[Haskell-cafe] Questions about slow GC with STArray
I've been following with interest the recent discussions on reddit about the extremely slow hash tables in Haskell compared to F# and OCaml, and as I understood it, this performance problem is caused by GC not liking mutable arrays http://hackage.haskell.org/trac/ghc/ticket/650 It appears from the discussion there that this is more than a simple bug, but a fundamental difficulty (slow writes vs slow GC trade-off). What I'm wondering though is how can this be unique to GHC: all arrays in OCaml and probably F# are mutable (and usually unboxed). How is this problem addressed there? Why is this supposed to be specific to boxed arrays only: wouldn't GC have to scan the whole mutable array whether it's boxed or unboxed? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] high probability of installation problems and quality of the glorious implementation
Brandon S. Allbery KF8NH allb...@ece.cmu.edu writes: I wonder when we'll get a good haskell virtual package on Debian? What would this package do? Install ghc + all the little pieces of libghc6-cruft needed to get a sane working environment? Sounds easy to do (after all, it's just an empty package with a bunch of dependencies, right?), but I'm unsure exactly what pieces you want included. This is the current ghc6 package: Provides: ghc, haskell-compiler, libghc6-array-dev, libghc6-base-dev, libghc6-bytestring-dev, libghc6-cabal-dev, libghc6-containers-dev, libghc6-directory-dev, libghc6-filepath-dev, libghc6-haskell98-dev, libghc6-hpc-dev, libghc6-old-locale-dev, libghc6-old-time-dev, libghc6-packedstring-dev, libghc6-pretty-dev, libghc6-process-dev, libghc6-random-dev, libghc6-readline-dev, libghc6-rts-dev, libghc6-template-haskell-dev, libghc6-unix-dev In Ubuntu 8.10, there are 90 separate libghc6.*dev packages, which ones do you think should be added to a GHC meta package? -k -- If I haven't seen further, it is by standing in the footprints of giants ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] minor typo in The Haskell 98 Report
Today, as I was reading through The Haskell 98 Report (see http://www.haskell.org/onlinereport/), I came across a minor typo, but it seems that the only way to fix such typos is to report them on one of the Haskell mailing lists; viz.: The original committees ceased to exist when the original Haskell 98 Reports were published, so every change was instead proposed to the entire Haskell mailing list. Therefore, please allow me to report this typo, though minor, here, as follows: The Haskell 98 Report - Preface (see http://www.haskell.org/onlinereport/preface-jfp.html), under the heading Haskell 98: language and libraries, fourth paragraph, second line: If these program were to be portable, a set of libraries would have to be standardised too. should be as follows: If these programs were to be portable, a set of libraries would have to be standardised too. (I.e., the word program should be plural.) Is this the proper place to report any forthcoming similar typos? -- Benjamin L. Russell -- Benjamin L. Russell / DekuDekuplex at Yahoo dot com http://dekudekuplex.wordpress.com/ Translator/Interpreter / Mobile: +011 81 80-3603-6725 Furuike ya, kawazu tobikomu mizu no oto. -- Matsuo Basho^ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [Haskell] [OT] Plural forms of the word octopus [Was: Re: Marketing Haskell]
[Shifted to haskell-cafe.] G'day all. Quoting Benjamin L.Russell dekudekup...@yahoo.com: According to the Merriam-Webster Online Dictionary, it is topoi (see http://www.merriam-webster.com/dictionary/topos). Topoi form a certain class of category. You can study topous, you can prove theorems about topois and you can discover properties of topon. (That last one is an omega, so it's pronounced more like top-own.) Where did you find octoposi? In my ancient copy of Liddell and Scott. Here's the online entry: http://tinyurl.com/ck8gst Cheers, Andrew Bromage ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] minor typo in The Haskell 98 Report
On 6 Apr 2009, at 08:56, Benjamin L.Russell wrote: Today, as I was reading through The Haskell 98 Report (see http://www.haskell.org/onlinereport/), I came across a minor typo, but it seems that the only way to fix such typos is to report them on one of the Haskell mailing lists; Thanks for the bug report. As noted on the page http://haskell.org/haskellwiki/Language_and_library_specification The report still has minor bugs. There are tracked at the Haskell 98 bugs page. Report any new bugs to Malcolm Wallace. (There are links for the bugs page, and for my email address.) Regards, Malcolm ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Questions about slow GC with STArray
Hello FFT, Monday, April 6, 2009, 11:07:33 AM, you wrote: this problem addressed there? Why is this supposed to be specific to boxed arrays only: wouldn't GC have to scan the whole mutable array whether it's boxed or unboxed? you need to scan only boxes: if array just contains plain cpu-level numbers, there is nothing to scan one way to solve this problem is to make one `modified` bit per each 256 elements rather than entire array so GC will have to scan only modified chunks -- Best regards, Bulatmailto:bulat.zigans...@gmail.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Questions about slow GC with STArray
On Mon, Apr 6, 2009 at 1:10 AM, Bulat Ziganshin bulat.zigans...@gmail.com wrote: you need to scan only boxes: if array just contains plain cpu-level numbers, there is nothing to scan Are those the only legal contents of STUArray? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Unary Minus
If I use :info (-) I get information on the binary minus. Is unary minus also a function? Thanks, Paul ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Questions about slow GC with STArray
On Monday 06 April 2009 4:10:43 am Bulat Ziganshin wrote: one way to solve this problem is to make one `modified` bit per each 256 elements rather than entire array so GC will have to scan only modified chunks For reference, I constructed a benchmark that takes advantage of GHC's tagging of whole arrays to approximate this: http://hpaste.org/fastcgi/hpaste.fcgi/view?id=3316 Since each array has a dirty bit, making a type that stores an array of arrays that add up to the desired size is similar to having a dirty bit for chunks the size of the sub-array. The test then fills a 10 million element array. However, something about the benchmark makes it perform poorly for both small chunks and large chunks. -sstderr reports that lots of copying occurs for small chunk sizes, and I haven't bothered to figure out why this is the case. You can, however, see that marking dirty chunks in this fashion would be profitable. The un-chunked array takes around a minute here, while with chunks of 10,000 (which seems to be about the optimal value with the above copying tradeoff), it takes about 6 seconds, and that's still with 60+% GC time. -- Dan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Unary Minus
If I use :info (-) I get information on the binary minus. Is unary minus also a function? You can define it yourself or use negate from the Prelude. Wouter ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Unary Minus
Paul Keir wrote: If I use :info (-) I get information on the binary minus. Is unary minus also a function? No, as far as I know the unary minus is part of the number literals. You can use negate if you want it as a function. Hope this helps, Martijn. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re[2]: [Haskell-cafe] Questions about slow GC with STArray
Hello Dan, Monday, April 6, 2009, 12:35:14 PM, you wrote: the size of the sub-array. The test then fills a 10 million element array. However, something about the benchmark makes it perform poorly for both small chunks and large chunks. -sstderr reports that lots of copying occurs for small chunk sizes, and I haven't bothered to figure out why this is the case. You can, however, see that marking dirty chunks in this fashion would be profitable. The un-chunked array takes around a minute here, while with chunks of 10,000 (which seems to be about the optimal value with the above copying tradeoff), it takes about 6 seconds, and that's still with 60+% GC time. i don't think that 60% GC time is bad for *this* benchmark. array filling is very trivial operation, after all. important part is 10x GC times reduce, apply these numbers to original benchmark -- Best regards, Bulatmailto:bulat.zigans...@gmail.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re[2]: [Haskell-cafe] Questions about slow GC with STArray
Hello FFT, Monday, April 6, 2009, 12:32:53 PM, you wrote: you need to scan only boxes: if array just contains plain cpu-level numbers, there is nothing to scan Are those the only legal contents of STUArray? numbers, chars, vanilla pointers. UArray just mimics C arrays, after all -- Best regards, Bulatmailto:bulat.zigans...@gmail.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] high probability of installation problems andquality of the glorious implementation
I want the Zen package: Make me one with everything. But would you find that on hackage?-) If an author had contemplated the perfect package, they wouldn't have put it on hackage, they wouldn't have a hackage account, they wouldn't have written the package, they might not even exist - you would just get the idea. Claus (inspired by the ZenBot entry in the list of programs that play on the computer Go server: http://senseis.xmp.net/?ComputerGoServer ) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Unary Minus
On Mon, 6 Apr 2009 12:13:09 +0200, Roel van Dijk vandijk.r...@gmail.com wrote: On Mon, Apr 6, 2009 at 12:04 PM, Benjamin L.Russell dekudekup...@yahoo.com wrote: Interesting. ?How is this hack implemented? This seems to be the relevant grammar: lexp6 - - exp7 lpat6 - - (integer | float)(negative literal) The '6's and the '7' are superscripts. Perhaps the hack is in the precedence of the expression in which an unary minus is allowed. Yes, I see it now. It's under 9.5 Context-Free Syntax, instead of being under 9.2 Lexical Syntax, so it's a syntactic rule, rather than a lexical rule. According to the rule, a left-expression of precedence level 6 consists of '-' followed by an expression of precedence level 7, and a left-pattern of precedence level 6 consists of '-' followed by (an integer or a float), and by definition, this is a negative literal. Integers and floats, in turn, are part of the lexical syntax. -- Benjamin L. Russell -- Benjamin L. Russell / DekuDekuplex at Yahoo dot com http://dekudekuplex.wordpress.com/ Translator/Interpreter / Mobile: +011 81 80-3603-6725 Furuike ya, kawazu tobikomu mizu no oto. -- Matsuo Basho^ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Unary Minus
