Author here: Jactl is a secure embeddable scripting language that compiles to bytecode and supports Java 8 and later versions. The article describes how Continuations were used to provide Virtual Thread-like behaviour for scripts. Blocking operations suspend a script which is then resumed from where it left off once the operation completes.

On the front page, there is an example about optional typing, but it's not very clear how the typing is coming in:

  def fib(x) { x <= 2 ? 1 : fib(x - 1) + fib(x - 2) }
  
  println "40th fibonacci number is ${fib(40)}"

TIL about jactl! Just reading the site right now. Many thanks for: no colored function (no async/wait) !

Any tips on using with gui/swing? rendering images/simple html, that would be awesome!

And what about (gasp) JSP? Or any other templating? It is old school, yeah but I like jsp include (with params) and jsp 'web components' (tags).

Anyway, thanks for writing jactl!

The continuation is only invoked once when a blocking operation completes so the print(5) would only be run once.