[Haskell-cafe] Space leak

[David Leimbach]

On Sat, Mar 13, 2010 at 3:58 PM, Arnoldo Muller <arnoldomuller at gmail.com>wrote:

> Jason,
>
> I am trying to use haskell in the analysis of bio data. One of the main
> reasons I wanted to use haskell is because lazy I/O allows you to see a
> large bio-sequence as if it was a string in memory.
> In order to achieve the same result in an imperative language I would have
> to write lots of error-prone iterators. I saw lazy I/O as a very strong
> point in favor of Haskell.
>
>
There's a safer lazy IO lib in Hackage:

http://hackage.haskell.org/package/safe-lazy-io

It seems the safer approach, though somewhat more confusing to some people,
is the Iteratee pattern.

The reasons why have probably been explained best on a paper on Oleg's site.



> Besides the space leaks that can occur and that are a bit difficult to find
> for a newbie like me, are there any other reasons to avoid Lazy I/O?
>

Perhaps these two links will enlighten you.   They did for me, and I'm now
working out how exactly to convert a really inefficient but explicit IO
program (char by char right now... yuck) to an Iteratee based parsing
situation on a work-related project.  Hopefully I'll be doing this all this
coming week, and I'll be able to publish some results on my blog.  (things
come up though a lot at work, so I'm keeping my fingers crossed on this
one).

http://okmij.org/ftp/Haskell/Iteratee/Lazy-vs-correct.txt
http://okmij.org/ftp/Streams.html

Dave

>
> Arnoldo.
>
>
> On Sat, Mar 13, 2010 at 6:46 PM, Jason Dagit <dagit at codersbase.com> wrote:
>
>>
>>
>> On Thu, Mar 11, 2010 at 3:44 PM, Arnoldo Muller <arnoldomuller at gmail.com>wrote:
>>
>>> Daniel,
>>>
>>> Thank you so much for helping me out with this issue!
>>>
>>> Thanks to all the other answers from haskel-cafe members too!
>>>
>>> As a newbie, I am not able to understand why zip and map would make a
>>> problem...
>>>
>>> Is there any link I could read that could help me to understand why in
>>> this case
>>> zip and map created a leak? What are some function compositions that
>>> should be
>>> avoided when doing lazy I/O?
>>>
>>
>> Actually, it's lazy I/O itself that should be avoided.
>>
>> Jason
>>
>
>
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