reduce with an inline fn

gistfile1.clj

(reduce (fn [result {:keys [name employer]}] (update-in result [employer] conj name)) {}
        [{:name "jay fields", :current-city "new york", :employer "drw.com"}
         {:name "john dydo", :current-city "new york", :employer "drw.com"}
         {:name "mike ward", :current-city "chicago", :employer "drw.com"}
         {:name "chris george", :current-city "new york", :employer "thoughtworks.com"}])