Converting a tapir+akka project to tapir+zio

tapir
1

TL;DR:
I have a “go to” default structure for services.
Up until today I used tapir with akka-http.
I want to try out ZIO, and need guidance.

I submitted a template repo with short README that explains the structure, and motivation:

There are 2 server modules there.

  • server which uses my regular akka-http code, and it works. You can just server/run in sbt, and try it out.
  • zerver which uses zio-http instead, and so far I wasn’t able to understand how everything should be stitched together.

Currently I get weird compile errors like:

[error] /home/hochgi/dev/tapir-service/zerver/src/main/scala/com/hochgi/example/zerver/Main.scala:28:63: type mismatch;
[error]  found   : List[sttp.tapir.ztapir.ZServerEndpoint[_, Any]]
[error]     (which expands to)  List[sttp.tapir.server.ServerEndpoint[Any,[β$0$]zio.ZIO[_$1,Throwable,β$0$]] forSome { type _$1 }]
[error]  required: List[sttp.tapir.ztapir.ZServerEndpoint[Any,sttp.capabilities.zio.ZioStreams]]
[error]     (which expands to)  List[sttp.tapir.server.ServerEndpoint[sttp.capabilities.zio.ZioStreams,[β$0$]zio.ZIO[Any,Throwable,β$0$]]]
[error]     val app = ZioHttpInterpreter(serverOptions).toHttp(Routes.all)
[error]                                                               ^
[error] /home/hochgi/dev/tapir-service/zerver/src/main/scala/com/hochgi/example/zerver/Routes.scala:19:73: type mismatch;
[error]  found   : sttp.tapir.server.ServerEndpoint[Any,_1[_]] where type _1[_] >: zio.ZIO[Any,Throwable,_] <: zio.ZIO[com.typesafe.config.Config,Throwable,_]
[error]  required: sttp.tapir.ztapir.ZServerEndpoint[Any,Any]
[error]     (which expands to)  sttp.tapir.server.ServerEndpoint[Any,[β$0$]zio.ZIO[Any,Throwable,β$0$]]
[error]     val apiEndpoints: List[ZServerEndpoint[Any, Any]] = endpoints.map(_._2)
[error]                                                                         ^
[error] /home/hochgi/dev/tapir-service/zerver/src/main/scala/com/hochgi/example/zerver/matapi/Info.scala:23:63: zio.URIO[com.typesafe.config.Config, _] takes no type parameters, expected: 1
[error]     allConfigEndpoint => allConfigEndpoint.serverLogicSuccess[URIO[Config, _]](_ => zioConfig)
[error]                                                               ^
[error] /home/hochgi/dev/tapir-service/zerver/src/main/scala/com/hochgi/example/zerver/matapi/Info.scala:26:50: zio.URIO[com.typesafe.config.Config, _] takes no type parameters, expected: 1
[error]     configEndpoint => configEndpoint.serverLogic[URIO[Config, _]]{ path =>
[error]                                                  ^

which I struggle to decipher.

Not sure if it’s more of a ZIO question or a tapir question, but figured it wouldn’t hurt to ask.
Any help, guidance, or links to relevant material I should read is greatly appreciated.
Thanks!

2

After some more reading, I managed to get it to work.
The way ZIO wants me to handle dependency injection feels a bit alien to me.
I’m not 100% sure I did it “as I should have”, with all the layers,
so if there’s any pointers, I’d still love to hear :pray:

3

I think you might have been missing the kindproject plugin, and using it in type parameters e.g. as follows: URIO[Config, *]?

As for structuring a ZIO application using tapir, maybe our template repository will provide some guidance: GitHub - softwaremill/realworld-tapir-zio: RealWorld.io with tapir and ZIO

1 Like
4

Thanks @adamw
Indeed, I haven’t used the kindproject plugin.
Will also take a look at the example project. Thanks!