[Haskell-cafe] what's the definition of satisfy and ? ?
I cannot understand the following code very well as i donot know the definition of satisfy and ?. -- | Case-insensitive variant of Parsec's 'char' function. caseChar:: Char - GenParser Char a Char caseChar c = satisfy (\x - toUpper x == toUpper c) -- | Case-insensitive variant of Parsec's 'string' function. caseString :: String - GenParser Char a () caseString cs= mapM_ caseChar cs ? cs Would somebody mind to explain the code in detail ? Sincerely! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] what's the definition of satisfy and ? ?
On Thu, May 21, 2009 at 2:10 PM, z_a...@163.com z_a...@163.com wrote: I cannot understand the following code very well as i donot know the definition of satisfy and ?. Did you check out the document of parsec? You can find definitions for 'satisty' and '?' in Text.ParserCombinators.Parsec.Char and Text.ParserCombinators.Prim, respectively. lee ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: what's the definition of satisfy and ? ?
z_a...@163.com z_a...@163.com wrote: I cannot understand the following code very well as i donot know the definition of satisfy and ?. Yes. Just look at the Parsec documentation, preferably Parsec 3, because Parsec versions prior to 3 were not well documented. -- | Case-insensitive variant of Parsec's 'char' function. caseChar:: Char - GenParser Char a Char caseChar c = satisfy (\x - toUpper x == toUpper c) -- | Case-insensitive variant of Parsec's 'string' function. caseString :: String - GenParser Char a () caseString cs= mapM_ caseChar cs ? cs This code looks incorrect to me. It should read: caseString :: String - GenParser Char a () caseString cs = Parsec.try (mapM_ caseChar cs) ? cs Greets, Ertugrul. -- nightmare = unsafePerformIO (getWrongWife = sex) http://blog.ertes.de/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell philosophy question
2009/5/17 Vasili I. Galchin vigalc...@gmail.com: Hello, I am confused between Haskell as delineated in the Haskell Report VS ghc pragmas which extend Haskell beyond the Haskell Report. I am sure I am not the first to ask. Caveat: on my part, I am not against innovation/extensions, but I don't like to see language bloat. This is not a negative/pegorative statement just a challenging one. Let's say that pragmas strong type your code. With the Haskell Report, you can parse a string into a certain block of code which does some kind of functionality. With these, you will get a different type that does prett ymuch the same thing. But these advanced types can also handle certain other tricks too. The philosophy is to use the pragmas then, as declarations so you know which parser to use, etc... It also lets people pass around blocks of data and know what to do with it, rather than relying on simple version numbers. Languages do pick up features all the time. If you're looking for a different perspective, it lets us strictly sort the extensions rather than relying on vague notions such as version number, 'from __future__ import *' (from python) or any of the other weird things you get when there are multiple revisions of a single language spec. In essence it's not that the language is any more bloated than what is normal, or you would still be using KR C to get your work done, because you were afraid of bloat. -Yaakov Nemoy ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell in 3 Slides
Joe Fredette schrieb: 3-4 slides imply 3-4 topics, so the question is what are the 3-4 biggest topics in haskell? I would think they would be: * Purity/Referential Transparency * Lazy Evaluation * Strong Typing + Type Classes * Monads If the goal is to be able to talk about different examples of Haskell code in the rest of the presentation, the big topic I'd choose would be called »How function definitions look like in Haskell«. Kalman ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell in 3 Slides
On 21/05/2009 09:40, Kalman Noel wrote: Joe Fredette schrieb: 3-4 slides imply 3-4 topics, so the question is what are the 3-4 biggest topics in haskell? I would think they would be: * Purity/Referential Transparency * Lazy Evaluation * Strong Typing + Type Classes * Monads If the goal is to be able to talk about different examples of Haskell code in the rest of the presentation, the big topic I'd choose would be called »How function definitions look like in Haskell«. Kalman ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe My bet : - type system without the type classes but with comparision with usual (c++) type systems. - function definitions, with a hint at pattern matching - lazyness. (see the searching a maybe list on the begineer list, it is a very good example). - advanced topic : monads, type classes, etc - just to say they are here and describe what they allow (state, exception), etc. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] the problem of design by negation
On Thu, May 21, 2009 at 00:54, Michael Mossey m...@alumni.caltech.edu wrote: I call it design by negation. When asked to justify his design, the lead software architect explains everything that *wouldn't* work. We couldn't have a unique key for every entry because blah blah blah. We couldn't use a garbage collector because blah blah. We couldn't write a sugar layer because then you have to document it separately blah blah. So the chosen design seems to be the only thing left after eliminating everything you can't do. I want to aspire to positive design. I want to list the goals, and think of design as making clever choices that meet all the goals. I think there is often a good default solution which is so obvious that experienced software architects won't even bother to mention. This is the case for both examples that you mention (unique keys in a database, garbage collection). They then go on to give reasons why the default solution would not work in their case. Thomas ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: EsotericBot 0.0.1
Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/esotericbot See the homepage for online copy of README and example configuration file: http://www.killersmurf.com/projects/esotericbot Esotericbot is a sophisticated, lightweight IRC bot, written in Haskell. Esotericbot launches sub-processes to respond to commands issued by users over IRC. Why would you use esotericbot? For lambdabot-4.2.2.1: sp...@utensil:~/esotericbot$ ps e v PID TTY STAT TIME MAJFL TRS DRS RSS %MEM COMMAND 23433 pts/3Sl+0:00 0 8228 84855 33476 1.6 lambdabot 15040 pts/5S+ 0:00 0 2171 28804 3292 0.1 ./esotericbot I'm not insinuating that lambdabot sucks in any way, ( for lambdabot is most excellent ) however, my hope is that esotericbot could attain equal functionality through plugins, whilst maintaining its small memory footprint. Esotericbot is small, designed to run on a server with limited memory - typically running at under 5mb of private memory. Features: * Advanced memory and time management options, utilizing POSIX resource management. For example, the memory used by all child processes, can be limited - commands be queued until the memory usage has dropped. * Privileged channel operator commands ( Currently, can be disabled and enabled by channel operators, without kicking. ) * Easy to add new plugins. A C library is included to make writing new plugins/adapting programs in C easy. * Set up through a configuration file. * Multiple channels. * Multi-threaded * Lightweight, typically running at under 5mb of private memory. Cons: * POSIX memory management, process forking, and chroot means that Esotericbot is POSIX only. * Esotericbot is, due to the libraries and extensions used, restricted to being compiled by the Glorious Glasgow Haskell Compiler. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: EsotericBot 0.0.1
On Thu, May 21, 2009 at 5:36 AM, sp...@killersmurf.com wrote: Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/esotericbot See the homepage for online copy of README and example configuration file: http://www.killersmurf.com/projects/esotericbot Esotericbot is a sophisticated, lightweight IRC bot, written in Haskell. Esotericbot launches sub-processes to respond to commands issued by users over IRC. Why would you use esotericbot? For lambdabot-4.2.2.1: sp...@utensil:~/esotericbot$ ps e v PID TTY STAT TIME MAJFL TRS DRS RSS %MEM COMMAND 23433 pts/3 Sl+ 0:00 0 8228 84855 33476 1.6 lambdabot 15040 pts/5 S+ 0:00 0 2171 28804 3292 0.1 ./esotericbot I'm not insinuating that lambdabot sucks in any way, ( for lambdabot is most excellent ) however, my hope is that esotericbot could attain equal functionality through plugins, whilst maintaining its small memory footprint. Esotericbot is small, designed to run on a server with limited memory - typically running at under 5mb of private memory. Features: * Advanced memory and time management options, utilizing POSIX resource management. For example, the memory used by all child processes, can be limited - commands be queued until the memory usage has dropped. * Privileged channel operator commands ( Currently, can be disabled and enabled by channel operators, without kicking. ) * Easy to add new plugins. A C library is included to make writing new plugins/adapting programs in C easy. * Set up through a configuration file. * Multiple channels. * Multi-threaded * Lightweight, typically running at under 5mb of private memory. Cons: * POSIX memory management, process forking, and chroot means that Esotericbot is POSIX only. * Esotericbot is, due to the libraries and extensions used, restricted to being compiled by the Glorious Glasgow Haskell Compiler. Hm, no 'quotes' or Haskell evaluation functionality? I guess this isn't a lambdabot killer yet! -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: Re: [Haskell-cafe] what's the definition of satisfy and ? ?
On Thu, May 21, 2009 at 6:48 PM, z_axis z_a...@163.com wrote: Sorry! I am a haskell newbie. then i will have a look at Text.ParserCombinators.Parsec.Char Don't forget to CC your reply to the list, so other people on the thread will see your reply. lee ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell in 3 Slides
On May 21, 2009, at 03:40 , Kalman Noel wrote: If the goal is to be able to talk about different examples of Haskell code in the rest of the presentation, the big topic I'd choose would be called »How function definitions look like in Haskell«. That would be (or lead directly to) referential transparency. -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon universityKF8NH PGP.sig Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell philosophy question
On May 21, 2009, at 03:13 , Yaakov Nemoy wrote: you would still be using KR C to get your work done, because you were afraid of bloat. Actually you'd still be using BCPL. :) -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon universityKF8NH PGP.sig Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: feed2twitter 0.2 hackage2twitter 0.2.1
To all the cool kids using the Twitter (and to anyone else): I'm happy to announce the first release of feed2twitter. Build on top of the excellent feed and hs-twitter packages, feed2twitter sends posts from a news feed to Twitter. The hackage2twitter executable is build on top of the feed2twitter library. It `tweets' the releases of new Hackage-packages. In the 3 days it has been running, it has already posted 70+ releases: http://twitter.com/Hackage - Tom Lokhorst http://hackage.haskell.org/cgi-bin/hackage-scripts/package/feed2twitter http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hackage2twitter ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: feed2twitter 0.2 hackage2twitter 0.2.1
