(lds) with coroutines #29

For generator output to work in lds, it will have to be translated to something like:

(:x)
(ld @dst @src)
(j.neof :x)

Buffers have a special behavior with lds (lds iterates the buffer without consuming its items).

Either that must be removed, or this "transformation" must be done at run-time: lds will return a flag to indicate if the operation should be retried or not.