f# - 如何从 f# 中的表达式返回单位

Question

我如何退货 unit来自 f# 中的表达式？例如:

let readInt =
        let str = Console.ReadLine()
        let (succ, num) = Int32.TryParse(str)
        match succ with
        | true -> Some(num)
        | _ -> None

    match readInt with
    | Some(v) -> Console.WriteLine(v)
    | None -> ignore //i don't want to do anything,
//     but i don't know how to ignore this brunch of the expression

Answer 1

F# 中(唯一可能的)单位值写为

()

所以你的代码变成

...
| None -> ()