I'd choose Elm but that's because I have the most experience with it. It's closed ecosystem (interop with JS libraries is more ceremonious than with other alter

I'd choose Elm but that's because I have the most experience with it. It's closed ecosystem (interop with JS libraries is more ceremonious than with other alternatives here), but it's wonderful (compiler-as-assistant, elm-format etc.). Honestly writing Elm just makes me happy :) ClojureScript is nice but my last experience with was before the Spec arrived. I've had a Slack bot running in Clojure, didn't look at it for three months and when I needed to fix a bug, I couldn't remember what shape the data was in, and kind of burned out trying to get back into it. That made me try something strongly statically typed. I reckon my experience would be different with Spec now. Purescript is like Elm, just with less hand-holding and more advanced everything. Might suit you if you like Haskell? No experience with ReasonML. Edit: speaking more generally, I'd take anything with algebraic datatypes. Thankfully most modern languages do have them nowadays.