`into` with more three arguments is a variant where the middle argument is a transducer. So your original code was trying to use default-config as a transducer, this code would work with either merge or into chained with ->:
(-> {} (into default-config) (into more-config)) I recently did a tutorial video on into you may also find interesting: https://www.youtube.com/watch?v=5_eRZRIuqiY Timothy Baldridge On Sat, Dec 17, 2016 at 11:22 AM, larry google groups < lawrencecloj...@gmail.com> wrote: > I was trying to combine 2 maps into a new map, as you can see here. I > printed both maps to the screen so I could see that, indeed, they were both > maps. And yet I got a NullPointerException on the last line here: > > (defn update-config > [more-config] > (swap! config-holder > (fn [old-config] > (let [default-config (if old-config old-config {})] > (println "default-config ") > (clojure.pprint/pprint default-config) > > (println "more-config") > (clojure.pprint/pprint more-config) > (into {} default-config more-config))))) > > > I took the last line and changed it so I only had the second map merging > with the first map: > > (into default-config more-config) > > This seems to fix the problem. > > Perhaps I have "into" and "merge" confused. What was I doing wrong? > > > > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with > your first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- “One of the main causes of the fall of the Roman Empire was that–lacking zero–they had no way to indicate successful termination of their C programs.” (Robert Firth) -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.