That is pretty nice and works well to avoid redefining the fields, thank you! The only downside that remains is the relation between Foo and Fooable. It won’t necessarily be intuitive for a newcomer to understand the difference between the two.
I suppose extensible records are not really made for this use case. For now on my real-life project, I’ve kept a record with isSelected defined in, without extensible records, as it’s much simpler. Only downside is, I have to sometimes provide bogus isSelected data just so I can pass it to some functions.
I’ll keep on coding and I might find a better way to solve the underlying problem 