Thank you for the explanation; until now I associated this behavior only to keywords not not symbols.
Johannes Am Samstag, 26. Oktober 2019 19:12:11 UTC+2 schrieb Andy Fingerhut: > > Both symbols and keywords, when placed inside of an expression in the > first position, e.g. (:my-keyword my-map), or ('some-symbol my-map), behave > as functions that "look themselves up" in the map that is the first > argument, and if that symbol or keyword is a key in that map, the > associated value is returned from the expression. This is most often used > for keywords, but it does also work for symbols, which is what is happening > in your expression. The number `1` is not a map, and both this kind of > lookup expression, as well as the function `get`, have always returned nil > when the thing-to-be-looked-up-in is not a map or set (or anything else > that implements the appropriate lookup interface methods being used in the > Java implementation under the covers there). > > Some other examples of similar behavior: > > $ clj > Clojure 1.10.1 > user=> ('f 1) > nil > user=> ('f 1 :not-found) > :not-found > user=> ('f {'f 17 :bar 8}) > 17 > user=> ('f {:bar 8} :not-found-value) > :not-found-value > user=> (get {'f 17 :bar 8} 'f) > 17 > user=> (get 1 'f) > nil > user=> (get 1 'f :not-found) > :not-found > > Andy > > > > On Sat, Oct 26, 2019 at 10:05 AM Johannes <bra...@nordakademie.de > <javascript:>> wrote: > >> ... instead of an exception? >> >> Can anyone explain it to me? >> >> Johannes >> >> -- >> You received this message because you are subscribed to the Google >> Groups "Clojure" group. >> To post to this group, send email to clo...@googlegroups.com >> <javascript:> >> Note that posts from new members are moderated - please be patient with >> your first post. >> To unsubscribe from this group, send email to >> clo...@googlegroups.com <javascript:> >> 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 clo...@googlegroups.com <javascript:>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/clojure/f2007954-107c-4918-bf0a-6bfd8040ba39%40googlegroups.com >> >> <https://groups.google.com/d/msgid/clojure/f2007954-107c-4918-bf0a-6bfd8040ba39%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > -- 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. To view this discussion on the web visit https://groups.google.com/d/msgid/clojure/8d0613d6-a084-4035-9208-226ed8a911d9%40googlegroups.com.