Carmack's aside about his 7 year old son learning to program brings up an interesting idea: What would happen if you taught a 7 year old to program with Haskell. I don't have any children, but I started programming at 7 so at the very least I can conduct a thought experiment about what it would mean if Haskell was the tool I had at my disposal instead of opaque C manuals and a hex editor I used to hack the Mech Warrior 2 binary when I couldn't beat a scenario.

My thoughts:

I probably would have intuitively grasped algebraic datatypes. It often frustrated me that I could not define new things like True and False to suit the game worlds I wanted to create.

I would have had little to know interest in math or recursion for its own sake. I'm pretty sure I would not have done well with those.

I would have probably written almost all of my code in the IO monad, with game rules defined outside.

Graphics programming in Haskell would have been no better than with any of the other languages.

Overall, I don't think Haskell would have stuck. I think I would have been easily frustrated, despite being able to structure programs better than I was able to in Basic. For proof of this, I look to my early abandonment of C/C++ for game development (even if the manuals were pretty much terrible). On the other hand, if I was presented a game written in Haskell (with source), maybe the outcome would have been different. I certainly managed to use a hex editor at that age, so if I had some goal I wanted to accomplish (like modifying the AI of a game), I think maybe anything would have been possible.