fn(clojure.core)

Macro

(fn name? [params* ] exprs*) (fn name? ([params* ] exprs*)+)

params => positional-params* , or positional-params* & next-param positional-param => binding-form next-param => binding-form name => symbol

Defines a function

; clojure/core.clj:2603
(defmacro fn
  (fn name? ([params* ] exprs*)+)

  params => positional-params* , or positional-params* & next-param
  positional-param => binding-form
  next-param => binding-form
  name => symbol

  Defines a function"
  [& sigs]
    (let [name (if (symbol? (first sigs)) (first sigs) nil)
          sigs (if name (next sigs) sigs)
          sigs (if (vector? (first sigs)) (list sigs) sigs)
          psig (fn [sig]
                 (let [[params & body] sig]
                   (if (every? symbol? params)
                     sig
                     (loop [params params
                            new-params []
                            lets []]
                       (if params
                         (if (symbol? (first params))
                           (recur (next params) (conj new-params (first params)) lets)
                           (let [gparam (gensym "p__")]
                             (recur (next params) (conj new-params gparam)
                                    (-> lets (conj (first params)) (conj gparam)))))
                         `(~new-params
                           (let ~lets
                             ~@body)))))))
          new-sigs (map psig sigs)]
      (with-meta
        (if name
          (list* 'fn* name new-sigs)
          (cons 'fn* new-sigs))
        *macro-meta*)))

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