Mill IDE Support

[Bleibtreu]

In fact, my personal experience is that IDEA's support isn't great. Using version 2025.2.4 with Mill 1.0.6, simple project modules initialized with Mill get marked with error red lines. Running the RUN command directly results in a “Main not found” error.

My personal view is that Mill's documentation needs to cater to beginners by providing crystal-clear step-by-step guidance. At minimum, it should clearly explain the purpose of key statements and ensure provided examples run seamlessly in most scenarios. Otherwise, it fails to inspire confidence.

That's my take.

PS: I fully acknowledge I'm a Scala beginner and not the “genius” the community talks about, but I still want to learn Scala. I've tried Mill at least three times without success. Ironically, SBT—known for its steep learning curve—supported my first project. I believe Mill's documentation fails to provide step-by-step guidance for simple IDE execution.

[lihaoyi]

Can you provide a zip containing a repo demonstrating these problems that we can look at?

[Bleibtreu]

I'm using the ‘scalalib/basic/1-simple’ template, and the situation matches the scenario described above. Personally, I don't feel very familiar with Mill, but even following the documentation, I couldn't quickly set up a solid scaffolding.

[Bleibtreu]

Sorry, I forgot to mention that my JDK version is 25 and my Scala version is 3.3.7.

[Bleibtreu]

[Bleibtreu]

[lihaoyi]

Thanks for your report. #6107 should mitigate one of the issues you reported is https://youtrack.jetbrains.com/projects/SCL/issues/SCL-24275/Mill-BSP-Import-sometimes-gets-into-bad-state, which I'm hoping the Jetbrains people will be able to fix upstream in intellij