Right. Besides getting this incantation right, as gp did only after editing their comment, you also have to cast to create values of NewType. But generally you want to avoid casting in typescript if you care about type safety, so now everybody has to remember the rule that in this particular circumstance it's the right thing to do.

There are helper libraries to ease this (zod supports branded types, I think?), but I guess my general point is that while typescript might give you the ingredients you need to implement type safety in cases like this if you try really hard and remember all your rules everywhere, it doesn't come naturally so it's hard to maintain at scale.

I was on the Tube and wanted to get my reply in before entering a tunnel. I already corrected it whilst I was underground.

I think the point still stands - is this really a big problem? I guess I couldn't recite the syntax from memory, because I usually use a utility type for this