Re: [Haskell-cafe] expanded standard lib
David Menendez [EMAIL PROTECTED] writes: Someone in a previous thread made an analogy between GHC and the linux kernel. I imagine that third-party Haskell distributions, consisting of GHC/Hugs/whatever and some bundled packages, would meet the desire for a batteries included Haskell implementation without tying the most popular libraries to GHC releases. Well - the various Linux distributions certainly could do this - providing a virtual haskell-libs package that just pulls in a bunch of commonly used packages. It'd be nice, of course, if that package was reasonably consistent across distributions, and if there were a corresponding installer for those other operating systems. -k -- If I haven't seen further, it is by standing in the footprints of giants ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Problems with do notation
worksFine = if True then putStrLn True else putStrLn False worksNOT = do if True then putStrLn True else putStrLn False worksAgain = do if True then putStrLn True else putStrLn False Of course the worksFine function returns an IO action, so has different behavior, but I mean the indentation is different. Is this by design? Also the following is rather strange: doubleDefError = let x = 1 x = 2 in x * x alsoDoubleDefError = do let x = 1 x = 2 return (x*x) doubleDefNOERROR = do let x = 1 let x = 2 return (x*x) Now I understand why this is (the second let starts a new invisible scope no?), but for newbies, this is all very strange :-) Cheers, Peter ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Problems with do notation
On Thu, 2007-11-22 at 09:19 +0100, Peter Verswyvelen wrote: worksFine = if True then putStrLn True else putStrLn False worksNOT = do if True then putStrLn True else putStrLn False worksAgain = do if True then putStrLn True else putStrLn False Of course the worksFine function returns an IO action, so has different behavior, but I mean the indentation is different. Is this by design? Also the following is rather strange: doubleDefError = let x = 1 x = 2 in x * x alsoDoubleDefError = do let x = 1 x = 2 return (x*x) doubleDefNOERROR = do let x = 1 let x = 2 return (x*x) Now I understand why this is (the second let starts a new invisible scope no?), but for newbies, this is all very strange :-) Now go and read about 'mdo' (recursive 'do' notation) ;) BTW, don't you get the same behaviour? foo = let x = 1 in let x = 2 in x * x ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Dynamically find out instances of classes (plugin system for haskell)
Hi, Is there any plugin system for haskell? For example, in Java, I can load all compiled classes from given directory, check their interfaces and run some methods through reflection etc. Is it possible in haskell, to load modules from given directory, and if in module there is instance of class then return instantiation of that class? I hope this is understandable what I'm trying to achieve here. Thank you, Radek. -- Codeside: http://codeside.org/ Przedszkole Miejskie nr 86 w Lodzi: http://www.pm86.pl/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Problems with do notation
On Nov 22, 2007 8:19 AM, Peter Verswyvelen [EMAIL PROTECTED] wrote:
worksFine =
if True
then putStrLn True
else putStrLn False
This is just an expression, the indentation is inconsequential.
worksNOT = do
if True
then putStrLn True
else putStrLn False
The first line, if True, sets the indentation level of the
statements in the do to two spaces. So this is interpreted as
worksNOT = do {
if True ;
then putStrLn True ;
else putStrLn False
}
Which is of course illegal.
worksAgain = do
if True
then putStrLn True
else putStrLn False
Here, the indentation level of the do is still two spaces, but then
then and else are at a higher indent than that, so they are
interpreted as part of the preceding expression. The rules are
actually very simple.
Luke
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Re: [Haskell-cafe] expanded standard lib
Duncan Coutts [EMAIL PROTECTED] writes: I did a quick popularity count by wget'ting the whole thing, and looking for hrefs under cgi-bin/packages/archive¹. That's quite fascinating. Thanks. You've convinced me we should add something like that :-). Note that that was only a direct count, I haven't implemented a real library rank. Please file a feature request: http://hackage.haskell.org/trac/hackage/ This okay? http://hackage.haskell.org/trac/hackage/ticket/183 -k -- If I haven't seen further, it is by standing in the footprints of giants ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: expanded standard lib
Ketil Malde wrote: David Menendez [EMAIL PROTECTED] writes: Someone in a previous thread made an analogy between GHC and the linux kernel. I imagine that third-party Haskell distributions, consisting of GHC/Hugs/whatever and some bundled packages, would meet the desire for a batteries included Haskell implementation without tying the most popular libraries to GHC releases. Well - the various Linux distributions certainly could do this - providing a virtual haskell-libs package that just pulls in a bunch of commonly used packages. It'd be nice, of course, if that package was reasonably consistent across distributions, and if there were a corresponding installer for those other operating systems. Meta-packages on hackage would do the trick, no? Regards, apfelmus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
RE: [Haskell-cafe] Dynamically find out instances of classes (pluginsystem for haskell)
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Radoslaw Grzanka Hi, Is there any plugin system for haskell? For example, in Java, I can load all compiled classes from given directory, check their interfaces and run some methods through reflection etc. Is it possible in haskell, to load modules from given directory, and if in module there is instance of class then return instantiation of that class? There are two libs that I'm aware of. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/plugins-1.0 http://hackage.haskell.org/cgi-bin/hackage-scripts/package/metaplug-0.1. 1 AFAICT, plugins is more mature and has a higher-level API, but the last time I looked it was not working on Windows under ghc = 6.6 (can anyone refute or verify this?) It's more like dynamic linking than Java's reflection: you have to already know what functions are in the module (and their types) to be able to call them. I'm not sure about directly creating values of data types exported from the module. 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. * ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Over-allocation
