how would you pause a

timer

type flow? it’s not really idiomatic, is it? or maybe akin to backpressure, i.e. downstream telling upstream to stop?

What are you trying to accomplish? It seems like you'd be mixing coroutines and Java concurrency, which could be a bit awkward. It might be easier to cancel the timer and create a new one instead.

Instagram stories ui .. the timer which auto-advances and can be paused via tap-n-hold

Do you mean something like?:

timerEnabled.transformLatest { if (it) emitAll(timer) }

@Nick Allen can you do a bit more? I see youre only allowing timer if timerEnabled, but that would mean its filtering, not pausing right? i.e. 1 2 3 …. 10 11 12?

It's not filtering, it's re-subscribing everytime it turns true. If timer is "hot" then it's basically a filter. If "cold", then it's more like 1,2 3 ... paused ... 1, 2, 3 (resubscribing restarts the flow) Perhaps you want to subscribe once and not skip values but just wait for timer to become unpaused again?

timer.onEach { timerEnabled.first { it } }

Don't use instagram so I know nothing of what's implied by that. Does your timer emit an index? Should pausing not skip values? If you tap mid-interval do you need resuming the timer to wait for the remaining part of the interval?

@Nick Allen yes pause and resume, and yes Id ideally want a stream of floats 0..1 here is a video, watch the progress bar at the top btw when it pauses its me holding the screen (google removed taps from screenrecording ughh), and resumes when I release