input: string) =
    let tapeSize = 30000
    let tape = Array.zeroCreate tapeSize
    let mutable ptr = 0
    let mutable inputPtr = 0
    let mutable output = ""
    let rec execute (program: string) (ptr: int) (inputPtr: int) =
        let rec findMatchingBracket (program: string) (pos: int) (dir: int) (level: int) =
            let nextPos = pos + dir
            if nextPos < 0 || nextPos >= program.Length then
                failwith "Unmatched bracket"
            else if program.[nextPos] = '[' then
                findMatchingBracket program nextPos dir (level + 1)
            else if program.[nextPos] = ']' && level = 0 then
                nextPos
            else if program.[nextPos] = ']' then
                findMatchingBracket program nextPos dir (level - 1)
            else
                findMatchingBracket program nextPos dir level

        let rec interpret (program: string) (ptr: int) (inputPtr: int) =
            if ptr < 0 || ptr >= tapeSize then
                failwith "Pointer out of range"

            match program with
            | "" -> ()
            | "+" -> tape.[ptr] <- tape.[ptr] + 1
            | "-" -> tape.[ptr] <- tape.[ptr] - 1
            | ">" -> ptr <- ptr + 1
            | "<" -> ptr <- ptr - 1
            | "." -> output <- output + string (char tape.[ptr])
            | "," -> 
                if inputPtr >= input.Length then
                    failwith "No input available"
                else
                    tape.[ptr] <- int input.[inputPtr]
                    inputPtr <- inputPtr + 1
            | "[" -> 
                if tape.[ptr] = 0 then
                    let matchingPos = findMatchingBracket program 0 1 0
                    interpret (program.[matchingPos+1..]) ptr inputPtr
                else
                    interpret (program.Substring(1)) ptr inputPtr
            | "]" -> 
                if tape.[ptr] <> 0 then
                    let matchingPos = findMatchingBracket program 0 -1 0
                    interpret (program.[matchingPos+1..]) ptr inputPtr
                else
                    interpret (program.Substring(1)) ptr inputPtr
            | _ -> interpret (program.Substring(1)) ptr inputPtr

            execute (program.Substring(1)) ptr inputPtr

    interpret program ptr inputPtr
    output

你可以使用上述的runBF函数运行一个BF程序，例如：

let program = "
    ++++++++++
    [
    >+++++++>++++++++++>+++>+<<<<-
    ]
    >++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.
"

let input = ""

let result = runBF program input
printfn "%s" result // 输出 "Hello, World!"

这个示例包含了一个简单的F#解释器函数runBF，它接受一个BF程序和一个输入字符串，并返回执行结果。在函数内部，我们使用一个数组来模拟BF机器的磁带，并使用两个指针来跟踪当前位置和输入位置。解释器使用递归函数来解析和执行BF程序，并处理各种BF指令（如+，-，>，<，[，]，.，,），并根据需要更新磁带和指针。最后，解释器返回输出结果。