On Jan 4, 2016, at 1:50 PM, Axel Kowald <[log in to unmask]> wrote:

> But playing with the code I think I spotted a bug in the Sequence class.
> The Sequence contructor for Collection does not set "size". Thus if I
> create my ParallelSequence with a Collection, size is zero, leading to a
> division by zero exception.

Looks like a bug to me.  Try this:

    public Sequence(Collection collection)
        steps = (Steppable[])(collection.toArray(
			new Steppable[collection.size()]));
        size = steps.length;

I'll commit that.