[Feature Request]: Ordered dictionary implementation

[Iainmon]

Summary of Feature

Description:

A well implemented ordered dictionary would be very nice to have. dict would behave just like map, but dict.keys() would iterate over keys in the order that they were originally inserted. If a key was removed and then reinserted, then it's new position would be last. If a key's value was just updated, then it's position would remain.

I have tried to implement this, but have had issues using it, especially when the value type is an owned class: https://github.com/Iainmon/ChAI/blob/main/lib/OrderedDict.chpl

Is this issue currently blocking your progress?

Yes.

[Iainmon]

Or if someone has a suggestion about how to improve my implementation, that would be fantastic 😄

[mppf]

I have tried to implement this, but have had issues using it, especially when the value type is an owned class: https://github.com/Iainmon/ChAI/blob/main/lib/OrderedDict.chpl

Can you show a reproducer of using it that runs into problems? It's true that owned can be tricky.

[Iainmon]

Thank you for your reply.

To reproduce it would be kind of tricky. Basically I had a class

class Layer : Module(?) {
  var subModules: dict(int,owned Module(?));
  proc init(in subs: owned Module(?)) {
    // want to convert to dict and transfer ownership
  }
}

and wanted to instantiate it via

var l = new Layer(new Module1(), new Module2());

but I was running into so many issues. The best solution was just to use shared as the convention for the ChAI library. I did not like the option of using nillable owned:

var l = new Layer(new Module1()?, new Module2()?);