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Today's Topics:
1. Fwd: Stuck in debug of loop detection (Lev Broido)
2. Re: Stack space overflow: using strict accumulator still
fails (Daniel Fischer)
3. Re: Stack space overflow: using strict accumulator still
fails (Hugo Ferreira)
4. Re: Stack space overflow: using strict accumulator still
fails (Hugo Ferreira)
5. Re: Stack space overflow: using strict accumulator still
fails (Daniel Fischer)
6. Re: Stack space overflow: using strict accumulator still
fails (Hugo Ferreira)
7. Re: Stack space overflow: using strict accumulator still
fails (Daniel Fischer)
8. Re: Stack space overflow: using strict accumulator still
fails (Hugo Ferreira)
----------------------------------------------------------------------
Message: 1
Date: Mon, 31 Oct 2011 15:24:02 +0200
From: Lev Broido <lev.bro...@gmail.com>
Subject: [Haskell-beginners] Fwd: Stuck in debug of loop detection
To: beginners@haskell.org
Message-ID:
<CAB=60u7zy2q5fbnhvz8fanhw8njerexe4nyrh41hc-f8q6c...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
---------- Forwarded message ----------
From: Lev Broido <lev.bro...@gmail.com>
Date: Mon, Oct 31, 2011 at 2:31 PM
Subject: Stuck in debug of loop detection
To: beginners@haskell.org, haskell-c...@haskell.org
Hi
I am playing around with building graph using 'tying the knote' technique ,
according to rule a is child of b iff predicate a b == true
Additional step is to detect loops in graph to enable it's print . Then I
am using graph traversal to detect loops prior to calling show .
For now I am stuck debugging loop detection . I am using 'trace' for a
first time and I am not sure I am fully understanding it's behavior
In additional I tried to make all calculations strict for debug .
Can you please provide tips / review code .
My code is at
http://pastebin.com/5RvQ42z2
Thanks,
Lev
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------------------------------
Message: 2
Date: Mon, 31 Oct 2011 22:14:28 +0100
From: Daniel Fischer <daniel.is.fisc...@googlemail.com>
Subject: Re: [Haskell-beginners] Stack space overflow: using strict
accumulator still fails
To: Hugo Ferreira <h...@inescporto.pt>
Cc: beginners@haskell.org
Message-ID: <201110312214.28261.daniel.is.fisc...@googlemail.com>
Content-Type: Text/Plain; charset="utf-8"
On Monday 31 October 2011, 10:36:53, Hugo Ferreira wrote:
> Hello,
>
> Apologies for the late reply but I had to prep the code.
>
> On 10/28/2011 09:43 AM, Daniel Fischer wrote:
> > On Thursday 27 October 2011, 17:02:46, Hugo Ferreira wrote:
> >> But something seems to be wrong here. If I do:
> >>
> >> scoreRule_ r zs = Z.foldlz' (scoreElem r) (0, 0) zs
> >>
> >> where scoreElem r s z =
> >>
> >> let (nCorrect, nIncorrect) = s in
> >> case ruleApplication r z of
> >>
> >> Just tag -> if tag == correct
> >>
> >> then (nCorrect+1, nIncorrect)
> >> else (nCorrect, nIncorrect+1)
> >>
> >> Nothing -> (nCorrect, nIncorrect)
> >>
> >> where c = Z.cursor z
> >>
> >> (correct,_) = c
> >>
> >> it works correctly, however this does not work:
> >>
> >> scoreRule_ r zs = Z.foldlz' (scoreElem r) (0, 0) zs
> >>
> >> where scoreElem r (!nCorrect, !nIncorrect) z =
> >>
> >> case ruleApplication r z of
> >>
> >> Just tag -> if tag == correct
> >>
> >> then (nCorrect+1, nIncorrect)
> >> else (nCorrect, nIncorrect+1)
> >>
> >> Nothing -> (nCorrect, nIncorrect)
> >>
> >> where c = Z.cursor z
> >>
> >> (correct,_) = c
> >>
> >> I have been staring at this for some time now, but cannot
> >> understand why it does not work. Any ideas?
