Nice post thanks for putting it together. My gut feeling is that the need
for information hiding is still overinflated, but... until someone builds a
200k LOC Clojure program who will know for sure?
Here's my shot at a solution for private data:
(defn set-private [m k x]
(let [the-meta (meta m)
new-private (assoc (:private the-meta) k x)]
(with-meta
(assoc m :private (hash new-private))
(assoc the-meta :private new-private))))
(defn get-private [m k]
(get (:private (meta m)) k))
(def my-object (set-private {} :first "Bob"))
(def my-other-object (set-private {} :first "Bob"))
(get-private my-object :first) ; -> "Bob"
(= my-object my-other-object) ; -> true
No secret keys, no other libraries, and I believe this supports equality
just fine. Since we're using metadata the data travels around easily
between operations.
---------- Forwarded message ----------
From: Mark Engelberg <[email protected]>
Date: Tue, Apr 21, 2009 at 6:41 AM
Subject: Re: Abstract data types in functional languages
To: [email protected]
On Mon, Apr 20, 2009 at 11:00 AM, Timo Mihaljov <[email protected]> wrote:
> Is the concept of Abstract Data Types [1] useful in Clojure?
>
> If yes, how would you implement one?
I have composed a lengthy response to this question, and added it to my
blog:
http://programming-puzzler.blogspot.com/2009/04/adts-in-clojure.html
I look forward to everyone's comments,
Mark
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