Parallelizing arbitrary iterators

[jrmuizel]

It would be nice to be able to parallelize programs like this:

    let f = File::open("foo.txt").unwrap();
    let f = BufReader::new(f);

    for line in f.lines().map(|x| something_very_expensive(x)) {
            println!("{}", line.unwrap());
    }

The assumption here is that something_very_expensive is expensive enough that we don't need to split the data into chunks larger than size 1.

[jrmuizel]

This would help provide functionality similar to perl6's hyper() function.

[jrmuizel]

It looks like https://github.com/TeXitoi/par-map provides this functionality

[bluss]

FYI this has been discussed in rayon before, for example in #297

[cuviper]

Closing as a duplicate of #46.