On Mon, 6 Apr 2009 12:13:09 +0200, Roel van Dijk vandijk.r...@gmail.com wrote: On Mon, Apr 6, 2009 at 12:04 PM, Benjamin L.Russell dekudekup...@yahoo.com wrote: Interesting. ?How is this hack implemented? This seems to be the relevant grammar: lexp6 - - exp7 lpat6 - - (integer | float)(negative literal) The '6's and the '7' are superscripts. Perhaps the hack is in the precedence of the expression in which an unary minus is allowed. What's interesting are the following definitions of the functions '-' (binary minus) and negate given in 8 Standard Prelude (see http://www.haskell.org/onlinereport/standard-prelude.html#$tNum): class (Eq a, Show a) = Num a where (+), (-), (*):: a - a - a negate :: a - a abs, signum :: a - a fromInteger :: Integer - a -- Minimal complete definition: -- All, except negate or (-) x - y= x + negate y negate x = 0 - x The type of negate, a - a, where a is a Num, is precisely what is needed for a unary minus. -- Benjamin L. Russell -- Benjamin L. Russell / DekuDekuplex at Yahoo dot com http://dekudekuplex.wordpress.com/ Translator/Interpreter / Mobile: +011 81 80-3603-6725 Furuike ya, kawazu tobikomu mizu no oto. -- Matsuo Basho^ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Unary Minus
Unary minus is a hack in the syntax for allowing the function negate to be written as prefix -. On Mon, Apr 6, 2009 at 10:36 AM, Martijn van Steenbergen mart...@van.steenbergen.nl wrote: Paul Keir wrote: If I use :info (-) I get information on the binary minus. Is unary minus also a function? No, as far as I know the unary minus is part of the number literals. You can use negate if you want it as a function. Hope this helps, Martijn. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Unary Minus
On Mon, Apr 6, 2009 at 12:04 PM, Benjamin L.Russell dekudekup...@yahoo.com wrote: Interesting. How is this hack implemented? This seems to be the relevant grammar: lexp6 - - exp7 lpat6 - - (integer | float)(negative literal) The '6's and the '7' are superscripts. Perhaps the hack is in the precedence of the expression in which an unary minus is allowed. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] EclipseFP proposal for Google Summer of Code
Hi Thomas, I send this e-mail because of possible scheduling issues: I will be away starting on April 15. So, if you want to ask me things, have suggestions for improvement, or want to do an interview or something, this can only be done *before* that date. I am pretty sure all the questions from Haskell will be asked in the next few days, so I wouldn't worry - although usually there aren't any. P.S. I hope it's okay that I post this to the haskell-cafe list as well; since haskell.org has no GSoC-specific mailing list, it seems to be the most appropriate place that I could find. We discuss SoC stuff on haskell-cafe so it's fine. Thanks Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re[4]: [Haskell-cafe] Questions about slow GC with STArray
Hello FFT, Monday, April 6, 2009, 12:56:51 PM, you wrote: Are those the only legal contents of STUArray? numbers, chars, vanilla pointers. UArray just mimics C arrays, after all I haven't gotten to learning about them in detail yet, but my hope was that STUArray was like vectorT in C++, and STArray was like vectorT*. Both are fairly general. well, that's good comparison for some degree, but the catch is that Haskell doesn't have unboxed types at all. therefore, [ST]UArray is something that you can't implement in pure Haskell, it's just like providing API to some C arrays. they are implemented via special operations in GHC runtime that are limited to support only numbers/chars/pointers. so you can't have UArray of Complex numbers (although you can use two array of Doubles of course) UArray is rather old thing, nowadays you may use StorableArray or one of many newer array/vector libraries. unfortunately, they tend to don't support ST monad, so you will need to write a little wrappers using unsafeIOtoST operation So if I need a array of complex numbers in Haskell, will I need an extra level of indirection compared to C? And in addition to that some serious issues with GC speed if those arrays need to be mutable? [1] http://haskell.org/haskellwiki/Library/ArrayRef [2] http://www.haskell.org/haskellwiki/Storable_Vector recent cafe threads http://www.haskell.org/pipermail/haskell-cafe/2008-July/045229.html http://www.haskell.org/pipermail/haskell-cafe/2009-March/057240.html -- Best regards, Bulatmailto:bulat.zigans...@gmail.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: Re[2]: [Haskell-cafe] Questions about slow GC with STArray
On Mon, Apr 6, 2009 at 1:49 AM, Bulat Ziganshin bulat.zigans...@gmail.com wrote: Are those the only legal contents of STUArray? numbers, chars, vanilla pointers. UArray just mimics C arrays, after all I haven't gotten to learning about them in detail yet, but my hope was that STUArray was like vectorT in C++, and STArray was like vectorT*. Both are fairly general. So if I need a array of complex numbers in Haskell, will I need an extra level of indirection compared to C? And in addition to that some serious issues with GC speed if those arrays need to be mutable? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Unary Minus
Interesting. How is this hack implemented? I just checked the BNF grammar for the lexical syntax of Haskell in The Haskell 98 Language Report (see the BNF grammer given under 9.2 Lexical Syntax under 9 Syntax Reference at http://www.haskell.org/onlinereport/syntax-iso.html), but had difficulty in deriving a unary minus. Could somebody please enlighten me on how to derive the expression -1 (a unary minus followed the the ascDigit 1) from the above-mentioned BNF grammar? Or is a unary minus not part of this grammar? -- Benjamin L. Russell On Mon, 6 Apr 2009 11:14:52 +0200, Lennart Augustsson lenn...@augustsson.net wrote: Unary minus is a hack in the syntax for allowing the function negate to be written as prefix -. On Mon, Apr 6, 2009 at 10:36 AM, Martijn van Steenbergen mart...@van.steenbergen.nl wrote: Paul Keir wrote: If I use :info (-) I get information on the binary minus. Is unary minus also a function? No, as far as I know the unary minus is part of the number literals. You can use negate if you want it as a function. Hope this helps, Martijn. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Benjamin L. Russell / DekuDekuplex at Yahoo dot com http://dekudekuplex.wordpress.com/ Translator/Interpreter / Mobile: +011 81 80-3603-6725 Furuike ya, kawazu tobikomu mizu no oto. -- Matsuo Basho^ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Paper: Translating donotation to SQL, Leijden, Meijer
Hi all, is the paper Translating donotation to SQL, Leijden, Meijer (1999) available anywhere? Günther ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] replicateM should be called mreplicate?
Considering these naming conventions: http://haskell.org/ghc/docs/latest/html/libraries/base/Control-Monad.html#3 • A postfix 'M' always stands for a function in the Kleisli category: The monad type constructor m is added to function results (modulo currying) and nowhere else. So, for example, filter :: (a - Bool) - [a] - [a] filterM :: (Monad m) = (a - m Bool) - [a] - m [a] • A postfix '_' changes the result type from (m a) to (m ()). Thus, for example: sequence :: Monad m = [m a] - m [a] sequence_ :: Monad m = [m a] - m () • A prefix 'm' generalizes an existing function to a monadic form. Thus, for example: sum :: Num a = [a] - a msum :: MonadPlus m = [m a] - m a replicateM has the following type: replicateM :: Monad m = Int - m a - m [a] Am I missing something or should this have been called mreplicate? greetings, -- Sjoerd Visscher sjo...@w3future.com___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Combining sequences
I downloaded it and it appears more complicated than just adding files to a directory. There's a setup and a build, and no assurances it will work with Hugs. I think I'll wait for more information. Michael --- On Mon, 4/6/09, Thomas Hartman tphya...@gmail.com wrote: From: Thomas Hartman tphya...@gmail.com Subject: Re: [Haskell-cafe] Combining sequences To: michael rice nowg...@yahoo.com Cc: Henning Thielemann lemm...@henning-thielemann.de, haskell-cafe@haskell.org Date: Monday, April 6, 2009, 12:26 AM It's not in hugs, nor in ghc. It's just in hackage. However, by the looks of it, you should probably be able to use it in hugs. I didn't actually check this, but the cabal file didn't name any fancy extensions, so it looks pretty cross-compiler. You can just go to http://hackage.haskell.org/cgi-bin/hackage-scripts/package/utility-ht-0.0.4 wget http://hackage.haskell.org/packages/archive/utility-ht/0.0.4/utility-ht-0.0.4.tar.gz untar and put them with the rest of the files your hugs compiler uses for package import. (I don't actually know how package installation works in hugs... isn't it just put the files into a dir?) thomas. 2009/4/5 michael rice nowg...@yahoo.com: Thanks. It looks like mergeBy will do the job, but is it available in Hugs? Michael --- On Sun, 4/5/09, Henning Thielemann lemm...@henning-thielemann.de wrote: From: Henning Thielemann lemm...@henning-thielemann.de Subject: Re: [Haskell-cafe] Combining sequences To: michael rice nowg...@yahoo.com Cc: haskell-cafe@haskell.org Date: Sunday, April 5, 2009, 9:09 PM On Sat, 4 Apr 2009, michael rice wrote: Is there a simple way to combine two sequences that are in ascending order into a single sequence that's also in ascending order? An example would be the squares [1,4,9,16,25..] combined with the cubes [1,8,27,64,125..] to form [1,1,4,8,9,16,25,27..]. http://hackage.haskell.org/packages/archive/utility-ht/0.0.4/doc/html/Data-List-HT.html#v%3AmergeBy ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Haskell EDSL to generate SQL?
