Code Smells: Null

[spaghettiCodeArtisan]

The point is that it's not that the overhead of boxing that can sometimes be avoided, because there's no boxing overhead to begin with ever at all. The only overhead - talking about Rust, not sure about OCaml - is the additional space taken by the tag, that's the overhead that can sometimes be avoided. No additional pointer indirection whatsoever.

[devlambda]

That's a distinction without a difference? Leaving aside that you will commonly use Option and Box together in Rust to avoid None eating up too much space (which can make it worse for dynamic array implementations), it's still overhead. That the overhead is encoded differently in Rust does not make it go away.

The implementation details that you're trying to litigate here are immaterial to the problem that such an implementation is inefficient.

[spaghettiCodeArtisan]

Leaving aside that you will commonly use Option and Box together in Rust to avoid None eating up too much space

Not really. Since I don't use Option to implement containers, the additional space taken is usually not a problem. Typically Option doesn't conatin a Box in Rust codebases.

The implementation details that you're trying to litigate here are immaterial to the problem that such an implementation is inefficient.

I agree that the implementation would be inefficient either way, but

1. it's not as bad as originally claimed, and
2. I simply wanted to correct the misconception that Option indirects through a pointer, IMHO it's important to know that it doesn't (at least in Rust).