Re: Interactive programming with Event Loop?

[Thompson, David]

Hello Christopher,

On Sat, Sep 30, 2017 at 1:23 AM, Christopher Howard
<address@hidden> wrote:
> Hi, I want to code a game using theChickadee framework, but I want to
> do it in an interactive programming environment, where I can evaluate
> things in the REPL while the Chickadee kernel is running, rather than
> needing to restart the kernel after each modification. The Chickadee
> kernel runs update hooks every so many milliseconds, so I think I just
> need to figure out a way to communicate code to an update hook, that it
> could execute. What would be the simplest and/or most sensible way to
> do this? (Threads? IPC? Communicate to a network port?)

Mark is right that a cooperative REPL server is the answer here.  We
both worked on that feature a few years ago for exactly this purpose.

Here is a simple example program that has a REPL server added in:

    (use-modules (chickadee)
                 (chickadee math vector)
                 (chickadee render sprite)
                 (chickadee render texture)
                 (system repl coop-server))

    (define sprite #f)
    (define repl #f)

    (define (load)
      (set! sprite (load-image "images/chickadee.png"))
      (set! repl (spawn-coop-repl-server)))

    (define (draw alpha)
      (draw-sprite sprite (vec2 256.0 176.0)))

    (define (update dt)
      (poll-coop-repl-server repl))

    (add-hook! load-hook load)
    (add-hook! update-hook update)
    (add-hook! draw-hook draw)
    (add-hook! quit-hook abort-game)

    (run-game)

Once the program is running, you can connect to the REPL server over a
tcp socket on port 37146.  If you use Geiser, which I highly
recommend, just run `M-x connect-to-guile` and use the default
connection settings.

Hope this helps,

- Dave