Don Stewart dons at galois.com writes: ByteStrings have all the same operations as lists though, so you can index, compare and take substrings, with the benefit that he underlying string will be shared, not copied. And only use 1 byte per element. Is there any parser built directly over ByteString that I could look at? Or maybe somebody implemented something like Text.ParserCombinators.ReadP for ByteString? From the first sight it seems doable, so there is light at the end of the tunnel :) -- Gracjan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] More problems [Tetris]
Hello Andrew, Wednesday, November 21, 2007, 9:26:45 PM, you wrote: It seems that the [Haskell] GLUT package isn't installed. at least i remember my own proposal to remove from GHC distribution graphics packages - because they are fat, rarely used and mostly outdated Hackage. ;-) But, alas, no. That doesn't work either. The reason? Well, apparently Cabal can't find sh. cabal by itself doesn't need sh. it's either required by library installation or it as just information message Not wanting to sound like somebody who just complains all day, but this kind of thing seems to be pretty typical of trying to get just about anything Haskell-related to work here. i agree. haskell world today is something like unix world 10 years ago. it attracts qualified people which step-by-step makes this world more attractive for casual users. but we are in the middle of the long road -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] expanded standard lib
snip Many other programming languages have packaging strategies that sound very similar. Several of them have managed to have a negative impact on platforms that already have good packaging technologies (i.e. almost every platform apart from Windows ;-). I'd hate to see Haskell go in a direction where packaging for e.g. Debian is made more difficult than it is at the moment. :) That would be very bad indeed. With careful implementation that shouldn't be a problem. Му reference to planet was regarding the ease of use and download of packages not installed in the system. That is integrated into the compiler via scheme macros or their equivalent in non-scheme languages: - just consider the following: (require (planet eval.ss (dherman javascript.plt 5 4))) if a package javascript verssion 5 4 by dherman is not present in your system or your user planet cache - download, and compile it, then proceed doing your normal compiler duties With distribution provided packages they will be present if installed by root. With user downloaded they go somewhere in home or whatever else sensible place is pointed in the environment. I simply don't see a conflict. It is the normal unix way. Being lazy is good after all. Having the tools infer all dependencies and provide them to you when you need them is a good thing as well. Just compare it with the: sudo apt-get xyz; echo I don't have root, I'll call dad, 'cause I want to compile I'm not sure if it is currently possible to implement that via template haskell. From the snippets I've glimpsed it implements a simple defmacro like mechanism. But does it allow executing actions at compile time? If yes, it can be done in a library and then tested for usability, packaging and destruction. I do think it is wrong to have it in the prelude, at least for quite a while, but having the option to do it is a plus. I think I went oveboard with this. Sorry for the longish post. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Dynamically find out instances of classes (pluginsystem for haskell)
Hi, Thanks for answer. There are two libs that I'm aware of. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/plugins-1.0 http://hackage.haskell.org/cgi-bin/hackage-scripts/package/metaplug-0.1. 1 Unfortunatly former needs gcc, latter does not compile . I will have to install msys or something I guess It's more like dynamic linking than Java's reflection: you have to already know what functions are in the module (and their types) to be able to call them. I'm not sure about directly creating values of data types exported from the module. I know the types - not a problem. I just don't know the names. Thanks, Radek. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: More problems [Tetris]
IMHO, no one in the right mind uses Windows voluntarily. :) I'm forced to use it at work, and it's a pain. But since many are forced to use Windows it would be nice if ghc was as well supported on Windows and Unix. On Nov 22, 2007 12:11 AM, Aaron Denney [EMAIL PROTECTED] wrote: On 2007-11-21, Andrew Coppin [EMAIL PROTECTED] wrote: In short, lots of Haskell-related things seem to be extremely Unix-centric and downright unfriendly towards anybody trying to set things up on Windows. If I didn't already know a bit about Unix, I'd be *really* stuck! I'd say, rather, that windows is unfriendly towards open and working common standards. -- Aaron Denney -- ___ 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] More problems [Tetris]
Peter Verswyvelen wrote: No GLUT is not bundled with GHC 6.8.1 anymore. Yes, that is weird. I think it's weird too, so I bug reported it: http://hackage.haskell.org/trac/ghc/ticket/1917 Jules ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Problems with do notation
On Thu, 22 Nov 2007, Peter Verswyvelen wrote: worksFine = if True then putStrLn True else putStrLn False worksNOT = do if True then putStrLn True else putStrLn False worksAgain = do if True then putStrLn True else putStrLn False Of course the worksFine function returns an IO action, so has different behavior, but I mean the indentation is different. Is this by design? That's somehow related to: http://www.haskell.org/pipermail/haskell-prime/2006-October/001771.html ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Problems with do notation
Hello Peter, Thursday, November 22, 2007, 11:19:20 AM, you wrote: Of course the worksFine function returns an IO action, so has different behavior, but I mean the indentation is different. Is this by design? to be exact, Haskell procedure is just a function returning an action. i recommend you to read http://haskell.org/haskellwiki/IO_inside the exact reason is different layout rules of expressions and do construct, as was already described -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re[4]: [Haskell-cafe] expanded standard lib
