I like Play, currently using for a personal project. But ultimately looking forward to the day where frameworks are replaced by mixing and matching libraries where you get just what you need and wire it up exactly how you want to without any limitations.

On the JVM and especially since version 2.1 Play is one of the most lightweight/modular frameworks. At it's core it's just a fast/async http server. So why can't that just be a library you pull in and fire up in a main method?

You can have an IDE or somthing like sbt recompile your changes on the fly so you can get rapid feedback. Ultimately more rapid feedback comes for automated tests vs refreshing your browser and verifying something manually (unless it's UI/lookandfeel changes which are not generally limited by having to compile)