if you implemented it using transduce instead of reduce, I think your code could be simpler

Thanks, I'll try that when I get home to my computer. Makes sense, don't think I even thought about that....

What do you think about it at a higher level? Is it a "proper" transducing context with the caveats I've mentioned?

it seems good enough, but I don't know if I can say much without a chance to really try it