Hello Thomas, Wednesday, November 21, 2007, 6:30:17 PM, you wrote: zoho writer: online, not xml editor, but at least able to export into pdf/html/doc/.. It's not open source + it doesn't do what we need - Bang! \also they host stuff for you, and only have limited room for free usage. Relying on a company is not the way to go here (think of BitKeeper). this is actually commercial service which provides some form of try-before-you-buy facility. GHC docs, naturally, are not the thing they will be happy to host :) but at least it's some example - online wysiwyg editor with html/pdf output which may show our way into future. as you've written, there are other online editors which are open-source and free so we will be desired clients for such service/software there is also google docs - providing less facilities that zoho; i can't compare it to other free variants neither don't know whether it's okay to use it for free focs -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Over-allocation
Gracjan Polak gracjanpolak at gmail.com writes: Don Stewart dons at galois.com writes: ByteStrings have all the same operations as lists though, so you can index, compare and take substrings, with the benefit that he underlying string will be shared, not copied. And only use 1 byte per element. Is there any parser built directly over ByteString that I could look at? Or maybe somebody implemented something like Text.ParserCombinators.ReadP for ByteString? From the first sight it seems doable, so there is light at the end of the tunnel :) Just a success report, after 58 min of coding I got kind of ReadP parser over ByteString working and my memory usage went down from 1500MB to... 1.2MB! Over 1000 times better! Incredible! Thanks for the suggestion to do it with ByteStrings! I hope to publish it when I clean it up enough! -- Gracjan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Dynamically find out instances of classes (plugin system for haskell)
Hello Radoslaw, Thursday, November 22, 2007, 11:34:56 AM, you wrote: Is there any plugin system for haskell? For example, in Java, I can there is also ghc-as-a-library shortly said, ghc doesn't have dynamic abilities, so providing features you need without compiling the whole program on the fly is hardly possible -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Dynamically find out instances of classes (pluginsystem for haskell)
Is there any plugin system for haskell? For example, in Java, I can load all compiled classes from given directory, check their interfaces and run some methods through reflection etc. Is it possible in haskell, to load modules from given directory, and if in module there is instance of class then return instantiation of that class? I hope this is understandable what I'm trying to achieve here. not really: the only classes in haskell are type classes, and if there is any class instance missing at compile time, you won't even get to runtime, so you don't have to worry about loading instances at runtime!-) perhaps you could describe the problem you are trying to solve, rather than the solution you would like to see? in general, ghci and hugs allow you to browse your modules, find out types and names, run tests, etc. ghci can be scripted to some extent (not always comfortably, but possibly sufficient if you only want to find and run all functions named test*, for instance), and if that isn't enough, ghc has an api that allows you to program your own variant of ghci, among other things. claus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Dynamically find out instances of classes (pluginsystem for haskell)
2007/11/22, Claus Reinke [EMAIL PROTECTED]: Is there any plugin system for haskell? For example, in Java, I can load all compiled classes from given directory, check their interfaces and run some methods through reflection etc. Is it possible in haskell, to load modules from given directory, and if in module there is instance of class then return instantiation of that class? I hope this is understandable what I'm trying to achieve here. not really: the only classes in haskell are type classes, and if there is any class instance missing at compile time, you won't even get to runtime, so you don't have to worry about loading instances at runtime!-) Maybe I wasn't clear enough, maybe It is too much OO, maybe this is exploiting language, maybe there are better ways. ;) Let's say that in common module I have declaration (written from head, so may not compile - only for illustration) class Foo a where fun :: a - String This is my interface declaration. Now in seperate modules I have: data GreatFooInstance = GreatFooInstance instance Foo GreatFooInstance where fun a = 1 in another module I have data GreatFooInstance' = GreatFooInstance' instance Foo GreatFooInstance' where fun a = 2 at my main program I want to load all modules from directory and receive a structure of (lack of vocabluary here) instantiated instances of the class like this: l :: Foo a = [a] l = [GreatFooInstance, GreatFooInstance'] This above is illegal in haskell I believe, so some other approach should be taken. The question is what is correct way (if any) to handle this. But if it was legal then the usage might be like: o = map foo l I cannot be more specifc because this is just theory, I'm playing with haskell to know it features and limits. The key here is to add and remove modules and find the list of modules at runtime, load it and (with known interface) call its functions. Hope it is clear enough now. Thanks, Radek. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Searched for mdo on haskell.org. Found nothing.
I was reading the 'Problems with do notation' thread and Thomas Schilling suggested reading about mdo. Not knowing mdo I thought that sounds interesting and went to http://haskell.org/ which redirects you to http://haskell.org/haskellwiki/Haskell and gives you a search box. Typing mdo and clicking the Search button gives Showing below 0 results starting with #1. No page title matches No page text matches Note: unsuccessful searches are often caused by searching for common words like have and from, which are not indexed, or by specifying more than one search term (only pages containing all of the search terms will appear in the result). Maybe mdo is too common to be indexed? So I went to Google and searched for Haskell mdo and top of the list is this page : http://www.haskell.org/ghc/docs/latest/html/users_guide/syntax-extns.html which is Chapter 8. GHC Language Features 8.3. Syntactic extensions which describes mdo. Did I do something wrong when searching haskell.org? Richard. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Searched for mdo on haskell.org. Found nothing.
On 22/11/2007, Richard Kelsall [EMAIL PROTECTED] wrote: Did I do something wrong when searching haskell.org? You didn't use Google first? ;-) Seriously though, using the search box at haskell.org seems to be a dead loss. I'm sure this has come up in the past. D. -- Dougal Stanton [EMAIL PROTECTED] // http://www.dougalstanton.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Searched for mdo on haskell.org. Found nothing.
