JsAPI: Adapters and TypeScript

[iskiselev]

Let's start discussion of this discussion in parallel to #532.

I believe that we need some convenient way to interact between translated C# code and JavaScript.
Main problem here is dynamic nature of JavaScript. On other hand, we now, that TypeScript lives with it, and even provide statically typed mapping files for many existing pure-JavaScript libraries.

We can begin with such *.d.ts files. If we will be able to map them to some C# interfaces (it should be roundtrip, so that we should be able map produced C# interfaces back), we'll be able to pass our C# objects implementing them as input parameters to C# methods - and treat method results as C# objects.

Really, here we have second problem - we can't use raw JS object as .Net interface implementer (and vice versa). So we need an adapters layer - 2 of them, for wrapping .Net object and export it to JavaScript and wrapping JavaScrpt object and exporting it to .Net.

We may need to view, how same interaction implemented in https://github.com/bridgedotnet/Bridge and probably discuss it with them - it would be only benefit for all of us if we'll have compatible interfaces mapping.
Looks like they have C# project, that is able to parse *.d.ts files - https://github.com/bridgedotnet/Retyped (other option would be write C# interface generators in TypeScript and use TypeScript compiler for extracting type information).

So, first step should be mapping of TypeScript interface to C#. Let's discuss it.

[iskiselev]

Looks like Wire formats (dotnet/roslyn#3910), that are in working list for C#7 (dotnet/roslyn#2136) with (Strong interest) mark could also help us solve JS-interop problem.

[kg]

Oh, nice! F# type providers are a great tool, so it's good to see they're thinking about things like that.