freezed VS Litho (By Facebook)

There is the `sealed` class modifier which allows for exhaustive matching on possible types: https://dart.dev/language/class-modifiers#sealed

There's also a package called freezed which offers similar utility (you might already be familiar with this seeing as you mentioned pattern matching): https://pub.dev/packages/freezed

I recall there being a reason unions aren't generally implemented, though I'm not sure where I read it. It was to do with union types being unnecessarily complex for the compiler and the code they tend to produce, at no real benefit to the programmer or the resulting program. Go's lack of unions is essentially based around the same reasoning.

Interesting. May I ask how this differs from something like Freezed https://pub.dev/packages/freezed and its from/ToJson features ? I haven't used it yet, but I'm just curious about the concept and use of these sort of packages.

The official site does show what you can use it for but to explain a bit more, it helps you work faster.

One rather minor suggestion: it took me a while to understand exactly what the benefits were, but the example shown on this page of the docs summarized it well. I would suggest showing an example like that at the top of the main Readme and first page of the site, before or right after the motivation section, similar to how Freezed immediately shows its value proposition.

Read more on what you can do with Freezed.

freezed on pub.dev

We use freezed for our models, and then use withConverter in the firestore SDK to easily translate between firestore and our models... however we run into issues with concurrent updates to documents.

Once the package has been created, we will install freezed for JSON serialization and value equality , as this library provides helpful tools for these tasks. We will use json_serializable for JSON serialization. To install freezed and freezed_annotation, open your terminal inside the models package and use the command:

Data class: freezed

I've recently been exploring a codebase which is heavily using Freezed with Bloc. The resulting code base is almost an entirely different language altogether, and comes with almost triple the files of a non-freezed codebase.

Waiting for Litho to be the new UI development standard https://fblitho.com/

IIRC fb is using this custom list view https://fblitho.com/

Litho by Facebook

Just a little correction, none of facebook or instagram mobile app use react native. On android, facebook, messenger, and instagram use litho library (which facebook team has also developed)

It seems unlikely that FB would give up on Litho, which is extremely performance focused, to use react native instead. Not for their bread & butter flagship news feed anyway https://fblitho.com/

I've seen some old conference talks from their team about https://fblitho.com/. I believe that what they use or at least used.

Facebook's internal android repository is still mostly Java, but there is a large push to switch to Kotlin, and Kotlin's internal support has grown dramatically over the last couple of years. Coroutines have recently been allowed (although I'm personally not a fan of that decision). Flow/Compose are not necessary as we have internal tools that do similar things (looking at you, Litho).