Hi All Richard Kelsall wrote: I was reading the 'Problems with do notation' thread and Thomas Schilling suggested reading about mdo. Not knowing mdo I thought that sounds interesting and went to http://haskell.org/ which redirects you to http://haskell.org/haskellwiki/Haskell and gives you a search box. Typing mdo and clicking the Search button gives Showing below 0 results starting with #1. No page title matches No page text matches Note: unsuccessful searches are often caused by searching for common words like have and from, which are not indexed, or by specifying more than one search term (only pages containing all of the search terms will appear in the result). Maybe mdo is too common to be indexed? So I went to Google and searched for Haskell mdo and top of the list is this page : http://www.haskell.org/ghc/docs/latest/html/users_guide/syntax-extns.html which is Chapter 8. GHC Language Features 8.3. Syntactic extensions which describes mdo. Did I do something wrong when searching haskell.org? Properly not. I think the problem is that haskell.org do not index words, that have length = 3. MediaWiki (which I think haskell.org uses) do not by default index short words (length = 3 or length = 4 - can't remember which). If you search for yhc you also get zero results, which does not make sense either. Greetings, Mads Lindstrøm ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
RE: [Haskell-cafe] Dynamically find out instances of classes (pluginsystem for haskell)
Bayley, Alistair-2 wrote: There are two libs that I'm aware of. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/plugins-1.0 http://hackage.haskell.org/cgi-bin/hackage-scripts/package/metaplug-0.1. 1 There is also http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hint-0.1 I managed to install it (though not without some hassle, i.e. having to use multiple Cabal versions), and make simple examples work. -- Grzegorz -- View this message in context: http://www.nabble.com/Dynamically-find-out-instances-of-classes-%28plugin-system-for-haskell%29-tf4855053.html#a13897174 Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Searched for mdo on haskell.org. Found nothing.
Thomas Schilling wrote: On Thu, 2007-11-22 at 13:23 +, Richard Kelsall wrote: I was reading the 'Problems with do notation' thread and Thomas Schilling suggested reading about mdo. Not knowing mdo I thought that sounds interesting and went to Gah, I was too lazy to add the proper references: A Recursive do for Haskell by Erkök and Launchbury http://www.cse.ogi.edu/PacSoft/projects/rmb/recdo.pdf A Recursive do for Haskell: Design and Implementation by Erkök and Launchbury http://www.cse.ogi.edu/PacSoft/projects/rmb/mdo.pdf And here's a nice use case for it: Assembly: Circular Programming with Recursive do by O'Connor http://www.haskell.org/sitewiki/images/1/14/TMR-Issue6.pdf Thank you. I'll have a read of those. I didn't mean to suggest you should have given all the details, just that haskell.org confused me by saying mdo didn't exist. I've just tried some other words from that page in the Search box and couldn't see any pattern to whether the page appears in the search results. Very strange. Maybe a message along the lines of We are hoping some generous person will improve this search feature at some point. The source code is here ... The search currently produces incomplete results. Please try Google if you do not find an answer. would be useful? Richard. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The Yampa Arcade: source code available?
I am also happy to hear this. When will the new version be released? Thanks, Bit On Nov 21, 2007 7:11 PM, Paul L [EMAIL PROTECTED] wrote: Just to echo back to the question whether Yampa/AFRP is still being developed, the answer is YES. We are working on an updated version at Yale. But really, we have many choices of doing reactive programming, and AFRP is only one of them. And even for AFRP, there are many choices of combinators and event switch constructs. There is still more research work to be done before we can settle on the interface for next version. I agree that more examples in the line of Space Invaders will serve the purpose of not only illustrating the capability, but also as tutorials to get people started. We'll first clean up existing code and bring it up to date, from which hopefully more examples could be developed. -- Regards, Paul Liu Yale Haskell Group http://www.haskell.org/yale On 11/20/07, Peter Verswyvelen [EMAIL PROTECTED] wrote: Thanks for the feedback. Unfortunatly the Space Invaders game uses HGL, which is not supported on Windows anymore. Is it supported on Linux? Frag does compile and run on Windows using GHC 6.6.1, so that might be a better starting point. What is the current consensus regarding (A)FRP? Is it a dead end? Are approaches like Modelica better suited for the job? From the point of view of a veteran assembly/C++ game hacker like myself, it is funny to see that the same problems popup when doing reactive programming in a pure language like Haskell or an imperative language like C++... Recursive dependencies are problematic, be it with signals in FRP or with objects in C++. In videogames using an imperative language, this is often solved by just adding a global single frame delay between what is read and what is written. Ugly, but works in many cases. Or a third object is introduced that breaks the recursive dependency between the two problematic objects. If I'm correct, when switching from FRP to AFRP signals (type Signal a = Time - a) are no first class values anymore, only signal functions (type SF a b = Signal a - Signal b) are first class. Furthermore the handling of recursive dependencies/feedback is done solely in a loop arrow. I must say it is frustratring. I finally got to understand FRP from the SOE book, only to find out that it is not really the way to go ;-) Now I'm trying to grasp AFRP. It is incredibly interesting stuff, but for a not-so-abstract-thinking-average programmer like me, it is not an obvious task. Maybe *using* AFRP is easier than understanding the inner details... Maybe it would be a good idea for the community if someone (maybe me, if I find the time ;-) to write a very very simple game using AFRP and GHC 6.8.1? Even simpler than the Space Invaders game (which does not work anymore anyway), but which does show dynamic collections and switching? Maybe like Andrew Coppin mentioned, a very simple Tetris clone? Of course, this is not legal, Tetris is copyrighted, but maybe for tutorial purposes it can be allowed :) Don Stewart wrote: sk: On 19.11.2007, at 19:54, Peter Verswyvelen wrote: I can find the paper, but is the source code for that Space Invaders alike game also available somewhere? it's included here: http://haskell.org/yampa/afrp-0.4-src.tgz btw, does anybody know what's the current state of affairs with yampa/ afrp? is the framework still developed further? Can we get this uploaded to hackage? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ 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] Searched for mdo on haskell.org. Found nothing.
