gistfile1.txt

trait InputRange<T> {
    pure fn is_empty(&self) -> bool;
    pure fn head(&self) -> &self/T;
    pure fn tail(&self) -> Self;
}

pure fn each<T, U: InputRange<T>>(range: U, blk: fn(v: &T) -> bool) {
    while !range.is_empty() && blk(range.head()) {
        range = range.tail();
    }
}