There's definitely parts of any language I feel I'll probably never understand, at least under the requirements of what I need to get done in my day to day work

There's definitely parts of any language I feel I'll probably never understand, at least under the requirements of what I need to get done in my day to day work. With Scala though that percentage was much higher, and the code that I didn't understand felt much more daunting. I went into Scala wanting to use it for a new project, expecting to pick it up like I had other languages but unfortunately I was unprepared for the task/sheer scale and had to switch back to a language I knew well. Whenever I have time I'll continue to study it fully aware of the rewards, but with a better understanding of the time required to get to grips with it.