Re: [Haskell-cafe] viewing HS files in Firefox
Isaac Dupree wrote: When I try to go to one of the Module.hs files, e.g. on darcs.haskell.org, it now has type HS and Firefox refuses to display it (and only lets me download it). Does anyone know how to make Firefox treat certain file types as others (HS as plain text, in particular)? so that I can browse them with any convenience It is really annoying, and it is an astoundingly old bug in firefox. Apparently it's very hard to fix due to annoying details of the firefox architecture. It would be simplest for everyone if haskell.org was prepared to send out the files as text/plain (even though this is the wrong mime type), as I believe it used to do. The browser plugins can help, though. Jules ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: Re[2]: [Haskell-cafe] Fusing foldr's
On 10/29/07, Bulat Ziganshin [EMAIL PROTECTED] wrote: you may also look at these data: 1,225,416 bytes allocated in the heap 152,984 bytes copied during GC (scavenged) 8,448 bytes copied during GC (not scavenged) 86,808 bytes maximum residency (1 sample(s)) 3 collections in generation 0 ( 0.00s) 1 collections in generation 1 ( 0.00s) if your hypothesis is true, amount of data copied and number of generation-1 collection should be much less in the second case Indeed. avg4: 880,935,612 bytes allocated in the heap 319,064,404 bytes copied during GC (scavenged) 318,965,812 bytes copied during GC (not scavenged) 201,080,832 bytes maximum residency (9 sample(s)) 1681 collections in generation 0 ( 1.67s) 9 collections in generation 1 ( 13.62s) avgP: 1,761,224,604 bytes allocated in the heap 714,644 bytes copied during GC (scavenged) 593,184 bytes copied during GC (not scavenged) 184,320 bytes maximum residency (2 sample(s)) 1908 collections in generation 0 ( 0.04s) 2 collections in generation 1 ( 0.00s) Allocation is cheap, copying expensive. All the best, /Josef ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re[4]: [Haskell-cafe] Fusing foldr's
Hello Josef, Tuesday, October 30, 2007, 4:13:04 PM, you wrote: 201,080,832 bytes maximum residency (9 sample(s)) 1681 collections in generation 0 ( 1.67s) 9 collections in generation 1 ( 13.62s) 184,320 bytes maximum residency (2 sample(s)) 1908 collections in generation 0 ( 0.04s) 2 collections in generation 1 ( 0.00s) Allocation is cheap, copying expensive. not copying itself, but generation-1 garbage collections. while g-0 collection scans 256kb which lives in CPU cache, g-1 collection scans entire 100-200 mb of data that is very slow. try to use -H1g option, though :) -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Letting the darcs test fail, if QuickCheck tests fail
When following the description on http://www.haskell.org/haskellwiki/How_to_write_a_Haskell_program#Add_some_automated_testing:_QuickCheck then darcs will run the QuickCheck tests on each 'darcs record', but the new patch is also accepted by darcs if one of the tests fail. What is the most simple way to let 'darcs record' fail, when a QuickCheck test fails? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Letting the darcs test fail, if QuickCheck tests fail
On 10/30/07, Henning Thielemann [EMAIL PROTECTED] wrote: When following the description on http://www.haskell.org/haskellwiki/How_to_write_a_Haskell_program#Add_some_automated_testing:_QuickCheck then darcs will run the QuickCheck tests on each 'darcs record', but the new patch is also accepted by darcs if one of the tests fail. What is the most simple way to let 'darcs record' fail, when a QuickCheck test fails? The same thing bit me when I prepared a package recently. The way I solved it was to call the function quickCheck' instead of test. It returns a boolean indicating if the test was successful or not. If it's false I call exitWithFailure. I posted some code to the wikibook: http://en.wikibooks.org/wiki/Talk:Haskell/Packaging Note that quickCheck' is only available in QuickCheck 2. All the best, /Josef ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Letting the darcs test fail, if QuickCheck tests fail