Mads Lindstrøm wrote: ... Did I do something wrong when searching haskell.org? Properly not. I think the problem is that haskell.org do not index words, that have length = 3. MediaWiki (which I think haskell.org uses) do not by default index short words (length = 3 or length = 4 - can't remember which). If you search for yhc you also get zero results, which does not make sense either. ... Yes, it does look like MediaWiki and so I guess from the number of configuration options (if this is the right software) http://www.mediawiki.org/wiki/Manual:Configuration_settings there ought to be some clever setting somewhere rather than it needing any programming. Maybe the full search has been switched off to save resources? Experimenting with the search it seems to miss some longer words too, but I can't see a pattern to it. Richard. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Call external program and get stdout
Hi, How can I call a program (like, for instance, 'grep text *') and get the standard output? All actions I found (executeFile, system) do not give me the output of the program. Thanks, Maurício ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Tetris
On Nov 21, 2007 5:00 PM, Peter Verswyvelen [EMAIL PROTECTED] wrote: Last time I checked the SDL binding did not work properly on Windows when using GHCi. The next version of hsSDL (current darcs) has documentation that explains how to get ghci working. The trick is to make copies of the SDL.dll, since for some reason the way hsSDL is built through cabal, ghci looks for this dll under 2 additional names. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Call external program and get stdout
Maurício wrote: Hi, How can I call a program (like, for instance, 'grep text *') and get the standard output? All actions I found (executeFile, system) do not give me the output of the program. http://haskell.org/ghc/docs/latest/html/libraries/process-1.0.0.0/System-Process.html ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Dynamically find out instances of classes (pluginsystem for haskell)
the standard way to do that is use an existential wrapper: (This needs -fglasgow-exts or some flags) module Main where class Interface x where withName :: x - String data A = A String instance Interface A where withName (A string) = Interface A with ++ string ++ data B = B Int instance Interface B where withName (B int) = Interface B with ++ show int ++ data WrapInterface where WrapInterface :: forall z. Interface z = z - WrapInterface a :: A a = A seven b :: B b = B 7 listOfWrapInterface :: [WrapInterface] listOfWrapInterface = [ WrapInterface a , WrapInterface b , WrapInterface (A ()) , WrapInterface (B (-2007)) ] nameOfWrapped :: WrapInterface - String nameOfWrapped (WrapInterface q) = withName q instance Interface WrapInterface where withName = nameOfWrapped main = do putStrLn (show (map nameOfWrapped listOfWrapInterface)) putStrLn (show (map withName listOfWrapInterface)) In ghci this prints: *Main main [ Interface A with seven , Interface B with 7 , Interface A with () , Interface B with -2007 ] [ Interface A with seven , Interface B with 7 , Interface A with () , Interface B with -2007 ] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Dynamically find out instances of classes (pluginsystem for haskell)
ChrisK [EMAIL PROTECTED] wrote: the standard way to do that is use an existential wrapper: Does this relate to the basket of fruit problem in object oriented languages? You created the existential wrapper to allow a multimorphic list type? -- _jsn ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Composing monads
Hi, If I have two computations a-IO b and b-IO c, can I join them to get an a-IO c computation? I imagine something like a liftM dot operator. Thanks, Maurício ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Composing monads
On 22 Nov 2007, at 10:17 AM, Maurí cio wrote: Hi, If I have two computations a-IO b and b-IO c, can I join them to get an a-IO c computation? I imagine something like a liftM dot operator. This is called Kleisli composition, by the way; it's defined as (=) in Control.Monad. jcc ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to abort a computation within Continuation Monad?
On Thu, 2007-11-22 at 01:01 -0500, Dimitry Golubovsky wrote: Hi, I finally was able to write a function which grabs the remainder of the computation in Cont monad and passes it to some function, in the same time forcing the whole computation to finish by returning a final value. I am not sure what kind of wheel I have reinvented, but here it is: -- Home-grown continuation delimiter function. Passes remainder of the -- whole computation to a given function and forces the whole computation -- to complete by returning a final value. Something similar to returning -- a final value in plain CPS instead of invoking the continuation. -- f: function which the remainder of the program will be passed to. -- Remainder will not be evaluated. -- r: final value of the whole computation that the latter will be -- terminated with. delimit f r = Cont $ \c - runCont (return 0) $ \a - f (runCont (return a) c) r This is more complicated than it needs to be. runCont (return 0) = \k - k 0 so delimit f r = Cont $ \c - f (c 0) r ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Call external program and get stdout
Jules Bean wrote:
Maurício wrote:
Hi,
How can I call a program (like, for instance,
'grep text *') and get the standard output?
All actions I found (executeFile, system) do
not give me the output of the program.
http://haskell.org/ghc/docs/latest/html/libraries/process-1.0.0.0/System-Process.html
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I was using the following:
{-
A small function for blindly running a process until it completes
its output and then waiting for its exit code.
We return both the output (excluding stderr) plus the exit code.
-}
getProcessOutput :: String - IO (String, ExitCode)
getProcessOutput command =
-- Create the process
do (_pIn, pOut, pErr, handle) - runInteractiveCommand command
-- Wait for the process to finish and store its exit code
exitCode - waitForProcess handle
-- Get the standard output.
output - hGetContents pOut
-- return both the output and the exit code.
return (output, exitCode)
You'll need the following imports:
import System.IO
( hGetContents )
import System.Process
( runInteractiveCommand
, waitForProcess
)
import System.Exit
( ExitCode ( .. ) )
regards
allan
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Re: [Haskell-cafe] Re: More problems [Tetris]
Lennart Augustsson wrote: IMHO, no one in the right mind uses Windows voluntarily. :) I'm forced to use it at work, and it's a pain. But since many are forced to use Windows it would be nice if ghc was as well supported on Windows and Unix. What he said. ;-) I will say this: GHC itself (and the libraries that come with it) seem to work very well on Windows already. Download installer, double-click, press [Next] a few times, congratulations, you have a fully functional (get it?!) Haskell development box. Not much to improve there. (Well... GHC only adds itself to the current user's PATH, not system-wide. A switch for this would be nice...) It's just installing anything from Hackage which turns out to be really difficult. I understand Windows developers are a tad rare round here, so maybe that's understandable. I'd certainly be interested in hearing about anything practical that I can do to improve things on the Windows side... ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] question about ghci on windows ...
