So far, in Rust, that has always felt unidiomatic and I haven't seen this pattern around a lot. It always felt like reimplementing Option/Result but worse: "Why

So far, in Rust, that has always felt unidiomatic and I haven't seen this pattern around a lot. It always felt like reimplementing Option/Result but worse: "Why use this when something conceptually similar exists in the stdlib?" But that is exactly the point: it's only conceptually similar, but in this case deceivingly so. In Rust, we make abundant use of newtypes; this enum is also a new type. Only once it is treated as such does actual type safety kick in. I take it the same principle applies to Haskell. Good to know there's some merit to it.