My impression of Haskell is that (1) people who use Haskell as a hobby often write libraries to show off (2) people who use Haskell professionally write proprie

My impression of Haskell is that (1) people who use Haskell as a hobby often write libraries to show off (2) people who use Haskell professionally write proprietary software. One of the problems with languages like Haskell, Erlang, and Lisp is that they’re so flexible that you often don’t know what you’re getting into when you read somebody else’s codebase. You often see projects written in these languages with a small core team that understands e.g. SBCL and the various macro libraries they use to get work done, or Haskell and the monad transformer stack they use in their app, and it’s very hard over the long-term to on-board new team members and bring them up to speed at a rate which keeps the team healthy. Maybe this is an inherent problem with “flexible/powerful” languages. There are a few Haskell tools around that people do regularly use—Git Annex, although Git LFS seems to have edged it out in popularity, and Pandoc, which I’d say is powerful and irreplaceable. Maybe zero people are writing lens libraries in C, but C does have a fair number of different string libraries around, exception / error handling libraries, and a bunch of people churning out terrible “single-header” libraries which only exist because average C programmers aren’t good at working with common, mediocre C build systems.