Brandon S. Allbery KF8NH wrote: On Nov 21, 2007, at 19:57 , Galchin Vasili wrote: Hi Ian, I am trying to dump out all function signatures exported from System.Directory. I just tried inside ghci: :! ghc --show-iface System.Directory. This is getting closer ... thank you! However, now there appears to be a path problem because I get an error message: System.Directory: openBinaryFile: does not exist (No such file or directory). ?? Just for reference: --show-iface is intended to operate on an explicitly specified .hi file, not a module name. You could locate System\Directory.hi in the ghc lib directory and run ghc --show-iface on that, or just use :browse. Also, --show-iface dumps low-level compiler data. In particular, it doesn't necessarily show you exactly what the module exports - but rather, it shows you when GHC might inline into client modules. ;-) If you want the callable interface, you want to be using the :browse command, not playing with interface files. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Composing monads
On Nov 22, 2007, at 13:17 , Maurí cio wrote: If I have two computations a-IO b and b-IO c, can I join them to get an a-IO c computation? I imagine something like a liftM dot operator. If you have GHC 6.8.1, this is the Kleisli composition operator (=) in Control.Monad. (There is also (=) which corresponds to (=).) Prelude Control.Monad :i (=) (=) :: (Monad m) = (a - m b) - (b - m c) - a - m c -- Defined in Control.Monad infixr 1 = Prelude Control.Monad :i (=) (=) :: (Monad m) = (b - m c) - (a - m b) - a - m c -- Defined in Control.Monad infixr 1 = -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED] system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED] electrical and computer engineering, carnegie mellon universityKF8NH ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Dynamically find out instances of classes (pluginsystem for haskell)
Jason Dusek wrote: ChrisK [EMAIL PROTECTED] wrote: the standard way to do that is use an existential wrapper: Does this relate to the basket of fruit problem in object oriented languages? You created the existential wrapper to allow a multimorphic list type? When you access the wrapped data then *_ONLY_* thing you can do with it is via the type class(es) that the GADT was wrapping. The example I gave had a single type class: data WrapInterface where WrapInterface :: forall z. Interface z = z - WrapInterface One could have multiple interfaces: data WrapInterface where WrapInterface :: (Interface z,Show z,Num z) = z - WrapInterface One could have more than one piece of data, note that WrapInterface takes three parameters: data WrapInterface where WrapInterface :: Interface z = z - z - z - WrapInterface One could do both: data WrapInterface where WrapInterface :: (Interface z1, Show z2,Num z3) = z1 - z2 - z3 - WrapInterface And so on. You can even write something like: data WrapInterface' where WrapInterface' :: a - (a-String) - WrapInterface' listExample = [ WrapInterface' Hello (show . (++ World)) , WrapInterface' 17 (show . succ) , WrapInterface' True (show . not) ] apply :: WrapInterface' - String apply (WrapInterface' item function) = function item main = do putStrLn (show (map apply listExample)) Now a WrapInterface' holds item a and a function a-String. When you unwrap this in a case statement you can then apply the function to the item to get the String. The output in ghci is: *Main main [\HelloWorld\,18,False] -- Chris ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] libSDL [Tetris]
Bit Connor wrote: Hello Andrew, ...yep, configure fails because it can't find sh. (Again.) This error can safely be ignored on windows. Apparently so. (A bit confusing then, no?) I'm rather loathed to install a Unix emulator just so I can install things from Hackage. cygwin is not required to build hsSDL on windows. Glad to hear it. :-) By the way, it turns out that SDL at least comes with a little text file explaining how to build it on Windows. (I overlooked this the first time.) Sadly, after following the instructions I still can't build it. The changes it told me to make didn't seem to have any effect. (And manually editing configuration files and C headers isn't my idea of a good time anyway...) What error are you getting? Many pages of them. Mostly about undefined symbols. I've deleted all the files now; I'll maybe have another go at it later so I can tell you the exact error. The next version of hsSDL (or current darcs) will not require editing of C headers. Good. :-) Editing the cabal config file is necessary so that the SDL include files and libs can be found. ...because Windows uses DLLs instead of [whatever it is that Unix does]? Out of curiosity, is there a reason I'm trying to compile the code myself in the first place? Is it just because that's the Unix way, or is there some deep reason why we can't just download prebuilt binaries? I am in favour of the idea of providing prebuilt binaries. Do you think something like the gtk2hs windows installer would be good? Gtk2hs is certainly drop-dead easy to install, no doubt about that. (Modulo some tricky path fiddling if you install Glade seperately as well... but that's no fault of the Haskell package.) Personally, given how tricky it generally is to build *most* things from source code (you have to have all the right tools to do it), I'd prefer to see *all* packages available in binary form. However, I guess the number of packages and possible target platforms makes this prohibitive... ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: More problems [Tetris]
Brandon S. Allbery KF8NH wrote: On Nov 22, 2007, at 14:25 , Andrew Coppin wrote: It's just installing anything from Hackage which turns out to be really difficult. I understand Windows developers are a tad rare round here, so maybe that's understandable. I'd certainly be interested in hearing about anything practical that I can do to improve things on the Windows side... I suspect this requires a wrapper around Cabal so a suitably equipped Windows developer can build a package and then wrap it up in an InstallerVise (or etc.) installer. What's actually involved in installing a 100% Haskell package? I was under the impression you just need to put the compiled code somewhere nice, and then tell GHC where you put it? Would it not be possible to write a Cabal package description that just takes a bunch of binary objects, puts them somewhere, and tells GHC? (Obviously if the package is a binding to some external library things become more complex...) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: More problems [Tetris]