On Tue, Oct 30, 2007 at 05:24:21PM +0100, Henning Thielemann wrote: When following the description on http://www.haskell.org/haskellwiki/How_to_write_a_Haskell_program#Add_some_automated_testing:_QuickCheck then darcs will run the QuickCheck tests on each 'darcs record', but the new patch is also accepted by darcs if one of the tests fail. What is the most simple way to let 'darcs record' fail, when a QuickCheck test fails? You can do this with QuickCheck 2 using quickCheck', but I don't know how to do this with QuickCheck 1. xmonad uses a function mytests, which I guess is pretty much copied from the code of QuickCheck 1, with tracking of errors added in. It's ugly, but it's only a few dozen lines. Another option would be to grep the output of the test suite to look for failure. -- David Roundy Department of Physics Oregon State University ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] viewing HS files in Firefox
Jules Bean wrote: Isaac Dupree wrote: When I try to go to one of the Module.hs files, e.g. on darcs.haskell.org, it now has type HS and Firefox refuses to display it (and only lets me download it). Does anyone know how to make Firefox treat certain file types as others (HS as plain text, in particular)? so that I can browse them with any convenience It is really annoying, and it is an astoundingly old bug in firefox. Apparently it's very hard to fix due to annoying details of the firefox architecture. It would be simplest for everyone if haskell.org was prepared to send out the files as text/plain (even though this is the wrong mime type), as I believe it used to do. ... Yes, it does appear to be a bug in Firefox https://bugzilla.mozilla.org/show_bug.cgi?id=57342 not to attempt to display text/x-haskell as if it were text/plain, but to get really obsessive I'm not convinced text/plain is strictly speaking the 'wrong' media-type if that's what the user-agent requests. For example, my FireFox 1.5.0.5 says to the server it will Accept these media-types text/xml, application/xml, application/xhtml+xml, text/html; q=0.9, text/plain; q=0.8, image/png,*/*; q=0.5 This is in order of what it would most like to get back from the server. The server then goes off and tries to find the best media-type for my browser - it can supply different ones depending on what the browser says it wants. By returning it as text/x-haskell the server has given the resource to my browser in */* which is the least wanted media-type. This is perfectly correct behaviour, but if the server was also capable of providing the same thing as text/plain it would be better to give this, or even better a pretty coloured text/html one if the server had one available. I think the underlying file returned as text/x-haskell or text/plain can be the exact same file assuming all x-haskell are also plain. Could be wrong, but that's my understanding of content negotiation. Richard. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Strictness leak
Some time ago, I posted this code:
countIO :: String - String - Int - [a] - IO [a]
countIO msg post step xs = sequence $ map unsafeInterleaveIO ((blank
outmsg (0::Int) c):cs)
where (c:cs) = ct 0 xs
output = hPutStr stderr
blank= output ('\r':take 70 (repeat ' '))
outmsg x = output ('\r':msg++show x) hFlush stderr
ct s ys = let (a,b) = splitAt (step-1) ys
next = s+step
in case b of [b1] - map return a ++ [outmsg (s+step)
hPutStr stderr post return b1]
[] - map return (init a) ++ [outmsg
(s+length a) hPutStr stderr post return (last a)]
_ - map return a ++ [outmsg s return
(head b)] ++ ct next (tail b)
It wraps a list with IO operations, so that progress can be reported
while evaluating the list elements. Unfortunately, there seems to be
a stricness leak here - and consequently, it does not work on an
infinite list.
I'm not sure why this happens, can anybody else see it?
-k
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Re: [Haskell-cafe] Strictness leak
Hello,
countIO :: String - String - Int - [a] - IO [a]
countIO msg post step xs = sequence $ map unsafeInterleaveIO
((blank outmsg (0::Int) c):cs)
where (c:cs) = ct 0 xs
output = hPutStr stderr
blank= output ('\r':take 70 (repeat ' '))
outmsg x = output ('\r':msg++show x) hFlush stderr
ct s ys = let (a,b) = splitAt (step-1) ys
next = s+step
in case b of [b1] - map return a ++ [outmsg
(s+step) hPutStr stderr post return b1]
[] - map return (init a) ++
[outmsg (s+length a) hPutStr stderr post return (last a)]
_ - map return a ++ [outmsg s
return (head b)] ++ ct next (tail b)
It wraps a list with IO operations, so that progress can be reported
while evaluating the list elements. Unfortunately, there seems to be
a stricness leak here - and consequently, it does not work on an
infinite list.
Besides anything else, sequence will diverge on an infinite list. This can
be seen directly from the type:
sequence :: Monad m = [m a] - m [a]
It is necessary to compute all of the computations in the list before
returning any of the pure resulting list.