A bit off topic, but what's the chance we can get the Hackage RSS feed to include some more information about the package? I'd like to see at least the description, but it might be nice to see things like dependencies and home pages. /jve On Thu, May 21, 2009 at 2:55 PM, Tom Lokhorst t...@lokhorst.eu wrote: To all the cool kids using the Twitter (and to anyone else): I'm happy to announce the first release of feed2twitter. Build on top of the excellent feed and hs-twitter packages, feed2twitter sends posts from a news feed to Twitter. The hackage2twitter executable is build on top of the feed2twitter library. It `tweets' the releases of new Hackage-packages. In the 3 days it has been running, it has already posted 70+ releases: http://twitter.com/Hackage - Tom Lokhorst http://hackage.haskell.org/cgi-bin/hackage-scripts/package/feed2twitter http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hackage2twitter ___ 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] ANN: feed2twitter 0.2 hackage2twitter 0.2.1
-BEGIN PGP SIGNED MESSAGE- Hash: SHA512 On Thu, May 21, 2009 at 2:59 PM, John Van Enk wrote: A bit off topic, but what's the chance we can get the Hackage RSS feed to include some more information about the package? I'd like to see at least the description, but it might be nice to see things like dependencies and home pages. /jve On Thu, May 21, 2009 at 2:55 PM, Tom Lokhorst wrote: To all the cool kids using the Twitter (and to anyone else): I'm happy to announce the first release of feed2twitter. Build on top of the excellent feed and hs-twitter packages, feed2twitter sends posts from a news feed to Twitter. The hackage2twitter executable is build on top of the feed2twitter library. It `tweets' the releases of new Hackage-packages. In the 3 days it has been running, it has already posted 70+ releases: http://twitter.com/Hackage - Tom Lokhorst http://hackage.haskell.org/cgi-bin/hackage-scripts/package/feed2twitter http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hackage2twitter ___ 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 Someone coding it? The repo for Hackage is: http://code.haskell.org/hackage-server The relevant file seems to be: Distribution/Server/Pages/Recent.hs - -- gwern -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.9 (GNU/Linux) iEYEAREKAAYFAkoVplEACgkQvpDo5Pfl1oI3SACglwKSDOyVMnO7XM8xNMEWs3fW 7k8An2p77xOiM+/phCJ5oq00odgqjlbw =Bn8E -END PGP SIGNATURE- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: feed2twitter 0.2 hackage2twitter 0.2.1
Oh, and while we're talking off topic. I don't know who's in charge of this, but I think it would be nice to have urls like: http://hackage.haskell.org/feed2twitter It would allow me to type in a url from memory instead of having to copy-paste it. As well as not requiring a url-shortener on Twitter. This could be done with something like Apache's mod-rewrite. - Tom On Thu, May 21, 2009 at 8:59 PM, John Van Enk vane...@gmail.com wrote: A bit off topic, but what's the chance we can get the Hackage RSS feed to include some more information about the package? I'd like to see at least the description, but it might be nice to see things like dependencies and home pages. /jve On Thu, May 21, 2009 at 2:55 PM, Tom Lokhorst t...@lokhorst.eu wrote: To all the cool kids using the Twitter (and to anyone else): I'm happy to announce the first release of feed2twitter. Build on top of the excellent feed and hs-twitter packages, feed2twitter sends posts from a news feed to Twitter. The hackage2twitter executable is build on top of the feed2twitter library. It `tweets' the releases of new Hackage-packages. In the 3 days it has been running, it has already posted 70+ releases: http://twitter.com/Hackage - Tom Lokhorst http://hackage.haskell.org/cgi-bin/hackage-scripts/package/feed2twitter http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hackage2twitter ___ 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
[Haskell-cafe] Function Returning Type?
I wrote this function as I am just learning Haskell. What it does is it generates a list of all rational numbers between 0 and 1, but I only have it show the first 20. rationals n :: Integer - String rationals n = (putStr . unlines . map show) (take n (nub [x % y | y - [1..], x - [1..y], x y])) Now my problem is the type declaration, the first line. I get the error Invalid type signature. I googled this error and I was not able to find out why it is giving it to me. I have also tried: rationals n :: Integer - [Ratio] but it gives me the same error. Please someone point me in the right direction. Thanks. -- View this message in context: http://www.nabble.com/Function-Returning-Type--tp23658819p23658819.html 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] ANN: feed2twitter 0.2 hackage2twitter 0.2.1
Hmm, or even: http://hackage.haskell.org/?p=feed2twitter On Thu, May 21, 2009 at 3:10 PM, Tom Lokhorst t...@lokhorst.eu wrote: Oh, and while we're talking off topic. I don't know who's in charge of this, but I think it would be nice to have urls like: http://hackage.haskell.org/feed2twitter It would allow me to type in a url from memory instead of having to copy-paste it. As well as not requiring a url-shortener on Twitter. This could be done with something like Apache's mod-rewrite. - Tom On Thu, May 21, 2009 at 8:59 PM, John Van Enk vane...@gmail.com wrote: A bit off topic, but what's the chance we can get the Hackage RSS feed to include some more information about the package? I'd like to see at least the description, but it might be nice to see things like dependencies and home pages. /jve On Thu, May 21, 2009 at 2:55 PM, Tom Lokhorst t...@lokhorst.eu wrote: To all the cool kids using the Twitter (and to anyone else): I'm happy to announce the first release of feed2twitter. Build on top of the excellent feed and hs-twitter packages, feed2twitter sends posts from a news feed to Twitter. The hackage2twitter executable is build on top of the feed2twitter library. It `tweets' the releases of new Hackage-packages. In the 3 days it has been running, it has already posted 70+ releases: http://twitter.com/Hackage - Tom Lokhorst http://hackage.haskell.org/cgi-bin/hackage-scripts/package/feed2twitter http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hackage2twitter ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- /jve -- /jve ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] The Computer Language Benchmarks Game: pidigits
Hi all,
I recently decided to rewrite the pidigits benchmark of the debian shootout
(shootout.alioth.debian.org) as toy project.
