Provide Vec::dedup_by in addition to Vec::dedup #1301
Description
I would like to dedup a Vec of structs using a property of the struct. I do not want to map since I want to maintain the contents of the Vec. The stdlib Vec can sort_by using a comparator F: FnMut(&T, &T) -- it would be consistent for Vec to dedup_by using the same kind of comparator.
My contrived example:
#[derive(PartialEq)]
struct CoolThing( pub &'static str, pub u8 );
fn main(){
let mut things = vec![
CoolThing("Jimbo", 10), CoolThing("Billy", 10)
];
let uniq_things = things.dedup_by(|x| x.1);
assert!( vec![CoolThing("Billy",10)] == uniq_things )
}