On Jul 18, 2014, at 5:45 AM, Brian Craft <[email protected]> wrote:
> => (empty [:foo 5])
> []
> => (first (mapv identity {:foo 5}))
> [:foo 5]
> => (empty (first (mapv identity {:foo 5})))
> nil
=> (class (first (mapv identity {:foo 5})))
clojure.lang.MapEntry
=> (class (first (mapv (fn [[k v]] [k v]) {:foo 5})))
clojure.lang.PersistentVector
=> (empty (first (mapv (fn [[k v]] [k v]) {:foo 5})))
[]
by mapping identity over the map you're returning a vector of MapEntries (which
print/deconstruct like a two element array).
Cheers,
Bob
>
> What just happened there? Is this expected? In the second and third cases the
> type of the vector is clojure.lang.MapEntry, which I expect is the root of
> the behavior, but this seems very inconsistent. Is there a way to get the
> behavior one would expect? Should clojure.core/empty be avoided?
>
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