use num::Float;

struct MulIter<T,I>
    where T : Float,
          I : Iterator<Item = T>

{
    iter: I,
    scalar: T,
}

impl<T, I> MulIter<T, I>
    where T : Float,
          I: Iterator<Item = T>,
{
    pub fn new(iter: I, scalar: T) -> MulIter<T, I> {
        MulIter {
            iter,
            scalar,
        }
    }
}

impl<T, I> Iterator for MulIter<T, I>
    where T : Float,
          I: Iterator<Item = T>,
{
    type Item = T;
    fn next(&mut self) -> Option<T> {
        match self.iter.next() {
            Some(value) => Some(value * self.scalar),
            None => None,
        }
    }
}