I am not sure how would you would simulate them. With enums and structs, I suppose?
However, it also has true sum types:
type SumType interface { isSumType() }
type A string
func (A) isSumType()
type B int
func (B) isSumType()
interfaces in go aren’t types, so no, that’s not a sum type, it’s just an interface.
The set of objects that can fulfill that interface is not just string and int, it’s anything in the world that someone might decide to write an isSumType function for.
> it’s anything in the world that someone might decide to write an isSumType function for.
No. Notice the lowercase tag name. It is impossible for anyone else to add an arbitrary type to the closed set.
Unless your argument is that sum types fundamentally cannot exist? Obviously given a more traditional syntax like,
...one can come along and add C just the same. I guess that is true in some natural properties of the universe way. It is a poor take in context, however.