[Haskell-cafe] nun.haskell.org http services down?
http://{code,community,projects}.haskell..org/ seem to be inaccessible.
Could someone please look into it?
Thanks, Jens
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Re: [Haskell-cafe] nun.haskell.org http services down?
Why does this happen so often? Broken hardware, software crash,
bandwidth overuse, etc.? I have 200GB of bandwidth/month on the
tryhaskell.org server. It's not much but hopefully I can make a
Hackage mirror out of it one weekend for when the main server goes
down.
On 5 May 2010 09:05, Jens Petersen peter...@haskell.org wrote:
http://{code,community,projects}.haskell..org/ seem to be inaccessible.
Could someone please look into it?
Thanks, Jens
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Re: [Haskell-cafe] Fwd: Error instaling Happstack on Windows - cabal bug?
Hi all
A cursory look at Happstack.Crypto.MD5 shows it uses -fvia-c:
{-# LANGUAGE BangPatterns #-}
{-# OPTIONS_GHC -funbox-strict-fields -fvia-c -optc-funroll-all-loops
-optc-O3 #-}
--
-- Module : Happstack.Crypto.MD5
-- License : BSD3
GHC (on Windows) comes with perl so it shouldn't need installing again.
As an expedience, one could try removing the OPTIONS_GHC pragma to see
if it compiles at least (there may be other modules that use fvia-c
too).
Best wishes
Stephen
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[Haskell-cafe] class Arbitrary in quickcheck
I've notice a behaviour of quickcheck that is unexpected to me. With
this code:
import Test.QuickCheck
main = check myconfig
((\v - v == v) :: (Maybe Double,Maybe Double) - Bool)
myconfig = defaultConfig{configMaxTest=10,
configEvery = \n args - show n ++ :\n
++ unlines args}
I am relying on the default Arbitrary instances to generate pairs of
maybe doubles. But to my surprise, all of the pairs have these patterns:
(Just _ Just _)
(Nothing, Nothing)
I never see patterns:
(Just _, Nothing)
(Nothing, Just _)
Why is this the case?
Thanks,
Tim
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Re: [Haskell-cafe] class Arbitrary in quickcheck
your quick check property (in a different way of writing) is the following:
prop_1 :: Maybe Double - Bool
prop_1 v = v == v
but what you want is actually the following:
prop_2 :: Maybe Double - Maybe Double - Bool
prop_2 v1 v2 = v2 == v2
if I understood the problem correctly, using prop_2 should solve it. just
run
verboseCheckhttp://hackage.haskell.org/packages/archive/QuickCheck/1.1.0.0/doc/html/Test-QuickCheck.html#v:verboseCheckon
these two and observe the results.
Best,
On 5 May 2010 08:47, Tim Docker t...@dockerz.net wrote:
I've notice a behaviour of quickcheck that is unexpected to me. With
this code:
import Test.QuickCheck
main = check myconfig
((\v - v == v) :: (Maybe Double,Maybe Double) - Bool)
myconfig = defaultConfig{configMaxTest=10,
configEvery = \n args - show n ++ :\n
++ unlines args}
I am relying on the default Arbitrary instances to generate pairs of
maybe doubles. But to my surprise, all of the pairs have these patterns:
(Just _ Just _)
(Nothing, Nothing)
I never see patterns:
(Just _, Nothing)
(Nothing, Just _)
Why is this the case?
Thanks,
Tim
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Re: [Haskell-cafe] ANN: precis-0.3.1 - Cabal package diff tool
On Thu, 29 Apr 2010, Stephen Tetley wrote: I've upload precis to Hackage - a diff tool for Cabal packages. I have added a note to: https://www.haskell.org/haskellwiki/Package_versioning_policy ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Haskell and scripting
Limestraël limestrael at gmail.com writes: (*) functional language, because I want to keep the benefit of functional programming for scripting. So no Lua, no Python... You might want to take another look at lua. It is pretty darn functional. Also fast, small, and seems to be even easier to embed in haskell than in c. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] class Arbitrary in quickcheck
There is a typo, in my previous post, It should have been: prop_2 v1 v2 = v1
== v2
not: prop_2 v1 v2 = v2 == v2
Moreover, I realised that the (nice) function verboseCheck doesn't exist in
QuickCheck 2. However you can always do the following in ghci, to see
whether my suggestion works or not:
sample (arbitrary :: Gen (Maybe Double, Maybe Double) )
On 5 May 2010 09:01, Ozgur Akgun ozgurak...@gmail.com wrote:
your quick check property (in a different way of writing) is the following:
prop_1 :: Maybe Double - Bool
prop_1 v = v == v
but what you want is actually the following:
prop_2 :: Maybe Double - Maybe Double - Bool
prop_2 v1 v2 = v2 == v2
if I understood the problem correctly, using prop_2 should solve it. just
run
verboseCheckhttp://hackage.haskell.org/packages/archive/QuickCheck/1.1.0.0/doc/html/Test-QuickCheck.html#v:verboseCheckon
these two and observe the results.
Best,
On 5 May 2010 08:47, Tim Docker t...@dockerz.net wrote:
I've notice a behaviour of quickcheck that is unexpected to me. With
this code:
import Test.QuickCheck
main = check myconfig
((\v - v == v) :: (Maybe Double,Maybe Double) - Bool)
myconfig = defaultConfig{configMaxTest=10,
configEvery = \n args - show n ++ :\n
++ unlines args}
I am relying on the default Arbitrary instances to generate pairs of
maybe doubles. But to my surprise, all of the pairs have these patterns:
(Just _ Just _)
(Nothing, Nothing)
I never see patterns:
(Just _, Nothing)
(Nothing, Just _)
Why is this the case?
Thanks,
Tim
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--
Ozgur Akgun
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[Haskell-cafe] Re: Is anyone using Haddock's support for frames?
+1 to keep it until equivalent functionality is made mainline I've had tinyurl.com/haskelldoc aliased to the main frame page (http://www.haskell.org/ghc/docs/6.12.2/html/libraries/frames.html) and used it extensively on a daily basis for GHC libraries and GHC API browsing. Navigating the current non-framed, disparate, seperate documetation feels painful and slow. I would note though that the frames pages arn't currently working on hackage: e.g. http://hackage.haskell.org/packages/archive/text/0.7.1.0/doc/html/frames.html). BTW, I would point out the two best documentation systems I've seen in other languages (javadoc[1] and rubydock[2]) are frame based and (IMO) very easy to navigate. [1] http://java.sun.com/javase/6/docs/api/ [2] http://www.ruby-doc.org/core/ Cheers, Tris On Tue, May 04, 2010 at 08:19:45PM +0200, David Waern wrote: Hi Since version 2.4.0 Haddock has generated HTML output that uses frames (index-frames.html) in addition to the normal output. We'd like to deprecate this feature unless there is a significant amount of users. The reason is two-fold: * We probably want to replace the frames with something more modern (like a sidebar on the same page) in the future * We are rewriting the HTML backend and it would be nice to avoid unnecessary work So if you're using this feature and want to keep it, please speak up! cc:ing cvs-ghc@ in case they have any users of the frames due to the size of the GHC code base. (This might have been the the original motivation for the feature). Thanks, David ___ Cvs-ghc mailing list cvs-...@haskell.org http://www.haskell.org/mailman/listinfo/cvs-ghc ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] nun.haskell.org http services down?
I think it would be nice in general to be able to mirror at least hackage.haskell.org. Something like rsync would be close to ideal for this purpose. Reasons I would like to mirror hackage: 1 - Provide alternative when the main hackage is down 2 - Access to the sources of all uploaded packages for analysis purposes ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] nun.haskell.org http services down?
On Wed, 5 May 2010, Roel van Dijk wrote: I think it would be nice in general to be able to mirror at least hackage.haskell.org. Something like rsync would be close to ideal for this purpose. Reasons I would like to mirror hackage: 1 - Provide alternative when the main hackage is down 2 - Access to the sources of all uploaded packages for analysis purposes It would be also interesting to have alternative upload servers. That's certainly more complicated, but I know that the AmiNet manages this problem, e.g.: http://de.aminet.net/ The secondary upload servers queue the uploads and forward it to the main server, when it is available. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Fwd: Error instaling Happstack on Windows - cabal bug?
Stephen Tetley stephen.tet...@gmail.com writes:
Hi all
A cursory look at Happstack.Crypto.MD5 shows it uses -fvia-c:
{-# LANGUAGE BangPatterns #-}
{-# OPTIONS_GHC -funbox-strict-fields -fvia-c -optc-funroll-all-loops
-optc-O3 #-}
I would hazard a guess that this is at an attempt to improve performance
(I wouldn't know if it actually does or not though).
--
Ivan Lazar Miljenovic
ivan.miljeno...@gmail.com
IvanMiljenovic.wordpress.com
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Re: [Haskell-cafe] ANN: precis-0.3.1 - Cabal package diff tool
Hi Henning Thanks. I'm open to suggests for prettifying the output, or adding further comparisons. While coding precis, I decided that trying to police version numbers would be impractical so I decided to focus on changes/diffs instead. By the way - on the Package version policy page, Section 2 (Version Numbers) takes a lot of reading to make sense of (and I'm notionally a native English speaker). Maybe item 3 should state that D increases rather than the nebulus other version components. http://www.haskell.org/haskellwiki/Package_versioning_policy Best wishes Stephen ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] class Arbitrary in quickcheck
On 5 May 2010 09:01, Ozgur Akgun ozgurak...@gmail.com wrote: your quick check property (in a different way of writing) is the following: prop_1 :: Maybe Double - Bool prop_1 v = v == v I think you misunderstood me. The property was fabricated just for the example. My question was why, when I generate random values for (Maybe t, Maybe t) using the Arbitrary type class, do I always see two Nothing values or two Just values, and never one of each? Tim ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: precis-0.3.1 - Cabal package diff tool
On Wed, 5 May 2010, Stephen Tetley wrote: I'm open to suggests for prettifying the output, or adding further comparisons. While coding precis, I decided that trying to police version numbers would be impractical so I decided to focus on changes/diffs instead. Sure, but it helps to get an approximation of the necessary version bumps, right? By the way - on the Package version policy page, Section 2 (Version Numbers) takes a lot of reading to make sense of (and I'm notionally a native English speaker). Maybe item 3 should state that D increases rather than the nebulus other version components. http://www.haskell.org/haskellwiki/Package_versioning_policy I have not written the body of that page. Since it is a wiki feel free to improve whatever you think must be improved. Regards, Henning ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Long] Re: [Haskell-cafe] Re: Why cabal forces reinstallation of happstack-utils?
