exception-handling - 如何在 F# 中没有警告的情况下捕获任何异常 (System.Exception)？

Question

我试图捕获异常，但编译器发出警告:此类型测试或向下转换将始终保持

let testFail () =
    try
        printfn "Ready for failing..."
        failwith "Fails"
    with
    | :? System.ArgumentException -> ()
    | :? System.Exception -> ()

问题是:如何在没有警告的情况下做到这一点？ (我相信一定有办法做到这一点，否则应该没有警告)

像 C#

try
{
    Console.WriteLine("Ready for failing...");
    throw new Exception("Fails");
}
catch (Exception)
{
}

Answer 1

C#:

void testFail()
{
    try
    {
        Console.WriteLine("Ready for failing...");
        throw new Exception("Fails");
    }
    catch (ArgumentException)
    {
    }
    catch
    {
    }
}

F# 等效:

let testFail () =
    try
        printfn "Ready for failing..."
        failwith "Fails"
    with
    | :? System.ArgumentException -> ()
    | _ -> ()

C#:

void testFail()
{
    try
    {
        Console.WriteLine("Ready for failing...");
        throw new Exception("Fails");
    }
    catch (ArgumentException ex)
    {
    }
    catch (Exception ex)
    {
    }
}

F# 等效:

let testFail () =
    try
        printfn "Ready for failing..."
        failwith "Fails"
    with
    | :? System.ArgumentException as ex -> ()
    | ex -> ()

C#:

void testFail()
{
    try
    {
        Console.WriteLine("Ready for failing...");
        throw new Exception("Fails");
    }
    catch
    {
    }
}

F# 等效:

let testFail () =
    try
        printfn "Ready for failing..."
        failwith "Fails"
    with
    | _ -> ()

正如乔尔所指出的，你不会想使用 catch (Exception)在 C# 中，出于同样的原因，您不使用 | :? System.Exception ->在 F# 中。