[enneff]

> Go's language spec is a much fuzzier document targeted towards language users — much like e.g. Python's language reference — there is no way you can write a clean-slate implementation just from the language spec.

That's not correct. The Go spec is designed to be a precise specification of the language, targeted at language implementers. Ian Lance Taylor (incidentally, the author of these generics proposals) wrote gccgo based on that spec. There have been a couple of other implementations based on that spec since.

The main Go compiler itself was implemented from that spec, too. The spec comes first.