How am I supposed to use `mutableStateListOf`? I h...

# compose

[martmists]

How am I supposed to use mutableStateListOf? I have a DisposableEffect(someStateList) but it doesn't get re-triggered when I add to/remove from the list. What's the intended use-case?

[shikasd]

It's likely that the surrounding composable is recomposing, but the list value is the same as before (because you are using the same state list as key).
I think you want someStateList.toList here

[Zach Klippenstein (he/him) [MOD]]

If you’re doing something with the list in the effect, you can avoid recomposing by reading your list in something like snapshotFlow. If you really want to recompose though, and have to call toList, then why not just store an immutable list in a mutableStateOf?

[martmists]

I see, I was hoping mutableStateListOf was a way to handle mutations to a MutableList in Compose, but I guess swapping out lists is an okay alternative.

[Zach Klippenstein (he/him) [MOD]]

I was hoping mutableStateListOf was a way to handle mutations to a MutableList in Compose

It is.

[Zach Klippenstein (he/him) [MOD]]

If you're doing something like this:

DisposableEffect(someStateList) { <-- This doesn't read the list and the instance is always the same, so the effect will never restart.
  someStateList.forEach { … } <-- This will read the current value of the list, but not restart.
}

Then you have 2 options. First, what Andrei suggested:

DisposableEffect(someStateList.toList()) { <-- This is now a state read and will return a different instance when it changes.
  someStateList.forEach { … }
}

And if you want to avoid recomposing entirely:

LaunchedEffect(someStateList) {
  snapshotFlow { <-- This lambda will restart whenever the list changes.
    someStateList.forEach { … }
  }.collect()
}