Syntax – clojure: [] What do you do in the function parameter list?

I'm trying to solve clojure's joy and want to know_ The function of syntax in function parameter vector

Example:

(def available-processors
    (.availableProcessors (Runtime/getRuntime)))

(prn "available processors: " available-processors)

(def pool
    (Executors/newFixedThreadPool (+ 2 available-processors)))

(defn dothreads!
    [func & {thread-count :threads exec-count :times :or {thread-count 1 exec-count 1}}]
    (dotimes [t thread-count]
        (.submit pool #(dotimes [_ exec-count] (func)))))

What is the form of underline?

#(dotimes [_ exec-count] (func))

Solution

I believe that by convention, clojure uses underscores as placeholders for required but unused parameters As Keith Bennet said:

Your example is consistent with this "use" because you do not need to use the first parameter of dotime as an indexer, but the form needs to be bound