However, it seems that on my machine, the code seems to be more performant than
both the current entry and the proposed replacement (see
http://www.haskell.org/haskellwiki/Shootout/Pidigits) for the same number of
lines.
Do you think it might be worth submitting my entry? Here is my code,:
{-# OPTIONS -O2 -optc-O3 #-}
--
-- The Great Computer Language Shootout
-- http://shootout.alioth.debian.org/
-- by Arnaud Payement
--
import System
data F = F Integer Integer Integer Integer
extract s@(F k n a d) = ((n*3+a) `div` d, (n*4+a) `div` d, s)
update (F k n a d) = F (k+1) (n*k) ((a+n*2)*y) (d*y) where y = 2*k+1
next state = let (u, v, s'@(F k n a d)) = extract (update state) in
if (n a || (u /= v)) then next s' else (show u, F k (n*10) ((a-d*u)*10) d)
digits = (, (F 1 1 0 1)):[next state | state - map snd digits]
pr (d:t) k n | k n = putStr
| k `mod` 10 /= 0 = putStr d pr t (k+1) n
| otherwise = putStrLn (d ++ \t: ++ show k) pr t (k+1) n
main = pr (map fst (tail digits)) 1 . read . head = getArgs
Best,
Arnaud
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Re: [Haskell-cafe] Function Returning Type?
jrw4 wrote: I wrote this function as I am just learning Haskell. What it does is it generates a list of all rational numbers between 0 and 1, but I only have it show the first 20. rationals n :: Integer - String rationals n = (putStr . unlines . map show) (take n (nub [x % y | y - [1..], x - [1..y], x y])) Now my problem is the type declaration, the first line. I get the error Invalid type signature. I googled this error and I was not able to find out why it is giving it to me. I have also tried: rationals n :: Integer - [Ratio] but it gives me the same error. Please someone point me in the right direction. Thanks. Just rationals :: Integer - String suffices. (Without the argument 'n'.) This makes sense, since rationals has type Integer. rationals n has type String. (But you still cannot declare that in toplevel that way.) Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Function Returning Type?
Jochem Berndsen wrote: This makes sense, since rationals has type Integer I meant Integer - String obviously. Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: feed2twitter 0.2 hackage2twitter 0.2.1
On Thu, May 21, 2009 at 09:10:23PM +0200, Tom Lokhorst wrote: Oh, and while we're talking off topic. I don't know who's in charge of this, but I think it would be nice to have urls like: http://hackage.haskell.org/feed2twitter YES! Also a /package/doc link. So we could have a static link that would always go the latest version of the API docs for a given package. -- John It would allow me to type in a url from memory instead of having to copy-paste it. As well as not requiring a url-shortener on Twitter. This could be done with something like Apache's mod-rewrite. - Tom On Thu, May 21, 2009 at 8:59 PM, John Van Enk vane...@gmail.com wrote: A bit off topic, but what's the chance we can get the Hackage RSS feed to include some more information about the package? I'd like to see at least the description, but it might be nice to see things like dependencies and home pages. /jve On Thu, May 21, 2009 at 2:55 PM, Tom Lokhorst t...@lokhorst.eu wrote: To all the cool kids using the Twitter (and to anyone else): I'm happy to announce the first release of feed2twitter. Build on top of the excellent feed and hs-twitter packages, feed2twitter sends posts from a news feed to Twitter. The hackage2twitter executable is build on top of the feed2twitter library. It `tweets' the releases of new Hackage-packages. In the 3 days it has been running, it has already posted 70+ releases: http://twitter.com/Hackage - Tom Lokhorst http://hackage.haskell.org/cgi-bin/hackage-scripts/package/feed2twitter http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hackage2twitter ___ 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 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: feed2twitter 0.2 hackage2twitter 0.2.1
vanenkj: A bit off topic, but what's the chance we can get the Hackage RSS feed to include some more information about the package? I'd like to see at least the description, but it might be nice to see things like dependencies and home pages. what you really want is a way to query hackage programmatically. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The Computer Language Benchmarks Game: pidigits
arnaud.payement: Hi all, I recently decided to rewrite the pidigits benchmark of the debian shootout (shootout.alioth.debian.org) as toy project. However, it seems that on my machine, the code seems to be more performant than both the current entry and the proposed replacement (see http://www.haskell.org /haskellwiki/Shootout/Pidigits) for the same number of lines. Do you think it might be worth submitting my entry? Here is my code,: If it is faster, and correct, please submit it ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Function Returning Type?
Jochem, rationals n = (putStr . unlines . map show) (take n (nub [x % y | y - [1..], x - [1..y], x y])) rationals n :: Integer - [Ratio] I meant Integer - String obviously. Er... what about rationals :: Int - IO () ? ;-) To the original poster: next time, just leave the function definition without the signature and query GHCi for the correct type: Prelude :m + List Prelude List :m + Ratio Prelude List Ratio let rationals n = (putStr . unlines . map show) \ (take n (nub [x % y | y - [1..], x - [1..y], x y])) Prelude List Ratio :t rationals rationals :: Int - IO () Cheers, Stefan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Function Returning Type?
