Comment by Ericson2314

Your comment is wrong is wrong. You are talking about "encapsulation tricks", where you don't make illegal states unrepresentable, but just all the construction so you can audit than declare the unrepresented state won't be constructed.

Sometimes this is good, but the benefits are a lot lower, and many an overzealous programmer has taking the "boolean blindness" "string blindness" argument too far with copious newtypes.

Actually ruling out invalid states by construction, however, is way more valuable, and far more likely to be worth the work. It requires more thought than just newtyping away, but that's a feature, not a bug.