Sure, tup is very nice, but it doesn't solve the problem in a way that leads to anywhere near efficient re-compilation on small changes (for Scala, at least --

Sure, tup is very nice, but it doesn't solve the problem in a way that leads to anywhere near efficient re-compilation on small changes (for Scala, at least -- it might be workable for Java). For that you need something like zinc[1]. This is because the dependency units in Scala don't map cleanly to files. > Another instance of a hard problem ("reimplementing [...] a Scala compiler") that turns into a very easy problem once you look at it from the right angle. Only if you don't solve the problem fully. TBH, not even zinc solves the problem 100% and sometimes does a little bit of unnecessary re-compilation. It is very good, though. [1] https://github.com/typesafehub/zinc https://github.com/typesafehub/zinc