@kcvinu @miran, yes I'm using devel. I also prefer tagged union (also called sum types) in general to avoid the pointer indirection.
Just be aware that with the second solution (inheritance/polymorphism) any user of your library can extend your base type with its own and reuse the methods you define while with the first solution (object variant/tagged union/sum type) adding a new subtype means modifying all proc using this type. The following blog post "[Sum Types Are Coming](https://chadaustin.me/2015/07/sum-types/)" summarizes that very well: > With sum types, it’s easy to add uses but hard to add cases. > With > interfaces, it’s easy to add cases but hard to add uses. Uses are new procs: it's easy to add new ones with sum types "proc foo = case ...", while with interfaces you need to update the base interface and add methods for each derived classes. Cases are new subtypes: just derive from the base type in interfaces, but with sum types you need to update your case statement in all the procs.