At Sun, 05 Apr 2009 14:32:21 +0200, Günther Schmidt wrote: What is the best resource to look for more detail examples? No idea. I have not used it in years. And, last I checked, it is far from perfect. For example, I believe that field names must be unique across all tables. Also, there was a project, coddfish that may be of interest. http://wiki.di.uminho.pt/twiki/bin/view/Research/PURe/CoddFish I think it provides a more direct mapping to SQL. - jeremy ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Infix tuple comma query (,)
module Main where data (:%^) a b = a :%^ bderiving (Show) main = do print $ 18 :%^ (Just 99) print $ (,) 9 10 print $ 9 , 10 The last line in the code above causes a compile error. Why does infix use of the comma (tuple constructor?) function fail without brackets? Thanks, Paul ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Combining sequences
Am Montag 06 April 2009 17:12:42 schrieb michael rice: I downloaded it and it appears more complicated than just adding files to a directory. There's a setup and a build, and no assurances it will work with Hugs. I think I'll wait for more information. Michael Try installing it with Cabal: ./Setup.lhs configure --hugs if that doesn't say otherwise, chances are that it will work, so try ./Setup.lhs build sudo ./Setup.lhs install If it doesn't work, you can copy the code from Data.List.HT ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Infix tuple comma query (,)
Am Montag 06 April 2009 17:53:24 schrieb Paul Keir: module Main where data (:%^) a b = a :%^ bderiving (Show) main = do print $ 18 :%^ (Just 99) print $ (,) 9 10 print $ 9 , 10 The last line in the code above causes a compile error. Why does infix use of the comma (tuple constructor?) function fail without brackets? Tuples are special baked-in syntax. The parentheses are part of the tuple constructor(s). It may be confusing you that you can use it prefix as well as aroundfix. Thanks, Paul ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: SVGFonts 0.1
I hereby publish my first library in Haskell. SVGFonts 0.1 It parses the pretty unknown SVG Font format to produce outlines of characters. The big advantage of this format is that it is XML, which means easy parsing and manipulating. Because I haven't found any svg-files on the Internet the typical way is to convert a more popular format (i.e. .ttf) into SVG Font via fontforge. This library may be useful if you want to have a direct access to specific algorithms which is of course harder when using a binding (i.e. Jeff Heards FTGL binding). The speed is improvable (see TO DO list) and since since this is my first library there might some errors which I am not aware of (please tell me). I also wonder why the library doesn't appear under graphics on hackage, although there is Category: Graphics in my cabal file. Depending on which library I like more, I will maybe integrate SVGFonts into LambdaCube or Fieldtrip Cheers, Tillmann ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: SVGFonts 0.1
This sounds very cool. Is is just a program, or is there a library sitting behind it? From your .cabal file, it seems to be just a binary program. Is this correct? http://hackage.haskell.org/packages/archive/SVGFonts/0.1/SVGFonts.cabal On Mon, Apr 6, 2009 at 1:22 PM, Tillmann Vogt tillmann.v...@rwth-aachen.dewrote: I hereby publish my first library in Haskell. SVGFonts 0.1 It parses the pretty unknown SVG Font format to produce outlines of characters. The big advantage of this format is that it is XML, which means easy parsing and manipulating. Because I haven't found any svg-files on the Internet the typical way is to convert a more popular format (i.e. .ttf) into SVG Font via fontforge. This library may be useful if you want to have a direct access to specific algorithms which is of course harder when using a binding (i.e. Jeff Heards FTGL binding). The speed is improvable (see TO DO list) and since since this is my first library there might some errors which I am not aware of (please tell me). I also wonder why the library doesn't appear under graphics on hackage, although there is Category: Graphics in my cabal file. Depending on which library I like more, I will maybe integrate SVGFonts into LambdaCube or Fieldtrip Cheers, Tillmann ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- /jve ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] replicateM should be called mreplicate?
On Mon, Apr 6, 2009 at 10:02 AM, Sjoerd Visscher sjo...@w3future.com wrote: Considering these naming conventions: http://haskell.org/ghc/docs/latest/html/libraries/base/Control-Monad.html#3 • A postfix 'M' always stands for a function in the Kleisli category: The monad type constructor m is added to function results (modulo currying) and nowhere else. So, for example, filter :: (a - Bool) - [a] - [a] filterM :: (Monad m) = (a - m Bool) - [a] - m [a] • A postfix '_' changes the result type from (m a) to (m ()). Thus, for example: sequence :: Monad m = [m a] - m [a] sequence_ :: Monad m = [m a] - m () • A prefix 'm' generalizes an existing function to a monadic form. Thus, for example: sum :: Num a = [a] - a msum :: MonadPlus m = [m a] - m a replicateM has the following type: replicateM :: Monad m = Int - m a - m [a] Am I missing something or should this have been called mreplicate? Not necessarily. If you use replicateM in the identity monad, you get replicate. Similarly with filterM and filter, or foldM and foldl. In contrast, msum and sum are essentially mconcat specialized to the monoids (mplus, mzero) and ((+), 0), respectively. Of course, this suggests that mfix should be fixM, so perhaps a better distinction is that mplus and mfix need to be defined per-monad, whereas filterM and replicateM are generic. -- Dave Menendez d...@zednenem.com http://www.eyrie.org/~zednenem/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] community.haskell.org unreachable?
Works for me. The admin address referenced there is support [AT] community.haskell.org On Mon, Apr 6, 2009 at 1:32 PM, Claus Reinke claus.rei...@talk21.comwrote: I seem to be having problems reaching anything on that server. Does anyone know what is going on, or who to contact? It would help if the haskellwiki page http://www.haskell.org/haskellwiki/Haskell.org_domain would mention the admin address directly, instead of referring to http://community.haskell.org/admin/ which is also unreachable. Claus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: SVGFonts 0.1
On Mon, Apr 6, 2009 at 7:32 PM, Tillmann Vogt tillmann.v...@rwth-aachen.de wrote: It is a real library made of pure Haskell. What is wrong with my .cabal file? The issue is not about whether it is pure Haskell. You have simply marked it up as an executable rather than a library. Executable Fonts Main-is:test/Fonts.hs Build-Depends: haskell98, base, OpenGL, GLUT, xml, parsec --Max ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Making videos of your project
Btw, there seem to be many Haskells on YouTube - should we have some way of marking clips related to our Haskell? I've used haskell.org as a tag, but noone else has, yet - also, perhaps there should be a Haskell channel or something? And just in case there are others on the same Windows adventure:-) Is there anyone here with experience in screencasting of text-based applications, who could offer advice on how to produce screencasts on windows/xp? The basic screencasting (capture+annotation/editing) is not the problem, eg, CamStudio seems ok, and Wink gives me more control for mostly input-driven sessions (where I want screenshots whenever something useful happens, not long videos of my mousepointer wavering about the screen;-). Both can generate .swf. .. I think making .swf is a mistake, but I'm not sure. I should have believed you there!-) I did actually check that Youtube listed .swf among its supported file types before making my screencast, but when I had actually joined and uploaded, I discovered that it would fail on conversion.. More detailed search in the user forums indicated that this is a common problem, with no solution other than to convert to another, video- rather than animation-based, format. Problem is, .swf is very suited to this particular input-driven kind of screencast (and renders just fine in my browser), eg, Wink has a non-video capture mode that only adds frames when something happens (the only negative: while one can extend the time frames are shown, I've not yet found a way to reduce the minimum time, so typing looks rather unnaturally ssllooww). Any attempt to convert my just over 1Mb .swf files (one screencast, split and edited into 3 sections of 4 minutes or less) to something listed as supported (such as .avi, .mpeg2) resulted in huge files sizes (60Mb and upwards) that would be impractical to upload with my old narrowband connection (might just be that I don't have the right compressing codecs for these formats?). Fortunately, while trying to find some way of contacting YT staff, I stumbled on other help pages that mentioned .wmv in their version of supported file types. For that, one of the codecs on my machine produces files that are only 10x the size of the original .swf, so I'm slowly uploading them to YT, and the first two parts have now been published without conversion failure. I was sorely tempted just to upload the small .swfs to haskell.org, instead of the .wnk-.swf(1Mb)-.avi(60Mb)-.wmf(10Mb) plus tedious upload route I had to follow with the free or preinstalled tools available to me. But community.haskell.org seems to be having enough trouble right now, without hosting clips there.. I rendered it in 2 or 3 formats (at 640x480 etc, following the you tube / google video recommendations), and uploaded the one that looked best. You-tube immediately(ish) makes a low quality version available (320x240?), and a high quality version(480x360?), with more readable text etc, is available a little later. Testing with multiple formats/codecs/uploads is recommended, though the conversion can be somewhat nightmarish (too many options and tools, many of which look less than trustworthy, too complex, too expensive, or all of the above; and too few roads to something that works). For 640x400 uploads, the near immediately available version seems readable enough (search for tag haskell.org or wait for the announcement;-). I would recommend working in a 640x480 screen area. If you can't show anything in that area, then people won't be able to see anything in your video (at the size/quality youtube shows it, at least). Sound advice, which I followed in the end. Just took some more preparation to find a setup that would fit the screencast, rather than my usual working habits. I also noticed that I had somehow managed to switch off my ClearType support, which explained the initially low quality font rendering. Thanks, Claus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Ghc: -O harmful?
