It doesn't seem confusing to me. You are taking complete control of
the set's local notion of ordering and equality. This is what I'd
expect.
Here's an example. First, a handy little function from Haskell:
(defn on [key f]
#(apply f (map key %&)))
Then:
user> (sorted-set-by (on :id compare)
{:id 42 :name "Per" :age 28}
{:id 0 :name "Methuselah" :age 9000}
{:id 42 :name "Rep" :age 82})
#{{:id 0, :name "Methuselah", :age 9000} {:id 42, :name "Per", :age 28}}
That is, it's eliminating entries with duplicate primary keys in favor
of earlier occurrences.
-Per
On Fri, Apr 16, 2010 at 9:38 PM, Sean Devlin <francoisdev...@gmail.com> wrote:
> Here's the source for sorted-set-by:
>
> (defn sorted-set-by
> "Returns a new sorted set with supplied keys, using the supplied
> comparator."
> ([comparator & keys]
> (clojure.lang.PersistentTreeSet/create comparator keys)))
>
> This is because your comparator is saying that everything is equal.
> PersistentTreeSet delegates a lot of work to PersistentTreeMap, so the
> object is happily replacing every element when the comparator is zero.
>
> I'm not sure if this is a bug or the intended behavior... I'm leaning
> toward the latter, even though it's confusing.
>
> Sean
>
> On Apr 16, 8:25 am, Razvan <gigi.clan...@gmail.com> wrote:
>> Hi,
>>
>> Is this the intended behavior?
>>
>> (sorted-set-by (constantly 0) 1 2 3 4) returns #{1}.
>>
>> I would expect the set to contain all the elements, and the comparator
>> to only affect sort order.
>>
>> Razvan
>>
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