scastie VS Play WS

From personal experience Scala also works. It's 100% possible to learn monads using https://scastie.scala-lang.org/ as a scratch pad.

Instead I typically use https://scastie.scala-lang.org, or an ammonite script, or just create a new file that extends App in my test directory. The thing that worksheets do better is that you can import things from your project (like the little app in the test dir) but they also show runtime values (like repl or scastie). However I've just never gotten them to actually work.

I strongly recommend you play around with the local Scala REPL. I have Scala 2.13 on my main dev computer and Scala 3 on my other computer. The local REPL will let you know when things are deprecated and give you hints as to what you should use instead. Scastie https://scastie.scala-lang.org/ can also be a big help.

Operationally, as you might expect from a language borne from academia, Scala tooling can be problematic and compilation can be slow--particularly if you are not yet using Scala 3, which only recently emerged and is very slowly percolating through the ecosystem (Remember the Python 2 to Python 3 transition?). But type inference, a vast standard library, and the time-tested reliability of the JVM make you very productive once you get the hang of them. Performance varies with the JVM you're running, but regardless you do have to contend with the size of compiled objects and the latency of garbage collection at runtime. When you want to experiment, you can skip the ceremony of writing a class or test and instead use a command-line REPL, an online REPL called Scastie you can share, or an outstanding third-party command-line REPL called Ammonite. Dependency management is achieved with SBT typically but also more general JVM build tools like Gradle and Maven.

I am using https://scastie.scala-lang.org/ which does compile server side in Scala. The UI is a bit hard to handle tho.

https://github.com/scalacenter/scastie#how-do-i-embed-scastie

Take a look at https://github.com/playframework/play-ws build.sbt. it is a scala lib built with sbt-assembly to shade dependencies and avoid binary incompatibility. That is the only reason to build a lib with sbt-assembly.

In this example, the code uses Play WS Standalone as a REST client to fetch JSON containing a UUID. Play WS has an asynchronous, non-blocking API based on Future, so you need to provide an ExecutionContext via Akka. That's all the boilerplate at the beginning of this example. Sometimes it will be done for you as when you use Play WS in the context of Play Framework. Nonetheless, you should be aware it has to happen somewhere.