Re: [Haskell-cafe] Re: Hackage on Linux
Erik de Castro Lopo wrote: Andrew Coppin wrote: Windows has more package management facilities than most people realise. For example, go install Office 2007. In fact, just install Excel 2007, not the whole thing. Windows Installer can automatically figure out that you *do* need to install the Spell Checker (since Excel uses that), but you do *not* need to install the Grammar Checker (since only Word and PowerPoint use that, and you haven't selected to install those). Not only does it decide what to install, but you can query it Thats a specific installer for a specific program. It is. But my point is, it's not the program installer itself that provides all this functionallity. It's the Windows operating system. A 3rd party program can, for example, ask if component X of MS Office is installed, and if so, where it's located. You can set things up so that if some 3rd party needs to access a feature of MS Office that isn't currently installed, it installs it (if the installation files are cached; it used to ask for you to insert the install CD). For native Windows stuff, there are ways to check what version of DirectX is installed and update it if necessary; you don't have to write that code yourself, it's provided by the OS. Just like under (say) Debian, you don't have to implement apt-get yourself, it's provided for you. About the only thing *not* provided is the ability to automatically fetch the installer for whatever it is you need. And that's because usually to obtain the installer, you need to *pay money* to whatever company it is that *sells* it. The whole problem with windows is that every 3rd party program is responsible for its own installation and removal and is free to do that in its own way. It also encourgaes monolithic installers, installers that include everything. Each application can of course install itself in its own way. For some, that's as simple as unzipping an install image and putting it somewhere convinient. For others, it means running an elaborate installation program. But, the point I'm trying to get at is, there *is* a standard installation system (which you can of course choose not to package your application with), and if you use it, it gives you things like dependency resolution and telling you what stuff is installed where and so on. I agree with your last point, however; not having a central location where software can be obtained from *does* encourage monolithic installers. The installer is essentially a mini repo that contains the package and all its dependences; it then uses Windows to decide which [if any] of those dependencies are already installed or else need to be installed. However, the software you are complaining about is mostly FOSS software that had its genesis on Linux/Unix and assumes that build dependencies can be resolved at compile time and that install dependencies can be resolved at install time. Windows of course fails these two assumptions completely. On Linux, if I do, say, cabal install zlib, it falls over and tells me it can't find the zlib headers. So I go install them, rerun the command, and it works. On Windows, I issue the same command and it falls over and says that autoconf doesn't exist. It doesn't even *get* to the part where it looks for header files! Interestingly, even though everybody claims that it's impossible to support C bindings on Windows, gtk2hs has managed it somehow. If you try to built it, it complains that it can't find the GTK+ headers. Go install those, add them to the search path, and suddenly it builds just fine. No problems with it. Go figure... Until something like apt-get becomes popular, widespread and well supported, you are going to continue to feel pain. As I say, gtk2hs builds just fine today. (The upstream packaging of the Windows GTK+ port leaves a little to be desired, but that's not a Haskell problem.) It's as trivial as unpacking a few zip files and tweaking the search path. hoping that Linux and Mac devs will fix windows problems is not going to get you anywhere. How about hoping that Linux and Mac devs are going to realise that Windows doesn't have some of the problems that people claim it does? Hmm, thinking about it... nah, that's not happening anytime soon either. ;-) I guess it depends on whether you think your students are going into datacenter support (probably Unix) or desktop support or application development (obviously all desktops are Windows). Here's a funny thing. I know a large number of professional software engineers and people who mix that with sys admin work. Only a tiny fraction of those people write code for the windows platform. Do I conclude from my data that most developers develop for Linux? ...which leads us back to my I guess it depends then? My obviously all desktops are Windows was not meant to be entirely serious. But it's not exactly a revelation to state that
