I'm not a programming language theorist or in any sort of functional-programming-static-type-system ivory tower – I just want to catch more bugs prior to runtime without needing to write tedious mechanical tests of method contracts. I find good type checking insanely refreshing. I find that I need fewer tests, they are easier to write, and they test more essential attributes of the program.

I've written lots of useful stuff in Python and Ruby, but I've also sunk lots of time into tests that I would have preferred not to need to write.