A good example would be regex. After validating it when writing the program it should always compile, although this could also be solved with a proc macro that validates the regex at compile time.

[–] mobotsar@sh.itjust.works 4 points 5 months ago* (last edited 5 months ago) (2 children)

If it's guaranteed to not be None, why is it an Option?

[–] marcos@lemmy.world 2 points 5 months ago* (last edited 5 months ago)

Oh, it can happen when you do calculations with compile-time constants...

But the GP's claim that it's a "frequent" thing is suspect.

(Crashing is also useful when you are writing and-user applications, but you'll probably want .expect like in the meme.)

[–] Korne127@lemmy.world 1 points 5 months ago

A very typical use-case would be getting something from a HashMap (or a Vector) and calling unwrap because you know it must exist (as you got a reference to the index or object that must be valid in the HashMap or Vector).
Or if you call a function that returns Option<…> depending on the current state and you know that it must return Some(…) in the current situation.