[Haskell-cafe] (automatic) type classes context inference
Hello everyone, I am developing a toolset in which I have several (multiparameter) type classes; It is often the case that I can only define a data-type X as an instance of one such class (say A), if X is an instance of another class (say B); The thing is that, while it is hard for me, because of all the type parameters that I have to deal with, to add 'X is an instance of B' to the context cxt_A in 'instance cxt_A = A X' ghc is always able to correctly infer all type parameters; In fact, I always get: 'Could not deduce (B X t1 ... tn) from the context cxt_A arising from ... Probable fix: add (B X t1 ... tn) to the context cxt_A ...' In my case, this is the fix that I always need: most of the times, I am just copy-pasting (B X t1 ... tn) to cxt_A! Is there a way, say a compilation option, to avoid this? can anyone please help me here? :) thank you very much -- João Paulo Fernandes Universidade do Minho www.di.uminho.pt/~jpaulo ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] type classes and logic
Daniel Fischer wrote: class BEING human = HUMAN human where Sub-classing is logical implication BEING(human) = HUMAN(human) All types t that make BEING(t) = true also make HUMAN(t)=true No, it's the other way round. Every HUMAN is also a BEING, hence HUMAN(t) = BEING(t) Could I say that HUMAN is a subset of BEING? Sebastian Fischer wrote: You can define subclasses even if no instances exist. And as Daniel said, the code class BEING human = HUMAN human where defines a subclass HUMAN of BEING which means that every instance of HUMAN must also be a BEING. You can read it as: a BEING is also a HUMAN by the following definitions. Thanks for pointing out my error But I am still not sure of the interpretation of logical implication wrt to sub-classes. Lets simplify the representation and just regard the classes in the example as propositions (instead of predicates). I am not sure if this simplification still makes the example valid. Below is a reasonable interpretation of propositional logical implication. a) If I wear a raincoat then I stay dry (sufficient condition) wareRaincoat = stayDry b) I will stay dry only if I ware a raincoat(necessary condition) stayDry = wareRaincoat In the light of the above examples how should I interpret the class-to-subclass relation as logical implication? Is it a) If BEING then HUMAN (sufficient condition): BEING = HUMAN b) HUMAN is true only if BEING (necessary condition): HUMAN = BEING c) Neither? Thanks, Pat This message has been scanned for content and viruses by the DIT Information Services E-Mail Scanning Service, and is believed to be clean. http://www.dit.ie ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] multi-line strings (Was: Hackage on Linux)
Hi, Am Samstag, den 28.08.2010, 08:18 +1000 schrieb Ivan Lazar Miljenovic: On 28 August 2010 00:02, Felipe Lessa felipe.le...@gmail.com wrote: On 8/27/10, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: Admittedly, Haskell has no multi-line String support which would make defining something like the Description field harder... Quick correction: Haskell *does* have multi-line strings. For example: This is a\ \ nice string I meant in the sense of Python, etc. where you didn't have to insert newline characters, etc. in. A similar problem is solved by http://github.com/jgm/hsb2hs which might be useful if you need to embed larger pieces of text. Greetings, Joachim -- Joachim nomeata Breitner mail: m...@joachim-breitner.de | ICQ# 74513189 | GPG-Key: 4743206C JID: nome...@joachim-breitner.de | http://www.joachim-breitner.de/ Debian Developer: nome...@debian.org signature.asc Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] multi-line strings (Was: Hackage on Linux)
On 28 August 2010 20:55, Joachim Breitner m...@joachim-breitner.de wrote: Hi, Am Samstag, den 28.08.2010, 08:18 +1000 schrieb Ivan Lazar Miljenovic: On 28 August 2010 00:02, Felipe Lessa felipe.le...@gmail.com wrote: On 8/27/10, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: Admittedly, Haskell has no multi-line String support which would make defining something like the Description field harder... Quick correction: Haskell *does* have multi-line strings. For example: This is a\ \ nice string I meant in the sense of Python, etc. where you didn't have to insert newline characters, etc. in. A similar problem is solved by http://github.com/jgm/hsb2hs which might be useful if you need to embed larger pieces of text. Huh, very nice; thanks for the link. Unfortunately, it doesn't look like John has released a version on Hackage yet :( Then again, the first commit on github was the beginning of this month... -- 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] multi-line strings (Was: Hackage on Linux)
