TypeScript type inference issue

Question

I\'m using TypeScript with the MongoDB node.js driver. Note, this is not a Mongo question, its just the particular use case of this issue I\'m having.

Pretty much ev

Answer 1

I was wrong, this doesn't work in C# either. Here's the example of the same code from TypeScript, written in C#, that does not work:

using System.IO;
using System;
using System.Threading.Tasks;

class Program
{
    static void Main()
    {
        Console.WriteLine("Hello, World!");
        var task = Wrapper(cb => FakeMongoFunctionWithCallback(5, cb));
    }

    static void FakeMongoFunctionWithCallback(int arg, Action callback)
    {
        // just pass through the arg into the callback, pretending we went to a db and came back with that result
        callback(null, arg);
    }

    static Task Wrapper(Action> action) {
        var tcs = new TaskCompletionSource();
        action((err, res) => {
            if (err != null) tcs.SetException(err);
            else tcs.SetResult(res);
        });

        return tcs.Task;
    } 
}