> >
> > No. Looks perfectly okay (well, the indentation is wrong, but that's
> > the same for the working version above and is probably due to the
> > mail client).
>
> Not really. That's pretty much the indentation I am using. I actually
> had additional trace statements. Can you please tell me what's wrong?
You're not having the 'where's on their own lines ;)
Seriously: I hadn't bothered to view it in fixed-width font and
underestimated how much my mail client compresses contiguous whitespace.
>
> > Can you post the complete source for diagnosis?
>
> I have attached the code + cabal files. I think that is all that is
> required. I am not sending the training data because it is too large
> (+7 Mega bytes). That is available at http://nlpwp.org/nlpwp-data.zip
Been a bugger to hunt down, but I finally found it.
The culprit is *drumroll, ba-dum tish*:
a one-character typo in Data.List.Zipper.
foldlz' isn't. The recursive call is to foldlz, not foldlz'.
------------------------------
Message: 3
Date: Mon, 31 Oct 2011 22:12:03 +0000
From: Hugo Ferreira <h...@inescporto.pt>
Subject: Re: [Haskell-beginners] Stack space overflow: using strict
accumulator still fails
To: Daniel Fischer <daniel.is.fisc...@googlemail.com>
Cc: beginners@haskell.org
Message-ID: <4eaf1d33.8070...@inescporto.pt>
Content-Type: text/plain; charset=UTF-8; format=flowed
On 10/31/2011 09:14 PM, Daniel Fischer wrote:
> On Monday 31 October 2011, 10:36:53, Hugo Ferreira wrote:
>> Hello,
>>
>> Apologies for the late reply but I had to prep the code.
>>
>> On 10/28/2011 09:43 AM, Daniel Fischer wrote:
>>> On Thursday 27 October 2011, 17:02:46, Hugo Ferreira wrote:
>>>> But something seems to be wrong here. If I do:
>>>>
>>>> scoreRule_ r zs = Z.foldlz' (scoreElem r) (0, 0) zs
>>>>
>>>> where scoreElem r s z =
>>>>
>>>> let (nCorrect, nIncorrect) = s in
>>>> case ruleApplication r z of
>>>>
>>>> Just tag -> if tag == correct
>>>>
>>>> then (nCorrect+1, nIncorrect)
>>>> else (nCorrect, nIncorrect+1)
>>>>
>>>> Nothing -> (nCorrect, nIncorrect)
>>>>
>>>> where c = Z.cursor z
>>>>
>>>> (correct,_) = c
>>>>
>>>> it works correctly, however this does not work:
>>>>
>>>> scoreRule_ r zs = Z.foldlz' (scoreElem r) (0, 0) zs
>>>>
>>>> where scoreElem r (!nCorrect, !nIncorrect) z =
>>>>
>>>> case ruleApplication r z of
>>>>
>>>> Just tag -> if tag == correct
>>>>
>>>> then (nCorrect+1, nIncorrect)
>>>> else (nCorrect, nIncorrect+1)
>>>>
>>>> Nothing -> (nCorrect, nIncorrect)
>>>>
>>>> where c = Z.cursor z
>>>>
>>>> (correct,_) = c
>>>>
>>>> I have been staring at this for some time now, but cannot
>>>> understand why it does not work. Any ideas?
>>>
>>> No. Looks perfectly okay (well, the indentation is wrong, but that's
>>> the same for the working version above and is probably due to the
>>> mail client).
>>
>> Not really. That's pretty much the indentation I am using. I actually
>> had additional trace statements. Can you please tell me what's wrong?
>
> You're not having the 'where's on their own lines ;)
You mean, I have to use something like:
where
(correct,_) = Z.cursor z
instead of
where (correct,_) = Z.cursor z
I googled the rules and found
http://en.wikibooks.org/wiki/Haskell/Indentation. Doesn't seem to be a
requirement.
