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@RutledgePaulV

RutledgePaulV/nil-guarding.clj

Created November 23, 2016 17:29
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A macro for wrapping execution of a single form such that the form is not evaluated and nil is returned when given any nil arguments
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nil-guarding.clj
(defmacro ? [form]
(let [f (first form) args (rest form)]
`(let [_# (list ~@args)]
(when (every? some? _#)
(apply ~f _#)))))
@RutledgePaulV
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(? (println "stuff"))
stuff
=> nil
(? (println "stuff" nil))
=> nil
(? (str "one" "two"))
=> "onetwo"
(? (str "one" nil))
=> nil
(? (println "stuff" nil))
=> nil
(? (println "stuff" "more stuff"))
stuff more stuff
=> nil
(? (println (+ 1 2) "more stuff"))
3 more stuff
=> nil
(? (println (or nil) "more stuff"))
=> nil
(? (println (str "hello" nil) "more struff"))
hello more struff
=> nil
(? (println (? (str "hello" nil)) "more struff"))
=> nil

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