api.rs

pub struct ThreadScope<'a> {
    
}

// Not sure about this, but doesn't seem necessary or
// particularly useful to be able to pass it to another thread
impl<'a> !Sync for ThreadScope<'a> { }

fn scope<'a,F,R>(f: F) -> R
    where F: FnOnce(&ThreadScope<'a>)

impl ThreadScope<'a> {
    fn spawn<F,R>(&self, f: F) -> Future<'a,R>
        where F: FnOnce()->R + Send + 'a
}

struct Future<'a,R> {
}

impl<'a,R> Future<'a,R> {
    fn join(self) -> R
}

example.rs

scoped(|scope| {
    let (left, right) = slice.split();
    let result1 = scope.spawn(|| process(left));
    let result2 = scope.spawn(|| process(right));
    scope.spawn(|| something_else());
    let sum = result1.join() + result2.join(); // if join is called, thread is joined, but otherwise it is joined when scope is exited
    ...
    
})