-Jeff
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Re: [Haskell-cafe] Strictness leak
You mean for the IO monad, right?
take 10 $ execWriter $ sequence $ repeat $ tell ([3]::[Int])
/ Emil
On 10/30/2007 02:04 PM, Jeff Polakow wrote:
Hello,
countIO :: String - String - Int - [a] - IO [a]
countIO msg post step xs = sequence $ map unsafeInterleaveIO
((blank outmsg (0::Int) c):cs)
where (c:cs) = ct 0 xs
output = hPutStr stderr
blank= output ('\r':take 70 (repeat ' '))
outmsg x = output ('\r':msg++show x) hFlush stderr
ct s ys = let (a,b) = splitAt (step-1) ys
next = s+step
in case b of [b1] - map return a ++ [outmsg
(s+step) hPutStr stderr post return b1]
[] - map return (init a) ++
[outmsg (s+length a) hPutStr stderr post return (last a)]
_ - map return a ++ [outmsg s
return (head b)] ++ ct next (tail b)
It wraps a list with IO operations, so that progress can be reported
while evaluating the list elements. Unfortunately, there seems to be
a stricness leak here - and consequently, it does not work on an
infinite list.
Besides anything else, sequence will diverge on an infinite list. This
can be seen directly from the type:
sequence :: Monad m = [m a] - m [a]
It is necessary to compute all of the computations in the list before
returning any of the pure resulting list.
-Jeff
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[Haskell-cafe] Hugs running on cygwin
Hello, When I was downloading and installing the cygwin tool set on my laptop, I noticed that Hugs doesn't appear to be in the toolset. What would it take to get Hugs running on top of cygwin? I guess the Hugs Makefile would have to be modified to correctly link in any of the cygwin Unix libraries. Regards, Bill Halchin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [Haskell] Image manipulation
Jerzy, There is a simple framework for performing filtering operations on images lazily: http://sigfpe.blogspot.com/2006/12/evaluating-cellular-automata-is.html (Scroll down to the 2D example in the comments.) 2D digital filters lend themselves nicely to a comonadic framework though you probably have to drop the comonads for operations other than convolution type things. And you're right, doing this lazily at the pixel level is expensive. However, if we replace pixels with 256x256 blocks, say, where the blocks themselves are strict but the images are lazily made up of blocks, then we have the potential for a nice and efficient image processing library that inherits its laziness directly from Haskell. On 10/30/07, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: Dan Piponi adds to a short exchange: jerzy.karczmarczuk: [iso-8859-1] Bj�rn Wikstr�m writes: Hi! I have lots and lots of images (jpegs) that I would like to manipulate and shrink (in size). They are around 5 Mb big, so I thought this would be a good Haskell project since it's a lazy evaluating language. ... I must say that I don't see much use of laziness here. Laziness plays a big role in real world image processing. Typically, in applications like Apple's Shake, you build a dataflow representation of the image processing operations you wish to perform, and the final result is computed lazily so as to reduce the amount of computation. For example, if you blur an image, and then zoom in on the top left corner, then only the top left corner will be loaded up from the original image (assuming your image file format supports tiled access). You still work on tiles or scan-lines, rather than individual pixels, so the laziness has a 'coarse' granularity. But I'm not sure if this is what the original poster was talking about. I am neither... Still, Dan, I think that there is quite a difference between incremental processing of signals, and images, etc., and the *lazy evaluation* of them. Of course, a stream is consumed as economically as it can, but not less. If you filter an image (shrinking, so some low-pass MUST be done), a pixel must be loaded with its neighbourhood, which means *some* scan lines. With a JPEG this means that a 8x8 block should be loaded also with its vicinity. But would you suggest that individual pixel processors should be lazy? It would be useless, and probably resulting in some penalties. So, the laziness of Haskell for me here is less than useful. Nw, the lazy *generation* of streams is another story... Generating music (low level, i.e. sound patterns) through lazy algorithms is quite interesting. Jerzy Karczmarczuk ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Type inference problem with division (/)
On 10/30/07, noa [EMAIL PROTECTED] wrote: Hi! I have the following function: theRemainder :: [String] - [String] - Double theRemainder xs xt = sum( map additional (unique xs) ) where additional x = poccur * (inf [ppos,pneg]) --inf takes [Double] where xsxt = zip xs xt pi = countPos xr -- countPos returns an Int ni = (length xr) - pi len = length xs len2 = length xr ppos = pi/len2 -- THESE ARE THE PROBLEM pneg = ni/len2 -- THESE ARE THE PROBLEM poccur = (pi+ni)/len xr = (filter ((\y - (fst y)==x)) (xsxt)) And I am getting this error message with ghc: matrix.hs:54:31: Couldn't match expected type `Double' against inferred type `Int' In the expression: ppos In the first argument of `inf', namely `[ppos, pneg]' In the second argument of `(*)', namely `(inf [ppos, pneg])' How can I change the declaration of ppos nad pneg so they are treated as Double for the inf function? ppos = pi/len2; pi and len2 are both Ints, so dividing them gives you an Int. To convert to a Double, write ppos = fromIntegral (pi/len2). (Type :t fromIntegral in ghci to see what else fromIntegral can be used for.) Cheers, Tim -- Tim Chevalier * catamorphism.org * Often in error, never in doubt After three days without programming, life becomes meaningless. -- James Geoffrey ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Type inference problem with division (/)
