Haxe compiler on the Web is a great learning experience.
I have seen others and myself use it to help figure out code solutions.
I think there could be:
More Haxe target language options.
Do every output language that Haxe supports now.
That really shows the unique strength of Haxe.
Instead of Radio Buttons for selecting a target language
Change to Check Boxes for the various languages.
I think Java and Python might especially be wanted by someone using Try Haxe because there may be low overhead. Java or Python may be already available to Run, even on phone platforms.
What would be even more impressive is to allow fairly significant input as the Haxe code to compile. Allowing multiple .hx source files from a src directory as is typical when building a Haxe project locally.
I think there was some discussion about allowing the Haxe compiler to run on platforms other than Desktops or Laptops. Making these suggested changes to Try Haxe ! could be like an big wave of acceptance for Haxe Then to get the Haxe compiler to run on less capable platforms would not be as urgent.