2017-09-06 9:58 GMT+02:00 Cecil Westerhof <cldwester...@gmail.com>:
> I want to start using Clojure again. I made the following simple function
> to generate a PIN:
> (defn create-pin
> ([] (create-pin 8))
> ([n]
> (let [chars (map char (range (int \0) (inc (int \9))))]
> (reduce str (repeatedly n #(rand-nth chars))))))
>
> So far so good. But I want to improve a little.
>
> I think n should at least be four, but not greater as 16. What is the
> Clojure way to do this?
>
> The next step is that I want to use hexadecimal numbers. So I should use
> (range (int \0) (inc (int \9))) combined with (range (int \A) (inc (int
> \F))).
> How would I do that?
>
> Is there anything I should do differently?
>
> Of-course I make a general function that is then called from create-pin
> and create-pin-hex.
>
With the help of this list I rewrote it to:
(def digits
(apply str (map char (range (int \0) (inc (int \9))))))
(def hex-digits
(apply str digits (map char (range (int \A) (inc (int \F))))))
(defn create-pin
([] (create-pin 8))
([n]
{:pre [(<= n 16)
(>= n 4)]}
(reduce str (repeatedly n #(rand-nth digits)))))
(defn create-pin-hex
([] (create-pin-hex 8))
([n]
{:pre [(<= n 16)
(>= n 4)]}
(reduce str (repeatedly n #(rand-nth hex-digits)))))
Indention is not great: I have to find out how to modify emacs for it.
By the way does has clojure something like super? Using:
(defn create-pin-hex
([] (create-pin-hex 8))
is asking for trouble. After copy/pasting from create-pin I almost forgot
to change it.
--
Cecil Westerhof
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