Op 21 May 2009, om 21:52 heeft Stefan Holdermans het volgende geschreven: Jochem, rationals n = (putStr . unlines . map show) (take n (nub [x % y | y - [1..], x - [1..y], x y])) rationals n :: Integer - [Ratio] I meant Integer - String obviously. Er... what about rationals :: Int - IO () Of note here though, the original type Integer - String is more desirable – the Int/Integer part doesn't matter so much, what matters is the IO type – we can no longer pass the value that rationals generates into another function, because it printed it and dumped it. Lets fix the function instead: rationals :: Int - [Rational] rationals n = take n $ nub [x % y | y - [1..], x - 1..], x y] showLines :: Show a = [a] - String showLines = unlines . map show rationalsS :: Int - String rationalsS = showLines . rationals Now we can chose to use the actual rationals we got out of the function, we can chose to use the string we get back, we can reuse our function for showing multiple showable values, and we can print any of these if we chose :). Bob___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Function Returning Type?
To the original poster: next time, just leave the function definition without the signature and query GHCi for the correct type: Remember that the type checker is your friend; let it work for you :) Mark ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell programmers in São Carlo s - SP - Brazil?
São Caetano, SP, Brazil - right next to São Paulo. UFABC Student. Fernando Henrique Sanches 2009/5/19 Maurício briqueabra...@yahoo.com Anybody else around here? Best, Maurício ___ 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] ANN: Haskell Hackathon in Philadelphia
Hi all! We are in the early stages of planning a Haskell hackathon/get together, Hac φ, to be held this summer at the University of Pennsylvania, in Philadelphia. Right now we're looking at two possible dates: June 19-21or July 24-26 If you might be interested in attending, please add your name on the wiki page: http://www.haskell.org/haskellwiki/Hac_%CF%86 You can also note whether either of those dates absolutely doesn't work for you. (If you don't have an account on the wiki, you can email Ashley Yakeley for an account [1], or feel free to just respond to this email.) Expect more details (such as a nailed-down date) soon, once we have gauged the level of interest. Hope to see you in Philadelphia! Brent (byorgey) Daniel Wagner (dmwit) [1] http://haskell.org/haskellwiki/HaskellWiki:New_accounts ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Introducing Instances in GHC point releases
So this is annoying (CCing -cafe) I need NominalDiffTime and UTCTime to have Typeable instances. In 6.10.1, they didn't ship with them out of the box, so I added them. Apparently, in 6.10.3, they DO ship with those instances out of the box. Annoyingly, that means that my code breaks on 6.10.3. Even more annoyingly, __GLASGOW_HASKELL__ is still 610, so I can't even work around this via cpphs. There appears to be no way to make code that requires those Typeable instances work with both 6.10.1 and 6.10.3. Yet another reason to avoid API incompatibilities in point releases. Does anybody have an idea on the best way to handle this? -- John Don Stewart wrote: convertible appears broken with 6.10.3. Any thoughts? Writing new package config file... done. Downloading convertible-1.0.1... Configuring convertible-1.0.1... Preprocessing library convertible-1.0.1... Preprocessing executables for convertible-1.0.1... Building convertible-1.0.1... [1 of 8] Compiling Data.Convertible.Base ( Data/Convertible/Base.hs, dist/build/Data/Convertible/Base.o ) [2 of 8] Compiling Data.Convertible.Utils ( Data/Convertible/Utils.hs, dist/build/Data/Convertible/Utils.o ) [3 of 8] Compiling Data.Convertible.Instances.Map ( Data/Convertible/Instances/Map.hs, dist/build/Data/Convertible/Instances/Map.o ) [4 of 8] Compiling Data.Convertible.Instances.Num ( Data/Convertible/Instances/Num.hs, dist/build/Data/Convertible/Instances/Num.o ) [5 of 8] Compiling Data.Convertible.Instances.C ( Data/Convertible/Instances/C.hs, dist/build/Data/Convertible/Instances/C.o ) [6 of 8] Compiling Data.Convertible.Instances.Time ( Data/Convertible/Instances/Time.hs, dist/build/Data/Convertible/Instances/Time.o ) Data/Convertible/Instances/Time.hs:61:9: Duplicate instance declarations: instance Typeable NominalDiffTime -- Defined at Data/Convertible/Instances/Time.hs:61:9-32 instance Typeable NominalDiffTime -- Defined in time-1.1.3:Data.Time.Clock.UTC Data/Convertible/Instances/Time.hs:64:9: Duplicate instance declarations: instance Typeable UTCTime -- Defined at Data/Convertible/Instances/Time.hs:64:9-24 instance Typeable UTCTime -- Defined in time-1.1.3:Data.Time.Clock.UTC cabal: Error: some packages failed to install: HDBC-2.1.0 depends on convertible-1.0.1 which failed to install. convertible-1.0.1 failed during the building phase. The exception was: ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Introducing Instances in GHC point releases