On 22 Nov 2007, at 11:16 AM, Andrew Coppin wrote: Aaron Denney wrote: On 2007-11-21, Andrew Coppin [EMAIL PROTECTED] wrote: In short, lots of Haskell-related things seem to be extremely Unix-centric and downright unfriendly towards anybody trying to set things up on Windows. If I didn't already know a bit about Unix, I'd be *really* stuck! I'd say, rather, that windows is unfriendly towards open and working common standards. Or you could say that Windows *is* a common standard. (I stop short of working.) But it's unclear where such circular semantic fidgetting gets us. ;-) Or you could say that focusing on ‘standards’ is a good way to side- step the issue of whether those standards are technically sound or not; and that if the combination of Windows and Haskell is technically unsound, there are four possibilities: (0) Windows and Haskell are both themselves technically unsound; (1) Windows is technically unsound, and Windows + Haskell incorporates this unsoundness; (2) Haskell is technically unsound, and Windows + Haskell incorporates this unsoundness; or (3) Windows and Haskell are both technically sound, but in incompatible ways. I lean towards (1), naturally. But this doesn't answer the question of whether the lowest-cost solution is to fix Windows or work around it, of course. jcc ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] More problems [Tetris]
Bulat Ziganshin wrote: Hello Andrew, Wednesday, November 21, 2007, 9:26:45 PM, you wrote: Hackage. ;-) But, alas, no. That doesn't work either. The reason? Well, apparently Cabal can't find sh. cabal by itself doesn't need sh. it's either required by library installation or it as just information message Cabal doesn't give me this message for other packages, so presumably something about GLUT makes Cabal think that sh is necessary. i agree. haskell world today is something like unix world 10 years ago. it attracts qualified people which step-by-step makes this world more attractive for casual users. but we are in the middle of the long road OK, so we agree a problem exists. Now, what can we do to solve it? :-) My first question would be: - Is there a viable alternative to sh scripts for installing packages? If there is, it would seem it's just an issue of getting everybody to migrate to it. If there isn't, it looks like we need to make one... ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: More problems [Tetris]
Aaron Denney wrote: On 2007-11-21, Andrew Coppin [EMAIL PROTECTED] wrote: In short, lots of Haskell-related things seem to be extremely Unix-centric and downright unfriendly towards anybody trying to set things up on Windows. If I didn't already know a bit about Unix, I'd be *really* stuck! I'd say, rather, that windows is unfriendly towards open and working common standards. Or you could say that Windows *is* a common standard. (I stop short of working.) But it's unclear where such circular semantic fidgetting gets us. ;-) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: More problems [Tetris]
On Nov 22, 2007, at 14:25 , Andrew Coppin wrote: It's just installing anything from Hackage which turns out to be really difficult. I understand Windows developers are a tad rare round here, so maybe that's understandable. I'd certainly be interested in hearing about anything practical that I can do to improve things on the Windows side... I suspect this requires a wrapper around Cabal so a suitably equipped Windows developer can build a package and then wrap it up in an InstallerVise (or etc.) installer. -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED] system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED] electrical and computer engineering, carnegie mellon universityKF8NH ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Dynamically find out instances of classes (pluginsystem for haskell)
Claus Reinke wrote:
I hope this is understandable what I'm trying to achieve here.
not really: the only classes in haskell are type classes, and
if there is any class instance missing at compile time, you
won't even get to runtime, so you don't have to worry
about loading instances at runtime!-)
perhaps you could describe the problem you are trying
to solve, rather than the solution you would like to see?
In [gasp!] Java, you can just stick compiled files into a folder, and
write your main program such that ts scans this folder, loads anything
it finds, and executes specific code within it. In other words, an
instant plugin system. I imagine this is what the original poster is after.
I'm not 100% sure, but I think hsplugins can dynamically load compiled
*.o files in this way. Not sure whether this requires the person running
the main program to have GHC installed though.
Unlike Java, there's no reflection capabilities. This isn't too bad
though; just write your own class definition to allow your main program
to query the thing it just loaded and find out what it offers.
class Describable d where
available_functions :: d - [FunctionInfo]
data FunctionInfo = FunctionInfo {name :: String, description ::
String, ...}
Unlike general reflection (where you try to guess things from function
names and so on), this can be taylored to exactly the kind of plugins
you're trying to write.
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Re: [Haskell-cafe] More problems [Tetris]
On Nov 22, 2007, at 14:22 , Andrew Coppin wrote: My first question would be: - Is there a viable alternative to sh scripts for installing packages? If there is, it would seem it's just an issue of getting everybody to migrate to it. If there isn't, it looks like we need to make one... ActiveState Perl? Unfortunately, as long as you can't guarantee everything being installed in consistent places and/or invoked in consistent ways (which on Windows is well-nigh impossible due to conflicting version requirements) you need a way to search the system for stuff. If you don't want to require that people on Windows have a reasonable scripting language installed for such, you get to bundle (or write) one. It would be nice if Windows devs had come up with something like pkg- config; it'd be possible to do a minimal implementation just using CMD.EXE scripts (don't bother with the full GNU pkg-config framework, just have each package bundle a %foo%-CONFIG.CMD that dumps locations, compiler flags, etc. in an easily parsed form) and then a relatively simple Haskell module could check for packages by running their config scripts. But this requires convincing all the non- Haskell third party libraries (GLUT, SDL, etc.) to add config scripts to their distributions; practically, I don't see this happening. -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED] system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED] electrical and computer engineering, carnegie mellon universityKF8NH ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Dynamically find out instances of classes (pluginsystem for haskell)
I'm not 100% sure, but I think hsplugins can dynamically load compiled
*.o files in this way.