Hi, Am Samstag, den 28.08.2010, 21:11 +1000 schrieb Ivan Lazar Miljenovic: A similar problem is solved by http://github.com/jgm/hsb2hs which might be useful if you need to embed larger pieces of text. Huh, very nice; thanks for the link. Unfortunately, it doesn't look like John has released a version on Hackage yet :( Then again, the first commit on github was the beginning of this month... probably won’t happen, unless someone steps up as a maintainer (you?): http://www.haskell.org/pipermail/haskell-cafe/2010-August/081398.html Hmm, now that I look at the thread, you took part in it (when the discussion turned to TH on different arches) :-) Greetings, Joachim -- Joachim nomeata Breitner mail: m...@joachim-breitner.de | ICQ# 74513189 | GPG-Key: 4743206C JID: nome...@joachim-breitner.de | http://www.joachim-breitner.de/ Debian Developer: nome...@debian.org signature.asc Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Haddock: Documentation of instances with un-documentable type arguments
Perhaps Haddock could exclude class instance reporting when it cannot find a documentable link to a parameter? The cannot find documentable link problem also comes up in situations like this (that don't involve type classes): module Ex ( foo ) where data Secret = Secret foo = Secret Should haddock generate documentation for foo (since it is exported) or not (since its result type is not exported)? Now imagine something like instance Show Secret (inside the Ex module). The user of the module then can write show foo, and so it should be documented? J.W. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] multi-line strings (Was: Hackage on Linux)
On 28 August 2010 21:33, Joachim Breitner m...@joachim-breitner.de wrote: Hi, Am Samstag, den 28.08.2010, 21:11 +1000 schrieb Ivan Lazar Miljenovic: A similar problem is solved by http://github.com/jgm/hsb2hs which might be useful if you need to embed larger pieces of text. Huh, very nice; thanks for the link. Unfortunately, it doesn't look like John has released a version on Hackage yet :( Then again, the first commit on github was the beginning of this month... probably won’t happen, unless someone steps up as a maintainer (you?): http://www.haskell.org/pipermail/haskell-cafe/2010-August/081398.html Hmm, now that I look at the thread, you took part in it (when the discussion turned to TH on different arches) :-) Huh, that goes to show how many mailing list messages there are that I forgot about that thread ;-) I'd be willing to take over maintainership except I have about 3 different libraries I'm working on that need a lot of TLC, and I don't really have a use case for hsb2hs (I don't do that much with Strings). -- 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: Haddock: Documentation of instances with un-documentable type arguments
On 28 August 2010 21:33, Johannes Waldmann waldm...@imn.htwk-leipzig.de wrote: Perhaps Haddock could exclude class instance reporting when it cannot find a documentable link to a parameter? The cannot find documentable link problem also comes up in situations like this (that don't involve type classes): module Ex ( foo ) where data Secret = Secret foo = Secret Should haddock generate documentation for foo (since it is exported) or not (since its result type is not exported)? The more important question is why doesn't it have a type signature? :p How does GHC deal with that kind of situation? Off the top of my head, I would think that in terms of how you could use it, that would be equivalent to also exporting Secret (the type, not the constructor); i.e. module Ex (Secret, foo) where -- 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: Haddock: Documentation of instances with un-documentable type arguments
in terms of how you could use it, that would
be equivalent to also exporting Secret [...]
well, expect that you cannot use the type's name in signatures,
so you'd have to rely on type inference.
Out of curiosity I just checked javadoc's behaviour on
public class Ex {
public interface Show { }
static private class Secret implements Show { }
public Secret foo () { return new Secret (); }
static public class Known implements Show { }
public Known bar () { return new Known (); }
}
and it does generate documentation for all the public identifiers,
with a non-linked result type for foo,
and it does not list Secret among the known instances for Show.
