Find a good example for .while_some() about itertools HOT 3 CLOSED

That looks like it'd do it. It does have one downside: the need to explicitly unpack the Option<A> to generate the next element, but that's not insurmountable, and hopefully shouldn't be a big optimisation problem.

Here's a really basic example, rewritten slightly to fit the playpen.

from itertools.

True, that is a big downside.
You could use mutable state (much uglier in your eyes I presume).

let mut n = 0;
let ns = WhileSome::new(RepeatCall::new(move || if n <= 5 { let nn = n; n += 1; Some(nn) } else { None }))

from itertools.

In that case, I'd prefer to go with the Option::and_then approach. I mean, iterator chaining is fundamentally about chaining operations together in a linear expression; having to break out and create state storage is (for me, at least) a heavy push toward "maybe I should just do this with a for loop".

Unless I was doing a lot of these, I'd probably just live with the Option::and_then. Having this lowers the effort barrier enough that, had this already existed, I wouldn't have bothered to make my own adaptor. :)

from itertools.