has-some

Implement the opposite of is_empty to promote better semantics for iterator filters (and other situations) where !T.is_empty() is counterintuitive, as well as introduce filter_friendly versions of T::is_empty.

Using is_empty in an iterator filter method is relatively verbose because you can't pass the T::is_empty function when the iterator item is a reference, and, anyway, you usually want to retain things that are not empty, a predicate for which you'll always need a closure.

Basically, it stands that the semantics of "not is_empty" are annoying (well, to me) when "has some" is clearer, and even T::is_empty is annoying when using filters.

This crate, then, addresses those annoyances.

Examples

It's not really rocket science, but here you go with an example where is_empty passed as a function reference to an iterator filter does work:

use has_some::HasSome

let vector = vec!["some_data".to_owned(), "".to_owned(), "more data".to_owned(), "".to_owned()];
let vector2 = vector.clone();

// If you want the empties, you can do
let empties = vector.into_iter().filter(String::is_empty).collect::<Vec<String>>();
assert_eq!(["", ""], empties.as_slice());

// If you want the non-empties, you can now do
let non_empties = vector2.into_iter().filter(String::has_some).collect::<Vec<String>>();
assert_eq!(["some_data", "more data"], non_empties.as_slice());

And a common example where you have Items that are double references:

use has_some::HasSome

let vector = vec!["some_data", "", "more data", ""];

// If you want the empties, you can do
let empties = vector.iter().filter(str::is_empty3).collect::<Vec<&&str>>();
assert_eq!([&"", &""], empties.as_slice());

// If you want the non-empties, you can now do
let non_empties = vector2.iter().filter(str::has_some3).collect::<Vec<&&str>>();
assert_eq!([&"some_data", &"more data"], non_empties.as_slice());

CHANGES

2.0.0

• Added the filter-friendly methods - will break custom implementations that are based on the version 1 trait
• Added an implementation for str
• Improved and updated documentation

1.0.0

Just has_some