My memory is fuzzy on all of the above, so this all just represents the impression it left on me. > When was the last time you tried Scala? Around 2 years ago

My memory is fuzzy on all of the above, so this all just represents the impression it left on me. > When was the last time you tried Scala? Around 2 years ago, as well. It showed so much promise but I ran into so many problems using it day to day. > What about it troubled you? The main things I use in the stdlib are collections (CanBuildFrom aside, they're pretty solid), Future (although I prefer scalaz.concurrent.Task), and Option. In 2.12, Either is finally usable too! Unreadable type signatures, mainly. And the collection hierarchy was rather bewildering. > I've only run into a single type checker crash (NPE) in my 2 years. I wasn't complaining about NPEs. IIRC Scalas type system is actually turing complete. I ran into it trying to do fairly mundane things - it crashed when I was writing a simple interepter I think. > A full compile of our ~250 file (idr loc) service took like 2 minutes. But I pretty much never did full compiles. Sbt incremental compilation of a handful of files would take a coupe seconds. This makes the feedback loop of running tests/the repl pretty quick, and unlike with other fast-feedback-loop languages (like Ruby), I get really strong checks from the compiler in each loop. True. SBT helps a lot by being incremental. It's absolutely glacial compared to Java where you don't even notice it, but a slow incremental compile system is still better than all but the fastest batch compilers. So I agree with you there. Except... > It's true that the repl leaks memory but that's by design: every repl evaluation is stored in a variable (res0, res1, etc). I've run into memory trouble once or twice when loading large production data into the repl, which would store it in one of these variables. I realise that the memory usage of a running repl is bound to grow as you enter in commands. But I've never seen something grow as rapidly as the sbt console. I'd have to restart it every 3-4 times I'd reload the small file I was working on, because I simply can't spare a GB of memory in order to run an interpreter. I never had any issues with say ruby, even when ruby was much slower, and my personal machine was abysmal (less than 1gb of ram). Maybe it's not so much a memory leak as just very sloppy use of memory.