I have quite a personal interest in learning more about pure FP, type systems, theorem provers and all the hot stuff. But: you're also comparing Haskell to com

I have quite a personal interest in learning more about pure FP, type systems, theorem provers and all the hot stuff. But: you're also comparing Haskell to completely dynamic languages like Ruby or JS. There are things in the middle. Even Java lets you avoid many silly typing errors and if you use something like Kotlin (and you use it well, not just as a slightly more modern Java), you can IMHO get quite far in terms of correctness for typical web backends. Now the power of languages like Haskell may be warranted in more complex scenarios and I don't want to claim there are no benefits to it, but there are degrees in between the madness that is JS and something like Haskell.