> Seriously: I hadn't bothered to view it in fixed-width font and
> underestimated how much my mail client compresses contiguous whitespace.
>
>>
>>> Can you post the complete source for diagnosis?
>>
>> I have attached the code + cabal files. I think that is all that is
>> required. I am not sending the training data because it is too large
>> (+7 Mega bytes). That is available at http://nlpwp.org/nlpwp-data.zip
>
> Been a bugger to hunt down, but I finally found it.
> The culprit is *drumroll, ba-dum tish*:
> a one-character typo in Data.List.Zipper.
> foldlz' isn't. The recursive call is to foldlz, not foldlz'.
>
Now I am baffled B-(
The package docs state:
foldlz' is foldlz with a strict accumulator
Why would/should one not use the strict version here?
What do you mean when you say "recursive call"?
TIA,
Hugo F.
------------------------------
Message: 4
Date: Mon, 31 Oct 2011 22:16:55 +0000
From: Hugo Ferreira <h...@inescporto.pt>
Subject: Re: [Haskell-beginners] Stack space overflow: using strict
accumulator still fails
To: Daniel Fischer <daniel.is.fisc...@googlemail.com>
Cc: beginners@haskell.org
Message-ID: <4eaf1e57.1000...@inescporto.pt>
Content-Type: text/plain; charset=UTF-8; format=flowed
On 10/31/2011 09:14 PM, Daniel Fischer wrote:
> On Monday 31 October 2011, 10:36:53, Hugo Ferreira wrote:
>> Hello,
>>
>> Apologies for the late reply but I had to prep the code.
>>
>> On 10/28/2011 09:43 AM, Daniel Fischer wrote:
>>> On Thursday 27 October 2011, 17:02:46, Hugo Ferreira wrote:
>>>> But something seems to be wrong here. If I do:
>>>>
>>>> scoreRule_ r zs = Z.foldlz' (scoreElem r) (0, 0) zs
>>>>
>>>> where scoreElem r s z =
>>>>
>>>> let (nCorrect, nIncorrect) = s in
>>>> case ruleApplication r z of
>>>>
>>>> Just tag -> if tag == correct
>>>>
>>>> then (nCorrect+1, nIncorrect)
>>>> else (nCorrect, nIncorrect+1)
>>>>
>>>> Nothing -> (nCorrect, nIncorrect)
>>>>
>>>> where c = Z.cursor z
>>>>
>>>> (correct,_) = c
>>>>
>>>> it works correctly, however this does not work:
>>>>
>>>> scoreRule_ r zs = Z.foldlz' (scoreElem r) (0, 0) zs
>>>>
>>>> where scoreElem r (!nCorrect, !nIncorrect) z =
>>>>
>>>> case ruleApplication r z of
>>>>
>>>> Just tag -> if tag == correct
>>>>
>>>> then (nCorrect+1, nIncorrect)
>>>> else (nCorrect, nIncorrect+1)
>>>>
>>>> Nothing -> (nCorrect, nIncorrect)
>>>>
>>>> where c = Z.cursor z
>>>>
>>>> (correct,_) = c
>>>>
>>>> I have been staring at this for some time now, but cannot
>>>> understand why it does not work. Any ideas?
>>>
>>> No. Looks perfectly okay (well, the indentation is wrong, but that's
>>> the same for the working version above and is probably due to the
>>> mail client).
>>
>> Not really. That's pretty much the indentation I am using. I actually
>> had additional trace statements. Can you please tell me what's wrong?
>
> You're not having the 'where's on their own lines ;)
> Seriously: I hadn't bothered to view it in fixed-width font and
> underestimated how much my mail client compresses contiguous whitespace.
>
>>
>>> Can you post the complete source for diagnosis?
>>
>> I have attached the code + cabal files. I think that is all that is
>> required. I am not sending the training data because it is too large
>> (+7 Mega bytes). That is available at http://nlpwp.org/nlpwp-data.zip
>
> Been a bugger to hunt down, but I finally found it.