Hello all,
I have a haskell program that runs an order of magnitude slower
when compiled with optimisations turned on. This happens on 6.8.2
as well as 6.10.1:
p...@r4at184:/tmp[1]% ghc --make -fforce-recomp -o out buga.hs
[1 of 1] Compiling Main ( buga.hs, buga.o )
Linking out ...
p...@r4at184:/tmp% time ./out 3-med.in |/dev/null
./out 3-med.in | /dev/null 0,03s user 0,00s system 99% cpu 0,038 total
p...@r4at184:/tmp% ghc --make -fforce-recomp -o out buga.hs -O
[1 of 1] Compiling Main ( buga.hs, buga.o )
Linking out ...
p...@r4at184:/tmp% time ./out 3-med.in |/dev/null
./out 3-med.in | /dev/null 0,99s user 0,01s system 99% cpu 1,001 total
p...@r4at184:/tmp[1]% ghc --make -fforce-recomp -o out buga.hs -O2
[1 of 1] Compiling Main ( buga.hs, buga.o )
Linking out ...
p...@r4at184:/tmp% time ./out 3-med.in |/dev/null
./out 3-med.in | /dev/null 0,99s user 0,01s system 99% cpu 1,004 total
p...@r4at184:/tmp% ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.8.2
psxx:/tmp$ ghc --make -fforce-recomp -o out buga.hs
[1 of 1] Compiling Main ( buga.hs, buga.o )
Linking out ...
psxx:/tmp$ time ./out 3-med.in |/dev/null
real0m0.028s
user0m0.011s
sys 0m0.007s
psxx:/tmp$ ghc --make -fforce-recomp -o out buga.hs -O
[1 of 1] Compiling Main ( buga.hs, buga.o )
Linking out ...
psxx:/tmp$ time ./out 3-med.in |/dev/null
real0m0.252s
user0m0.225s
sys 0m0.011s
psxx:/tmp$ ghc --make -fforce-recomp -o out buga.hs -O2
[1 of 1] Compiling Main ( buga.hs, buga.o )
Linking out ...
Vazeny pane, cekam na Vase rozkazy.
psxx:/tmp$ time ./out 3-med.in |/dev/null
real0m0.239s
user0m0.225s
sys 0m0.010s
psxx:/tmp$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.10.1
The GHC documentation states that
-O2:
Means: Apply every non-dangerous optimisation, even if it means
significantly longer compile times. The avoided dangerous
optimisations are those that can make runtime or space worse if
you're unlucky. They are normally turned on or off individually.
If I understand this correctly, the dangerous optimisations should not
be performed with -O. Am I doing anything wrong? Am I hitting a bug
in GHC optimiser? A known one?
The program source:
--
p...@r4at184:/tmp$ cat buga.hs
{-# LANGUAGE FlexibleContexts #-}
import Control.Monad
import Control.Monad.State
data Predpoc a = Nic | Kus { delka :: Int,
levy :: Predpoc a,
pravy :: Predpoc a }
deriving Show
gList i = Kus 1 Nic Nic
gPredpoc kus1 kus2 =
Kus (delka kus1 + delka kus2)
kus1 kus2
pop :: MonadState [a] m = m a
pop = get = \(x:xs) - put xs return x
mbuild :: MonadState [Int] m = Int - m (Predpoc Int)
mbuild 1 = gList `liftM` pop
mbuild n = liftM2 gPredpoc (mbuild n1) (mbuild n2)
where n1 = n`div`2
n2 = n - n1
build n li = evalState (mbuild n) li
best :: Predpoc Int - Int - Int - Int
best kus i j
| i == 1 j == delka kus
= delka kus
| j = del1 = best (levy kus) i j
| i del1= best (pravy kus) (i-del1) (j-del1)
| otherwise = best (levy kus) i del1 +
best (pravy kus) 1 (j-del1)
where
del1 = delka (levy kus)
main = do
n - read `liftM` getLine
pole - liftM (build n . map read . words) getLine
replicateM_ 100 $ do
getLine
print $ best pole 42 420
--
The sample input file (30k) can be downloaded from
http://pikomat.mff.cuni.cz/petr/3-med.in
I suspect that the main's variable pole (which is a large
binary tree of type Predpoc Int) may be built from scratch in each
iteration of the replicateM_ loop.
Petr
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Re: [Haskell-cafe] ANN: SVGFonts 0.1
What your cabal file describes is a single executable, Executable Fonts main-is: tests/Fonts.hs This just tells us to build the file tests/Fonts.hs into a single executable named 'Fonts'. You probably want to retructure your project a bit into something like this. ./LICENSE ./README ./Setup.hs ./src ./src/SVGFonts ./src/SVGFonts/KETTriangulation.hs ./src/SVGFonts/PointOfView.hs ./src/SVGFonts/ReadFont.hs ./SVGFonts.cabal ./test ./test/Fonts.hs ./test/GirlsareWeird.svg ./test/LinLibertineO.svg ./test/Scriptin.svg ./TODO Here's what your cabal file should probably look like: Name: SVGFonts Version: 0.1 Description: parse svg-font files and generate outlines of letters and sentences License: GPL License-file: LICENSE Author: Tillmann Vogt Maintainer: tillmann.v...@rwth-aachen.de Build-Type: Simple Cabal-Version:=1.2 library build-depends: haskell98, base, OpenGL, GLUT, xml, parsec exposed-modules: SVGFonts.KETTriangulation SVGFonts.PointOfView SVGFonts.ReadFont That isn't exact, but it should be close. /jve On Mon, Apr 6, 2009 at 1:32 PM, Tillmann Vogt tillmann.v...@rwth-aachen.dewrote: John Van Enk schrieb: This sounds very cool. Is is just a program, or is there a library sitting behind it? From your .cabal file, it seems to be just a binary program. Is this correct? http://hackage.haskell.org/packages/archive/SVGFonts/0.1/SVGFonts.cabal On Mon, Apr 6, 2009 at 1:22 PM, Tillmann Vogt tillmann.v...@rwth-aachen.dewrote: It is a real library made of pure Haskell. What is wrong with my .cabal file? -- /jve ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] replicateM should be called mreplicate?
On Mon, Apr 6, 2009 at 11:42 AM, David Menendez d...@zednenem.com wrote: Of course, this suggests that mfix should be fixM, so perhaps a better distinction is that mplus and mfix need to be defined per-monad, whereas filterM and replicateM are generic. Don't you think that is an incidental distinction, not an essential one? It would be like naming our favorite operations mbind and joinM, just because of the way we happened to write the monad class. Luke -- Dave Menendez d...@zednenem.com http://www.eyrie.org/~zednenem/ http://www.eyrie.org/%7Ezednenem/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: SVGFonts 0.1
John Van Enk schrieb: This sounds very cool. Is is just a program, or is there a library sitting behind it? From your .cabal file, it seems to be just a binary program. Is this correct? http://hackage.haskell.org/packages/archive/SVGFonts/0.1/SVGFonts.cabal On Mon, Apr 6, 2009 at 1:22 PM, Tillmann Vogt tillmann.v...@rwth-aachen.dewrote: It is a real library made of pure Haskell. What is wrong with my .cabal file? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] community.haskell.org unreachable?
I seem to be having problems reaching anything on that server. Does anyone know what is going on, or who to contact? It would help if the haskellwiki page http://www.haskell.org/haskellwiki/Haskell.org_domain would mention the admin address directly, instead of referring to http://community.haskell.org/admin/ which is also unreachable. Claus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] cabal haddock and Paths_Xxx
Hello, cabal generates a Paths_Xxx file for me which I import and use, but cabal haddock doesn't seem to like it much. If I don't specify the generated module at all in my cabal file, cabal haddock generates visible documentation for the module, which is not what I want: the module should stay internal. If I specify it in either Exposed-Modules or Other-Modules, 'cabal configure; cabal haddock' fails with: cabal: can't find source for Paths_Xxx in ., dist/build/autogen While 'cabal configure; cabal build; cabal haddock' fails with: cabal: can't find source for module Paths_Xxx Can I have the best of both, i.e. generate docs without problems and use the generated module? Thanks, Martijn. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Ghc: -O harmful?
-fno-state-hack?
xofon:
Hello all,
I have a haskell program that runs an order of magnitude slower
when compiled with optimisations turned on. This happens on 6.8.2
as well as 6.10.1:
p...@r4at184:/tmp[1]% ghc --make -fforce-recomp -o out buga.hs
[1 of 1] Compiling Main ( buga.hs, buga.o )
Linking out ...
p...@r4at184:/tmp% time ./out 3-med.in |/dev/null
./out 3-med.in | /dev/null 0,03s user 0,00s system 99% cpu 0,038 total
p...@r4at184:/tmp% ghc --make -fforce-recomp -o out buga.hs -O
[1 of 1] Compiling Main ( buga.hs, buga.o )
Linking out ...
p...@r4at184:/tmp% time ./out 3-med.in |/dev/null
./out 3-med.in | /dev/null 0,99s user 0,01s system 99% cpu 1,001 total
p...@r4at184:/tmp[1]% ghc --make -fforce-recomp -o out buga.hs -O2
[1 of 1] Compiling Main ( buga.hs, buga.o )
Linking out ...
p...@r4at184:/tmp% time ./out 3-med.in |/dev/null
./out 3-med.in | /dev/null 0,99s user 0,01s system 99% cpu 1,004 total
p...@r4at184:/tmp% ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.8.2
psxx:/tmp$ ghc --make -fforce-recomp -o out buga.hs
[1 of 1] Compiling Main ( buga.hs, buga.o )
Linking out ...
psxx:/tmp$ time ./out 3-med.in |/dev/null
real 0m0.028s
user 0m0.011s
sys 0m0.007s
psxx:/tmp$ ghc --make -fforce-recomp -o out buga.hs -O
[1 of 1] Compiling Main ( buga.hs, buga.o )
Linking out ...
psxx:/tmp$ time ./out 3-med.in |/dev/null
real 0m0.252s
user 0m0.225s
sys 0m0.011s
psxx:/tmp$ ghc --make -fforce-recomp -o out buga.hs -O2
[1 of 1] Compiling Main ( buga.hs, buga.o )
Linking out ...
