I'd say the former was more idiomatic Clojure. There's no need to make
refs compatible with atoms (otherwise why have two different
concurrency primitives in the first place).
Additionally, earmuffs (like *this*) should only be used on vars that
you expect to override in a binding, like *out* or *err*. They aren't
for all global vars. You should rename "*counts*" to just "counts".
- James
On 28 November 2010 22:36, Takahiro Hozumi <fat...@googlemail.com> wrote:
> Hi,
> This is trivial question.
> Which style do you like?
>
> (def *counts* (ref {}))
>
> (defn dec-or-dissoc! [key]
> (dosync
> (let [n (@*counts* key)]
> (if (< 1 n)
> (alter *counts* assoc key (dec n))
> (alter *counts* dissoc key)))))
>
> (defn dec-or-dissoc! [key]
> (dosync
> (alter *counts*
> (fn [m]
> (let [n (m key)]
> (if (< 1 n)
> (assoc m key (dec n))
> (dissoc m key)))))))
>
> I think former style is normal, but latter is easy to replace ref with
> atom.
> Thanks.
>
> --
> Takahiro Hozumi
>
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