A modern programming language that makes developers happier.

kotlinlang

`derivedStateOf` vs `remember` . When should I prefer one over the other?

derivedStateOf is for when you need to read State objects to calculate your value. If you already have a State, it might be a good fit. Remember takes explicit keys, so it can handle that as well but is a bit more verbose. 

If you find yourself writing something like
```val input: State&lt;Int&gt; = …
val```
 state by remember {
```  mutableStateOf(input.value * 2)
}.apply { value = input.value * 2 }

```
hen it might be time for derivedStateOf

Wow slack is useless, just ate an entire paragraph I typed in that message :man-facepalming:

Anyway if you excuse that garbage formatting, if you’re remembering a mutable state and updating it yourself, that’s when you might be able to use derivedStateOf

Ah thanks. I'll be using that `derivedStateOf` more now.

From what I remember, you don't need derivedStateOf. You can just do val sum = a + b

Yes, for this example, you can just do the calculation. In a real use case, you’d presumably be doing some more expensive calculation.