I just made this project public It s far from finished but a

Question

I just made this project public It s far from finished but already implements basic functionality using Oolong and Compose <https github com pardom lambda news>

Michal Harakal · Answer

First things first Just kudos to your work After playing a little bit with the news app and oolong samples my mind just got blow away exploding head Beeing noob in FP area and just started with Jetpack Compose I can see that your are using `contramap` for binding MVU model to Jeppack s model But I don t get it about lifecycle who is reposnsible for that I ve seen in other sample use of Android s ViewModel bound with using `observeAsState` to Jetpack Also you are using ` Model`which is already deprecated with dev12 Also looking forward to see iOS part

pardom · Answer

Thanks for checking it out So let s first address the question about activity lifecycle The Oolong runtime is hosted in the `Application` process and is therefore independent of any `Activity` When an `Activity` in this case there is only one has a configuration change e g orientation change it will first remove its render function from the runtime here Then when the new activity is created it will provide its render function to the runtime here That is all that is needed handle configuration change because the runtime is not part of the activity An Oolong user may not like this approach in which case you can host the runtime in a `ViewModel` The UI state is managed by the runtime and job of Android Compose is to simply provide dependencies and render UI

pardom · Answer

As for `contramap` this has nothing to do with the lifecycle but rather delegation to child components i e screens The root component of the app delegates to child components by wrapping their model msg props `contramap` is a function that allows you to easily map from a child `Dispatch lt ChildMsg gt ` to the root `Dispatch lt AppMsg gt ` <https github com pardom lambda news blob master lambda news view src main kotlin news lambda app component AppComponent kt L45>

pardom · Answer

Looking at the source of `contramap` should help in understanding it <https github com oolong kt oolong blob master oolong src commonMain kotlin oolong dispatch util kt L36>

pardom · Answer

It takes a `Dispatch lt A gt ` a function ` B gt A` and returns a `Dispatch lt B gt `

pardom · Answer

Similarly there is a function `contramap` which helps in delegating from a parent `Next` to a child `Next` <https github com oolong kt oolong blob master oolong src commonMain kotlin oolong next util kt L50>

pardom · Answer

As for your last comment about ` Model` I plan to migrate soon but I m waiting for the next version of AS Preview Canary 10 is pretty laggy grimacing

Michal Harakal · Answer

Thank you for your answer for me is important to know that ModelView is not necessary and we can have perfectly multiplatform sharable code with MVU stiil keeping iOS in mind just reimplementing the render function Which is a really good news I expect some good news regarding Jetpack Compose this week slightly smiling face

pardom · Answer

gt for me is important to know that ModelView is not necessary and we can have perfectly multiplatform sharable code with MVU stiil keeping iOS in mind just reimplementing the render function That was one of the primary goals with Oolong The platform is not the problem domain so it shouldn t be coupled to your domain logic Nor should it concern itself with what to render but rather how