Reason appears ;-) When calling a Java method assume a null return and wrap it up in an Option just as you'd do with Haskell when interfacing with the "outside

Reason appears ;-) When calling a Java method assume a null return and wrap it up in an Option just as you'd do with Haskell when interfacing with the "outside" world. As for Scala compilation speed, Haskell's not gonna win that battle, ghc is to scalac as scalac is to javac, which is to say, the last is first and the first is last in terms of compilation speed. Also, IIRC only Yesod provides incremental builds, no? With SBT incremental builds most code changes incur a < 1 second recompilation hit. As for the IDE story, the secret to a performant Scala IDE is to turn off automatic builds in Eclipse and let SBT run the show. With the SBT eclipse plugin there's a setting that allows SBT compilation target and Eclipse target to be shared so you never have to clean/build in Eclipse -- this is a huge win, the difference between standard dog slow Eclipse performance, and snappy, oh this is real nice if only the haters knew, joy ;-)