Well, then I checked haddock (2.7.2) for
module Ex ( foo, bar, Known ) where
data Secret = Secret
foo = Secret
instance Show Secret
data Known = Known
bar = Known
instance Show Known
and it behaves identically (does not mention Secret as a known instance).
So, is this the behaviour that the original poster wanted?
J.W.c
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Re: [Haskell-cafe] Re: Haddock: Documentation of instances with un-documentable type arguments
On Sat, Aug 28, 2010 at 1:41 PM, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: On 28 August 2010 21:33, Johannes Waldmann waldm...@imn.htwk-leipzig.de wrote: Perhaps Haddock could exclude class instance reporting when it cannot find a documentable link to a parameter? The cannot find documentable link problem also comes up in situations like this (that don't involve type classes): module Ex ( foo ) where data Secret = Secret foo = Secret Should haddock generate documentation for foo (since it is exported) or not (since its result type is not exported)? The more important question is why doesn't it have a type signature? :p How does GHC deal with that kind of situation? Off the top of my head, I would think that in terms of how you could use it, that would be equivalent to also exporting Secret (the type, not the constructor); i.e. module Ex (Secret, foo) where I tried this once, because I was wondering the same thing. Basically it works the way I expected: if you export functions which have a given type in their signature, but the type is not exported, you can use the functions and combine them however you want, but you can't explicitly mention or use the unexported type anywhere. At the time I actually had a use case in mind for why this would be useful, but I can't remember what it was. -- 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 -- Work is punishment for failing to procrastinate effectively. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Re: Hackage on Linux
On 28/08/10 02:15, Ivan Lazar Miljenovic wrote: On 28 August 2010 11:09, Brandon S Allbery KF8NH allb...@ece.cmu.edu wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 8/27/10 05:58 , Simon Farnsworth wrote: If you don't mind, I'd like a proper reference for this; looking at the Linux kernel documentation as you suggest tells me that the kernelspace to userspace ABI is supposed to be 100% stable, such that I can take all the binaries (including shared libraries) from an i386 Linux 2.0 system, and run them in a chroot on my x86-64 Linux 2.6.35 system. Maybe it's supposed to be, but even with more recent stuff (like, say, binary GHC releases --- which use glibc shared even if Haskell libs aren't) I quite often see programs fail to run because the kernel changed something and the kernel/userspace interface changed as a result. A written policy is worthless if it isn't followed. Well, I have no need to recompile glibc and packages that depend upon it every time I update my kernel... So maybe glibc changes, but not the kernel AFAICT. I've been following this part of the discussion with some interest. Mainly because I've been a Linux user since kernel version 1.2, and I've *never* had any of the problems people mention here. So I'm wondering, what are you doing to your systems? /M -- Magnus Therning(OpenPGP: 0xAB4DFBA4) magnus＠therning．org Jabber: magnus＠therning．org http://therning.org/magnus identi.ca|twitter: magthe signature.asc Description: OpenPGP digital signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] type classes and logic
Daniel Fischer wrote: class BEING human = HUMAN human where Sub-classing is logical implication BEING(human) = HUMAN(human) All types t that make BEING(t) = true also make HUMAN(t)=true No, it's the other way round. Every HUMAN is also a BEING, hence HUMAN(t) = BEING(t) Could I say that HUMAN is a subset of BEING? That depends on whether predicates are sets.. But yes, every instance of HUMAN is also an instance of BEING, hence, the set of HUMAN instances is a subset of the set of BEING instances. In the light of the above examples how should I interpret the class-to-subclass relation as logical implication? Is it a) If BEING then HUMAN (sufficient condition): BEING = HUMAN b) HUMAN is true only if BEING (necessary condition): HUMAN = BEING c) Neither? b). Every HUMAN is a BEING. Cheers, Sebastian -- Underestimating the novelty of the future is a time-honored tradition. (D.G.) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Hackage on Linux
