Lamina undo siphon - Clojure

Question

I'm using Lamina to implement a basic pubsub pattern.

When a client subscribes to a topic I create a new channel for it (if it doesn't already exist) and then siphon it to the client's channel. However, I can't figure out how to reverse this to let the client unsubscribe. I've been searching the docs and googling but can't find anything.

How do I undo what siphon does?

Answer 1

Typically you'd make a bridge channel that you can close, so the linkage is:

topic-channel -> bridge-channel -> client-channel

In 0.5.0, this is easy because siphon is variadic:

(defn cancellable-siphon [src dst]
   (let [bridge (channel)]
     (siphon src bridge dst)
     #(close bridge)))