> The culprit is *drumroll, ba-dum tish*:
> a one-character typo in Data.List.Zipper.
> foldlz' isn't. The recursive call is to foldlz, not foldlz'.
>
BTW, I changed foldlz' to foldlz and used (!) but still get the stack
overflow. Need I do anything else?
TIA,
Hugo F.
------------------------------
Message: 5
Date: Mon, 31 Oct 2011 23:31:21 +0100
From: Daniel Fischer <daniel.is.fisc...@googlemail.com>
Subject: Re: [Haskell-beginners] Stack space overflow: using strict
accumulator still fails
To: Hugo Ferreira <h...@inescporto.pt>
Cc: beginners@haskell.org
Message-ID: <201110312331.21118.daniel.is.fisc...@googlemail.com>
Content-Type: Text/Plain; charset="utf-8"
On Monday 31 October 2011, 23:12:03, Hugo Ferreira wrote:
> You mean, I have to use something like:
>
> where
> (correct,_) = Z.cursor z
>
> instead of
>
> where (correct,_) = Z.cursor z
Yes.
>
> I googled the rules and found
> http://en.wikibooks.org/wiki/Haskell/Indentation. Doesn't seem to be a
> requirement.
Hence the ";)".
> >
> > Been a bugger to hunt down, but I finally found it.
> > The culprit is *drumroll, ba-dum tish*:
> > a one-character typo in Data.List.Zipper.
> > foldlz' isn't. The recursive call is to foldlz, not foldlz'.
>
> Now I am baffled B-(
>
> The package docs state:
> foldlz' is foldlz with a strict accumulator
>
> Why would/should one not use the strict version here?
Because there's a typo in the implementation (notified the maintainer).
> What do you mean when you say "recursive call"?
Let's look at lists first.
The specification in the standard is
foldl f z [] = z
foldl f z (x:xs) = foldl f (f z x) xs
^^^^^
recursive call to foldl
Very similar for the list zipper, we have
foldlz :: (b -> Zipper a -> b) -> b -> Zipper a -> b
foldlz f x z
| endp z = x
| otherwise = foldlz f (f x z) (right z)
^^^^^^
And for foldlz', the intention was
foldlz' :: (b -> Zipper a -> b) -> b -> Zipper a -> b
foldlz' f x z
| endp z = x
| otherwise = acc `seq` foldlz' f acc (right z)
where acc = f x z
but in the otherwise branch, the ' has been omitted, so instead of
recursively calling itself with the new accumulator, it calls foldlz.
------------------------------
Message: 6
Date: Mon, 31 Oct 2011 22:42:30 +0000
From: Hugo Ferreira <h...@inescporto.pt>
Subject: Re: [Haskell-beginners] Stack space overflow: using strict
accumulator still fails
To: Daniel Fischer <daniel.is.fisc...@googlemail.com>
Cc: beginners@haskell.org
Message-ID: <4eaf2456.2070...@inescporto.pt>
Content-Type: text/plain; charset=UTF-8; format=flowed
On 10/31/2011 10:31 PM, Daniel Fischer wrote:
> On Monday 31 October 2011, 23:12:03, Hugo Ferreira wrote:
>> You mean, I have to use something like:
>>
>> where
>> (correct,_) = Z.cursor z
>>
>> instead of
>>
>> where (correct,_) = Z.cursor z
>
> Yes.
>
>>
>> I googled the rules and found
>> http://en.wikibooks.org/wiki/Haskell/Indentation. Doesn't seem to be a
>> requirement.
>
> Hence the ";)".
>
I see. B-)
>
>>>
>>> Been a bugger to hunt down, but I finally found it.
>>> The culprit is *drumroll, ba-dum tish*:
>>> a one-character typo in Data.List.Zipper.
>>> foldlz' isn't. The recursive call is to foldlz, not foldlz'.
