Elegance C#
0%

Either

Posted on In

install-package T1.Standard

Instead of using exceptions extensively, we should use Either as a replacement.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
public Result SayHello(string name)
{
    if( name == "hack" ) {
        throw new Exception("Bad Request");
    }
    return new Result
    {
        ErrorMessage = string.Empty
    };
}

try {
    return SayHello("xxxx");
} catch (Exception e1) {
    return new Result {
        ErrorMessage = e1.Message
    };
}

This is a C# implementation of the “Either” type. The Either type is a functional programming concept that allows you to represent values that can be one of two types, “left” or “right”. 

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
public Either<Result, Exception> SayHello(string name)
{
    if( name == "hack" ) {
        return new Either<Result, Exception>(new Exception("Bad Request"));
    }
    return new Either<Result, Exception>(new Result
    {
        ErrorMessage = $"Hi {name}"
    });
}

return SayHello("xxx").Match(
    result => result,
    ex => new Result {
        ErrorMessage = string.Empty,
    }
);