The great about types in Scala is that complex solutions to complex problems can be contained and don't infect the rest of the codebase. The average programmer

The great about types in Scala is that complex solutions to complex problems can be contained and don't infect the rest of the codebase. The average programmer can enjoy completely consistent names and signatures across different libraries, without having to know that the consistency comes from one method being applicable to various types, not manual labor repetitiously adding the same method to different types which can drift apart at any time without anyone noticing. HKTs are not that expensive. Slow compile times are usually caused by people doing Prolog at the typelevel in Scala.