Debugging expression evaluation

Question

I'm using IntelliJ idea Community edition (with Scala) and I'm trying to evaluate an expression. I hit Alt-F8 to open it in debug mode and then switch to 'Code Fragment Mode'. However, I'm allowed to only evaluate variables that already exist in memory, and am not allowed to declare new. When I do so, I get- 'Evaluation of variables is not supported'. Is there a plugin that I can use in debug mode to evaluate arbitrary code?

EDIT: So that it's clear, no worksheets are not what I'm looking for. I want to evaluate expressions using variables existing at runtime.

Answer 1

Have you considered using a Scala Worksheet, which is a kind of editor supported REPL. You can create one in your project, import code from your project, execute it and see the results instantly. It wont let you debug to a piece of code though, if that is your primary intention.

Answer 2

It's an old question, but for now there is a good answer:

https://www.jetbrains.com/help/idea/2016.1/evaluating-expressions.html

TL;DR: During debugging, click on a stack frame, and you'll be able to evaluate expressions in the context of that frame: Run|Evaluate Expression, and you can click "Code Fragment Mode" to enter multi-line stuff. IntelliJ autocomplete features would work properly too!