Scala module

I'll go with a top-to-bottom approach with the things I encountered, and how I tried to solve them in my project.

1. WorkflowClient

• WorkflowClient.start with io.temporal.workflow.Functions.Func arguments
• WorkflowClient.start with io.temporal.workflow.Functions.Proc arguments
• WorkflowClient.execute with io.temporal.workflow.Functions.Func arguments
• WorkflowClient.execute with io.temporal.workflow.Functions.Proc arguments

Solved this by writing some small wrappers. I don't think this is the way, but the code inside might be useful. These are the only type of functions I needed, didn't convert them all (e.g the ones that take more arguments)

def startAsync(f: T => Unit, arg: T): WorkflowExecution = {
   WorkflowClient.start(new Proc1[T]() {
     override def apply(j: T): Unit = f(j)
   }, t)
 }

 def executeAsyncVoid(f: () => Unit): Future[Unit] = {
   import scala.compat.java8.FutureConverters._

   WorkflowClient.execute(new Proc {
     override def apply(): Unit = f()
   }).toScala.map[Unit](_ => ())
 }

 def executeAsync[T](f: () => T): Future[T] = {
   import scala.compat.java8.FutureConverters._

   WorkflowClient.execute(new Func[T] {
     override def apply(): T = f()
   }).toScala
 }

2. Scala specific object types serialization/deserialization

• Option
• List (basically all Scala collections)

We can probably solve this when Jackson will be integrated in java-sdk

3. Workflow.await requiring a Supplier, instead of passing a function reference

Again, solved in a simple wrapper

 def await(duration: Duration, f: () => Boolean) {
    Workflow.await(duration, new Supplier[lang.Boolean] {
      override def get(): lang.Boolean = f()
    })
  }

4. Java way of referencing some method (not sure how this syntax it's called in Java)
   (Mostly the same as 1. but I put it in a different issue as it's a little bit a different problem)

WorkflowClient.execute(workflow::getGreeting, "World") -> notice the double colon

5. Accepting Scala Duration type

Start by reviewing the listed WorkflowClient.start/execute and Workflow.await interop cases, then assess Scala Option and collection serialization and Scala Duration support. The Java method-reference example and existing wrapper snippets define additional requirements. Done means a coherent Scala module addresses the listed interop and type-conversion needs.