Using generic iterators instead of specific list types

Question

I\'m very new to Rust, coming from C# / Java / similar.

In C# we have IEnumerable that can be used to iterate almost any kind of array or list.

Answer 1

Here is the full version of Map, and here is the function that builds it.

A minimal implementation would look something like

fn map(i: I, f: F) -> Map where
    F: FnMut(E) -> B,
    I: Iterator
{
    Map {iter: i, f: f}
}

pub struct Map {
    iter: I,
    f: F,
}

impl Iterator for Map where F: FnMut(I::Item) -> B {
    type Item = B;

    fn next(&mut self) -> Option {
        self.iter.next().map(|a| (self.f)(a))
    }
}

Playpen link. Note that the map used inside the iterator is the method on Option; this isn't recursively defined!

It's not too convenient to write, but boy is it fast!

---

Now, to write this for an arbitrary "enumerable" type one would change map to

fn map(i: I, f: F) -> Map where
    F: FnMut(E) -> B,
    I: IntoIterator
{
    Map {iter: i.into_iter(), f: f}
}

IntoIterator is basically IEnumerable, only instead of GetEnumerator there's into_iter.