> I like the idea of supporting combining key values via multimethods, as then custom behaviour can be defined that depends on the key. @weavejester ok so something like?

(derive :foo.bar/merge-key :duct.core/merge-key)

(defmethod :foo.bar/vector-merge-key [& vecs] 
  (apply concat vecs)

not sure if the derive is necessary; but was thinking it might be useful to be able to identify merge-keys. Could potentially wrap up in a defmergekey macro, to help make intent more explicit.

@weavejester the duct profile idea seem interesting. How are they different to include? Curious to hear more about how they might work…