On Wed, 2010-05-05 at 12:13 +1000, Ivan Miljenovic wrote: On 5 May 2010 12:04, Maciej Piechotka uzytkown...@gmail.com wrote: 1. I downloaded happstack-utile[1] 2. Edited cabal file 3. Installed it successfully linking with parsec 3.1 4. I tried to run cabal install happstack --constraint 'parsec = 3' 5. It complains that happstack-utile needs to be installed against parsec 2 [1] Now it is HStringTemplate but problem is the same Did you try editing the HStringTemplate cabal file to remove its constraint against parsec = 3? Yes. See point 2. Also, is there any reason why you're forcing that constraint through (yes, upstream should start using parec-3, but why use --constraint to try and force it yourself)? Because it would download and rebuild packages on its own: % cabal install happstack --dry-run -v /usr/bin/ghc --numeric-version looking for package tool: ghc-pkg near compiler in /usr/bin found package tool in /usr/bin/ghc-pkg /usr/bin/ghc-pkg --version /usr/bin/ghc --supported-languages Reading installed packages... /usr/bin/ghc-pkg dump --global /usr/bin/ghc-pkg dump --user /usr/bin/ghc --print-libdir Reading available packages... Resolving dependencies... selecting happstack-0.5.0 (hackage) and discarding HStringTemplate-0.2, 0.3, 0.3.1, 0.3.2, 0.4, 0.4.1, 0.4.2, happstack-0.2.1, 0.3.1, 0.3.2, 0.4.1, happstack-data-0.1, 0.2.1, 0.3.1, 0.3.2, 0.3.3, 0.4.1, happstack-ixset-0.1, 0.2.1, 0.3.1, 0.3.2, 0.4.1, happstack-server-0.1, 0.2.1, 0.3.1, 0.3.2, 0.3.3, 0.4.1, happstack-state-0.1, 0.2.1, 0.3.1, 0.3.2, 0.3.3, 0.3.4, 0.4.1, happstack-util-0.1, 0.2.1, 0.3.1, 0.3.2, 0.4.1, harp-0.2.1, hsp-0.2, 0.4, 0.4.4, 0.4.5, 0.5.0, 0.5.1, hsx-0.4, 0.4.4, 0.4.5, 0.4.6, 0.4.8, 0.5.0, 0.5.1, 0.5.2, 0.5.5, 0.5.6, 0.6.0, 0.6.1 and 0.6.2 selecting happstack-data-0.5.0 (hackage) and discarding HaXml-1.19, 1.19.1, 1.19.2, 1.19.3, 1.19.4, 1.19.5, 1.19.6, 1.19.7, 1.20, 1.20.1, 1.20.2, syb-with-class-0.1, 0.2, 0.3, 0.4, 0.5, 0.5.1, 0.6, text-0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.7.0.1, time-1.0, 1.1.2.0, 1.1.2.1, 1.1.2.2, 1.1.2.3, 1.1.2.4 and 1.1.3 selecting happstack-server-0.5.0 (hackage) and discarding sendfile-0.1, 0.2, 0.3, 0.3.1, 0.4, 0.5, utf8-string-0.1, 0.2, 0.3, 0.3.1, 0.3.1.1, 0.3.2 and 0.3.3 selecting happstack-state-0.5.0 (hackage) selecting harp-0.4 (installed or hackage) selecting hsp-0.5.2 (installed or hackage) and discarding HJScript-0.4, 0.4.4, 0.4.5, 0.4.6, 0.4.7, 0.4.8 and 0.4.9 selecting HJScript-0.5.0 (installed or hackage) and discarding HJavaScript-0.4, 0.4.4 and 0.4.5 selecting hsx-0.7.0 (installed or hackage) and discarding haskell-src-exts-0.2.1, 0.3.2, 0.3.3, 0.3.4, 0.3.5, 0.3.7, 0.3.9, 0.3.10, 0.3.11, 0.3.12, 0.4.1, 0.4.2, 0.4.3, 0.4.3.1, 0.4.4, 0.4.4.1, 0.4.5, 0.4.6, 0.4.8, 0.5.2, 0.5.3, 0.5.4, 0.5.5, 0.5.6, 0.5.7, 1.0.0, 1.0.1, 1.1.0, 1.1.1, 1.1.3, 1.1.3.1, 1.1.4, 1.2.0, 1.3.0, 1.3.1, 1.3.2, 1.3.3, 1.3.4, 1.3.5 and 1.4.0 selecting sendfile-0.6.1 (hackage) selecting syb-with-class-0.6.1 (installed or hackage) and discarding template-haskell-2.2.0.0, 2.3.0.0 and 2.3.0.1 selecting syb-with-class-instances-text-0.0.1 (installed or hackage) selecting text-0.7.1.0 (installed or hackage) and discarding deepseq-1.0.0.0 selecting deepseq-1.1.0.0 (installed or hackage) and discarding array-0.1.0.0, containers-0.1.0.0 and 0.1.0.1 selecting ghc-prim-0.2.0.0 (installed) selecting ffi-1.0 (installed) selecting rts-1.0 (installed) selecting zlib-0.5.2.0 (installed or hackage) and discarding zlib-0.2, 0.3, 0.4, 0.4.0.1, 0.4.0.2, 0.4.0.3, 0.4.0.4 and 0.5.0.0 selecting html-1.0.1.2 (installed or hackage) and discarding html-1.0 and 1.0.1.1 selecting xhtml-3000.2.0.1 (installed or hackage) and discarding xhtml-3000.0.0, 3000.0.1, 3000.0.2.1, 3000.0.2.2, 3000.1.0.0 and 3000.2.0.0 selecting stm-2.1.1.2 (installed or hackage) and discarding stm-2.1, 2.1.1.0 and 2.1.2.0 selecting happstack-ixset-0.5.0.1 (hackage) and discarding happstack-ixset-0.5.0 selecting happstack-util-0.5.0.1 (installed or hackage) and discarding SMTPClient-0.1, 0.2, 0.3, 1.0, 1.0.1, happstack-util-0.5.0, network-2.0 and 2.1.0.0 selecting SMTPClient-1.0.2 (installed or hackage) and discarding hsemail-1.0, 1.1, 1.2, 1.3, 1.4 and 1.5 selecting hsemail-1.6 (installed or hackage) selecting unix-compat-0.1.2.1 (installed or hackage) and discarding unix-compat-0.1, 0.1.1 and 0.1.2.0 selecting strict-concurrency-0.2.3 (installed or hackage) and discarding strict-concurrency-0.1, 0.2, 0.2.1 and 0.2.2 selecting hslogger-1.0.10 (installed or hackage) and discarding hslogger-1.0.2, 1.0.4, 1.0.5, 1.0.6, 1.0.7 and 1.0.9 selecting binary-0.5.0.2 (installed or hackage) and discarding binary-0.2, 0.3, 0.4, 0.4.1, 0.4.2, 0.4.3, 0.4.3.1, 0.4.4, 0.5 and 0.5.0.1 selecting MaybeT-0.1.2 (hackage) and discarding MaybeT-0.1.0 and 0.1.1 selecting HaXml-1.13.3 (hackage) and discarding HaXml-1.13.2 selecting network-2.2.1.7 (installed or hackage) and discarding network-2.2.0.0, 2.2.0.1, 2.2.1, 2.2.1.1, 2.2.1.2, 2.2.1.3, 2.2.1.4, 2.2.1.5 and
Re: [Long] Re: [Haskell-cafe] Re: Why cabal forces reinstallation of happstack-utils?
