I've worked in a number of languages and fwiw I've never written such error-free code as I have in Scala when embracing the type system (to a reasonable degree)

I've worked in a number of languages and fwiw I've never written such error-free code as I have in Scala when embracing the type system (to a reasonable degree) and embracing immutability/fp patterns. We write only the tests that truly matter, something I've never felt is possible in a dynamic language as I personally feel you need lots of tests which are more or less provided for free by the type checker.