Crosscut

It can make sense to make the fields of a nominally typed record private. (Let's ignore variants for now. That's a topic for another day.) I initially thought, that all nominal types should be private by default. I even considered (and that's still not off the table) to call the nominal keyword opaque because of that.

Making nominal/opaque have this double meaning would not be very orthogonal, but that might be a worthwhile trade-off. It would avoid having field visibility as a separate feature. Fields that should be accessible, can be made so by adding a function that makes them so. It would make the overall system much simpler.

Such a design would also set a tone. It could encourage safe abstractions, as opposed to APIs whose correct operation is the user's responsibility. I'm all for that, but I can also see how it could backfire. There is such a thing as too much abstraction. Then again, maybe I don't need to worry about that, if structural types and public fields are the much more accessible default.