I got really into Scala a couple of years ago, and then worked on a big Scala project. One of the problems is that if you throw average Java developers into it,

I got really into Scala a couple of years ago, and then worked on a big Scala project. One of the problems is that if you throw average Java developers into it, and don't give them the time to learn the language properly-- these were smart engineers, it was a lack-of-time problem rather than an ability issue-- you get a lot of Scala-in-Java. The code is just as unreadable, "enterprisey", and unattractive as it would be in Java. I would use Scala for a personal project where I felt I needed compiler-time typing: I was writing something for the ages, or where bugs might be truly intolerable (say, high-frequency trading) but code would remain small. I wouldn't recommend it for a huge project, though. (Then again, I generally wouldn't recommend huge projects.) Scala tends to fall down on large projects, especially if the developers aren't skilled. Cyclical dependencies (yes, I know they shouldn't exist, but they will if you have a team of 25+ engineers and a wide skill spectrum) defeat incremental compilation, which matters when your compile speed is ~500LoC/second (Scala's compiler is very powerful). Also, SBT is a nightmare. I haven't used Scala's macro system but I can't imagine it being as clean as Clojure's. I like Scala on its terms alone, even if I've seen it go wrong on large codebases. (Java has the same issues, but it has tools that rescue you. It's an ugly hackish thing, to rely on tools to deal with code messes; but they're there.) I like static typing (at least, the theory that comes from it.) However, I tend to think that what most programmers really want when they say they want "static typing" is something more like Prismatic's Schema: runtime checks that can be turned on or off (performance) as needed. I think Clojure's easier to read and to write. It just looks harder, because people exaggerate the parentheses problem, which is not much of one at all. If anything, the only thing that's somewhat hard to explain to newcomers is quoting (e.g. why '(1 2 3) returns (1 2 3) at REPL but (1 2 3) is an error). The quotes were the hardest thing for me to get right when I started in Lisp.