Verbs

To declare a Verb, write a normal Go function with the following signature, annotated with the Go comment directive //ftl:verb:

//ftl:verb
func F(context.Context, In) (Out, error) { }

eg.

type EchoRequest struct {}

type EchoResponse struct {}

//ftl:verb
func Echo(ctx context.Context, in EchoRequest) (EchoResponse, error) {
  // ...
}

To declare a Verb, write a normal Kotlin function with the following signature, annotated with the Kotlin annotation @Verb:

@Verb
fun F(Context, In): Out { }

eg.

data class EchoRequest
data class EchoResponse

@Verb
fun echo(ctx: Context, request: EchoRequest): EchoResponse {
  // ...
}

To call a verb use ftl.Call(). eg.

out, err := ftl.Call(ctx, echo.Echo, echo.EchoRequest{})

To call a verb, import the module's verb client, add it to your verb's signature, then call() it. eg.

import ftl.time.TimeClient

@Verb
fun echo(req: EchoRequest, time: TimeClient): EchoResponse {
  val response = time.call()
  // ...
}

val response = time.call()