With Lodash I also get currying and sort of pattern matching (via conditional execution). To be fair, I probably should have said that I was considering the si

With Lodash I also get currying and sort of pattern matching (via conditional execution). To be fair, I probably should have said that I was considering the situation when commonly used libraries are available. Immutability isn't enforced, but I have all the tools that I need to choose to handle data immutably. I completely agree with you on types though. I don't know that much about TypeScript, but perhaps it would help? You definitely have a point that functional programming would be much better in JS if these features were built in and/or enforced. However, the problem is: what's the alternative? Haskell/Clojure/Ocaml jobs aren't exactly common. And at least in terms of Haskell and Ocaml, I've found the syntax to be pretty arcane.