Review again MessageBoard example

[t0yv0]

I have tried to clean up a bit. It's a great sample! Indeed, Flow seems not so useful here.. Some thoughts/tasks:

• review Helpers section and move to main lib if needed (or utility module)
• review LoginForm - see how using View instead of Var.Set for error-msgs
• need better styling, looks a little odd
• "hallway usability test" - grab someone and let them use it, record comments
• improve login checking with (slow) async, let's see if we can make it realistic
• check if things are "too generative" - are we reusing DOM nodes enough?

[t0yv0]

For async login, this could work:

let u : Var<string> = ...
let p : Var<string> = ...
let input : Var<Credentials> = ...
let output =
   input.View
   |> View.MapAsync (fun cred ->
          async {
               let! ok = Server.Check cred
               if ok then .. else ..
          })
let onLogin () =
   input.Value <- Credentials.Create u.Value p.Value

This avoids the checking-on-every-sneeze, and uses Async support in the view layer, kind of.

Need to think about feeback a bit - the end result of this seems to contribute to LoggedIn: View<option<User>>. Currently too many Vars..