I've done cross-platform development with Scala (JVM/JS). I'll tell you, with all the tooling support (sbt) that Scala has right now, it's not all that much eas

I've done cross-platform development with Scala (JVM/JS). I'll tell you, with all the tooling support (sbt) that Scala has right now, it's not all that much easier than what you can do with Reason. Typically, you get libraries like `foo-scalajs` and `foo-scala` which are basically cross-compiled from a single codebase which is divided into three major parts: common, JS, and JVM. With Reason you can do the same thing (in fact people have). On top of which, Reason's functors (higher-order modules) allow you to write for multiple platforms in a very clean and decoupled way. They are a great, great boon for software engineering and folks like e.g. the MirageOS have used them to great advantage to target say the unikernel and Unix environments for their apps.