1. No enums
  2. No variant types

No enums

You can define something like an enum this way. The problem is that it’s fake: you don’t get any benefits of typing, though it seems like you should.

type EnumThing int

const (
	A EnumThing = iota
	B
)

func foo(e EnumThing) {
}

You can pass -42 to foo and the compiler won’t complain. There is no easy way around this. i haven’t found a place where the design decision is explained.

No variant types

The reasoning is given here and I guess I’ll have to learn about interfaces before I can say if that’s justified. For now, yes, I miss variant types, just as I miss enums.