Simple test:

static (int, int) Foo(int i)
{
return (i+2, 1*2);
}

Current "result" :
Predefined type 'System.ValueTuple`2' is not defined or imported

Expected:
To compile (and work of course :-)

This includes updating "4.7.2" "Compiler" to accept C# 7.x and at least linking the proper dll with ValueTuple-a for "Roslyn 2.0"

Why would you make a Nuget Header Directive available for C# but not for VB.Net?

It would be nice to have a user page that lists the Fiddles that we have created. A main page of sorts.

Sometimes I need to check a code that works with local timezone which should be different from UTC. It would be great to have an ability to specify timezone in that cases. Thank you!

Such as controller or class or new .cHTML ...

Change the text color with Console.ForegroundColor

That the code can be used:
Console.ForegroundColor = ConsoleColor.DarkBlue;

Console.Write ("Hello");

Console.ForegroundColor = ConsoleColor.DarkRed;

Console.WriteLine ("World");

Please add this, at least as an option. Otherwise we can lose work. Thank you!

some class libraries loaded from nuget need setting assembly attributes located in assemplyInfo.cs otherwise it fire an exception, like:

[assembly: AssemblyCompany("Company xyz")]
[assembly: AssemblyCopyright("Copyright © 2018 Company xyz")]

Enable setting these attributes in assemplyInfo.cs

Allow the usage of debugging such as stepping into a function, out of a function, run, memory mapping, local variables and the whole nine yards. It is vital if you don't want users to write constantly Console.WriteLine() statements.

Kindly, add debugging!

Please enable vim key bindings. VsVim is one of the most downloaded Visual Studio extension, which is an indication of Vim key binding's popularity among .net devs.

For example: I define a class Person in a fiddle named PersonClass.
Then I base a new fiddle PersonUseExample on existing fiddle PersonClass, so I don't need to declare the class again, just démonstrate how I can use it.

The idea is probably easier to implementis but similar to the exiting request: https://dotnetfiddle.uservoice.com/forums/228764--net-fiddle-ideas/suggestions/6056568-allow-multiple-files-for-console-projects

When try to add nuget package System.Text.Encoding, keep receive error in browser console: common:Uncaught Error:

Uncaught Error: Incorrect version name
at Object.n.addPackage (common:1)
at HTMLAnchorElement.<anonymous> (common:1)
at HTMLBodyElement.dispatch (jquery:1)
at HTMLBodyElement.y.handle (jquery:1)

On top of each fiddle, it says "by <author's user name>". The author's username should be a link to take the user to all his/her fiddles.

Why is the list limited to 10 fiddles? We should be able to see all of them, or at least have a page size option.

Monaco-editor is MIT licensed and made by Microsft.
It's the same text editor used in VSCode, and it is open source!
It also has many interesting features like code diff and editor customization.

See more here:
https://github.com/Microsoft/monaco-editor
https://microsoft.github.io/monaco-editor/playground.html