[julia-users] Potential bug in Task/iterators?

[Sebastian Nowozin]

Hi everyone,

I followed the pattern proposed at 
http://slendermeans.org/julia-iterators.html (see the "fibtask" function) 
in order to define an iterator that is traversing a tree data structure as 
follows:

function search(rt::Tree)
    function _search(node::InteriorNode)
        for cn in node.children
            _search(cn)
        end
    end
    function _search(node::LeafNode)
        for obj in node.children
            produce(obj.membervar)
        end
    end
    function _search()
        _search(rt.root)
    end
    Task(_search)
end

This function dispatches based on the type of node (interior or leaf) and 
iterates over objects stored with each leaf node of the tree (it is a 
B-tree).  Eventually I would like to write statements such as:

   for leaf in search(tree)
      ...
   end

I tested the above code on both Windows 8.1 with latest 64 bit build as 
well as on Ubuntu 14.04 git trunk, with code as follows:

   S = search(tree)
   L = collect(S)

This yields the following error, with line 25 being the collect statement:

ERROR: i not defined
 in schedule_and_wait at task.jl:251
 in consume at task.jl:162
 in collect at array.jl:233
 in collect at array.jl:240
 in include at ./boot.jl:244
 in include_from_node1 at loading.jl:128
 in process_options at ./client.jl:285
 in _start at ./client.jl:354
while loading test_tree1.jl, in expression starting on line 25

Is the above an invalid use of the Task interface?  If so, what are the 
constraints on the produce statements, and how to fix the above code?

Any help is appreciated.  If it would help I could open an issue on the 
Julia issue tracker.

Thanks,
Sebastian