Vazeny pane, cekam na Vase rozkazy.
psxx:/tmp$ time ./out 3-med.in |/dev/null
real 0m0.239s
user 0m0.225s
sys 0m0.010s
psxx:/tmp$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.10.1
The GHC documentation states that
-O2:
Means: Apply every non-dangerous optimisation, even if it means
significantly longer compile times. The avoided dangerous
optimisations are those that can make runtime or space worse if
you're unlucky. They are normally turned on or off individually.
If I understand this correctly, the dangerous optimisations should not
be performed with -O. Am I doing anything wrong? Am I hitting a bug
in GHC optimiser? A known one?
The program source:
--
p...@r4at184:/tmp$ cat buga.hs
{-# LANGUAGE FlexibleContexts #-}
import Control.Monad
import Control.Monad.State
data Predpoc a = Nic | Kus { delka :: Int,
levy :: Predpoc a,
pravy :: Predpoc a }
deriving Show
gList i = Kus 1 Nic Nic
gPredpoc kus1 kus2 =
Kus (delka kus1 + delka kus2)
kus1 kus2
pop :: MonadState [a] m = m a
pop = get = \(x:xs) - put xs return x
mbuild :: MonadState [Int] m = Int - m (Predpoc Int)
mbuild 1 = gList `liftM` pop
mbuild n = liftM2 gPredpoc (mbuild n1) (mbuild n2)
where n1 = n`div`2
n2 = n - n1
build n li = evalState (mbuild n) li
best :: Predpoc Int - Int - Int - Int
best kus i j
| i == 1 j == delka kus
= delka kus
| j = del1 = best (levy kus) i j
| i del1= best (pravy kus) (i-del1) (j-del1)
| otherwise = best (levy kus) i del1 +
best (pravy kus) 1 (j-del1)
where
del1 = delka (levy kus)
main = do
n - read `liftM` getLine
pole - liftM (build n . map read . words) getLine
replicateM_ 100 $ do
getLine
print $ best pole 42 420
--
The sample input file (30k) can be downloaded from
http://pikomat.mff.cuni.cz/petr/3-med.in
I suspect that the main's variable pole (which is a large
binary tree of type Predpoc Int) may be built from scratch in each
iteration of the replicateM_ loop.
Petr
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Re: [Haskell-cafe] community.haskell.org unreachable?
Works for me. The admin address referenced there is support [AT] community.haskell.org Thanks. Yes, it is working again for me too, now, but had been quite persistently unreachable before, while www.haskell.org was reachable, so I'd be surprised if the the problem was at this end of the connection. If I read the bandwith graph correctly, there was a peak followed by several hours of silence, matched by odd memory usage (though I don't see what the load average is trying to tell us?): http://community.haskell.org/mrtg/daily.html Claus On Mon, Apr 6, 2009 at 1:32 PM, Claus Reinke claus.rei...@talk21.comwrote: I seem to be having problems reaching anything on that server. Does anyone know what is going on, or who to contact? It would help if the haskellwiki page http://www.haskell.org/haskellwiki/Haskell.org_domain would mention the admin address directly, instead of referring to http://community.haskell.org/admin/ which is also unreachable. Claus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] strange performance issue with takusen 0.8.3
Dear All, I have an application where some simple data extracted from some source files is inserted into a PostgreSQL database. The application uses Takusen and is compiled with GHC 6.8.3. Some (59 in the test data) of the selects take on average 460ms each for a total time for this sample run of 30s. I prepare one select statement at the beginning of the run into which I then bind the specific values for every one of the selects. It does not seem to make a difference whether I do this or whether I just use a new statement for every select. For comparison, I have collected the SQL statements in a file with PREPARE ... and DEALLOCATE for _every_ select and then run this file through psql. This takes 2s! During the run of the GHC-compiled executable the cpu load goes up. In top I see %CPU of above 72%. Any ideas that might enlighten are welcome. Best regards, Marko pgpcwfuYc2MfV.pgp Description: PGP signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Numeric Prelude and identifiers (Was: fad 1.0 -- Forward AutomaticDifferentiation library)
Henning Thielemann schrieb: On Sun, 5 Apr 2009, Kalman Noel wrote: I'm wondering, too, if the Numeric Prelude could be organized more cleanly if we had a fancier module system - does someone have sufficient experience with, say, ML-style module systems to tell? Are you complaining about the organisation or about the identifiers? If you mean the former, then what organisation do you propose? I'm not complaining, and I'm not sure what I mean :) I may like a scheme where functions operating on a type or type class live in a module seperate from the type (class) definition, so you could import a specific module to get only, say, (Ring, (*), one, ...). But that would be too tedious in the Haskell hierarchical module system, which is why I was asking about others. If you mean the latter ... Many proposals about extended import facilities I saw were complicated and could simply be avoided using the naming style I use. I'm ready to believe you that the naming style you chose is optimal within the hierarchical module system. Regards, Kalman ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Combining sequences
Hi Daniel, Thanks, but apparently no go. This isn't critical, as I already have a function that will combine two sequences. Michael = Michael [mich...@localhost untitled folder]$ cd utility-ht-0.0.4 [mich...@localhost utility-ht-0.0.4]$ ls LICENSE Setup.lhs src utility-ht.cabal [mich...@localhost utility-ht-0.0.4]$ ./Setup.lhs configure --hugs /usr/bin/env: runhaskell: No such file or directory --OOPS! [mich...@localhost utility-ht-0.0.4]$ su Password: [r...@localhost utility-ht-0.0.4]# ./Setup.lhs configure --hugs /usr/bin/env: runhaskell: No such file or directory [r...@localhost utility-ht-0.0.4]# --- On Mon, 4/6/09, Daniel Fischer daniel.is.fisc...@web.de wrote: From: Daniel Fischer daniel.is.fisc...@web.de Subject: Re: [Haskell-cafe] Combining sequences To: haskell-cafe@haskell.org Cc: michael rice nowg...@yahoo.com Date: Monday, April 6, 2009, 12:04 PM Am Montag 06 April 2009 17:12:42 schrieb michael rice: I downloaded it and it appears more complicated than just adding files to a directory. There's a setup and a build, and no assurances it will work with Hugs. I think I'll wait for more information. Michael Try installing it with Cabal: ./Setup.lhs configure --hugs if that doesn't say otherwise, chances are that it will work, so try ./Setup.lhs build sudo ./Setup.lhs install If it doesn't work, you can copy the code from Data.List.HT ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Linking hmatrix without LAPACK
Hi Alberto! Thanks for your informative reply. I looked in to the versions of liblapack on my system... it turns out there is indeed a liblapack.dylib that (apparently) comes with Mac OS X. How to tell ghc to link to that instead is still in question. I can run simple matrix operations in ghci as you suggest (in fact, runTests 20 succeeds wonderfully); however, I created the following simple module (test.hs) and it fails: module Main where import Numeric.LinearAlgebra.Tests main = do runTests 20 I tried plain --make, as well as the -dynamic flag, and then I tried the -L shell argument to point to the /usr/lib dir where the liblapack.dylib library is located: $ ghc --make test.hs -o test [1 of 1] Compiling Main ( test.hs, test.o ) Linking test ... ld: in /opt/local/lib/liblapack.a( ), not a valid archive member collect2: ld returned 1 exit status $ ghc --make -dynamic test.hs -o test Linking test ... ld: library not found for -lHShmatrix-0.5.0.1-ghc6.10.1 collect2: ld returned 1 exit status $ ghc --make -L/usr/lib test.hs -o test Linking test ... Undefined symbols: _zgemm_, referenced from: _multiplyC in libHShmatrix-0.5.0.1.a(lapack-aux.o) _zgesv_, referenced from: _linearSolveC_l in libHShmatrix-0.5.0.1.a(lapack-aux.o) _zpotrf_, referenced from: _chol_l_H in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dpotrf_, referenced from: _chol_l_S in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgemm_, referenced from: _multiplyR in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgesv_, referenced from: _linearSolveR_l in libHShmatrix-0.5.0.1.a(lapack-aux.o) _zgetrf_, referenced from: _lu_l_C in libHShmatrix-0.5.0.1.a(lapack-aux.o) _zgetrs_, referenced from: _luS_l_C in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgetrf_, referenced from: _lu_l_R in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgetrs_, referenced from: _luS_l_R in libHShmatrix-0.5.0.1.a(lapack-aux.o) ld: symbol(s) not found collect2: ld returned 1 exit status I attempted to install hmatrix with the -faccelerate option, but when using ghc --make for the above test code, I received the same error messages noted previously. Is there a way to tell if the - faccelerate was acknowledged and that the alternate library was used? One more clue: I took a look at the directions found on the page at mit.edu/harold... it turns out I had installed atlas/lapack unnecessarily. That explains the mysterious not a valid archive member message. Nevertheless, I am still befuddled by the Undefined symbols above. ghc --make is still unable to figure out where the liblapack.dylib file is in spite of ghci's success. Any suggestions from here? Regards, Duane Johnson P.S. I'm CC'ing the Haskell Cafe so that our journey so far can be archived. On Apr 6, 2009, at 12:22 PM, Alberto Ruiz wrote: Hi Duane, I have seen your messages to Haskell Cafe but I am still thinking about the problem... :) Can you run simple matrix operations in ghci? $ ghci Prelude import Numeric.LinearAlgebra Prelude Numeric.LinearAlgebra let m = (22) [1..4 :: Double] (...Loading packages...) Prelude Numeric.LinearAlgebra m m (22) [ 7.0, 10.0 , 15.0, 22.0 ] If so, some version of blas/lapack can be found in your system, it is strange that ghc --make doesn't find them. Perhaps the problem is that dynamic libraries like liblapack.so are required instead of static ones like liblapack.a. (In ubuntu they are in the devel packages for blas/lapack.) I am not familiar with Mac OS, but if you can use the accelerate framework in your system you may try the -faccelerate configuration option for hmatrix: cabal install hmatrix -faccelerate See also the following page (steps 3-8). It explains how to install hmatrix on Mac OS (required for other project). http://mit.edu/harold/Public/easyVisionNotes.html Please let me know if any of these methods works for you. Thanks for your message, Alberto Duane Johnson wrote: Hi Alberto, I've been very happy with hmatrix as I've used it in ghci, and I should first thank you for making such an excellent package. I've had trouble when linking it using ghc --make on Mac OS (Leopard). Below are two messages I sent to the Haskell Cafe mailing list. Do you have any insight into either question: 1. How to link without atlas/lapack 2. What the not a valid archive member message means? Thank you! Duane Johnson Brigham Young University Provo, UT Begin forwarded message: From: Don Stewart d...@galois.com Date: April 5, 2009 11:48:38 PM MDT To: Duane Johnson duane.john...@gmail.com Subject: Re: [Haskell-cafe] Re: Linking hmatrix without LAPACK It would be best to contact the author of hmatrix directly. duane.johnson: On a related note, I've installed Atlas, and I get the following error when linking: Linking SilkwormGame ... ld: in /opt/local/lib/liblapack.a(), not a valid archive member collect2: ld
Re: [Haskell-cafe] Combining sequences
On Mon, 6 Apr 2009, nowg...@yahoo.com wrote: Michael [mich...@localhost untitled folder]$ cd utility-ht-0.0.4 [mich...@localhost utility-ht-0.0.4]$ ls LICENSE Setup.lhs src utility-ht.cabal [mich...@localhost utility-ht-0.0.4]$ ./Setup.lhs configure --hugs /usr/bin/env: runhaskell: No such file or directory --OOPS! [mich...@localhost utility-ht-0.0.4]$ su Password: [r...@localhost utility-ht-0.0.4]# ./Setup.lhs configure --hugs /usr/bin/env: runhaskell: No such file or directory [r...@localhost utility-ht-0.0.4]# $ runhugs Setup.lhs configure --hugs might work___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ghc --make unable to find dynamic library, but ghci can
Hi Haskellers, This is related to my previous message, Linking hmatrix without LAPACK. Apparently, ghc --make is not finding the lapack.dylib library where ghci is (dylib is Mac OS X specific) . For example, the following test module does NOT work when compiled with ghc --make: module Main where import Numeric.LinearAlgebra.Tests main = do runTests 20 But the following runs fine in ghci: $ ghci GHCi, version 6.10.1: http://www.haskell.org/ghc/ :? for help [...loading packages...] Prelude :m Numeric.LinearAlgebra.Tests Prelude Numeric.LinearAlgebra.Tests runTests 20 [...loading packages...] -- mult OK, passed 100 tests. OK, passed 100 tests. [...more tests pass...] Can anyone point me in the right direction? Thank you, Duane Johnson ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Combining sequences
On Sun, 5 Apr 2009, michael rice wrote: Thanks. It looks like mergeBy will do the job, but is it available in Hugs? The package is Haskell98 and needs no further package, thus it should work with almost every Haskell system. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Ghc: -O harmful?
Am Montag 06 April 2009 20:37:46 schrieb Don Stewart:
-fno-state-hack?
That, or
{-# LANGUAGE BangPatterns #-}
main = do
n - read `liftM` getLine
!pole - liftM (build n . map read . words) getLine
replicateM_ 100 $ do
getLine
print $ best pole 42 420
if the state-hack is beneficial in other places of the programme.
The bang on pole tells GHC to calculate it only once, not inline it.
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[Haskell-cafe] Monad transformer to consume a list
Hello, is there a monad transformer to consume an input list? I've got external events streaming into the monad that are consumed on demand and I'm not sure if there's something better than a StateT. //Stephan -- Früher hieß es ja: Ich denke, also bin ich. Heute weiß man: Es geht auch so. - Dieter Nuhr ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Monad transformer to consume a list
On Mon, 6 Apr 2009, Stephan Friedrichs wrote: Hello, is there a monad transformer to consume an input list? I've got external events streaming into the monad that are consumed on demand and I'm not sure if there's something better than a StateT. I wondered that, too. I wondered whether there is something inverse to Writer, and Reader is appearently not the answer. Now I think, that State is indeed the way to go to consume a list. Even better is StateT List Maybe: next :: StateT [a] Maybe a next = StateT Data.List.HT.viewL -- see utility-ht package ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] GHC accepts libraries compiled with Visual Studio?
To my surprise GHC seems to accept .lib files (produced by e.g. Visual Studio on Windows) directly; I don't need to convert these to .a files using e.g. reimp That's really cool. Is this by design or did I miss something? The manual does not seem to mention this. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Strange type error with associated type synonyms
{-# LANGUAGE TypeFamilies, TypeSynonymInstances, ScopedTypeVariables #-}
The following is a class of memo tries indexed by d:
class Fun d where
type Memo d :: * - *
abst :: (d - a) - Memo d a
appl :: Memo d a - (d - a)
-- Law: abst . appl = id
-- Law: appl . abst = id (denotationally)
Any such type Memo d is naturally a functor:
memo_fmap f x = abst (f . appl x)
The type of memo_fmap (as given by ghci) is (Fun d) = (a - c) -
Memo d a - Memo d c. (Obviously this would also be the type of fmap
for Memo d, so we could declare a Functor instance in principle.) If
we add this signature:
memo_fmap' :: Fun d = (a - b) - Memo d a - Memo d b
memo_fmap' f x = abst (f . appl x)
it doesn't type check:
TypeSynonymTest.hs:14:17:
Couldn't match expected type `Memo d1 b'
against inferred type `Memo d b'
In the expression: abst (f . appl x)
In the definition of `memo_fmap'':
memo_fmap' f x = abst (f . appl x)
TypeSynonymTest.hs:14:32:
Couldn't match expected type `Memo d a'
against inferred type `Memo d1 a'
In the first argument of `appl', namely `x'
In the second argument of `(.)', namely `appl x'
In the first argument of `abst', namely `(f . appl x)'
Failed, modules loaded: none.
As I understand it, the type checker's thought process should be along
these lines:
1) the type signature dictates that x has type Memo d a.
2) appl has type Memo d1 a - d1 - a for some d1.
3) we apply appl to x, so Memo d1 a = Memo d a. unify d = d1
But for some reason, step 3 fails. If we annotate appl with the
correct type (using scoped type variables), it type checks:
-- thanks to mmorrow on #haskell for this
memo_fmap'' :: forall a b d. Fun d = (a - b) - Memo d a - Memo d b
memo_fmap'' f x = abst (f . (appl :: Memo d a - d - a) x)
My ghc is 6.8.2, but apparently this happens in 6.10 as well.
--
Peter Berry pwbe...@gmail.com
Please avoid sending me Word or PowerPoint attachments.
