[kamov]

Sum types allow for more robust modeling of the API boundary in libraries, so in fact having a better type system is desirable even when "just gluing libraries", because it can make incorrect program states physically unrepresentable.

[mplewis]

Sum types are great – but Go manages to be unreasonably effective even in their absence.

[GaryNumanVevo]

> unreasonably effective

I'm really tired of this PR speak when it comes to programming languages. Why / how is it unreasonably effective? More effective than what?