[Haskell-cafe] Cleaning up stable names?

Luke Palmer lrpalmer at gmail.com
Tue Sep 1 14:31:42 EDT 2009

Have you considered computing a hash of the scene graph description
(compositionally)?  This gives you all the same advantages, including
re-using shared subparts of the graph (which would be unlikely to stay
around for very long as stable names).


On Tue, Sep 1, 2009 at 11:02 AM, Peter Verswyvelen<bugfact at gmail.com> wrote:
> I was planning to use them for caching OpenGL display lists and render
> targets. These are generated from a pure scene graph description, and
> if the same description is handed over to the render engine, it would
> just reuse the previously cached OpenGL object.  I can of course just
> embedding and IORef inside the pure structures, that would also work I
> guess
> On Tue, Sep 1, 2009 at 6:09 PM, Job Vranish<jvranish at gmail.com> wrote:
>> Well usually, when I've used stable names, I've just used them to check if
>> things are the same, and then thrown them away. So no chance for a space
>> leak. It's usually unsafe to keep stable names around for very long as they
>> can lose their ability to tell if two things are the same (if this surprises
>> you, you should carefully reread
>> http://haskell.org/ghc/docs/latest/html/libraries/base/System-Mem-StableName.html#v%3AmakeStableName
>> ).
>> Out of curiosity, how are you planning on using them?
>> - Job
>> On Tue, Sep 1, 2009 at 3:40 AM, Peter Verswyvelen <bugfact at gmail.com> wrote:
>>> but without that function, stable names are not that useful I guess? they
>>> would cause a space leak?
>>> On Mon, Aug 31, 2009 at 10:59 PM, Job Vranish <jvranish at gmail.com> wrote:
>>>> I also would like a isStableNameTargetAlive function.
>>>> Though if you had such a function then you probably _could_ make a
>>>> deRefStableName function, which, since there isn't one, probably means that
>>>> such a function would be hard to make.
>>>> - Job
>>>> On Sun, Aug 30, 2009 at 4:54 PM, Peter Verswyvelen <bugfact at gmail.com>
>>>> wrote:
>>>>> >From the documentation, I don't think I grasp how stable names work.
>>>>> From the docs:
>>>>> "There is no deRefStableName operation. You can't get back from a stable
>>>>> name to the original Haskell object. The reason for this is that the
>>>>> existence of a stable name for an object does not guarantee the existence of
>>>>> the object itself; it can still be garbage collected."
>>>>> From this I can conclude that stable names behave a bit like weak
>>>>> pointers.
>>>>> However, suppose I have a hash table of these stable names. How can I
>>>>> remove the redundant stable names from the table? I mean removing stable
>>>>> names that refer to an object that is garbage collected? I don't see any
>>>>> function for checking that (e.g. isStableNameTargetAlive or something)
>>>>> Thanks,
>>>>> Peter
>>>>> _______________________________________________
>>>>> Haskell-Cafe mailing list
>>>>> Haskell-Cafe at haskell.org
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