evolve and seen the ecosystem and community evolve. An attribute of Scala is that the Scala compiler generates fragile byte-code. This means that all the code in an executable (JAR or WAR) must be compiled with the same library and compiler versions. If you're using Scala 2.9.1 in your project, you must compile against a version of Lift that's compiled against Scala 2.9.1 and all the Lift dependencies must also be compiled against that version of Scala. This is a reason that Lift has precious few Scala library dependencies. It's also a reason that Lift is sprawling... there are a lot of modules in Lift that need to be cross-compiled and rather than having an external ecosystem of modules, we need to make them part of Lift to make sure they are all compiled against all the versions of Scala that Lift supports.