Supporting Scala.js / Scala Native on the server

[kubukoz]

Hi! I'm working on the Smithy4s interop for Caliban on the server, in which you could derive a Schema for a Smithy service.

This works fine on the JVM, but Smithy4s supports the two other platforms as well (Native only on Scala 3, though), and I would love to get at least some of that working with Caliban. This would clearly require Caliban to cross-compile as well.

I see that there's Scala.js in the build already, but it seems to be limited to the laminext and client modules.

As far as blockers/difficulties go, I'm only aware of:

• Timestamp types which don't have a portable implementation
• ???

If there's anything else you know of, such as any required dependencies that aren't being cross-published, let me know please! I'm happy to get the ball rolling on adding the build axes and getting the shared part of the server to cross-publish. Specifically I'm interested in caliban-cats.

[ghostdogpr]

We had Scala.js cross-compiling for the server a long time ago but dropped it because it was annoying dependency-wise and there was nobody using it.

What would be the use case? None of the http libraries behind the adapters support Scala.js nor Scala Native AFAIK.

[kubukoz]

Http4s works on both of these platforms :)

[ghostdogpr]

Oh I see, I was looking at the weird versions here https://mvnrepository.com/artifact/org.http4s/http4s-dsl

[ghostdogpr]

The issues I see for the core module only:

• magnolia: we're still using the old version, the new one by softwaremill supports Scala.js and Native, hopefully it doesn't break anything
• play-json only supports Native and Scala.js on Scala 3 in a RC version
• zio-query and zio-json don't support Scala Native

[ghostdogpr]

Since my previous message, we switched to the latest magnolia and there's a version of play-json for Scala.js. That means we should be able to support Scala.js easily now

[ghostdogpr]

For Scala native, i see zio-Json supports it now so the only blocker might be zio-query which is probably easy to port.