April 2010 - Haskell-Cafe

Re: [Haskell-cafe] Broken ghc documentation links
by Ivan Lazar Miljenovic 26 Apr '10

26 Apr '10

"haskell(a)kudling.de" <haskell(a)kudling.de> writes: > While the URL http://www.haskell.org/hoogle/ contains the word "Hoogle", the URL > http://haskell.org/ghc/docs/6.12.1/html/libraries/base-4.2.0.0/Prelude.html… > does not and it does no mention "Hoogle" on the page either. > > How did you determine that the latter is related to Hoogle? Oh, sorry, I misunderstood what you were doing; I thought the actual link you got from Hoogle was wrong (since a lot of people recently have been complaining that Hoogle should now point to the 6.12.2 documentation). In this case, you should talk to GHC maintainers. -- Ivan Lazar Miljenovic Ivan.Miljenovic(a)gmail.com IvanMiljenovic.wordpress.com

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Fwd: Re: [Haskell-cafe] Broken ghc documentation links
by haskell＠kudling.de 26 Apr '10

26 Apr '10

FYI ---------- Ursprüngliche Nachricht ---------- Von: "haskell(a)kudling.de" <haskell(a)kudling.de> An: Ivan Lazar Miljenovic <ivan.miljenovic(a)gmail.com> Cc: Neil Mitchell <ndmitchell(a)gmail.com> Datum: 26. April 2010 um 13:45 Betreff: Re: [Haskell-cafe] Broken ghc documentation links Hi, > So, the problem is that there are broken links _in Hoogle_; have you > thought about contacting the author Neil Mitchell directly? While the URL http://www.haskell.org/hoogle/ contains the word "Hoogle", the URL http://haskell.org/ghc/docs/6.12.1/html/libraries/base-4.2.0.0/Prelude.html… does not and it does no mention "Hoogle" on the page either. How did you determine that the latter is related to Hoogle? Bye, Lnny

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Ada-style ranges
by haskell＠kudling.de 26 Apr '10

26 Apr '10

Hi list, how would you describe Ada's ranges in Haskell's typesystem? http://en.wikibooks.org/wiki/Ada_Programming/Types/range I feel, you can not because this is a runtime property. Bye, Lenny

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Unicode strings and runCommand / runProcess
by John Goerzen 26 Apr '10

26 Apr '10

Here is a very interesting little problem. ghci GHCi, version 6.12.1: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude> :m System.Process Prelude System.Process> runCommand "echo привет" ?@825B This is a minimal test case for a bug reported in HSH at http://github.com/jgoerzen/hsh/issues#issue/1 It is not entirely clear to me what the behavior here should be. It seems inconsistent with the default behavior of System.IO to, apparently, just strip the bits higher than 0xFF. On the other hand, when it's OS commands we're talking about, it's not entirely clear to me if the default should be to encode in UTF-8. There should almost certainly be an *option* controlling this, and perhaps a version of runProcess that accepts ByteStrings. Thoughts? -- John

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London HUG domain expired
by Bayley, Alistair 26 Apr '10

26 Apr '10

> From: glasgow-haskell-users-bounces(a)haskell.org > [mailto:glasgow-haskell-users-bounces@haskell.org] On Behalf > Of Denys Rtveliashvili > > On the side note, is London HUG still active? The website > seems to be down... Looks like the London HUG domain (londonhug.net) registration has expired. Neil Bartlett was the registrant. Neil: do you plan to renew? Alistair ***************************************************************** Confidentiality Note: The information contained in this message, and any attachments, may contain confidential and/or privileged material. It is intended solely for the person(s) or entity to which it is addressed. Any review, retransmission, dissemination, or taking of any action in reliance upon this information by persons or entities other than the intended recipient(s) is prohibited. If you received this in error, please contact the sender and delete the material from any computer. *****************************************************************

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singleton types
by Günther Schmidt 26 Apr '10

26 Apr '10

Hello, HaskellDB makes extensive use of Singleton Types, both in its original version and the more recent one where it's using HList instead of the legacy implementation. I wonder if it is possible, not considering feasibility for the moment, to implement HaskellDB *without* using Singleton Types. Luke Palmer demonstrates in one blog post replacing type classes with data structures, so I wonder if this could also be applied in this setting. Best regards Günther

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Re: FGL up for adoption
by Louis Wasserman 26 Apr '10

26 Apr '10

I'd be really interested; I have a lot of improvements I'd personally like to make. Louis Wasserman wasserman.louis(a)gmail.com http://profiles.google.com/wasserman.louis

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Announcement: Data.ISO3166_CountryCodes version 0.1
by Jon Fairbairn 26 Apr '10

26 Apr '10

Just uploaded to hackage. Package providing datatype generated from the ISO3166 country code list. This was originally part of my Typeful HTMLs stuff, but I thought it deserved a wider audience. I think anything that uses country codes should use this datatype! As this is my first attempt at using cabal and uploading to hackage, expect errors and omissions. In particular, as I didn't want it to depend on template haskell, the build process generates the module's source file, which means that that file shouldn't be in the tarball. Cabal complains that it's missing if it's not there, so I created an empty .hsc file to shut it up. I'm sure this is not the right way, so I'd be glad to hear what is. -- Jón Fairbairn Jon.Fairbairn(a)cl.cam.ac.uk http://www.chaos.org.uk/~jf/Stuff-I-dont-want.html (updated 2009-01-31)

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I need help getting started
by mitchell＠kaplan2.com 26 Apr '10

26 Apr '10

Hi, I'm just starting to learn, or trying to learn Haskell. I want to write a function to tell me if a number's prime. This is what I've got: f x n y = if n>=y then True else if gcd x n == 1 then f x (n+1) y else False primeQ x = f x 2 y where y = floor(sqrt(x)) The compiler is very unhappy. Apparently there's some ambiguity in this, and I'm kind of running around in circles. I'd appreciate any help that will get me started.

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Threads freezing
by Eitan Goldshtrom 26 Apr '10

26 Apr '10

Hello fellow Haskell programmers, I seem to be having problems with some threads of mine. I wrote an OpenGL program that employs some threads (forkIO) in order to separate any calculations from the OpenGL code. At first it all seemed to be working just fine. Then I added some code for keyboard input to reset the program when you press 'r'. Since then my threads have been giving me problems. Just a second after the program starts all the calculations stop. The program is still running the code to display graphics (I tested this by putting "putStrLn "still displaying" into the display function) but the threads that do all of the computation don't seem to return from their threadDelay, which is only a delay of 5000 microseconds. I tried getting rid of the code for keyboard input but the problem is still there. I tried to run the program on another computer and it ran just fine (without keyboard input). Does anyone have any idea what could be going on? Additionally, I just tried compiling it to an executable and it seems that when I run it from that it works fine, with the keyboard input too. So I'm guessing the problem is with the interpreter? I'm not really sure. Haskell is still pretty mysterious to me. -Eitan

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