Maciej Piechotka uzytkown...@gmail.com writes: Also, I note that you seem to use the Gentoo Haskell overlay (as you've made bug reports about it) but you're also building packages by hand; this can also lead to problems (don't mix your packages kids!). Possibly but: - I'd like to have gtk2hs, haskell-platform and ghc on system level instead of compiling it on my own. With exception of darcs i'm not using anything else from there. - Haskell overlay don't have all packages I need sufficiently fast. Well - it don't have everything I need in the first place. Well, we only update and include packages that _we_ know about and use; if a package is out of date or you want a new one, pop in to #gentoo-haskell and ask use. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: ANNOUNCE: happstack 0.5.0
On May 4, 2010, at 11:20 PM, Michael Snoyman wrote: Hey Jeremy, I see below that you included the experimental WAI support. I'm excited to try it out, but I don't see it in happstack-server (maybe I'm blind). Could you point it out? Hello, I should have been more explicit about this, sorry about that. The experimental WAI support is only available via darcs, in the happstack- wai sub-directory. darcs get http://patch-tag.com/r/mae/happstack cd happstack/happstack-wai You can browse here: http://www.patch-tag.com/r/mae/happstack/snapshot/current/content/pretty/happstack-wai The core is mostly there, though it is missing some of the Guards, and the FileServe module. Probably less than a day to finish it off I guess. Would be nice to do that now that 0.5 is out. The happstack-wai version would not be a drop-in replacement for happstack-server. There are some differences, such as the wai version supporting enumerators :) But, porting from happstack-server to happstack-wai should not require major changes. What remains to be seen is if happstack-wai actually provides better performance than happstack-server. alas, there is no happstack-wai specific demo at the moment. But, if there was, it would look a lot like a normal happstack-server app... - jeremy ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Haskell and scripting
How do you embed Lua in Haskell? 2010/5/5 Niclas W nicl...@gmail.com Limestraël limestrael at gmail.com writes: (*) functional language, because I want to keep the benefit of functional programming for scripting. So no Lua, no Python... You might want to take another look at lua. It is pretty darn functional. Also fast, small, and seems to be even easier to embed in haskell than in c. ___ 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 and scripting
Limestraël limestr...@gmail.com writes: How do you embed Lua in Haskell? http://hackage.haskell.org/package/hslua -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] class Arbitrary in quickcheck
On 5 May 2010 11:38, Tim Docker t...@dockerz.net wrote: On 5 May 2010 09:01, Ozgur Akgun ozgurak...@gmail.com wrote: your quick check property (in a different way of writing) is the following: prop_1 :: Maybe Double - Bool prop_1 v = v == v I think you misunderstood me. The property was fabricated just for the example. OK that's possible :) My question was why, when I generate random values for (Maybe t, Maybe t) using the Arbitrary type class, do I always see two Nothing values or two Just values, and never one of each? Let me try to understand you then. What happens when you run the following command in ghci? sample (arbitrary :: Gen (Maybe Int, Maybe Int) ) Do you still always get (Just _, Just _) or (Nothing, Nothing) pairs, or do you also get some (Nothing, Just _) or (Just _, Nothing) pairs? Ozgur ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Haskell and scripting
Thanks! However, I don't forget that my goal is to get a system monitor configuration language. Lua may have some functional components, it remains imperative, I think a more declarative language like Scheme would be more appropriate (and there is also a scheme interpreter, haskeem). What do you think about it? 2010/5/5 Ivan Lazar Miljenovic ivan.miljeno...@gmail.com Limestraël limestr...@gmail.com writes: How do you embed Lua in Haskell? http://hackage.haskell.org/package/hslua -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re[2]: [Haskell-cafe] Re: Haskell and scripting
Hello Ivan, Wednesday, May 5, 2010, 4:43:48 PM, you wrote: How do you embed Lua in Haskell? http://hackage.haskell.org/package/hslua tutorial: http://haskell.org/haskellwiki/HsLua -- 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] Re: ANNOUNCE: happstack 0.5.0
On Wed, May 5, 2010 at 2:41 PM, Jeremy Shaw jer...@n-heptane.com wrote: On May 4, 2010, at 11:20 PM, Michael Snoyman wrote: Hey Jeremy, I see below that you included the experimental WAI support. I'm excited to try it out, but I don't see it in happstack-server (maybe I'm blind). Could you point it out? Hello, I should have been more explicit about this, sorry about that. The experimental WAI support is only available via darcs, in the happstack-wai sub-directory. darcs get http://patch-tag.com/r/mae/happstack cd happstack/happstack-wai You can browse here: http://www.patch-tag.com/r/mae/happstack/snapshot/current/content/pretty/happstack-wai The core is mostly there, though it is missing some of the Guards, and the FileServe module. Probably less than a day to finish it off I guess. Would be nice to do that now that 0.5 is out. The happstack-wai version would not be a drop-in replacement for happstack-server. There are some differences, such as the wai version supporting enumerators :) But, porting from happstack-server to happstack-wai should not require major changes. What remains to be seen is if happstack-wai actually provides better performance than happstack-server. alas, there is no happstack-wai specific demo at the moment. But, if there was, it would look a lot like a normal happstack-server app... - jeremy It wouldn't look like a normal WAI app? If you want something like that, Simon Hengel wrote a nice Hello World for WAI; it's available in the github repo[1]. As far as performance goes, I can't imagine you'd see any significant difference without an enumerator-biased test, but I could be wrong. If you want to try something, I'd suggest outputting the contents of a file (obviously without the sendfile syscall). If you want help writing a WAI version, let me know, I'd be interested in the results of a comparison. Michael [1] http://github.com/snoyberg/wai/blob/master/README.lhs ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Why cabal forces reinstallation of happstack-utils?
Maciej Piechotka schrieb: On Wed, 2010-05-05 at 01:09 +0200, Daniel Fischer wrote: On Mittwoch 05 Mai 2010 00:55:38, Maciej Piechotka wrote: I try to configure happstack with parsec 3.1. It seems to fail due to cabal: happstack-util.cabal says parsec 3, so --constraint=parsec 3 and the given dependencies are incompatible, hence it can't be configured. Probably parsec 3 was specified because parsec-3.0 was significantly slower than parsec-2.*. I updated local copy, as shown, but cabal wants to rebuild it anyway. My question was rather why the repo is considered at all when the package is installed. Surprisingly using plain Cabal (runhaskell Setup configure; runhaskell Setup build; runhaskell Setup install) often works in these cases. Cabal-install is somehow too clever and if it cannot resolve the dependencies it thinks this must be impossible. If it finds a package, that it could not have installed by itself, it tries to install it by itself. First I thought that this due to cabal-install trying to find appropriate flag assignments by itself. However, Duncan Coutts told me that plain Cabal tries this as well. I have no idea, what the key difference between cabal-install and plain Cabal is. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Anglohaskell preparations?
Hi everyone. It's just over three months until the traditional time for Anglohaskell, so I wanted to ask: is anyone willing to step up and run it this year? We had a volunteer at last year's event, but I've forgotten who. It was also suggested that emails about the organisation and planning of the event be sent to the Hackathon mailing list, though it might be an idea to keep this thread on -cafe for now. If the event's going to run, we really need to try for dates and a venue in the next month or so. It's been a great event in previous years, and I'd love for it to happen again! -- fli...@flippac.org ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: ANNOUNCE: happstack 0.5.0
On May 5, 2010, at 8:01 AM, Michael Snoyman wrote: alas, there is no happstack-wai specific demo at the moment. But, if there was, it would look a lot like a normal happstack-server app... It wouldn't look like a normal WAI app? If you want something like that, Simon Hengel wrote a nice Hello World for WAI; it's available in the github repo[1]. Actually, I am wrong, I did have a little demo app: http://www.patch-tag.com/r/mae/happstack/snapshot/current/content/pretty/happstack-wai/Main.hs It looks exactly like a normal happstack app, and offers no clues that it is WAI based. main :: IO () main = simpleHTTP 8000 $ msum [ dir foo $ ok $ toResponse foo -- handles /foo , dir bar $ ok $ toResponse bar -- handles /bar , do nullDir-- handles / ok $ toResponse hello , notFound $ toResponse Invalid URL -- handles anything else ] In this demo, the routing dispatching is handled by the filter combinators such as 'dir' and 'nullDir' (there are also ones like 'path' which can be used for path components which represent 'variable' components such as integers). The combinators are based around MonadPlus -- hence the use of msum to combine them. They are tried in the order presented until one matches completely and returns a 'Response'. Of course, we could use web-routes instead. the functions like, 'ok' and 'notFound' take care of setting the response code. The 'toResponse' function takes care of converting the values (in this case strings) to a 'Response', and setting the Content-type. There are other features not shown here, such as looking up values submitted as POST data , via the query string, or as cookies. There is also stuff for dealing with exceptions, escaping early and returning a Response, ways to apply filters (such as gzip compression), ways to add on-the-fly validation (of html or other content types), and more! It is this high-level interface that makes happstack-server interesting. Hence the interest in using WAI for the 'backend' stuff that isn't really all that visible in the first place. As far as performance goes, I can't imagine you'd see any significant difference without an enumerator-biased test, but I could be wrong. If you want to try something, I'd suggest outputting the contents of a file (obviously without the sendfile syscall). If you want help writing a WAI version, let me know, I'd be interested in the results of a comparison. As for 'performance', there is the raw speed. But also issues like stability and reliability. And bugs. Or fixes for real-world usage. For example, implementing cookie handling by the spec does not quite work. There are some workarounds needed to handle cookies issued by google. And webkit and chrome browsers have issues with double quotes around the domain. Of course, these are also the reasons, ultimately, to use WAI. Instead of everyone having to learn that cookies are broken, and fix them in every framework, we can just do the hacks once, and everyone wins. - jeremy ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Why cabal forces reinstallation of happstack-utils?
