Hey Stephen,
On Fri, Sep 21 2018, Stephen Feyrer wrote:
user=> (def some-numbers ‘(2 4 6 8)) #This is my value to test
later.
#’user/some-numbers
At this point we have some-numbers = '(2 4 6 8)
user=> (def evens? (partial (when (apply = (map even?
some-numbers)))))
#’user/evens?
Let's work through this:
(map even? '(2 4 6 8)) = '(true true true true)
(apply = '(true true true true)) = true
(when true) = nil
(partial nil) = nil
This means that we have evens? = nil
user=> (evens? (println “one”))
one
NullPointerException user/eval239 (NO_SOURCE_FILE:74)
So now we have:
(println "one") = nil (with the side effect of printing "one")
(nil nil) throws NullPointerException
Clojure is attempting to call nil as a function, which throws a
NullPointerException.
I hope that helps! I'm not sure what you're actually trying to do,
so it's hard for me to give advice on how to do it.
Carlo
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