Yes, they return Unit, but the Compose annotation is hooked up to a compiler plugin and this causes some magic in generating a model/hierarchy of the views (that is what I understood from my unit-testing question here: https://kotlinlang.slack.com/archives/CJLTWPH7S/p1557666472013700?thread_ts=1557666472.013700&cid=CJLTWPH7S )

soooooo crappy creepy

"Any sufficiently advanced technology is indistinguishable from magic"

Any codegen and reflection is indistinguishable from legacy-code.

I believe that codegen and more intelligent compilers can actually make programming less repetitive. Reflection is mostly bad as it breaks compile time type safety.

Programming can be less repetitive without reflection/codegen. But this requires more intelligent programmers...

It's just a matter of what tools programmers learn. If you learn

@JsonClass(generateAdapter = true)

, you will never need to know how to write a custom json serializer. Maybe it's a bad thing, maybe not. But then who knows how to write assembly these days...

But I thank all gods in heaven for abstractions and i’m willing to call a plumber or deal with the occasional leaks myself on occasion …. 🙂 I can’t imagine drawing all pixels myself, making sure that ordering UDP packages are in order and reliable (most of the time), dealing with garbage collection, etc. I think a lot of abstractions are good trade-offs (and some are not)

Is the use of annotations in Compose a good trade off considering there is a lot of magic involved with them (also increases build time)? Were other methods explored which don't require the use of annotations/meta-programming?

Of course it is a bad trade-off. Of course there are other methods.

The annotation is just a signal to the compiler. Compose isn't an annotation processor, so you won't have the drawbacks you're used to with annotation processors.

@Ryan Mentley I'm curious why it doesn't use a keyword (like

suspend

for coroutines) by the way. That would hint at compiler support more. Or maybe plugins cannot add keywords ?

@mbonnin You're exactly correct - plugins cannot add keywords. There's some discussion toward the end of this thread between Leland and Roman: https://kotlinlang.slack.com/archives/CJLTWPH7S/p1558440714121300