On Wednesday 05 May 2010 15:45:38, Henning Thielemann wrote: Maciej Piechotka schrieb: On Wed, 2010-05-05 at 01:09 +0200, Daniel Fischer wrote: On Mittwoch 05 Mai 2010 00:55:38, Maciej Piechotka wrote: I try to configure happstack with parsec 3.1. It seems to fail due to cabal: happstack-util.cabal says parsec 3, so --constraint=parsec 3 and the given dependencies are incompatible, hence it can't be configured. Probably parsec 3 was specified because parsec-3.0 was significantly slower than parsec-2.*. I updated local copy, as shown, but cabal wants to rebuild it anyway. My question was rather why the repo is considered at all when the package is installed. Maciej, if you need to edit further .cabal files, you could make a minor- minor version bump, x.y.z - x.y.z.1 e.g., maybe that would convince cabal- install not to reinstall. Surprisingly using plain Cabal (runhaskell Setup configure; runhaskell Setup build; runhaskell Setup install) often works in these cases. That's not surprising. runhaskell ./Setup.hs configure can only go by what the .cabal file in the current directory and ghc-pkg say. If you edit the .cabal file to install e.g. happstack-util-0.5.0 with parsec-3, the changed .cabal file and the ghc-pkg output are consistent, so Cabal sees no reason to reinstall. cabal-install presumably looks at the downloaded index from Hackage (it must recursively follow the dependencies to see which of them must be installed before [and in which order]). The happstack-util .cabal file there says parsec 3. But ghc-pkg says - there is no parsec 3 installed or - happstack-util-0.5.0 was built with parsec-3.* (don't know which check comes first if both are made). That is inconsistent with what cabal-install knows from other sources, hence it assumes it's broken. Cabal-install is somehow too clever and if it cannot resolve the dependencies it thinks this must be impossible. If it finds a package, that it could not have installed by itself, it tries to install it by itself. First I thought that this due to cabal-install trying to find appropriate flag assignments by itself. However, Duncan Coutts told me that plain Cabal tries this as well. I have no idea, what the key difference between cabal-install and plain Cabal is. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Haskell and scripting
As the author of haskeem, I'm thrilled that you are considering it, but to be honest I'm not quite sure it's embeddable in the way (I think) you want. If you want to give it a try, though, I'd be more than happy to try to help. best, Uwe On 5/5/10, Limestraël limestr...@gmail.com wrote: Thanks! However, I don't forget that my goal is to get a system monitor configuration language. Lua may have some functional components, it remains imperative, I think a more declarative language like Scheme would be more appropriate (and there is also a scheme interpreter, haskeem). What do you think about it? 2010/5/5 Ivan Lazar Miljenovic ivan.miljeno...@gmail.com Limestraël limestr...@gmail.com writes: How do you embed Lua in Haskell? http://hackage.haskell.org/package/hslua -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] lhs2TeX - lhs2TeX.fmt missing
Hi all, I am trying to get lhs2TeX to work. I installed the package using cabal, and now I try to run it on a very simple *.lhs file. But it blames me and says user error, cannot find lhs2TeX.fmt: lhs2TeX: user error (File `lhs2TeX.fmt' not found in search path: And, when I check the search path, there really is no lhs2TeX.fmt file. Should I download it separately or something like that? PS: Thanks for the great package to the authors! Best, Ozgur Akgun ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Haskell and scripting
Maciej Piechotka wrote: After change of file you have to wait a long time as it compiles and links with yi. But Yi is a far bigger application than what Limestraël is talking about. One of my computers is very old and much less powerful than yours (let's just say that it has far less than 1 Gb memory in total). On that machine, xmonad, still much larger than Limestraël's app, recompiles its configuration file almost instantaneously. And of course, even that fast recompile only happens when I change the configuration, which is almost never. I would try the xmonad approach to scripting in Haskell. It is much simpler to implement than any of the others, and much neater if you find that it works well. Regards, Yitz ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Benchmarks game updated to ghc 6.12.2
Ketil Malde ketil at malde.org writes: As for code size, the programs are heavily tuned for speed. iirc there was a community effort 2 or 3 years ago, but now ghc has changed enough that the compiler and runtime parameters seem to need re-tuning. Is it an idea to go back a few steps to more idiomatic code? Perhaps as a separate track? There's always room for 2 or 3 Haskell programs per task - not necessarily The Good, the Bad and the Ugly - but you'll already find the cliched example of a faster more convoluted Haskell program and a more concise but slower Haskell program. (Idiomatic code? Aren't there idioms for writing fast Haskell too?) I also worry a bit that source code optimization for a specific compiler makes it more difficult to take advantage of compiler optimization improvements. These are tiny tiny programs - when those compiler optimization improvements arrive re-write the programs to take advantage of them ;-) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Benchmarks game updated to ghc 6.12.2
igouy2: Ketil Malde ketil at malde.org writes: As for code size, the programs are heavily tuned for speed. iirc there was a community effort 2 or 3 years ago, but now ghc has changed enough that the compiler and runtime parameters seem to need re-tuning. Even longer ago -- some of those 'optimized' programs date to 2005 if I recall. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Interest in a Mathematics AI strike force ?
Alp Mestanogullari wrote: Hello -cafe, When I started learning Haskell, I saw the AI page [1] which aimed at creating a sound, uniform and handy framework for AI programming in Haskell. I added my name on it and thought a bit about it. I even wrote a first version of HNN [2], a neural network library, quite early in my Haskell days. I found that idea to be great but did not see any actual effort around this. So, I'm now thinking again about that and even enlarging it to mathematics AI. Thus, I would like to have an idea of the number of people interested in being involved in such an effort. There are several tools out there on hackage but they aren't that much uniform and neither play nicely together. I'm pretty convinced this could be improved and as a Mathematics student I'm highly interested in that. If enough people are interested, we could for example set up a mailing list and a trac to organize the effort and then people could just discuss and write Haskell modules when time permits. Any comment, idea, reaction, interest ? [1] http://www.haskell.org/haskellwiki/AI [2] http://www.haskell.org/haskellwiki/HNN -- Alp Mestanogullari http://alpmestan.wordpress.com/ http://alp.developpez.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe Yea, I'm interested. Over the last several months I've been reading a few books on AI and have been trying to distill a Haskell library out of them: The library is pretty primitive so far, but this is what i have laid out: - Neural Networks (usable) - Blackboard Architecture (work in progress) - FSM (usable) - Genetic Algorithms (usable) - Goal Oriented Behaviors (work in progress) - Goal Oriented Planning (work in progress) - Markov Chains (work in progress) - Steering (usable) - Fuzzy Logic (usable) - Decision Tree (work in progress) At the moment I'm working on some constrained delaunay triangulation algorithms to use for spatial reasoning / path planning. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Would it be evil to add deriving Typeable to newtype Q?
Hi everybody, Is it reasonable to add deriving Typeable to newtype Q? In case you wonder why I want to do that, it is because I've constructed a Q [Dec] inside a monad, I want to extract it from the monad (via runIO) and the monad has constraint Typeable over this parameter. I've also tried to write the Typeable instance in my own module (not Language.Haskell.TH.Syntax). But I've got no luck since the Q type constructor is exported but the data constructor is not. Thanks. -- Leonel Fonseca. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Interest in a Mathematics AI strike force ?
On Wed, May 5, 2010 at 6:10 PM, Neal Alexander relapse@gmx.com wrote: Yea, I'm interested. Over the last several months I've been reading a few books on AI and have been trying to distill a Haskell library out of them: The library is pretty primitive so far, but this is what i have laid out: - Neural Networks (usable) - Blackboard Architecture (work in progress) - FSM (usable) - Genetic Algorithms (usable) - Goal Oriented Behaviors (work in progress) - Goal Oriented Planning (work in progress) - Markov Chains (work in progress) - Steering (usable) - Fuzzy Logic (usable) - Decision Tree (work in progress) At the moment I'm working on some constrained delaunay triangulation algorithms to use for spatial reasoning / path planning. That looks awesome! Would you have some time to drop by the #haskell-math IRC channel ? I'm planning to ask for a mailing list and a wiki for the project because a single mailing list thread won't be of help here. But for the moment most discussions happen on #haskell-math. Anyway, would you be willing to integrate your library in that project ? Side note : we're currently discussing the minimal algebra framework we will have to ship with the library, letting us implement general algorithms instead of specific ones (why being restricted to integers when any group / ring / field can be used ? etc). -- Alp Mestanogullari http://alpmestan.wordpress.com/ http://alp.developpez.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Interest in a Mathematics AI strike force ?
On Wed, May 5, 2010 at 12:10 PM, Neal Alexander relapse@gmx.com wrote: - Goal Oriented Behaviors (work in progress) - Goal Oriented Planning (work in progress) I have a library for PDDL parsing and representation[1] that I used in a recent paper. It's heavy complex types to deal with various extensions to the language. I'm currently updating it for another project, so if you're interested, please let me know! -Ron [1] http://www.cs.umd.edu/projects/planning/data/alford09translating/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Interest in a Mathematics AI strike force ?
That could be interesting. I guess we can discuss its integration, and how it would be done. Thus, you may be interested in my next message, about the mailing list and the repository. Thanks for your interest! On Wed, May 5, 2010 at 8:03 PM, Ron Alford ronw...@volus.net wrote: On Wed, May 5, 2010 at 12:10 PM, Neal Alexander relapse@gmx.com wrote: - Goal Oriented Behaviors (work in progress) - Goal Oriented Planning (work in progress) I have a library for PDDL parsing and representation[1] that I used in a recent paper. It's heavy complex types to deal with various extensions to the language. I'm currently updating it for another project, so if you're interested, please let me know! -Ron [1] http://www.cs.umd.edu/projects/planning/data/alford09translating/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Alp Mestanogullari http://alpmestan.wordpress.com/ http://alp.developpez.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: lhs2TeX - lhs2TeX.fmt missing
By the way, if someone on this list has got too much time, he could write something that would fulfill the goals of literate programming -- à la web and cweb. Knuth was able to make books with his source code. I believe that lhs2tex is great for classes about haskell or fp, but I never found it satisfying for programs with several modules, for instance. El 05/05/2010, a las 12:42, Ozgur Akgun escribió: OK, I've found them! They were under /Users/username/.cabal/share/lhs2tex-1.15 and this path was not in the search path of lhs2TeX. I'm using Snow Leoprad. This might be a bug I guess? Anyway, problem solved for me. Best, On 5 May 2010 16:03, Ozgur Akgun ozgurak...@gmail.com wrote: Hi all, I am trying to get lhs2TeX to work. I installed the package using cabal, and now I try to run it on a very simple *.lhs file. But it blames me and says user error, cannot find lhs2TeX.fmt: lhs2TeX: user error (File `lhs2TeX.fmt' not found in search path: And, when I check the search path, there really is no lhs2TeX.fmt file. Should I download it separately or something like that? PS: Thanks for the great package to the authors! Best, Ozgur Akgun -- Ozgur Akgun ___ 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] Re: Interest in a Mathematics AI strike force ?
Okay, people, if you're interested in this project, there are several things you should / may want to do. First, we now have a mailing list for discussing what should be part of that project, how things will be organized, etc. Please subscribe on this page : http://projects.haskell.org/cgi-bin/mailman/listinfo/hasklab We also have patch-tag project : https://patch-tag.com/r/alpmestan/hasklab/home If you want to participate: - if you already have a patch-tag account, just contact me (via the mailing list for example) for adding you to the project, so that you'll be able to push to the repo - if you don't have a patch-tag account, sign-up on http://patch-tag.com/and then ask for being added to the project. All the details about getting the code or whatever (there is none for the moment, in the upcoming days most of the activity should be on the mailing list) are listed on hasklab's patch-tag page. Finally, we also have a patch-tag wiki, here : https://patch-tag.com/r/alpmestan/hasklab/wiki/ I will edit it the wiki tonight to give some informations about what we discussed, the priorities, etc. Thanks all for your interest, please subscribe to the mailing list in order to discuss about what people are willing to do, how we should to it, etc. -- Alp Mestanogullari http://alpmestan.wordpress.com/ http://alp.developpez.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell and scripting
I'm still not always sure how things are done in Haskell, but I'd like to propose another alternative, or, saying more correctly, I'd like to question how real this alternative is. What if scripting would be done with something like lambdabot, mueval or hint? Do scripts always need to be compiled? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Is anyone using Haddock's support for frames?
