How to do prioritize select?

[siiky]

Hi again :)

I'm trying to use CHICKEN exclusively for a course I'm enrolled in, which is proving to be very interesting and rewarding, but also challenging. In this course we're using Maelstrom to implement and experiment with distributed algorithms and distributed programming, and I hit a limitation with my previous "recipe", in that I have no easy way of implementing timeouts, heartbeats, and the like. Because of that I'm turning now to gochan which is more at-home for me (having a bit of experience with Erlang and Go).

However, I have a problem: let's say I have two channels Ci and Ct (for input and timeout), and that the main thread does a gochan-select on both of them. Would it be possible to somehow prioritize one of the channels over the other (Ct over Ci, specifically)?

Without the "shuffle" mentioned in #6 it's obvious to me how: just order the Ct before the Ci. (In the meantime I'll remove the shuffle from gochan-select*)

[kristianlm]

Hi siiky,
Thanks for giving gochan a try.

I'm afraid there are no mechanisms for priority in place. Like you discovered, shuffle is hardcoded in.

You can however cheat i bit in some cases, like this:

(gochan-select
  ((pri1 -> msg fail) ...)
  (else 
    (gochan-select
        ((pri1 -> msg fail) ...)
        ((pri2 -> msg fail) ...))))

Where the two bodies of pri1 should be identical. That ensures handling of channel pri1 before pri2 at the start of that snippet.

[siiky]

Oh of course! I forgot about that trick! Thanks