>>
>> Now I am baffled B-(
>>
>> The package docs state:
>> foldlz' is foldlz with a strict accumulator
>>
>> Why would/should one not use the strict version here?
>
> Because there's a typo in the implementation (notified the maintainer).
>
>> What do you mean when you say "recursive call"?
>
> Let's look at lists first.
>
> The specification in the standard is
>
> foldl f z [] = z
> foldl f z (x:xs) = foldl f (f z x) xs
> ^^^^^
> recursive call to foldl
>
> Very similar for the list zipper, we have
>
> foldlz :: (b -> Zipper a -> b) -> b -> Zipper a -> b
> foldlz f x z
> | endp z = x
> | otherwise = foldlz f (f x z) (right z)
> ^^^^^^
>
> And for foldlz', the intention was
>
> foldlz' :: (b -> Zipper a -> b) -> b -> Zipper a -> b
> foldlz' f x z
> | endp z = x
> | otherwise = acc `seq` foldlz' f acc (right z)
> where acc = f x z
>
> but in the otherwise branch, the ' has been omitted, so instead of
> recursively calling itself with the new accumulator, it calls foldlz.
>
Ok, I though the typo was on my side.
So you have found a bug.
My hat is off to you.
Thanks,
Hugo F.
------------------------------
Message: 7
Date: Mon, 31 Oct 2011 23:46:43 +0100
From: Daniel Fischer <daniel.is.fisc...@googlemail.com>
Subject: Re: [Haskell-beginners] Stack space overflow: using strict
accumulator still fails
To: Hugo Ferreira <h...@inescporto.pt>
Cc: beginners@haskell.org
Message-ID: <201110312346.43484.daniel.is.fisc...@googlemail.com>
Content-Type: Text/Plain; charset="utf-8"
On Monday 31 October 2011, 23:16:55, Hugo Ferreira wrote:
> BTW, I changed foldlz' to foldlz and used (!)
No good. foldlz needs (in this case) the laziness in the accumulator.
> but still get the stack overflow. Need I do anything else?
You can patch your ListZipper (cabal unpack ListZipper; correct the typo;
increment version number in ListZipper.cabal; cabal install), then you can
use foldlz' with a strict accumulator. Or you can use foldlz with a lazy
accumulator, doesn't make much difference for the brown corpus.
Also, in tokenTagFreqs, replace M.insertWith (twice) with M.insertWith',
you're filling your maps with thunks as is. Evaluating entries on the spot
reduces time and memory requirements.
------------------------------
Message: 8
Date: Mon, 31 Oct 2011 22:59:47 +0000
From: Hugo Ferreira <h...@inescporto.pt>
Subject: Re: [Haskell-beginners] Stack space overflow: using strict
accumulator still fails
To: Daniel Fischer <daniel.is.fisc...@googlemail.com>
Cc: beginners@haskell.org
Message-ID: <4eaf2863.2070...@inescporto.pt>
Content-Type: text/plain; charset=UTF-8; format=flowed
On 10/31/2011 10:46 PM, Daniel Fischer wrote:
> On Monday 31 October 2011, 23:16:55, Hugo Ferreira wrote:
>> BTW, I changed foldlz' to foldlz and used (!)
>
> No good. foldlz needs (in this case) the laziness in the accumulator.
>
>> but still get the stack overflow. Need I do anything else?
>
> You can patch your ListZipper (cabal unpack ListZipper; correct the typo;
> increment version number in ListZipper.cabal; cabal install), then you can
> use foldlz' with a strict accumulator. Or you can use foldlz with a lazy
> accumulator, doesn't make much difference for the brown corpus.
>
Hmmm.... how so? I get stack overflow.
You mean use the RTS options to increase memory.
> Also, in tokenTagFreqs, replace M.insertWith (twice) with M.insertWith',
> you're filling your maps with thunks as is. Evaluating entries on the spot
> reduces time and memory requirements.
>
Will report this to the book's authors.
Thanks once again,
Hugo F.
------------------------------
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