>>17The thing is, they
work, but they have issues at scale. Like, if you're putting a couple thousand elements in there, they work fine. If you're putting millions of things in, everything goes to shit. So, okay, don't put millions of things in a hashtable in Haskell for now. Write that part of your program in C or whatever. If all your program does is put millions of things in hashtables, that's when you stop using Haskell until it's fixed.
You can find thresholds like this for any programming language, though. Like, if you're writing a web app, and you need to change something every day, you're not gonna want to use C. But that doesn't invalidate C for all other possible kinds of programs. It just means it's a horrible fit for that particular niche.
Also, not long ago, this type of problem was much worse in Haskell, but some of the work to fix it has been done already. The rest is on their todo list.