See http://www.gnu.org/philosophy/no-word-attachments.html
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[Haskell-cafe] Re: Numeric Prelude and identifiers
On Mon, 6 Apr 2009, Kalman Noel wrote: I'm not complaining, and I'm not sure what I mean :) I may like a scheme where functions operating on a type or type class live in a module seperate from the type (class) definition, so you could import a specific module to get only, say, (Ring, (*), one, ...). But that would be too tedious in the Haskell hierarchical module system, which is why I was asking about others. It was precisely my goal to bundle the type with the functions that operate on it. Why do you want to separate them? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Volunteer
Hi, I learned that no one is doing generic unix source tarball, right now, and thought I might help to get it start. I have decent skills on Makefile, but knows very little about auto-tools. I can only spent a few hours every week on it, because I don't have too much spare time as a PhD student. But I still want to help, since it is quite important for Haskell to distribute as widely as possible. So, how should I start? I learned that ghc supports quite a lot of platforms in its tier2 support list through community supporters. I'm not sure what is the most convenient way to combine these into a generic source tarball. And what do we use to bootstrap ghc? Some pre-compiled binary? I'm not sure how I should start. Any insight? Best, Xiao-Yong P.S. I tried to send to haskell-platform, but got rejected. What's going on? -- begin error message -- ... while talking to community.haskell.org.: DATA 550 Unrouteable address 550 5.1.1 haskell-platf...@projects.haskell.org... User unknown 503 valid RCPT command must precede DATA -- end error message -- -- c/*__o/* \ * (__ */\ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Linking hmatrix without LAPACK
FYI, the following solution worked on Mac OS X (Leopard): ghc -o SilkwormGame --make -framework Accelerate Main.hs The key addition is -framework Accelerate. Thus, on Mac OS X, it is only necessary to install the gls library via macports. Atlas/ LAPACK/BLAS etc. come with the operating system framework above. Also, I had to replace a DYLD_LIBRARY_PATH assignment in my .profile with DYLD_FALLBACK_LIBRARY_PATH: export DYLD_LIBRARY_PATH=/opt/local/lib:/usr/local/cuda/lib becomes: export DYLD_FALLBACK_LIBRARY_PATH=/opt/local/lib:/usr/local/cuda/lib The above change permitted me to use Apple's libraries by default, and my macports libraries as fallbacks. In particular, when I installed the atlas package via macports, it seems to have updated a key libjpeg.dylib file, thus causing other headaches. Using the fallback method above, the problems went away. Regards, Duane Johnson On Apr 6, 2009, at 1:51 PM, Duane Johnson wrote: Hi Alberto! Thanks for your informative reply. I looked in to the versions of liblapack on my system... it turns out there is indeed a liblapack.dylib that (apparently) comes with Mac OS X. How to tell ghc to link to that instead is still in question. I can run simple matrix operations in ghci as you suggest (in fact, runTests 20 succeeds wonderfully); however, I created the following simple module (test.hs) and it fails: module Main where import Numeric.LinearAlgebra.Tests main = do runTests 20 I tried plain --make, as well as the -dynamic flag, and then I tried the -L shell argument to point to the /usr/lib dir where the liblapack.dylib library is located: $ ghc --make test.hs -o test [1 of 1] Compiling Main ( test.hs, test.o ) Linking test ... ld: in /opt/local/lib/liblapack.a( ), not a valid archive member collect2: ld returned 1 exit status $ ghc --make -dynamic test.hs -o test Linking test ... ld: library not found for -lHShmatrix-0.5.0.1-ghc6.10.1 collect2: ld returned 1 exit status $ ghc --make -L/usr/lib test.hs -o test Linking test ... Undefined symbols: _zgemm_, referenced from: _multiplyC in libHShmatrix-0.5.0.1.a(lapack-aux.o) _zgesv_, referenced from: _linearSolveC_l in libHShmatrix-0.5.0.1.a(lapack-aux.o) _zpotrf_, referenced from: _chol_l_H in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dpotrf_, referenced from: _chol_l_S in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgemm_, referenced from: _multiplyR in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgesv_, referenced from: _linearSolveR_l in libHShmatrix-0.5.0.1.a(lapack-aux.o) _zgetrf_, referenced from: _lu_l_C in libHShmatrix-0.5.0.1.a(lapack-aux.o) _zgetrs_, referenced from: _luS_l_C in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgetrf_, referenced from: _lu_l_R in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgetrs_, referenced from: _luS_l_R in libHShmatrix-0.5.0.1.a(lapack-aux.o) ld: symbol(s) not found collect2: ld returned 1 exit status I attempted to install hmatrix with the -faccelerate option, but when using ghc --make for the above test code, I received the same error messages noted previously. Is there a way to tell if the - faccelerate was acknowledged and that the alternate library was used? One more clue: I took a look at the directions found on the page at mit.edu/harold... it turns out I had installed atlas/lapack unnecessarily. That explains the mysterious not a valid archive member message. Nevertheless, I am still befuddled by the Undefined symbols above. ghc --make is still unable to figure out where the liblapack.dylib file is in spite of ghci's success. Any suggestions from here? Regards, Duane Johnson P.S. I'm CC'ing the Haskell Cafe so that our journey so far can be archived. On Apr 6, 2009, at 12:22 PM, Alberto Ruiz wrote: Hi Duane, I have seen your messages to Haskell Cafe but I am still thinking about the problem... :) Can you run simple matrix operations in ghci? $ ghci Prelude import Numeric.LinearAlgebra Prelude Numeric.LinearAlgebra let m = (22) [1..4 :: Double] (...Loading packages...) Prelude Numeric.LinearAlgebra m m (22) [ 7.0, 10.0 , 15.0, 22.0 ] If so, some version of blas/lapack can be found in your system, it is strange that ghc --make doesn't find them. Perhaps the problem is that dynamic libraries like liblapack.so are required instead of static ones like liblapack.a. (In ubuntu they are in the devel packages for blas/lapack.) I am not familiar with Mac OS, but if you can use the accelerate framework in your system you may try the -faccelerate configuration option for hmatrix: cabal install hmatrix -faccelerate See also the following page (steps 3-8). It explains how to install hmatrix on Mac OS (required for other project). http://mit.edu/harold/Public/easyVisionNotes.html Please let me know if any of these methods works for you. Thanks for your message, Alberto Duane Johnson wrote: Hi
Re: [Haskell-cafe] GHC accepts libraries compiled with Visual Studio?
I've noticed this before. I in fact have really only tried FTGL with VC compiled lib files... On Mon, Apr 6, 2009 at 5:34 PM, Peter Verswyvelen bugf...@gmail.com wrote: To my surprise GHC seems to accept .lib files (produced by e.g. Visual Studio on Windows) directly; I don't need to convert these to .a files using e.g. reimp That's really cool. Is this by design or did I miss something? The manual does not seem to mention this. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Configuring cabal dependencies at install-time
Is there a way to do something like autoconf and configure dependencies at install time? Building buster, I keep adding dependencies and I'd like to keep that down to a minimum without the annoyance of littering Hackage with dozens of packages. For instance, today I developed an HTTP behaviour and that of course requires network and http, which were previously not required. I'm about to put together a haxr XML-RPC behaviour as well, and that of course would add that much more to the dependency list. HaXml, haxr, and haxr-th most likely. so... any way to do that short of making a bunch of separate packages with one or two modules apiece? Otherwise I'm thinking of breaking things up into buster, buster-ui, buster-network, buster-console, and buster-graphics to start and adding more as I continue along. -- Jeff ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Infix tuple comma query (,)
The prefix notation for \a b c - (a,b,c) is (,,) Without the parentheses, it's not immediately clear whether foo $ a,b means foo (a,b) or foo (\c - (a,b,c)) or some other, bigger tuple size. Anyways, it's just syntax :) -- ryan On Mon, Apr 6, 2009 at 9:08 AM, Daniel Fischer daniel.is.fisc...@web.de wrote: Am Montag 06 April 2009 17:53:24 schrieb Paul Keir: module Main where data (:%^) a b = a :%^ b deriving (Show) main = do print $ 18 :%^ (Just 99) print $ (,) 9 10 print $ 9 , 10 The last line in the code above causes a compile error. Why does infix use of the comma (tuple constructor?) function fail without brackets? Tuples are special baked-in syntax. The parentheses are part of the tuple constructor(s). It may be confusing you that you can use it prefix as well as aroundfix. Thanks, Paul ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Volunteer
Dear Xiao-Yong, thank you very much for your willingness to help. I would suggest you look into some of the builds for various platforms as you mentioned. One infrastructure I find particularly interesting is pkgsrc (www.pkgsrc.org) which can be used to effortlessly build numerous packages from source on various OSs and platforms. The approach taken there for building GHC is to provide pre-compiled C sources of an early GHC version, that is then used to bootstrap a more recent version. Unfortunately, the GHC package in pkgsrc is currently limited to i386 only. As far as I understand this limitation is only due to the fact that the maintainer only generated the intermediate C sources for i386 and I would think a similar approach should work with other platforms. Take all this with a lot of salt: I have only looked into these matters cursorily, but it's where I would start looking deeper... Good luck and best regards, Marko At Mon, 06 Apr 2009 17:43:09 -0400, Xiao-Yong Jin wrote: Hi, I learned that no one is doing generic unix source tarball, right now, and thought I might help to get it start. I have decent skills on Makefile, but knows very little about auto-tools. I can only spent a few hours every week on it, because I don't have too much spare time as a PhD student. But I still want to help, since it is quite important for Haskell to distribute as widely as possible. So, how should I start? I learned that ghc supports quite a lot of platforms in its tier2 support list through community supporters. I'm not sure what is the most convenient way to combine these into a generic source tarball. And what do we use to bootstrap ghc? Some pre-compiled binary? I'm not sure how I should start. Any insight? Best, Xiao-Yong P.S. I tried to send to haskell-platform, but got rejected. What's going on? -- begin error message -- ... while talking to community.haskell.org.: DATA 550 Unrouteable address 550 5.1.1 haskell-platf...@projects.haskell.org... User unknown 503 valid RCPT command must precede DATA -- end error message -- -- c/*__o/* \ * (__ */\ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe pgpIgMzLuK3Ao.pgp Description: PGP signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Strange type error with associated type synonyms
On Mon, Apr 6, 2009 at 2:36 PM, Peter Berry pwbe...@gmail.com wrote: As I understand it, the type checker's thought process should be along these lines: 1) the type signature dictates that x has type Memo d a. 2) appl has type Memo d1 a - d1 - a for some d1. 3) we apply appl to x, so Memo d1 a = Memo d a. unify d = d1 This isn't true, though, and for similar reasons why you can't declare a generic instance Fun d = Functor (Memo d). Type synonyms are not injective; you can have two instances that point at the same type: data Unit1 = Unit1 data Unit2 = Unit2 newtype Identity x = Id x unit_abst x f = Id (f x) unit_appl (Id v) _ = v instance Fun Unit1 where type Memo Unit1 = Identity abst = unit_abst Unit1 appl = unit_appl instance Fun Unit2 where type Memo Unit2 = Identity abst = unit_abst Unit2 appl = unit_appl Now, Memo Unit1 a = Identity a = Memo Unit2 a, but that does not give us that Unit1 = Unit2. In fact, memo_fmap' is ambiguous; what should this application do? memo_fmap' id (Id ()) Should it look at the instance for Unit1, or Unit2, or some other instance we haven't given yet? You can use a data family instead, and then you get the property you want; if you make Memo a data family, then Memo d1 = Memo d2 does indeed give you d1 = d2. You can still use other types in your instances, just use newtype instance Memo Unit1 a = MemoUnit1 (Identity a) and add the appropriate newtype wrappers and unwrappers. But for some reason, step 3 fails. If we annotate appl with the correct type (using scoped type variables), it type checks: -- thanks to mmorrow on #haskell for this memo_fmap'' :: forall a b d. Fun d = (a - b) - Memo d a - Memo d b memo_fmap'' f x = abst (f . (appl :: Memo d a - d - a) x) Right, because now you have constrained appl ahead of time, passing in the correct type, instead of hoping the compiler can guess how you meant to use appl. I don't know if this function is callable, though; at the very least you need to annotate its call site to get the proper instance passed through. This is somewhat solvable with a proxy element to fix the instance of Fun: data Proxy d = Proxy memo_fmap_nonamb :: Fun d = Proxy d - (a - b) - Memo d a - Memo d b memo_fmap_nonamb _ f x = abst (f . appl x) I don't know if this version compiles without the type annotation; my guess is that it might! But even if it doesn't, once you add the proper annotation it is at least callable: test = memo_fmap_nonamb (Proxy :: Proxy Unit1) id (Id ()) I think, for this problem, data families are a better solution. They also let you write the generic Functor instance. -- ryan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Strange type error with associated type synonyms
Peter Berry:
{-# LANGUAGE TypeFamilies, TypeSynonymInstances,
ScopedTypeVariables #-}
The following is a class of memo tries indexed by d:
class Fun d where
type Memo d :: * - *
abst :: (d - a) - Memo d a
appl :: Memo d a - (d - a)
-- Law: abst . appl = id
-- Law: appl . abst = id (denotationally)
Any such type Memo d is naturally a functor:
memo_fmap f x = abst (f . appl x)
The type of memo_fmap (as given by ghci) is (Fun d) = (a - c) -
Memo d a - Memo d c. (Obviously this would also be the type of fmap
for Memo d, so we could declare a Functor instance in principle.) If
we add this signature:
memo_fmap' :: Fun d = (a - b) - Memo d a - Memo d b
memo_fmap' f x = abst (f . appl x)
it doesn't type check:
TypeSynonymTest.hs:14:17:
Couldn't match expected type `Memo d1 b'
against inferred type `Memo d b'
In the expression: abst (f . appl x)
In the definition of `memo_fmap'':
memo_fmap' f x = abst (f . appl x)
TypeSynonymTest.hs:14:32:
Couldn't match expected type `Memo d a'
against inferred type `Memo d1 a'
In the first argument of `appl', namely `x'
In the second argument of `(.)', namely `appl x'
In the first argument of `abst', namely `(f . appl x)'
Failed, modules loaded: none.
