Yeah, that will be too costly because it would have to make a server call pretty quickly to confirm that the code is complete. (The Roslyn desktop C# Interactive can do this because it's right on the desktop)
You can press Ctrl-Enter to send complete code, if you wish to send submissions faster.
Yeah, I understand. My expectations were just set a bit higher since you called it a REPL. Realistically, something like this fills a different use case anyway. When I want a REPL, I want to run it locally.
LINQPad is one of the best tools I've ever used. I can't recommend it enough for anybody who wants a C# or F# scratchpad, or wants to quickly query a database.
I didn't know that was possible. Even if you can compile Roslyn to JS to run on the client, you still need to compile most parts of the BCL as well, or else you still need to make a server call.
With some obvious caveats, I'm a big fan of the csharp REPL provided by Mono: http://www.mono-project.com/CsharpRepl