Ok, I think I should clarify. I believe that the framed view with a long list of modules on the left and the haddocks on the right is still useful. What I don't mind getting rid off is the third frame which shows the contents of the mini_* files. I would have preferred to have something similar in the regular haddock (instead of the synopsis or the contents) make it less obtrusive by using a small font and make it float: right. That will be possible with the new HTML backend so I'm all for removing the mini_* stuff. The long list of modules should ideally be grouped by package, but that can be added later. I don't think it took longer than a few days to implement, so it shouldn't be much of an issue to port it over to a new backend. On 5 May 2010 10:34, Tristan Allwood t...@zonetora.co.uk wrote: +1 to keep it until equivalent functionality is made mainline I've had tinyurl.com/haskelldoc aliased to the main frame page (http://www.haskell.org/ghc/docs/6.12.2/html/libraries/frames.html) and used it extensively on a daily basis for GHC libraries and GHC API browsing. Navigating the current non-framed, disparate, seperate documetation feels painful and slow. I would note though that the frames pages arn't currently working on hackage: e.g. http://hackage.haskell.org/packages/archive/text/0.7.1.0/doc/html/frames.html). BTW, I would point out the two best documentation systems I've seen in other languages (javadoc[1] and rubydock[2]) are frame based and (IMO) very easy to navigate. [1] http://java.sun.com/javase/6/docs/api/ [2] http://www.ruby-doc.org/core/ Cheers, Tris On Tue, May 04, 2010 at 08:19:45PM +0200, David Waern wrote: Hi Since version 2.4.0 Haddock has generated HTML output that uses frames (index-frames.html) in addition to the normal output. We'd like to deprecate this feature unless there is a significant amount of users. The reason is two-fold: * We probably want to replace the frames with something more modern (like a sidebar on the same page) in the future * We are rewriting the HTML backend and it would be nice to avoid unnecessary work So if you're using this feature and want to keep it, please speak up! cc:ing cvs-ghc@ in case they have any users of the frames due to the size of the GHC code base. (This might have been the the original motivation for the feature). Thanks, David ___ Cvs-ghc mailing list cvs-...@haskell.org http://www.haskell.org/mailman/listinfo/cvs-ghc ___ Cvs-ghc mailing list cvs-...@haskell.org http://www.haskell.org/mailman/listinfo/cvs-ghc -- Push the envelope. Watch it bend. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: Holumbus-Distribution 0.1.0 - distributed data structures
Hello, after a long year, I've finally managed to upload the new version of Holumbus-Distribution to Hackage. Holumbus-Distribution offers distributed data structures like Chan, MVar or functions. These data types can be used for inter-process communication. With the help of this library it is possible to build Erlang-Style mailboxes for an easy implementation of distributed systems in Haskell. You can find the library on Hackage at: http://hackage.haskell.org/package/Holumbus-Distribution And the project homepage at: http://www.holumbus.org (for the current documentation please refer to the example programs in the source bundle, the Wiki will be updated soon) The following data structures are implemented so far: * distributed Chan (DChan) like the Chan datatype, but it allows the writing and reading from other programs * distributed MVar (DMVar) like the MVar data type, but the content of the MVar is shared among multiple programs. * distributed Functions (DFunction) an easy way to do remote procedure calls, just like haxr * distributed Values (DValue) a variable which could only be written once and which could easily read by other programs * distributed Streams and Ports (DStream, DPort) just like the DChan, but this time, you are only allowed to read from the channel from one program This library was completely rewritten between version 0.0.1 and 0.1.0. The old packages can be found under Holumbus.Network.* while the new ones are located at Holumbus.Distribution.*. The old packages will be removed in future versions (0.2.0). This library itself is independent from other Holumbus libraries although it contains some modules which are only to be used by the other Holumbus libraries but this may change in the near future. Regards, Stefan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell and scripting
Actually lambdabot and mueval use the GHC api, and hint is supposed to be a wrapper around it. But using the API directly is quite simple, and the scripts are indeed compiled. I believe that the purpose of scripting an application is adding fun factor to it. How many haskell programmers are able to find fun in lua programming ? El 05/05/2010, a las 14:23, Michael Lazarev escribió: I'm still not always sure how things are done in Haskell, but I'd like to propose another alternative, or, saying more correctly, I'd like to question how real this alternative is. What if scripting would be done with something like lambdabot, mueval or hint? Do scripts always need to be compiled? ___ 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: lhs2TeX - lhs2TeX.fmt missing
I've generated large LaTeX documents with several modules without too much hassle. The key was to use %include a lot, as well as conditionals. Lots of %if False around import statements. -chris On 5 mei 2010, at 20:18, Pierre-Etienne Meunier wrote: By the way, if someone on this list has got too much time, he could write something that would fulfill the goals of literate programming -- à la web and cweb. Knuth was able to make books with his source code. I believe that lhs2tex is great for classes about haskell or fp, but I never found it satisfying for programs with several modules, for instance. El 05/05/2010, a las 12:42, Ozgur Akgun escribió: OK, I've found them! They were under /Users/username/.cabal/share/lhs2tex-1.15 and this path was not in the search path of lhs2TeX. I'm using Snow Leoprad. This might be a bug I guess? Anyway, problem solved for me. Best, On 5 May 2010 16:03, Ozgur Akgun ozgurak...@gmail.com wrote: Hi all, I am trying to get lhs2TeX to work. I installed the package using cabal, and now I try to run it on a very simple *.lhs file. But it blames me and says user error, cannot find lhs2TeX.fmt: lhs2TeX: user error (File `lhs2TeX.fmt' not found in search path: And, when I check the search path, there really is no lhs2TeX.fmt file. Should I download it separately or something like that? PS: Thanks for the great package to the authors! Best, Ozgur Akgun -- Ozgur Akgun ___ 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
Re: [Haskell-cafe] Re: Haskell and scripting
Yes, the xmonad approach is very neat, but I see 2 major (IMO) drawbacks to it: 1) The end-user has to have GHC, and all the necessary libraries to compile the configuration 2) A scripting language should be simple and QUICK to learn : Haskell is clean, powerful but its learning takes time Uwe, I noticed kind of recently the haskeem package, I have not tried it yet and I didn't know its usability. If you say it's not made for that, then I believe you. 2010/5/5 Yitzchak Gale g...@sefer.org Maciej Piechotka wrote: After change of file you have to wait a long time as it compiles and links with yi. But Yi is a far bigger application than what Limestraël is talking about. One of my computers is very old and much less powerful than yours (let's just say that it has far less than 1 Gb memory in total). On that machine, xmonad, still much larger than Limestraël's app, recompiles its configuration file almost instantaneously. And of course, even that fast recompile only happens when I change the configuration, which is almost never. I would try the xmonad approach to scripting in Haskell. It is much simpler to implement than any of the others, and much neater if you find that it works well. Regards, Yitz ___ 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] posting UTF8 data with Curl library
Hello! I need to submit data to HTTP server using UTF8 encoding. I found out that libcurl for haskell can work with Data.ByteString - but it seems not able to work with Data.ByteString.UTF8. Can you please advice, how do I convert Data.ByteString.UTF8 into Data.ByteString and visa versa? Thank you in advance! -- Eugene Dzhurinsky pgpofkoKQbrb2.pgp Description: PGP signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] posting UTF8 data with Curl library
On Wednesday 05 May 2010 23:05:10, Eugeny N Dzhurinsky wrote: Hello! I need to submit data to HTTP server using UTF8 encoding. I found out that libcurl for haskell can work with Data.ByteString - but it seems not able to work with Data.ByteString.UTF8. Can you please advice, how do I convert Data.ByteString.UTF8 into Data.ByteString and visa versa? It's the same type, so you can encode it using Data.ByteString.UTF8 and send it over the network as a plain old ByteString. On the receiving end, you read it as a plain ByteString and then interpret it as a utf-8 encoded ByteString. Thank you in advance! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Haskell and scripting
Concerning your second point, I think just about any functional language isn't going to be simple or quick to learn. It's simply not a way of approaching problems that your average person (even your average programmer) is used to dealing with. Things like fold and map, the work horses of functional programming, are simply too foreign to most peoples imperative way of approaching problems. -R. Kyle Murphy -- Curiosity was framed, Ignorance killed the cat. On Wed, May 5, 2010 at 16:29, Limestraël limestr...@gmail.com wrote: Yes, the xmonad approach is very neat, but I see 2 major (IMO) drawbacks to it: 1) The end-user has to have GHC, and all the necessary libraries to compile the configuration 2) A scripting language should be simple and QUICK to learn : Haskell is clean, powerful but its learning takes time Uwe, I noticed kind of recently the haskeem package, I have not tried it yet and I didn't know its usability. If you say it's not made for that, then I believe you. 2010/5/5 Yitzchak Gale g...@sefer.org Maciej Piechotka wrote: After change of file you have to wait a long time as it compiles and links with yi. But Yi is a far bigger application than what Limestraël is talking about. One of my computers is very old and much less powerful than yours (let's just say that it has far less than 1 Gb memory in total). On that machine, xmonad, still much larger than Limestraël's app, recompiles its configuration file almost instantaneously. And of course, even that fast recompile only happens when I change the configuration, which is almost never. I would try the xmonad approach to scripting in Haskell. It is much simpler to implement than any of the others, and much neater if you find that it works well. Regards, Yitz ___ 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
Re: [Haskell-cafe] Haskell and the Software design process
