Worst and most difficult to understand code I have ever seen. It is simultaneously confusing, hard, badly commented and uses every single Scala feature I have ever seen, including non-root imports in the middle of files, extensions of anonymous classes sometimes with other anonymous classes, and my least favourite: path depended typing (sometimes from non-root imports started in one of several traits that may or may not have circular inherietence patterns).

But that said, it has never been a problem outside the compiler.