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scaladebuggingjvmhotswap

Can Hot Swap be used with Scala?

Hot Swap is a feature of the JVM, that allows to redefine the body of methods without the need of restarting JVM.

This allows to shorten the edit/debug/test cycles.

With the Java language, it works for a long time.

I wonder if Scala supports it, when debugging. We currently use IDEA.

Solution

  • In my experience the default JVM HotSwap is way to limited to be of any use for Scala code, as most changes in the typical Scala code change method signatures or add/remove methods or classes under the hood (I think any local lambdas or functions are represented as separate Java classes).

    There is no specific support for Scala Hot Swap in the IntelliJ IDE.

    The article you have linked to mentions DCEVM. I have quite good experience with this, however to me it also stopped working once my project become more complex. It is not difficult to try and see how it works for you, though.