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javaclojureclojure-java-interop

Clojure REPL, interop, Unable to resolve symbol

Suppose files is a list of Javas File in Clojure and I want to obtain a list of file names. In the Leiningen REPL I can use, say,

(.getName (nth files 4))
=> "image.jpg"

but if I use

(map .getName files)

the REPL throws a CompilerException java.lang.RuntimeException: Unable to resolve symbol: .getName in this context. Why is that?

I can work around this problem with

(defn gn [file] (.getName file))
(map gn files)

but I would like to now if there is a more elegant way to map Java methods to lists in Clojure.

Solution

  • You could either use memfn (which some say you should not use, dont remember why, comments welcome) or simply a lambda:

    (map (memfn getName) files)   ;;#1
(map #(.getName %) files)     ;;#2

    as for why, well because these are methods and not functions.