Bullshit ;-) In theory that's how we'd like it to work, but just based on the SBT author's winding explanation of the under-the-hood mechanics (http://www.scala-sbt.org/release/docs/Detailed-Topics/Unders...), needless to say it's a very complex process, one that is far from exact in terms of user expectation (read: surprising). Also, If you use a framework, you're at its mercy. Take Play's routing, for example. Add a single route and EVERY route is recompiled, which means your controllers and, god forbid, their dependencies get thrown into the mix. If you're careful you can minimize the damage, but let's be honest, barring simplistic apps, you're in for ride, a few seconds here and there add up over the lifetime of a project.
It hasn't been a real problem for me. But I cant say the same for every kind of program developed in Scala. I'm not saying that it is not a problem and I dont recognize it. Its just that, for me, the problem is much smaller than some people here seem to think.
Maybe I've waited too long too many times for gcc to compile C/C++ that when I went to Scala I thought waiting some seconds to compile is okay =P