As I understand it, the type checker's thought process should be along
these lines:
1) the type signature dictates that x has type Memo d a.
2) appl has type Memo d1 a - d1 - a for some d1.
3) we apply appl to x, so Memo d1 a = Memo d a. unify d = d1
But for some reason, step 3 fails.
Step 3 is invalid - cf, http://www.haskell.org/pipermail/haskell-cafe/2009-April/059196.html
.
More generally, the signature of memo_fmap is ambiguous, and hence,
correctly rejected. We need to improve the error message, though.
Here is a previous discussion of the subject:
http://www.mail-archive.com/haskell-cafe@haskell.org/msg39673.html
Manuel
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Re: [Haskell-cafe] Lazy vs correct IO [Was: A round of golf]
Is the choice of whether or not to open/close with each chunk read something that we can reasonably hide from the I/O API's user? There is at least one way in which is semantically distinct -- that old trick of opening a tempfile and then unlinking it to hide it. It may be the sort of thing that you do on demand, too -- we have a file handle pool and as we run out of handles we switch to opening/closing. For a single really long read, opening/closing every 4k is just churn; if your doing thousands of long reads at once, though, it can't be helped. -- Jason Dusek ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] automatically inserting type declarations
I remember hearing about a Haskell mode for Vim, Emacs, Yi or VisualHaskell that inserts type declarations automatically (it's lazier to just check the type than to write it manually), but I can't remember any details. What editor mode / IDE was it? What do most people use with GHC on Linux? I'm more used to Vim than to Emacs. Yi sounds like something I might like. Is it stable enough to solve more problems than it would create? (I hate buggy and broken stuff) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Infix tuple comma query (,)
On Mon, Apr 6, 2009 at 8:53 AM, Paul Keir pk...@dcs.gla.ac.uk wrote: module Main where data (:%^) a b = a :%^ b deriving (Show) main = do print $ 18 :%^ (Just 99) print $ (,) 9 10 print $ 9 , 10 The last line in the code above causes a compile error. Why does infix use of the comma (tuple constructor?) function fail without brackets? Thanks, Paul When I want a lighter syntax for pairs (when doing a long list of them, e.g.), I often define () :: a - b - (a,b) a b = (a,b) and then you can indeed write print $ 1 2 (assuming you get precedence right). Alex ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Generating arbitrary function in QuickCheck
Hi, today, I want to ask about QuickCheck. I have known recently that arbitrary works on functions as well. I played on this for a while, and met a strange behavior. I tried to write property for sortBy. import Test.QuickCheck import Data.List instance Show (a - b) where show _ = function instance Arbitrary Ordering where arbitrary = elements [LT,EQ,GT] mySortBy :: (Ord a) = (a - a - Ordering) - [a] - [a] mySortBy = sortBy prop_mysortby_sorted :: (Int - Int - Ordering) - [Int] - Property prop_mysortby_sorted cmp ls = null ls `trivial` all eq_or_lt (zipWith cmp sorted (tail sorted)) where sorted = mySortBy cmp ls eq_or_lt ord = ord == EQ || ord == LT I had thought Arbitrary instance for Ord and property for sortBy both fine. But checking fails: ghci quickCheck prop_mysortby_sorted Falsifiable, after 2 tests: function [2,3] I guess arbitrary for (Int - Int - Ordering) generates a non-sense function like this: -- let (arb_compare :: Int - Int - Ordering) generated function. arb_compare 0 1 = GT arb_compare 1 0 = GT arb_compare _ _ = EQ Then, I want to ask two questions. 1. Is my guessing in function generated by arbitrary right? 2. If so, How do I generate right function? Thanks, Yusaku Hashimoto ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Generating arbitrary function in QuickCheck
Since the argument to sortBy must impose a linear ordering on its arguments, and any linear ordering may as well be generated by assigning an integer to each element of type 'a', and your sorting function is polymorphic, from the free theorem for the sorting function we may deduce that it suffices to test your function on integer lists with a casual comparison function (Data.Ord.compare), and there is no need to generate a random comparison function. 2009/4/7 Yusaku Hashimoto nonow...@gmail.com: Hi, today, I want to ask about QuickCheck. I have known recently that arbitrary works on functions as well. I played on this for a while, and met a strange behavior. I tried to write property for sortBy. import Test.QuickCheck import Data.List instance Show (a - b) where show _ = function instance Arbitrary Ordering where arbitrary = elements [LT,EQ,GT] mySortBy :: (Ord a) = (a - a - Ordering) - [a] - [a] mySortBy = sortBy prop_mysortby_sorted :: (Int - Int - Ordering) - [Int] - Property prop_mysortby_sorted cmp ls = null ls `trivial` all eq_or_lt (zipWith cmp sorted (tail sorted)) where sorted = mySortBy cmp ls eq_or_lt ord = ord == EQ || ord == LT I had thought Arbitrary instance for Ord and property for sortBy both fine. But checking fails: ghci quickCheck prop_mysortby_sorted Falsifiable, after 2 tests: function [2,3] I guess arbitrary for (Int - Int - Ordering) generates a non-sense function like this: -- let (arb_compare :: Int - Int - Ordering) generated function. arb_compare 0 1 = GT arb_compare 1 0 = GT arb_compare _ _ = EQ Then, I want to ask two questions. 1. Is my guessing in function generated by arbitrary right? 2. If so, How do I generate right function? Thanks, Yusaku Hashimoto ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Eugene Kirpichov Web IR developer, market.yandex.ru ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Generating arbitrary function in QuickCheck
On Mon, Apr 6, 2009 at 10:09 PM, Eugene Kirpichov ekirpic...@gmail.com wrote: Since the argument to sortBy must impose a linear ordering on its arguments, and any linear ordering may as well be generated by assigning an integer to each element of type 'a', and your sorting function is polymorphic, from the free theorem for the sorting function we may deduce that it suffices to test your function on integer lists with a casual comparison function (Data.Ord.compare), and there is no need to generate a random comparison function. Interesting. How is this free theorem stated for the sorting function? Intuitively I understand that if the type is polymorphic, then it seems reasonable to just pick one type and go with it. Thanks, Jason ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] replicateM should be called mreplicate?
On Mon, Apr 6, 2009 at 1:46 PM, Luke Palmer lrpal...@gmail.com wrote: On Mon, Apr 6, 2009 at 11:42 AM, David Menendez d...@zednenem.com wrote: Of course, this suggests that mfix should be fixM, so perhaps a better distinction is that mplus and mfix need to be defined per-monad, whereas filterM and replicateM are generic. Don't you think that is an incidental distinction, not an essential one? It would be like naming our favorite operations mbind and joinM, just because of the way we happened to write the monad class. Fair enough. I only added that comment when I noticed that my explanation for picking replicateM over mreplicate also applied to mfix. Looking through Control.Monad, I see that all the *M functions require Monad, whereas the m* functions require MonadPlus (or MonadFix). I wonder to what extent that pattern holds in other libraries? -- Dave Menendez d...@zednenem.com http://www.eyrie.org/~zednenem/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
