Same here. ML-family languages are my favorite. Haskell seems to be the most popular though I may be biased considering I consider myself a Haskeller.
That said, I use Clojure and would choose Clojure over either Haskell or OCaml, because of the live code-reload abilities Clojure comes with, which makes it really great for rapid development. And because Clojure emphasizes immutability so much, it's trivial to keep only the state around that you want to keep, and refresh the rest. I don't think I would be nearly as fast without that.
The Yi editor has similar capabilities.
I think hot code swapping has less to do with the language, and more to do with whatever surrounds it.
That's false.
Windows are affected to workspaces. They are sorted in a particular order (set by the user as they move the windows). Each workspace uses a particular layout. One particular window on each workspace last had focus. There's a "current workspace" pointer. That's a bit more than "very little to no state". All of that is preserved upon reload. And I bet my hat all that state was in-memory.
Then there is Yi, a text editor. There's no avoiding lots of in-memory state in there.
Live code reload in Haskell. It's real.
Can be in-memory state. Everything beyond toy-sized I've ever worked on has externalised this sort of state to a database of some kind, if only so you can run a second copy for the sake of failover. I don't believe your example is relevant.