Since those types come out of the time library, and that library's version *has* been bumped (I assume), couldn't you use Cabal to condition on the version of the time library to determine whether or not to have CPP set a -DTYPEABLE_IN_TIME flag, and then #ifdef out your versions of the instances? I suppose a nice compiler extension would be recessive instances which would take effect only if they did not overlap with another instance. Probably a lot of corner cases involving multiple recessive instances to work out, though. Alex On Thu, May 21, 2009 at 2:53 PM, John Goerzen jgoer...@complete.org wrote: So this is annoying (CCing -cafe) I need NominalDiffTime and UTCTime to have Typeable instances. In 6.10.1, they didn't ship with them out of the box, so I added them. Apparently, in 6.10.3, they DO ship with those instances out of the box. Annoyingly, that means that my code breaks on 6.10.3. Even more annoyingly, __GLASGOW_HASKELL__ is still 610, so I can't even work around this via cpphs. There appears to be no way to make code that requires those Typeable instances work with both 6.10.1 and 6.10.3. Yet another reason to avoid API incompatibilities in point releases. Does anybody have an idea on the best way to handle this? -- John Don Stewart wrote: convertible appears broken with 6.10.3. Any thoughts? Writing new package config file... done. Downloading convertible-1.0.1... Configuring convertible-1.0.1... Preprocessing library convertible-1.0.1... Preprocessing executables for convertible-1.0.1... Building convertible-1.0.1... [1 of 8] Compiling Data.Convertible.Base ( Data/Convertible/Base.hs, dist/build/Data/Convertible/Base.o ) [2 of 8] Compiling Data.Convertible.Utils ( Data/Convertible/Utils.hs, dist/build/Data/Convertible/Utils.o ) [3 of 8] Compiling Data.Convertible.Instances.Map ( Data/Convertible/Instances/Map.hs, dist/build/Data/Convertible/Instances/Map.o ) [4 of 8] Compiling Data.Convertible.Instances.Num ( Data/Convertible/Instances/Num.hs, dist/build/Data/Convertible/Instances/Num.o ) [5 of 8] Compiling Data.Convertible.Instances.C ( Data/Convertible/Instances/C.hs, dist/build/Data/Convertible/Instances/C.o ) [6 of 8] Compiling Data.Convertible.Instances.Time ( Data/Convertible/Instances/Time.hs, dist/build/Data/Convertible/Instances/Time.o ) Data/Convertible/Instances/Time.hs:61:9: Duplicate instance declarations: instance Typeable NominalDiffTime -- Defined at Data/Convertible/Instances/Time.hs:61:9-32 instance Typeable NominalDiffTime -- Defined in time-1.1.3:Data.Time.Clock.UTC Data/Convertible/Instances/Time.hs:64:9: Duplicate instance declarations: instance Typeable UTCTime -- Defined at Data/Convertible/Instances/Time.hs:64:9-24 instance Typeable UTCTime -- Defined in time-1.1.3:Data.Time.Clock.UTC cabal: Error: some packages failed to install: HDBC-2.1.0 depends on convertible-1.0.1 which failed to install. convertible-1.0.1 failed during the building phase. The exception was: ___ 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] ghc ./configure stalls on docbook DTD
On Mon, 2009-05-18 at 12:09 +0100, Simon Marlow wrote: I have the following complaint from Roman in my inbox, which I think is about the same thing: one big nuisance when building ghc is that configure tries to connect to the internet. The culprit is the FP_GEN_DOCBOOK_XML macro in aclocal.m4 which is used when checking for DocBook DTD. It generates an XML file which references http://www.oasis-open.org/docbook/xml/4.2 /docbookx.dtd and then runs xmllint which, naturally, wants to load the dtd. Depending on the quality of my internet connection and on the availability of oasis-open.org this check sometimes (infrequently but very annoyingly) takes up to a 2 or 3 minutes for me. Given that the DTD in question can be freely copied, why not redistribute it with ghc? Another www reference is in FP_GEN_FO (to http://www.w3.org/1999/XSL/Format) but that never seems to bite me. I know almost but not quite exactly nothing about how to find DTDs. But I do recall that Duncan mentioned to me recently that there's a much better way to do this - Duncan? Oh, yes, use --nonet to both xmllint and xsltproc. That's what we do for the Cabal user guide which is still using xml docbook, along with: ?xml version=1.0 encoding=US-ASCII? !DOCTYPE article PUBLIC -//OASIS//DTD DocBook XML V4.2//EN http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd; I expect the uri -//OASIS//DTD DocBook XML V4.2//EN is required so that it can match the uri in the local catalog. Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Introducing Instances in GHC point releases
On Thu, 2009-05-21 at 15:22 -0700, Alexander Dunlap wrote: Since those types come out of the time library, and that library's version *has* been bumped (I assume), couldn't you use Cabal to condition on the version of the time library to determine whether or not to have CPP set a -DTYPEABLE_IN_TIME flag, and then #ifdef out your versions of the instances? I was about to suggest this: #if MIN_VERSION_time(1,1,2) ... #endif because Cabal 1.6+ generates these cpp macros for you. Note that relying on the value of __GLASGOW_HASKELL__ would be wrong because the version of the time library is not directly related to the version of ghc. However, I note that all the recent versions of time are 1.1.2.x which means it didn't bump the API version when it added the instances. The PVP says: A.B is known as the major version number, and C the minor version number. When a package is updated, the following rules govern how the version number must change relative to the previous version: 1. If any entity was removed, or the types of any entities or the definitions of datatypes or classes were changed, or instances were added or removed, then the new A.B must be greater than the previous A.B. Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] HUnit
Hello, I have some code with several test cases that use HUnit. I added hunit as one of my cabal dependencies but cabal complained with: Setup: At least the following dependencies are missing: hutil -any What am I doing incorrectly? Thanks, Vasili ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] HUnit
vigalchin: Hello, I have some code with several test cases that use HUnit. I added hunit as one of my cabal dependencies but cabal complained with: Setup: At least the following dependencies are missing: hutil -any ^ Typo. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] generic filter through MonadPlus