* On Sunday, May 02 2010, Alexander Dunlap wrote: Of course, there are situations where it is really awkward to not use partial functions, basically because you *know* that an invariant is satisfied and there is no sane course of action if it isn't. To take a contrived example: f ys = let xs = (1:ys) in last xs uses the partial function last. Rewriting it in the non-partial style gives f ys = case (1:ys) of [] - Nothing xs - Just (last xs) but what possible meaning could a caller of the function ascribe to a Nothing result? It just means that there is a bug in f, which is what an error would tell you anyway. Of course, this particular function could easily be rewritten in such a way to be total, but I believe there are more complex examples where it is awkward/impossible to do so. You're just showing how difficult it is to reason about when the use of partial functions is safe: undefined), with your `non-partial style' version, you still leave open the case of (Just undefined), since we cannot convince ourselves that last only fails on empty lists here... One case where Maybe or Either might be less preferable to an exception is for the output of a lexer (ex. alex does this) because it means you can get some tokens without without forcing the whole input, and do some IO based on the results even if there is a mistake in either reading the input from disk or lexing it. But I think this situation of (ab)using lazy IO and exceptions is an oversimplification, and you can find appropriate alternatives such as iteratee which are more explicit about what is going on. -- Adam ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell XML Parsers
Hi, You might want to take a look at TagSoup (http://community.haskell.org/~ndm/tagsoup) - it parses XML/HTML lazily returning a stream of tags. It doesn't do nesting, but it does have good memory usage. Thanks, Neil On Fri, Apr 30, 2010 at 11:35 AM, R Senington sc06...@leeds.ac.uk wrote: Dear all, I have been looking at using XML for a little program I have been writing. The file I am currently trying to load is about 9MB, and I have now tried to use HaXml and HST. Without any of my own code, just a simple call to the basic parsers, they both use huge amount of memory. HST is the worst and about 7GB and climbing. HaXml uses 1.3Gb. The code I am using is HST xml - readFile file_name_here;k-runX (parseXmlDocument True) xml;print k and for HaXml x-readFile file_name_here let (Document _ _ e _) = xmlParse t x let t = myFilter $ CElem e print $ length t I have seen on previous posts to the cafe that other people have run into this problem with HST. Is this a general problem with XML in Haskell (I know that XML parsing is a slow and bulky process but this seems excessive)? Is there a known solution? Does anyone have any advice? Cheers RS ___ 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 and scripting
I do agree, but you will not object if I say that scheme is quicker to learn than Haskell. Most of all, I think Haskell is far too rigorous to serve scripting purposes for my app. Quick and dirty is clearly not the Haskell way. And is think its the very intrinsic nature of scripting to be done fast. Nevertheless, I'm not a bigot ^^, if you people think Lua is an appropriate language for what I'm trying to do, and if it is convenient to use with Haskell, then I'm willing to give it a go. 2010/5/5 Kyle Murphy orc...@gmail.com Concerning your second point, I think just about any functional language isn't going to be simple or quick to learn. It's simply not a way of approaching problems that your average person (even your average programmer) is used to dealing with. Things like fold and map, the work horses of functional programming, are simply too foreign to most peoples imperative way of approaching problems. -R. Kyle Murphy -- Curiosity was framed, Ignorance killed the cat. On Wed, May 5, 2010 at 16:29, Limestraël limestr...@gmail.com wrote: Yes, the xmonad approach is very neat, but I see 2 major (IMO) drawbacks to it: 1) The end-user has to have GHC, and all the necessary libraries to compile the configuration 2) A scripting language should be simple and QUICK to learn : Haskell is clean, powerful but its learning takes time Uwe, I noticed kind of recently the haskeem package, I have not tried it yet and I didn't know its usability. If you say it's not made for that, then I believe you. 2010/5/5 Yitzchak Gale g...@sefer.org Maciej Piechotka wrote: After change of file you have to wait a long time as it compiles and links with yi. But Yi is a far bigger application than what Limestraël is talking about. One of my computers is very old and much less powerful than yours (let's just say that it has far less than 1 Gb memory in total). On that machine, xmonad, still much larger than Limestraël's app, recompiles its configuration file almost instantaneously. And of course, even that fast recompile only happens when I change the configuration, which is almost never. I would try the xmonad approach to scripting in Haskell. It is much simpler to implement than any of the others, and much neater if you find that it works well. Regards, Yitz ___ 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
Re: [Haskell-cafe] Re: Haskell and scripting
On Wed, May 5, 2010 at 4:29 PM, Limestraël limestr...@gmail.com wrote: Yes, the xmonad approach is very neat, but I see 2 major (IMO) drawbacks to it: 1) The end-user has to have GHC, and all the necessary libraries to compile the configuration 2) A scripting language should be simple and QUICK to learn : Haskell is clean, powerful but its learning takes time For basic customization, many XMonad users (judging by questions on #xmonad) have little to no Haskell experience and get by. Further, it's easier to step down the power than to increase it; because we use Haskell, it's possible to have simpler configuration options like xmonad-light* * http://braincrater.wordpress.com/2008/08/28/announcing-xmonad-light/ isn't a very good explanation of xmonad-light, but I don't know of any others -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Haskell and scripting
Well, it is clear that, for me, the dyre approach is clearly the simplest to implement, since everything is in Haskell. Maybe I could start with it, and see if it suits me... (Sorry, I know, ^^ I keep changing my mind...) 2010/5/5 Gwern Branwen gwe...@gmail.com On Wed, May 5, 2010 at 4:29 PM, Limestraël limestr...@gmail.com wrote: Yes, the xmonad approach is very neat, but I see 2 major (IMO) drawbacks to it: 1) The end-user has to have GHC, and all the necessary libraries to compile the configuration 2) A scripting language should be simple and QUICK to learn : Haskell is clean, powerful but its learning takes time For basic customization, many XMonad users (judging by questions on #xmonad) have little to no Haskell experience and get by. Further, it's easier to step down the power than to increase it; because we use Haskell, it's possible to have simpler configuration options like xmonad-light* * http://braincrater.wordpress.com/2008/08/28/announcing-xmonad-light/ isn't a very good explanation of xmonad-light, but I don't know of any others -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] IO (Either a Error) question
ErrorT is just a newtype wrapper, changing the order/application of the type variables. newtype ErrorT e m a = ErrorT (m (Either e a)) runErrorT (ErrorT action) = action This gives the bijection: ErrorT :: m (Either e a) - ErrorT e m a runErrorT :: ErrorT e m a - m (Either e a) We can now redefine = for this new type to handle plumbing the error: instance (Error e, Monad m) = Monad (ErrorT e m) where return a = ErrorT (return (Right a)) m = f = ErrorT $ do ea - runErrorT m case ea of Left e - return (Left e) Right a - runErrorT (f a) fail s = ErrorT (return $ Left $ strMsg s) On Sun, May 2, 2010 at 1:50 AM, Eugene Dzhurinsky b...@redwerk.com wrote: :t ErrorT ErrorT :: m (Either e a) - ErrorT e m a At this point I am lost. I'm not sure that I do understand this type transformation correctly. So we have some sort of monadic type m, error type e and resut of type a. If m = IO, e - Error, a - String, than ErrorT :: IO (Either Error String) - ErrorT Error IO String Yep. I can think that can be written as ErrorT :: IO (Either Error String) - ErrorT Error (IO String) Am I correct? Nope. At the type level: ErrorT :: * - (* - *) - * - * That is, the to make the ErrorT concrete (kind *), you need a concrete type (e :: *) a type that takes a parameter (m :: * - *) and finally, a parameter (a :: *) (IO String) :: * whereas IO :: * - * String :: * The reason for this is because ErrorT is inserting Either in the proper place: ErrorT :: m (Either e a) - ErrorT e m a There's no way for ErrorT to do anything at the type level with (IO String). (Although if you go into crazy type system extensions, you could use GADTs to make a type that worked like that. Probably not useful, though!) Now we have (ErrorT e m) :: * - * which means it is eligible to be an instance of Monad, Functor, etc. So, if you can make your Error type an instance of this class, you can do this: runCalc = runErrorT (ErrorT (func1 p) = ErrorT . func2) Sorry, I don't understand how does it work. Can you please explain the type transformations involved here? Sorry, I typoed a bit here. runCalc p = runErrorT (ErrorT (func1 p) = ErrorT . func2) Lets just do some inference: func1 :: Int - IO (Either Error String) p :: Int func1 p :: IO (Either Error String) ErrorT (func1 p) :: ErrorT Error IO String func2 :: String - IO (Either Error [String]) (ErrorT . func2) :: String - ErrorT Error IO String (=) :: forall m a b. Monad m = m a - (a - m b) - m b IO is an instance of Monad If you make Error into an instance of Control.Monad.Error.Error then (ErrorT Error IO) is an instance of Monad So one instance of the type of (=): (=) :: ErrorT Error IO String - (String - ErrorT Error IO [String]) - ErrorT Error IO [String] (func1 p = ErrorT . func2) :: ErrorT Error IO [String] runErrorT (func1 p = ErrorT . func2) :: IO (Either Error [String]) And finally: runCalc :: Int - IO (Either Error [String]) -- ryan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Haskell and scripting
On Wednesday 05 May 2010 23:36:26, Limestraël wrote: but you will not object if I say that scheme is quicker to learn than Haskell. Well, I do object. Learning Haskell went like a breeze (not to perfection, but well enough). Only Python was nearly as easy and quick to learn. Learning Lisp dialects is much harder (to a large part because of the parentheses, which makes them near impossible to parse). ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Haskell and scripting
On May 5, 2010, at 3:09 PM, Daniel Fischer wrote: Learning Lisp dialects is much harder (to a large part because of the parentheses, which makes them near impossible to parse). On the contrary, the whole point of parentheses is that it makes Lisp *easier* to parse... for computers. :-) Cheers, Greg ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] darcs to mercurial migration
Hello, I'm switching from darcs to mercurial with some of my projects. I'd like to retain as much of the history as possible, what tools are there available for this? Günther ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] darcs to mercurial migration
Günther Schmidt wrote: Hello, I'm switching from darcs to mercurial with some of my projects. I'd like to retain as much of the history as possible, what tools are there available for this? The cannonical revision control conversion tool is called tailor: http://progetti.arstecnica.it/tailor/ I haven't used it myself but have heard that it has some problems. Obviously you shouldn't delete your old tree until you are 100% satisfied that the new one is intact. Erik -- -- Erik de Castro Lopo http://www.mega-nerd.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: class Arbitrary in quickcheck
On May 5, 10:57 pm, Ozgur Akgun ozgurak...@gmail.com wrote:
Let me try to understand you then. What happens when you run the following
command in ghci?
sample (arbitrary :: Gen (Maybe Int, Maybe Int) )
Do you still always get (Just _, Just _) or (Nothing, Nothing) pairs, or do
you also get some (Nothing, Just _) or (Just _, Nothing) pairs?
