That'll be a great addition to the book. Can I also recommend Yaron Minsky's talk on OCaml, specifically the part where he talks about "making invalid states i

That'll be a great addition to the book. Can I also recommend Yaron Minsky's talk on OCaml, specifically the part where he talks about "making invalid states impossible": https://youtu.be/-J8YyfrSwTk?t=1079 https://youtu.be/-J8YyfrSwTk?t=1079 I've found this to be the single most valuable programming technique I've learnt. Richard Feldman dives deeper into the topic with a lot more examples in https://youtu.be/IcgmSRJHu_8?t=73 https://youtu.be/IcgmSRJHu_8?t=73