It seems reasonable that filter should be generic. The underlying container need only support some kind of traversal, a zero element and a concatenation that eliminates zeroes. A `Monad` provides traversal via `join` and `fmap`; the remaining qualities are satisfied by `MonadPlus`. I've put together an implementation of `filter` for `MonadPlus` that works well enough for lists (though it presents somewhat greater obstacles to efficient compilation). I'm not sure whether `filter` is important enough to warrant its own generics package -- it's one of many collection operations that need to be generified. I'd like to know what folks think about the use of `MonadPlus` in this case. -- Jason Dusek |...an implementation of `filter`...| http://github.com/jsnx/genfil/blob/246026b975ec13587186681b7b346ae1e440d0c9/Data/Filter.hs ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Introducing Instances in GHC point releases
Duncan Coutts wrote: On Thu, 2009-05-21 at 15:22 -0700, Alexander Dunlap wrote: Since those types come out of the time library, and that library's version *has* been bumped (I assume), couldn't you use Cabal to condition on the version of the time library to determine whether or not to have CPP set a -DTYPEABLE_IN_TIME flag, and then #ifdef out your versions of the instances? I was about to suggest this: #if MIN_VERSION_time(1,1,2) ... #endif That would be slick. I'll give that a whirl. What version of Cabal does GHC 6.8 come from, and where can I read about the above feature? I imagine I may have to wrap the above in a __GLASGOW_HASKELL__ test for GHC 6.8 or something. Though if *cabal* and not GHC generates it, isn't that a bit hurting to my portability? (Can't just ghc --make with it, or ghci on it directly anymore, etc.) May be a needed tradeoff though. because Cabal 1.6+ generates these cpp macros for you. Note that relying on the value of __GLASGOW_HASKELL__ would be wrong because the version of the time library is not directly related to the version of ghc. Yeah, but when you've got nothing else to go on, it sometimes works in a pinch. However, I note that all the recent versions of time are 1.1.2.x which means it didn't bump the API version when it added the instances. Ashley, I'll forgive you this time ;-) I guess my larger point is just a plea to the community: please be really careful about what you do to GHC in point releases. This is not the first issue that has screwed me in the GHC 6.10.x point releases. GHC (and the community) used to be really good about this. Is there something causing a regression here, or is it my imagination? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Introducing Instances in GHC point releases
I guess my larger point is just a plea to the community: please be really careful about what you do to GHC in point releases. This is not the first issue that has screwed me in the GHC 6.10.x point releases. I hope that the Haskell Platform will solve a lot of these issues. Clear, planned releases. Careful attention to versioning. And GHC can stop shipping custom lib variants, and instead just take the latest platform bundle. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] A problem with par and modules boundaries...
I'll cut to the chase. The short program below works perfectly: when I compile it with -O2 -threaded and run with +RTS -N2 command-line options, I get a nearly 50% real-time improvement: $ time ./primes-test +RTS -N2 5001 real0m9.307s user0m16.581s sys 0m0.200s However, if I move the `parallelize' definition into another module and import that module, the performance is completely lost: $ time ./primes-test +RTS -N2 5001 real0m15.282s user0m15.165s sys 0m0.080s I'm confused. I know that `par` must be able work across modules boundaries, because Control.Parallel.Strategies is a module and presumably it works. What am I doing wrong? module Main where import Control.Parallel import Data.List (find) import Data.Maybe (maybe) --import Parallelizable parallelize a b = a `par` (b `pseq` (a, b)) test :: Integer - Integer - Integer test n1 n2 = let (p1, p2) = parallelize (product $ factors $ product [1..n1]) (product $ factors $ product [1..n2]) in p2 `div` p1 factors n = maybe [n] (\k- (k : factors (n `div` k))) (find (\k- n `mod` k == 0) [2 .. n - 1]) main = print (test 5000 5001) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] HUnit
my bad ... what about: vigalc...@ubuntu:~/FTP/Haskell/Swish-0.2.1$ cabal configure Configuring swish-0.2.1... cabal: At least the following dependencies are missing: hunit -any On Thu, May 21, 2009 at 6:20 PM, Don Stewart d...@galois.com wrote: vigalchin: Hello, I have some code with several test cases that use HUnit. I added hunit as one of my cabal dependencies but cabal complained with: Setup: At least the following dependencies are missing: hutil -any ^ Typo. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: ANN: TxtSushi 0.1
Hello, I just released TxtSushi 0.2 with the following updates: 1) Improved type coercion. Some of the rules I was using before did not make sense. At some point I will document what the rules are. 2) Added some extra functions/operators including a regex matcher. Here is the full list: SUBSTRING, UPPER, LOWER, TRIM, *, /, +, - (binary and unary), =, (not equal test), , =, , =, AND, OR, || (string concatination), =~ (regex matching) I expect updates to be pretty frequent (at least pre-1.0) so in order to avoid spamming you all with my announcements I'll just announce major updates from now on and if you want to follow progress more closely I'll post all updates to this feed. http://blog.keithsheppard.name/feeds/posts/default/-/TxtSushi Thanks, Keith On Sun, May 17, 2009 at 11:07 AM, Keith Sheppard keiths...@gmail.com wrote: Hello Haskell Cafe I have released the first version of TxtSushi which is a collection of command line utils (written in haskell of course) for processing tab-delimited and CSV files. It includes a util for doing SQL SELECTs on flat files. This is my first haskell project and feedback of all kinds is appreciated. Home Page: http://www.keithsheppard.name/txt-sushi Darcs Repository: http://patch-tag.com/r/txt-sushi/home Issue Tracking: http://code.google.com/p/txt-sushi I would like to say thanks to the haskell-beginners contributors, the author of Learn you a Haskell and the author of the parsec library all of which were very helpful. Regards Keith ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] HUnit
