Proposal: priority queues in containers

Gwern Branwen gwern0 at
Wed Mar 17 12:03:42 EDT 2010

On Wed, Mar 17, 2010 at 11:48 AM, Bryan O'Sullivan <bos at> wrote:
> On Wed, Mar 17, 2010 at 4:52 AM, Yitzchak Gale <gale at> wrote:
>> This I'm not sure about. I've considered using PQ's perhaps
>> two or three times during the past few years, and ended up not using
>> them at all.
> I'd prefer for personal anecdote not to be the driver of discussions like
> this. Personally, I've never used Data.Tree or Data.Graph from the
> containers package, and doubt that I ever will, but it doesn't break my arm
> or steal my wristwatch if they're available.

Skipping anecdote, then, let's look at dependencies. Does anyone use
the existing priority-queues? The ensemble doesn't look so bad that
one would always roll one's own priority queue, yet I don't see *any*
non-queue libraries/apps depending on any of the queue libraries:

(I'm not sure how often that's updated but I wouldn't expect being up
to date to make much of a difference.)

If there really are no users of priority-queue, that's a pretty good
argument for keeping priority-queue out of containers, leaving it on
Hackage, and coming back in a year or two to see whether there's been
any uptake.


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