On 10/30/07, Tim Chevalier [EMAIL PROTECTED] wrote: ppos = pi/len2; pi and len2 are both Ints, so dividing them gives you an Int. To convert to a Double, write ppos = fromIntegral (pi/len2). (Type :t fromIntegral in ghci to see what else fromIntegral can be used for.) You mean pi / fromIntegral len2, right? -- Felipe. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Type inference problem with division (/)
Hi! I have the following function: theRemainder :: [String] - [String] - Double theRemainder xs xt = sum( map additional (unique xs) ) where additional x = poccur * (inf [ppos,pneg]) --inf takes [Double] where xsxt = zip xs xt pi = countPos xr -- countPos returns an Int ni = (length xr) - pi len = length xs len2 = length xr ppos = pi/len2 -- THESE ARE THE PROBLEM pneg = ni/len2 -- THESE ARE THE PROBLEM poccur = (pi+ni)/len xr = (filter ((\y - (fst y)==x)) (xsxt)) And I am getting this error message with ghc: matrix.hs:54:31: Couldn't match expected type `Double' against inferred type `Int' In the expression: ppos In the first argument of `inf', namely `[ppos, pneg]' In the second argument of `(*)', namely `(inf [ppos, pneg])' How can I change the declaration of ppos nad pneg so they are treated as Double for the inf function? Cheers, Nick -- View this message in context: http://www.nabble.com/Type-inference-problem-with-division-%28-%29-tf4722111.html#a13500475 Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Type inference problem with division (/)
On 10/30/07, Tim Chevalier [EMAIL PROTECTED] wrote: On 10/30/07, noa [EMAIL PROTECTED] wrote: Hi! I have the following function: theRemainder :: [String] - [String] - Double theRemainder xs xt = sum( map additional (unique xs) ) where additional x = poccur * (inf [ppos,pneg]) --inf takes [Double] where xsxt = zip xs xt pi = countPos xr -- countPos returns an Int ni = (length xr) - pi len = length xs len2 = length xr ppos = pi/len2 -- THESE ARE THE PROBLEM pneg = ni/len2 -- THESE ARE THE PROBLEM poccur = (pi+ni)/len xr = (filter ((\y - (fst y)==x)) (xsxt)) And I am getting this error message with ghc: matrix.hs:54:31: Couldn't match expected type `Double' against inferred type `Int' In the expression: ppos In the first argument of `inf', namely `[ppos, pneg]' In the second argument of `(*)', namely `(inf [ppos, pneg])' How can I change the declaration of ppos nad pneg so they are treated as Double for the inf function? ppos = pi/len2; pi and len2 are both Ints, so dividing them gives you an Int. To convert to a Double, write ppos = fromIntegral (pi/len2). (Type :t fromIntegral in ghci to see what else fromIntegral can be used for.) You can't divide Ints with (/) at all -- they aren't Fractional. You'll probably want to either fromIntegral both pi and len2 or use div for integer division. (Also, pi is a bit of a confusing name; you may want to consider using another one.) Shachaf ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] help needed packaging curl bindings
i have decided to take on the task of packaging-up (for hackage) and documenting the curl bindings as available here: http://code.haskell.org/curl/ if the originators of this code are reading this and do not wish me to proceed please say so, i won't be offended otherwise i was wondering if people had good examples to point me to for providing the cross-platform support needed for a FFI-based module such as this. i have made the necessary changes to compile the code on freebsd, but for other platforms i am not sure at all, particularly non-unix style platforms like windows. my guess is that providing cross-platform support requires autoconf etc prior to the hackage build process (?) any info/references appreciated thanks brad pgpgos8fJXkpz.pgp Description: PGP signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Strictness leak
I forgot to send this reponse to haskell-cafe earlier... Hello, You mean for the IO monad, right? Sorry. I meant divergence is unavoidable for any strict Monad, such as IO. However, sequence will always compute over the entire list; if the resulting computation itself is lazy then the result can be inspected lazily. take 10 $ execWriter $ sequence $ repeat $ tell ([3]::[Int]) This is a good example. Note that the computation of sequence itself is infinite. snd $ runWriter $ sequence (repeat $ tell [3]) = return . take 10 will result in an infinite list, but fst $ runWriter $ sequence (repeat $ tell [3]) = return . take 10 will return a 10 element list. -Jeff --- This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden.___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