Well, I couldn't run the above code, as sample isn't part of
quickcheck-1.2.
But this made me wonder whether it's a version issue. This seems to
be the case. If I run this with quickcheck 2.1:
import Test.QuickCheck
main = quickCheckWith stdArgs{maxSuccess=10} f
f :: (Maybe Int,Maybe Int) - Bool
f (Just _,Just _) = True
f (Nothing,Nothing) = True
f _ = False
I see a failure almost instantly. This is what I want... I don't
expect all
of the generated pairs to have the same constructor in each field.
However, running this with quickcheck 1.2:
import Test.QuickCheck
main = quickCheckWith stdArgs{maxSuccess=10} f
f :: (Maybe Int,Maybe Int) - Bool
f (Just _,Just _) = True
f (Nothing,Nothing) = True
f _ = False
I see no failures... all of the generatd pairs have the same
constructor in each
field.
So the good news is that quickcheck 2.1 behaves as I expected. I'm
still curious
as to the behaviour of the older version.
Tim
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Re: [Haskell-cafe] Haskell XML Parsers
R Senington sc06...@leeds.ac.uk writes: Dear all, I have been looking at using XML for a little program I have been writing. The file I am currently trying to load is about 9MB, and I have now tried to use HaXml and HST. Without any of my own code, just a simple call to the basic parsers, they both use huge amount of memory. HST is the worst and about 7GB and climbing. HaXml uses 1.3Gb. If your needs are reasonably basic, you could consider trying: http://hackage.haskell.org/package/hexpat which is an FFI binding to expat. G -- Gregory Collins g...@gregorycollins.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Would it be evil to add deriving Typeable to newtype Q?
On 6 May 2010 02:17, Leonel Fonseca leone...@gmail.com wrote: Is it reasonable to add deriving Typeable to newtype Q? With GeneralizedNewtypeDeriving you mean? If so, then I don't see why it would be a problem. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Interest in a Mathematics AI strike force ?
Well, based on what you want your priorites to be, I might bow out then (at least until you start wanting to have graph-centric operations in there, then I might pitch in). On 6 May 2010 04:23, Alp Mestanogullari a...@mestan.fr wrote: We also have patch-tag project : https://patch-tag.com/r/alpmestan/hasklab/home Any particular reason for using patch-tag rather than code.haskell.org? For the wiki? My main objection to patch-tag is that projects are tied to the user who created them; as such, if you later on decide to leave the project then the entire thing has to be cloned and everyone's URLs will need changing (for homepage, etc.). This applies to github, etc. as well; I don't feel that they are ideal hosting sites for multi-user projects specifically because of this. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: lhs2TeX - lhs2TeX.fmt missing
On 6 May 2010 04:18, Pierre-Etienne Meunier pierreetienne.meun...@gmail.com wrote: By the way, if someone on this list has got too much time, he could write something that would fulfill the goals of literate programming -- à la web and cweb. Knuth was able to make books with his source code. I believe that lhs2tex is great for classes about haskell or fp, but I never found it satisfying for programs with several modules, for instance. I think the main difference between cweb and literate haskell is that the former allows documentation _anywhere_, whereas with literate haskell you can't suddenly cut out of a code block to have a discussion on what the next line means (instead you need to have an explicit comment). Unless GHC[i] starts stripping out all non-code from literate haskell files and joining all the code blocks together, I'm not sure if this situation can be remedied. El 05/05/2010, a las 12:42, Ozgur Akgun escribió: OK, I've found them! They were under /Users/username/.cabal/share/lhs2tex-1.15 and this path was not in the search path of lhs2TeX. I'm using Snow Leoprad. This might be a bug I guess? Not quite; the lhs2tex documentation says you need to put those .fmt, .sty, etc. files in a texmf directory. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Haskell and scripting
On 6 May 2010 08:25, Gregory Crosswhite gcr...@phys.washington.edu wrote: On May 5, 2010, at 3:09 PM, Daniel Fischer wrote: Learning Lisp dialects is much harder (to a large part because of the parentheses, which makes them near impossible to parse). On the contrary, the whole point of parentheses is that it makes Lisp *easier* to parse... for computers. :-) With the added advantage of making it easier for text editors to do automatic indentation properly for precisely the same reason (this is probably the only flaw with Haskell's indentation-centric coding style). -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] darcs to mercurial migration
2010/5/6 Günther Schmidt gue.schm...@web.de: I'm switching from darcs to mercurial with some of my projects. Out of curiosity, why? -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Interest in a Mathematics AI strike force ?
On Thu, May 6, 2010 at 2:19 AM, Ivan Miljenovic ivan.miljeno...@gmail.comwrote: Well, based on what you want your priorites to be, I might bow out then (at least until you start wanting to have graph-centric operations in there, then I might pitch in). Well, we do now want it to be graph-centric, but graphs definitely play a role here! We may want to implement algorithms relying on graphs. On 6 May 2010 04:23, Alp Mestanogullari a...@mestan.fr wrote: Any particular reason for using patch-tag rather than code.haskell.org? For the wiki? Yeah I thought about your objection, but the two main reasons are the gitit wiki (way handier for maths stuffs than trac's) and the easy handling of new contributors and project management -- it is way more manual on c.h.o for example, whereas everything is automated on patch-tag. The user-tied aspect is a bit annoying but should be fine ; i will definitely do mathematics and haskell for a while heh. -- Alp Mestanogullari http://alpmestan.wordpress.com/ http://alp.developpez.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Interest in a Mathematics AI strike force ?
On 6 May 2010 11:17, Alp Mestanogullari a...@mestan.fr wrote: On Thu, May 6, 2010 at 2:19 AM, Ivan Miljenovic ivan.miljeno...@gmail.com wrote: Well, based on what you want your priorites to be, I might bow out then (at least until you start wanting to have graph-centric operations in there, then I might pitch in). Well, we do now want it to be graph-centric, but graphs definitely play a role here! We may want to implement algorithms relying on graphs. OK, how about we do it this way: I'm currently involved in working on FGL with Louis Wasserman and Thomas Bereknyei and so can't really get involved with your strikeforce atm, but if you have an queries or want something done contact me and I'll see what I can do. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Set Operations In Haskell's Type System
On May 4, 9:46 am, Bartek Ćwikłowski paczesi...@gmail.com wrote:
hello,
2010/5/4 John Creighton johns2...@gmail.com:
I will continue to try to solve the problem on my own but at the
moment I'm able to get IsSuperSet to work but not the classes Isa,
Child and IsSubSet to work. Unlike set theory IsSubSet is not the same
as switching the order arguments in IsSuperSet because the searching
is done in the opposite direction. In one case we are searching the
parents and each child only has one parent. In the other Case we are
searching the children and each parent could have multiple children).
Since Subset is the opposite of Superset, you can search in the
easier (up) direction, so it really is as easy as reversing the
order of arguments.
It's not possible to write class/type-level function Child a b | a -
b, because functions (classes with fun-deps) must be deterministic. If
you want to enumerate all children (based on Parent class instances),
it's also impossible in this setup,
That's the approach I finally ended up taking. It seems to work so far
but I haven't tried using my child
function to build a subset or an isa function. My code is rather ugly
but it's the best I came up with. The
following are examples of the enumerations:
instance Parrent' () d Z Cat Feline --
instance Parrent' () d Z Feline Animal --
Z: means the first child
S Z: would be the second child instance
d is a type variable letting the relationship be bidirectional:
() is a dumby argument which is used in the case where their is no
instance.
It is used as follows:
instance (Parrent'' q d z anyChild anyParrent)=Parrent' q d z
anyChild anyParrent
instance (ItsAnOrphan ~ anyParrent)=Parrent'' q P1 n anyChild
anyParrent
instance (HasNoChildern ~ anyChild)=Parrent'' q N1 Z anyChild
anyParrent
instance (HasNoMoreChildern ~ anyChild)=Parrent'' q N1 (S n) anyChild
anyParrent
N1 is short for S Z
P1 is short for P Z (Negative numbers, P stands for previous)
it's probably possible with Oleg's
second-order typeclass programming[1].
[1]http://okmij.org/ftp/Haskell/types.html#poly2
But what are you actually trying to achieve? I can't thing of anything
useful that would require walking down the hierarchy tree (and
backtracking) and it has to be done at the type level.
Well, I need it for my Isa relationship defined so that
a isa d if their exists a b and c such that the following
conditions hold:
a isa subset of b,
b isa c
c is a subset of d
Thus we know d, but we need to search backwards to find c.
Anyway, I don't have the code for isa or subset yet but here is my
code for child (some more testing warranted):
Any hints on making it cleaner or more readable would be appreciated.
