[lifthrasiir]

In my experience branded types are relatively more fragile than normal types though. IIRC they badly behaved with infer types in particular, and it was quite hard to work around. This solution seems more versatile. (Of course, I want to see a built-in branded type support in TS as well.)

[lolinder]

This solution only works with strings, whereas branded types can be used with numbers as well, or any kind of object that you want to add stricter types to without modifying the runtime value.

I haven't observed any issues with branded types and infer—is there documentation somewhere about the problem?

[lifthrasiir]

As others pointed out, TypeScript sometimes reasons `string & object` or similar as an impossible type and can turn it into `never` at any time. I don't exactly recall whether `infer` triggered that or it was a separate issue, but that was a major problem in my experience.

[presentation]

FWIW I’ve been using branded types for years and never had this issue.