#(println "Hello, world!")
-> no arguments
#(println (str "Hello, " % "!"))
-> 1 argument (%
is a synonym for %1
)
#(println (str %1 ", " %2 "!"))
-> 2 arguments
and so on. Note that you do not have to use all %n
s, the number of arguments expected is defined by the highest n. So #(println (str "Hello, " %2))
still expects two arguments.
You can also use %&
to capture rest args as in
(#(println "Hello" (apply str (interpose " and " %&))) "Jim" "John" "Jamey")
.
From the Clojure docs:
Anonymous function literal (#())
#(...) => (fn [args] (...))
where args are determined by the presence of argument literals taking the
form %, %n or %&. % is a synonym for %1, %n designates the nth arg (1-based),
and %& designates a rest arg. This is not a replacement for fn - idiomatic
used would be for very short one-off mapping/filter fns and the like.
#() forms cannot be nested.