Similar to the automatic implicit conversion to boolean values in weakly typed languages

type	impl
float	self is not 0.0 / NaN
integer	self != 0
reference / smart pointer	inner value impl
raw pointer	!self.is_null
Option	self.is_some
Result	self.is_ok
Poll	self.is_ready
str / slice / array	!self.is_empty
collections	!self.is_empty
unit	false
bool	self
fn / tuple / char	true

Examples

use weak_true::weak_true;

#[weak_true]
fn main() {
    let mut a = vec![-1, 0, 1, 2];
    let mut b = vec![4, 3];

    while a && a[a.len()-1] {
        b.push(a.pop().unwrap());
    }

    assert_eq!(a, vec![-1, 0]);
    assert_eq!(b, vec![4, 3, 2, 1]);
}

use weak_true::WeakTrue;

assert!("c".weak_true());
assert!('c'.weak_true());
assert!('\0'.weak_true());
assert!([0].weak_true());
assert!((&0 as *const i32).weak_true());
assert!(Some(0).weak_true());

assert!(f64::NAN.weak_false());
assert!(0.0.weak_false());
assert!(0.weak_false());
assert!("".weak_false());
assert!([0; 0].weak_false());

assert_eq!(1.weak_then(|| "ok"), Some("ok"));
assert_eq!(0.weak_then(|| "ok"), None);

weak_true 0.2.1

Examples