Ask HN: What change in your programming technique has been most transformative? 6 years ago
Learning different programming paradigms. For example, logic programming with Prolog makes you think about solving certain problems quickly and efficiently in a declarative style. Strongly-typed functional languages like SML and OCaml make it easy to use types and pattern matching to reduce errors and shift some cognitive burden from yourself to the compiler. Lisps allow you to quickly prototype functions in the REPL and test them interactively, and thinking about code as data (homoiconicity) is a powerful concept.
In short, learning new programming paradigms completely changed my view of programming and these skills can translate over to more "mainstream" languages, so it is still a worthwhile effort.