[Haskell-cafe] uvector package appendU: memory leak?

[Don Stewart]

Can I close this ticket as not being to do with uvector?

-- Don

manlio_perillo:
> Claus Reinke ha scritto:
>>> But Claus was right, appendU is lazy; this seems to be the cause of  
>>> the problem.
>>
>> appendU is strict, insertWith just doesn't force it (follow the source link
>> in the haddocks to see why).
>>
>
> Ok, I see.
> But, IMHO, this should be clearly documented.
>
> I have updated my test code:
> http://hpaste.org/fastcgi/hpaste.fcgi/view?id=3103
>
> The interesting thing is that using appendU is *faster*.
>
> Using appendU:
> real	0m38.736s
> user	0m38.638s
> sys	0m0.048s
>
> Using snocU:
> real	0m41.279s
> user	0m40.939s
> sys	0m0.040s
>
>
> Memory usage is the same.
>
>>> However now I don't really understand why the two implementations  
>>> differs in lazyness.
>>>
>>> Or, to ask a different question, how can I make the version using  
>>> insertWith strict?
>>
>> deja vu:-(
>> http://www.haskell.org/pipermail/haskell-cafe/2009-March/057032.html
>>
>
> Your are right, sorry.
> The problem is that at that time I was not able to fully understand the  
> code!
>
> However, reading the code now, I prefer my version using alter.
>
>
> By the way, about insertWith/alter; from IntMap documentation:
>
> insertWithKey: O(min(n,W)
> alter: O(log n)
>
> So, alter is more efficient than insertWithKey?
> And what is that `W` ?
>
>> As you've noticed, alter also allows to enforce strictness.
>>
>> But piling up appendUs is still not a good idea. For a moment,
>> I thought that the stream representation's (+++) was handling
>> runtime fusion gracefully, but a simple test case suggests otherwise
>> at least for the simpler case of consU (the attached appendU.hs
>> doesn't do any appendUs, as the consU case already demonstrates
>> the issue; be careful with large numbers here, it'll quickly eat your ram):
>>
>
> I'm not sure to fully understand the code.
> But, again, IMHO it does not apply to my original problem.
>
> > [...]
>
>
> Thanks   Manlio