Retry a failing call in Rust
Rust interview exercise on Option & Result, difficulty 2 of 3. Solve it in the editor beside a worked example, or cold in Interview mode with the example hidden; the tests run the moment you do.
Write retry(f, attempts) that calls f until it returns Ok or it has been called attempts times, then returns the last result. f is always called at least once. It may change state between calls, so it is FnMut.
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Interview mode hides the example: solve it from memory, without the hint or the solution, and it counts as solved cold. Progress is saved in your browser, and in your account if you sign in.