But that was Haskell I guess. It's obviously not a "niche language trend" by now, so it was pretty clear it had staying power.
Definitely has paid off for me personally. My side projects move a lot faster and more stably now that I cut my teeth in production Haskell. A real free 10xer to my skills personally. And I gained the skills by getting my employer to finance my learning lmao.
This probably depends on the complexity of what you need to do, as well as how well you want to do it.
I've seen people writing their own packages and pieces of systems in months, to typically pretty underwhelming results. However when writing code with tests, proper documentation, getting started guides etc., then what you're saying does sound way more plausible, especially if scope creep of any sorts is also present.
Would you care to comment on what sorts of systems take years to properly develop, though? Because in my experience that could be applicable to very few software projects out there.
This is the core point I was disagreeing with:
In my experience (yes, I have used Elm and I enjoy various functional languages), this payoff never comes. There's always something more that needs attention, needs another developer, needs to be refactored because we forgot a use case, and so on.
And also in my experience, by the time you've invested the years of effort required to fill in gaps in the public package ecosystem, it's time to move on to the next niche language trend. I'd rather invest our time and energy in mainstream languages that have staying power, where we're not obligated to carry large parts of the open-source ecosystem by ourselves.