> You want enums, nope.

It has enums, and if you want exhaustive checking, use golangci-lint (as every good gopher should be already, considering the language ensured tooling would be easy to write) https://golangci-lint.run/usage/linters/#exhaustive

> You want functional constructs (map, filter), nope.

There are libraries for map/filter (just make sure you use one with deforestation)

> You want string array contains, nope.

https://pkg.go.dev/slices#Contains