-
{-# LANGUAGE EmptyDataDecls,
MultiParamTypeClasses,
ScopedTypeVariables,
FunctionalDependencies,
OverlappingInstances,
FlexibleInstances,
UndecidableInstances,
TypeFamilies #-}
{-# LANGUAGE TypeOperators #-} --10
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE TypeSynonymInstances #-}
u=undefined
bla = child Z Animal
bla2 = child (u::P1) Animal
bla3 = child (u::Z) Cat
bla4 = child (u::P1) Cat
bla5 = parrent Cat
bla6 = parrent Feline
bla7 = parrent Animal
--20
---Instance SubType Relations
data ItsAnOrphan = ItsAnOrphan
instance (Show ItsAnOrphan) where show _ = ItsAnOrphan
data HasNoMoreChildern = HasNoMoreChildern
instance (Show HasNoMoreChildern) where show _ = HasNoMoreChildern
data HasNoChildern = HasNoChildern
instance (Show HasNoChildern) where show _ = HasNoChildern
--30
class Parrent' () P1 Z a b =Parrent a b| a-b where -- Specific Cases
parrent :: a-b --
instance Parrent' () P1 Z a b = Parrent a b where
parrent _ = undefined::b
class Parrent' q d n a b | q d n a- b, q d n b -a
class Parrent'' q d n a b | q d n a - b,q d n b - a
--class Parrent''' q n a b | q n b - a
instance Parrent' () d Z Cat Feline --
instance Parrent' () d Z Feline Animal --
instance (Parrent'' q d z anyChild anyParrent)=Parrent' q d z
anyChild anyParrent
instance (ItsAnOrphan ~ anyParrent)=Parrent'' q P1 n anyChild
anyParrent
instance (HasNoChildern ~ anyChild)=Parrent'' q N1 Z anyChild
anyParrent
instance (HasNoMoreChildern ~ anyChild)=Parrent'' q N1 (S n) anyChild
anyParrent
class Child n a b|n a-b where -- a2 is the parrent of b
child :: n-a-b
child _ _ = undefined::b
instance (
Parrent' () N1 n b2 a,
Child' b2 n a b --b2==b or b2=HasNoChildern or
b2==HasNoMoreChildern
)=
Child n a b
class Child' b2 n a b | b2 n a - b --a2==a or a2=HasNoChildern or
a2==HasNoMoreChildern
class Child'' q b2 n a b|q b2 n a b -b
class Child''' q b2 n a b|q b2 n a b -b
instance Child' HasNoChildern Z a HasNoChildern
instance Child' HasNoMoreChildern (S n) a HasNoMoreChildern
Re: [Haskell-cafe] Re: Haskell and scripting
Fifty years ago someone came up with this idea of lisp and parentheses. By now in year 2010, I have never heard of any programmer who never made jokes about it. Now imagine the discussions in 2060 : - ahah, you're still programming with monads. lol - no but theyre ok for dirty scripting. - all these =, significative indentation, You're from the past dude. - Wtf !!? haskell's easy to compile. - So what ? ... good luck limestraël ;-) El 05/05/2010, a las 18:25, Gregory Crosswhite escribió: On May 5, 2010, at 3:09 PM, Daniel Fischer wrote: Learning Lisp dialects is much harder (to a large part because of the parentheses, which makes them near impossible to parse). On the contrary, the whole point of parentheses is that it makes Lisp *easier* to parse... for computers. :-) Cheers, Greg ___ 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: Interest in a Mathematics AI strike force ?
We won't hesitate. Anyway, a part of your work will benefit HNN ;-) (and potential a potential Bayesian network library, e.g) Good luck to you for the work on graphs guys! On Thu, May 6, 2010 at 3:20 AM, Ivan Miljenovic ivan.miljeno...@gmail.comwrote: On 6 May 2010 11:17, Alp Mestanogullari a...@mestan.fr wrote: On Thu, May 6, 2010 at 2:19 AM, Ivan Miljenovic ivan.miljeno...@gmail.com wrote: Well, based on what you want your priorites to be, I might bow out then (at least until you start wanting to have graph-centric operations in there, then I might pitch in). Well, we do now want it to be graph-centric, but graphs definitely play a role here! We may want to implement algorithms relying on graphs. OK, how about we do it this way: I'm currently involved in working on FGL with Louis Wasserman and Thomas Bereknyei and so can't really get involved with your strikeforce atm, but if you have an queries or want something done contact me and I'll see what I can do. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com -- Alp Mestanogullari http://alpmestan.wordpress.com/ http://alp.developpez.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Would it be evil to add deriving Typeable to newtype Q?
Re-CC'ing -cafe:
On 6 May 2010 12:54, Leonel Fonseca leone...@gmail.com wrote:
I wasn't aware of GeneralizedNewtypeDeriving.
I just edited the source file Language.Haskell.TH.Syntax
and left:
newtype Q a = Q { unQ :: forall m. Quasi m = m a }
deriving Typeable
Hang on, is Q something actually in the template-haskell library? In
that case, you can't just do deriving (Typeable) .
However, you might be able to generate the Typeable instance using
DrIFT (see http://hackage.haskell.org/package/DrIFT-cabalized for a
cabal-install-able package).
--
Ivan Lazar Miljenovic
ivan.miljeno...@gmail.com
IvanMiljenovic.wordpress.com
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[Haskell-cafe] macosx-app for wxHaskell
In order to run apps built with wxHaskell on OS X, you're supposed to wrap the binary using a script called macosx-app ( http://www.haskell.org/haskellwiki/WxHaskell/MacOS_X). Unfortunately, after running cabal install wx this file is not in ~/.cabal - it's also not in the wxHaskell source. Does anyone know where I can find it? Thanks, Bill ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] macosx-app for wxHaskell
On 6 May 2010 13:25, Bill Atkins watk...@alum.rpi.edu wrote: In order to run apps built with wxHaskell on OS X, you're supposed to wrap the binary using a script called macosx-app (http://www.haskell.org/haskellwiki/WxHaskell/MacOS_X). Unfortunately, after running cabal install wx this file is not in ~/.cabal - it's also not in the wxHaskell source. Does anyone know where I can find it? This thread looks relevant: http://www.mail-archive.com/wxhaskell-us...@lists.sourceforge.net/msg00826.html However, it seems that macosx-app has disappeared with the cabalisation of wxhaskell :s -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] forall (What does it do)
I've seen forall used in a few places related to Haskell. I know their is a type extension call explicit forall but by the way it is documnted in some places, the documentation makes it sound like it does nothing usefull. However on Page 27 of Haskell's overlooked object system: We define an existential envelope for shape data. data OpaqueShape = forall x. Shape x = HideShape x “Opaque shapes are (still) shapes.” Hence, a Shape instance: nstance Shape OpaqueShape where readShape f (HideShape x) = readShape f x writeShape f (HideShape x) = HideShape $ writeShape f x draw (HideShape x) = draw x When building the scribble list, we place shapes in the envelope. let scribble = [ HideShape (rectangle 10 20 5 6) , HideShape (circle 15 25 8) It seems that forall can be used as a form of up casting. That is if we have a parametric type we can treat the parametric types as homogeneous: The paper did not seem to regard this feature too highly: By contrast, the explicit constraint for the existential envelope cannot be eliminated. Admittedly, the loss of type inference is a nuance in this specific example. In general, however, this weakness of existentials is quite annoying. It is intellectually dissatisfying since type inference is one of the added values of an (extended) Hindley/ Milner type system, when compared to mainstream OO languages. Worse than that, the kind of constraints in the example are not necessary in mainstream OO languages (without type inference), because these constraints deal with subtyping, which is normally implicit. We do not use existentials in OOHaskell http://homepages.cwi.nl/~ralf/OOHaskell/paper.pdf but can't we just use the read shape function above if we want to be able to infer based on types. I understand that haskers tend to like things well typed but surely their are times when we would like to be able to flatten the type of our data somewhat. On another note, I also wonder how forall relates to type families. I know their are certain restrictions on where we can use type families in haskell. I wonder if we can get around these somewhat using forall. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] mixing map and mapM ?
I was doing the following: do status - mapM PF.getFileStatus filenames let times = map PF.modificationTime status let sorted = sortBy (\(_, t1) (_,t2) - compare t1 t2) (zip filenames times) and I thought, surely I can combine the status and times definitions into one line, only I can't. Hint ? Thanks, Brian ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] mixing map and mapM ?
On 6 May 2010 15:01, bri...@aracnet.com wrote: I was doing the following: do status - mapM PF.getFileStatus filenames let times = map PF.modificationTime status let sorted = sortBy (\(_, t1) (_,t2) - compare t1 t2) (zip filenames times) times - mapM (liftM PF.modificationTime . PF.getFileStatus) filenames However, I'd be tempted to leave it as is (and hope/assume that fusion does its magic). -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] mixing map and mapM ?
On Thu, 6 May 2010 15:07:30 +1000 Ivan Miljenovic ivan.miljeno...@gmail.com wrote: On 6 May 2010 15:01, bri...@aracnet.com wrote: I was doing the following: do status - mapM PF.getFileStatus filenames let times = map PF.modificationTime status let sorted = sortBy (\(_, t1) (_,t2) - compare t1 t2) (zip filenames times) times - mapM (liftM PF.modificationTime . PF.getFileStatus) filenames However, I'd be tempted to leave it as is (and hope/assume that fusion does its magic). well now it's obvious :-) I did have liftM in there, but just couldn't quite figure out how to tie things together. to be completely clear : liftM takes modificationTime from Status - EpochTime to IO Status - IO EpochTime so now it can operate on the results of getFileStatus, which returns `IO Status`. mapM gathers the [IO EpochTime] into `IO [EpochTime]` and then - gives [EpochTime]. It's a little more clear in the verbose form, isn't it ? Thanks ! Brian ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] mixing map and mapM ?
On 6 May 2010 15:20, bri...@aracnet.com wrote: well now it's obvious :-) I did have liftM in there, but just couldn't quite figure out how to tie things together. to be completely clear : liftM takes modificationTime from Status - EpochTime to IO Status - IO EpochTime You can see it that way, yes (of course, liftM works on all monads, not just IO). so now it can operate on the results of getFileStatus, which returns `IO Status`. Operate directly on the returned values; you could always use something like (return . modificationTime) = getFileStatus file as well. mapM gathers the [IO EpochTime] into `IO [EpochTime]` and then - gives [EpochTime]. No, it's the sequence function that does that (but mapM f = sequence . map f). -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Database connection pool
Hi all, I would like to pool my database connections in an application I'm writing, and so far haven't found any prior art on the subject (besides this[1]). I was wondering if: * There's a package somewhere that does this * Others have implemented it and have suggestions * There's some big gotchas The stackoverflow that I linked to gives one approach to this that seems valid. My original thought on an implementation was to use a Chan. That way: * When a connection is released, is goes to the end of the pool, so connections get used evenly (not sure if this actually matters in practice). * If a process dies and for some reason doesn't return its connection, there shouldn't be a problem. Of course, I'd use bracket, so such a situation should never arise anyway. * Keep the coding against MVar to a minimum to avoid normal multi-threaded pitfalls. I'm using HDBC in this case, but I don't think I'll be using any HDBC-specific code. Thanks, Michael [1] http://stackoverflow.com/questions/1141677/concurrent-db-connection-pool-in-haskell ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