Correct.
Not sure whether this requires the person running
the main program to have GHC installed though.
Yes, it does.
Thanks ciao,
Leif
Unlike Java, there's no reflection capabilities. This isn't too bad
though; just write your own class definition to allow your main program
to query the thing it just loaded and find out what it offers.
class Describable d where
available_functions :: d - [FunctionInfo]
data FunctionInfo = FunctionInfo {name :: String, description ::
String, ...}
Unlike general reflection (where you try to guess things from function
names and so on), this can be taylored to exactly the kind of plugins
you're trying to write.
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Re: [Haskell-cafe] Composing monads
On Nov 22, 2007 1:22 PM, Jonathan Cast [EMAIL PROTECTED] wrote: On 22 Nov 2007, at 10:17 AM, Maurí cio wrote: Hi, If I have two computations a-IO b and b-IO c, can I join them to get an a-IO c computation? I imagine something like a liftM dot operator. This is called Kleisli composition, by the way; it's defined as (=) in Control.Monad. jcc Even if you didn't know about (=) (I didn't, actually!), it's not too hard to write yourself: (=) :: (Monad m) = (a - m b) - (b - m c) - (a - m c) (=) f g a = f a = g There's no magic, just follow the types. =) -Brent ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Source code for Visual Haskell
Hi all, The documentation of Visual Haskell mentions that the source code is available under a BSD license. The code is not available from the download page (http://www.haskell.org/visualhaskell/downloads.html). Does anone know where to get it? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] libSDL [Tetris]
On Nov 22, 2007 9:39 PM, Andrew Coppin [EMAIL PROTECTED] wrote: Editing the cabal config file is necessary so that the SDL include files and libs can be found. ...because Windows uses DLLs instead of [whatever it is that Unix does]? The reason is that on Unix, there are standard location for header files and libraries. On windows, they can be anywhere, and in the case of SDL, they are inside the directory where SDL was installed. Out of curiosity, is there a reason I'm trying to compile the code myself in the first place? Is it just because that's the Unix way, or is there some deep reason why we can't just download prebuilt binaries? I am in favour of the idea of providing prebuilt binaries. Do you think something like the gtk2hs windows installer would be good? Gtk2hs is certainly drop-dead easy to install, no doubt about that. (Modulo some tricky path fiddling if you install Glade seperately as well... but that's no fault of the Haskell package.) Personally, given how tricky it generally is to build *most* things from source code (you have to have all the right tools to do it), I'd prefer to see *all* packages available in binary form. However, I guess the number of packages and possible target platforms makes this prohibitive... On GNU/Linux it is usually not tricky at all to build things from source, and a lot of people prefer it over installing binaries. I do agree that binary packages should be available for windows. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Searched for mdo on haskell.org. Found nothing.
Hi Andrew, Andrew Coppin wrote: In general, I find *most* search functions to be fairly unhelpful. Google is the shining exception to this rule; it almost always seems to figure out what you're after. I guess doing text searching is just a fundamentally difficult problem, and the guys at Google have spent a hell of a long time on it. text searching is a well-known problem. ranking search results by relevance is the key to google's success. read the paper about google to learn more: Sergey Brin and Lawrence Page, The Anatomy of a Large-Scale Hypertextual Web Search Engine in: Proceedings of the 7th International WWW Conference, 1998, Brisbane http://infolab.stanford.edu/~backrub/google.html http://infolab.stanford.edu/pub/papers/google.pdf Tillmann ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] http/ftp library
Hello Haskell-Cafe, i write a file-processing utility and want to allow users open URLs like the usual files. for this, i need a library with minimum the following http functionality: getFileSize url readBuf url bufPtr offset size ideally, it should also support ftp and allow to create ftp files: h - create url writeBuf h bufPtr size close h what libraries can i use? ghc 6.6.1, if it's important -- Best regards, Bulat mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] emacs haskellers: r-stripping files becomes popular
Additionally, I find this to be helpful for keeping out trailing whitespace: ;; Highlight trailing whitespace in haskell files (add-hook 'haskell-mode-hook '(lambda () (setq show-trailing-whitespace t))) Cheers, -Greg Heartsfield On Fri, Nov 16, 2007 at 06:14:57PM +0200, Valery V. Vorotyntsev wrote: Add the following lines to your ~/.emacs: --- BEGIN OF ELISP CODE --- ;(global-set-key (kbd f9 s) 'delete-trailing-whitespace) (defun delete-trailing-whitespace-if-confirmed () Delete all the trailing whitespace across the current buffer, asking user for confirmation. (if (and (save-excursion (goto-char (point-min)) (re-search-forward [[:space:]]$ nil t)) (y-or-n-p Delete trailing whitespace? )) (delete-trailing-whitespace))) (add-hook 'before-save-hook 'delete-trailing-whitespace-if-confirmed) --- END OF ELISP CODE --- Have fun! -- vvv ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] http/ftp library
if you need comprehensive support of http and ftp in one api/library, as far as i know, the curl bindings are your only choice related...i promised a while back to support packaging and documentation of the curl bindings. this work is now delayed until freebsd 7 gains haskell support (due to acquiring new hardware, i had to upgrade my os). sorry to anyone who expected immediate results. pgp8N7UFN2PYo.pgp Description: PGP signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
