Hi,
On 2 Nov., 03:25, Mike K <mbk.li...@gmail.com> wrote:
> (print-value-a [:b 7 :a 3])
> ; actually prints nil
You have to use apply. (apply print-value-a [:b 7 :a 3]).
Furthermore: how could (let [{a :a} [:b 7 :a 3]] [a]) possibly work?
Vectors are indexed by integers.
user=> (let [{a :a} [:b 7 :a 3]] [a])
[nil]
user=> (let [{a 2} [:b 7 :a 3]] [a])
[:a]
The map destructuring in the defn is a special case of defn, not
destructuring itself.
(defn foo [& {:keys [a b]}] ...)
is equivalent to
(defn foo [& options#] (let [{:keys [a b]} (apply hash-map
options#)] ...))
Now it should also be clear why you need apply in your example. How
should Clojure decide whether the vector is one argument to the
function or the whole rest argument? If you just say "sequable thing
=> rest argument" you wouldn't be able to pass seqs to functions with
a rest argument as a last argument. Not very compelling. So you need a
different way to tell Clojure what you want. And that way is apply.
The implementation of (read mind) is still stuck. ;)
Hope that helps.
Sincerely
Meikel
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