Hi all - anyone have some prod experince with MVI and Unidirectional data flow with Kotlin Flow/Coro...

# android

[Andy Gibel]

Hi all - anyone have some prod experince with MVI and Unidirectional data flow with Kotlin Flow/Coroutines?

[Andy Gibel]

I found a pretty great project here https://github.com/brewin/mvi-coroutines

[Andy Gibel]

The trouble I'm having is what always happens with UDF. How do you handle side effects like navigation

[Tash]

Yup! Used it for small to mid size projects. It’s great!

[Andy Gibel]

how did you end up dealing with navigation that you don't want to replay?

[Andy Gibel]

it's super clean for any state update: EVENT->UPDATE->STATE but when it comes to nav, it just doesn't fit as part of state

[Tash]

This was my rationale for handling things that don’t need to be replayed:

event/intent + state = new state

which means the primary purpose of `event`s / `intent`s is to update state.

if “something else” needs to act on these `event`s , a flow of these events must be siphoned off to that component

[Andy Gibel]

so you're speaking of a separate stand-alone flow for these cases?

[Tash]

kind of like:

fun reduce(event) {
      externalEventNotifier(event)
      updateState(event)
 }

[Andy Gibel]

Ah ok 👍 . Thanks for the insight - do you perhaps have some play code up on Github with this approach I might check out?

[Tash]

Yes. If needed, it could be made more flexible with something like this that differentiates between pre-reduce and post-reduce

fun reduce(event) {
      preReduceEventNotifier(event)
      updateState(event)
      postReduceEventNotifier(event)
 }

[Tash]

@Andy Gibel No problem. There is an MVI sample that I had created:
https://github.com/drinkthestars/pizza-flow/blob/master/mvi/src/main/kotlin/com/goofy/goober/ui/viewmodel/CurrentPizzaUIState.kt#L8

At the moment it has not been updated to use Flow to siphon off the events per se (hoping I have time to update it in the future). Right now, it invokes a simple lamba/listener.

[Andy Gibel]

nice 👍 Thanks!