Merging the return value of a decision causes duplicate values in vectors about liberator HOT 2 CLOSED

We had a similar issue caused by this "deep merge/concat" of combine, we solved it using ^:replace.
For those who wonder you can't use with-meta with all values but you can add it conditionally:

(defn rep [v]
  (if (instance? clojure.lang.IMeta v)
    (with-meta v {:replace true})
    v))

from liberator.

This is a know regression in the way combine works. liberator.util/combine works like a recursive merge but id will also concat lists, vectory and sets.

You can attach the meta data attribute :replace to prevent a merge:

user=> (combine {:foo [:bar :baz]} {:foo ^:replace [:qux]})
{:foo [:qux]}

from liberator.