Shorthand for Option.map(|x| some_predicate(x)).unwrap_or_default() | Rust Programming Language Community | Page 1

half roost Jul 7, 2022, 10:18 PM

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Hi! I've been finding myself wanting to evaluate some predicate against the contents of an Option, and get the resulting bool out, such that None => false, Some(x) if !some_predicate(x) => false, Some(x) if some_predicate(x) => true.

Is there a convenient shorthand from this? I've looked at the Option doc and can't find one, but I feel like I'm maybe missing something. I can also think of into_iter().any(|x| some_predicate(x)), but I don't know if that's really an improvement.

sinful ice Jul 7, 2022, 10:23 PM

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is_some_and (nightly) https://doc.rust-lang.org/std/option/enum.Option.html#method.is_some_and

Option in std::option - Rust

The Option type. See the module level documentation for more.

half roost Jul 7, 2022, 10:23 PM

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ah, dang, that is quite nice otherwise - thanks, I'll consider adding it to my nightly features!

agile sun Jul 7, 2022, 10:47 PM

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you can also do opt.map_or(false, some_predicate)

#Shorthand for Option.map(|x| some_predicate(x)).unwrap_or_default()