I believe you need to capitalize it correctly: HUnit. Alex On Thu, May 21, 2009 at 8:52 PM, Vasili I. Galchin vigalc...@gmail.com wrote: my bad ... what about: vigalc...@ubuntu:~/FTP/Haskell/Swish-0.2.1$ cabal configure Configuring swish-0.2.1... cabal: At least the following dependencies are missing: hunit -any On Thu, May 21, 2009 at 6:20 PM, Don Stewart d...@galois.com wrote: vigalchin: Hello, I have some code with several test cases that use HUnit. I added hunit as one of my cabal dependencies but cabal complained with: Setup: At least the following dependencies are missing: hutil -any ^ Typo. -- Don ___ 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] the problem of design by negation
Hi Michael, I'm going to hazard a guess. Please let me know how accurate it is. When asked to justify his design, the lead software architect explains everything that *wouldn't* work. We couldn't have a unique key for every entry because blah blah blah. We couldn't use a garbage collector because blah blah. We couldn't write a sugar layer because then you have to document it separately blah blah. So the chosen design seems to be the only thing left after eliminating everything you can't do. My guess is that your software architect is making flimsy arguments. It's usually very difficult to prove that something *wouldn't* work. In my experience, people make blanket statements about what cannot work, when the truth is that they just don't know how and don't have the imagination or will even to entertain the possibility of ways that they can't yet see. Instead of using logic and evidence, these people bolster their claims (often mistakenly called arguments) by putting across confident language (obviously, clearly, without a doubt), body posture, facial expression, and voice tone. When someone is on solid ground, these bravado tactics are unnecessary. (I think of obviously, etc as words that are useful only when inaccurate. See http://conal.net/blog/posts/fostering-creativity-by-relinquishing-the-obvious/.) One flimsy argument I often hear is It wouldn't work because how ..., or because what As if a question were an argument. I call this rather popular tactic proof by ignorance or proof by lack of imagination. I don't know where people get the idea that this sort of thing is rational. If I'm ever tempted to give it any weight, I think of Arthur Hoppe's proof of the existence of God: If there's no God, then who pops up the next kleenex? Some of my favorite quotes on this dynamic: Doubt is not a pleasant condition, but certainty is absurd. - Voltaire They are ill discoverers that think there is no land, when they can see nothing but sea. - Francis Bacon To be positive: To be mistaken at the top of one's voice. Ambrose Bierce The greatest obstacle to discovering the shape of the earth, the continents, and the oceans was not ignorance but the illusion of knowledge. - Daniel J. Boorstin advice One thing you may try is to ask the architect for evidence and/or logical proof of his claims that something cannot work. As much as you can, ask from a place of curiosity and even awe. After all, existence can often be proved by demonstrating an example, while non-existence proofs tend to be much more profound. And stick to your open-minded disbelief until you really see evidence or logical rigor. If the architect gets flustered and embarrassed, he may well go on the attack. After all, bravado signals weak ego, which can quickly become a cornered animal. So pay attention to his stress level, and help his salvage his ego, by suggesting he let you know more about the evidence and/or logic when he's worked it out. Be careful to stay in your integrity, neither going along with someone's forcefulness, nor representing yourself as having more grounds for confidence than you really do. /advice Whether or not my guess is accurate or my advice relevant, good luck! I'd love to hear how this situation develops. - Conal On Wed, May 20, 2009 at 3:54 PM, Michael Mossey m...@alumni.caltech.eduwrote: This is not directly related to Haskell, but it's a thought that occurred to me after exposure to the Haskell community. I've spent most of the past 15 years doing scientific programming. The lead software architect and software managers are using good software engineering practice, though (this is *scientific* programming, not *programming by scientists*, ha ha). But, there is a particular culture in my company that has become more obvious to me by contrast to the Haskell community. I call it design by negation. When asked to justify his design, the lead software architect explains everything that *wouldn't* work. We couldn't have a unique key for every entry because blah blah blah. We couldn't use a garbage collector because blah blah. We couldn't write a sugar layer because then you have to document it separately blah blah. So the chosen design seems to be the only thing left after eliminating everything you can't do. I want to aspire to positive design. I want to list the goals, and think of design as making clever choices that meet all the goals. I don't mean to suggest that design is never constrained. It often is. But it's a mindset I'm talking about. I don't like this mindset of design by negation. -Mike ___ 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
