When I was younger I used to write a lot of Common Lisp. A lot. And I also had this idea that Haskell/OCaml/Scheme were strict, ivory tower totalitarian languages, while Common Lisp was this incredibly powerful, expressive, liberating tool. For building organisms, not pyramids, like Sussman said. And the S-expressions were aesthetically appealing to me. But at the time I was working mostly on smaller commercial projects and solo open source projects.

Maybe it's cognitive decline from no longer being a teenager, or the experience of working on larger, O(100,000) line codebases with large teams, but nowadays I find a high degree of dynamism just exhausting. I don't want more expressive power, I want fewer nightmares.

A common problem I faced with Common Lisp is I'd write some module, then go on to write another module that depended upon the previous one, and get an exception through from the first module. Usually a type error. And I'd have to go back, context-switch, fix that, and climb back up to the other level.

With ML/OCaml/Haskell that is far less common. Being able to look at a module and say, "this is done and it's correct", is a very powerful thing. Confidence, rather than safety, is the primary benefit of static typing for me.

And I find that I no longer use the REPL. I've been working on a compiler in OCaml and for some reason Dune won't run utop (lol) so I've just not been REPL'ing and it's not been a problem. The code typechecks. Things work on the first run. If I change something, I get notified what needs updating.

The problem with interactive development is that it's like unit testing: it can prove the presence of bugs but not their absence. Type systems can eliminate large classes of bugs ahead of time.

Just so this is not entirely negative or depressing: there's something beautiful about how maximalist Common Lisp is. It's a big, messy language with every programming paradigm (and you can invent new ones) and different naming conventions in the core language itself. I was learning new things about Common Lisp years into using it productively. And I compared the experience to moving to a huge stately home, that has a room for the piano, a vast attic, a wine cellar, all manner of things, and then trying to move back to a shoebox apartment. Where do I fit the piano? CLOS, the MOP, the Lovecraftian beauty of LOOP and FORMAT: it's like a wild garden next to the (comparative) spartan minimalism of practically everything else. And it's beautiful.