fwiw, I think I now have the best version of that

(def mchain! (comp chain! (ingo a/merge) (p a/into [])))

since merge gives you results in the order they become ready, if you just compose a merge with the chain! operation, then you have a performant way to flatten out channels

ingo is just -> (defn ingo [f] (fn [c] (go (f (<! c)))))