On 28/08/10 09:55, Andrew Coppin wrote: [...] How about hoping that Linux and Mac devs are going to realise that Windows doesn't have some of the problems that people claim it does? Hmm, thinking about it... nah, that's not happening anytime soon either. ;-) Can you provide some links to further information, please? /M -- Magnus Therning(OpenPGP: 0xAB4DFBA4) magnus＠therning．org Jabber: magnus＠therning．org http://therning.org/magnus identi.ca|twitter: magthe signature.asc Description: OpenPGP digital signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] type classes and logic
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 8/28/10 06:17 , Patrick Browne wrote: In the light of the above examples how should I interpret the class-to-subclass relation as logical implication? Is it a) If BEING then HUMAN (sufficient condition): BEING = HUMAN b) HUMAN is true only if BEING (necessary condition): HUMAN = BEING c) Neither? (b). But there's an additional wrinkle: what it really says is A HUMAN is (...). Oh, and it's a BEING too. Which is to say, Haskell doesn't look at BEING until *after* it's decided something is a HUMAN. (Technically speaking, constraints are not used when selecting an instance; they're applied after the fact, and if the selected instance doesn't conform then it throws a type error.) - -- brandon s. allbery [linux,solaris,freebsd,perl] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.10 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkx5KOcACgkQIn7hlCsL25UWyQCfTblcgeEfwOci9KE7leVs07aN VT4AoJAwHqXoD6nbD+TZVRlAWj3N99SM =jA0B -END PGP SIGNATURE- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Slightly humorous: Headhunters toolbox (example for Germany)
On Sat, Aug 28, 2010 at 01:29, Vo Minh Thu wrote: It would be interesting to know some other sources: [...] number of attendees to e.g. Utrecht summer school on FP, ... Just a bit over 30, I think. And it was interesting to see a significant number of non-student participants. Perhaps around 20%. As an aside, we had some interesting projects, too. Sokoban in curses, DSP/sound DSL, regex visualization, Bash code escaping, etc. I hope to see some of them appear on Hackage soon. Regards, Sean ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Slightly humorous: Headhunters toolbox (example for Germany)
2010/8/28 Sean Leather leat...@cs.uu.nl: On Sat, Aug 28, 2010 at 01:29, Vo Minh Thu wrote: It would be interesting to know some other sources: [...] number of attendees to e.g. Utrecht summer school on FP, ... Just a bit over 30, I think. And it was interesting to see a significant number of non-student participants. Perhaps around 20%. As an aside, we had some interesting projects, too. Sokoban in curses, DSP/sound DSL, regex visualization, Bash code escaping, etc. I hope to see some of them appear on Hackage soon. That's the kind of aside that are so interesting. Please (fell free to) share some more insight of it in your blog if you've some time :) Cheers, Thu ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] (automatic) type classes context inference
i believe that a valid idiom is to define a class C that has no functions, but requires any instance to also be of type classes A and B, so that you can write: C a = blah rather than (A a,B a)= blah, though I don't know how often such is used in practice the same idea should apply more generally to multiparam type classes On Sat, Aug 28, 2010 at 5:44 AM, João Paulo jpa...@di.uminho.pt wrote: Hello everyone, I am developing a toolset in which I have several (multiparameter) type classes; It is often the case that I can only define a data-type X as an instance of one such class (say A), if X is an instance of another class (say B); The thing is that, while it is hard for me, because of all the type parameters that I have to deal with, to add 'X is an instance of B' to the context cxt_A in 'instance cxt_A = A X' ghc is always able to correctly infer all type parameters; In fact, I always get: 'Could not deduce (B X t1 ... tn) from the context cxt_A arising from ... Probable fix: add (B X t1 ... tn) to the context cxt_A ...' In my case, this is the fix that I always need: most of the times, I am just copy-pasting (B X t1 ... tn) to cxt_A! Is there a way, say a compilation option, to avoid this? can anyone please help me here? :) thank you very much -- João Paulo Fernandes Universidade do Minho www.di.uminho.pt/~jpaulo ___ 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] (automatic) type classes context inference
On Sat, Aug 28, 2010 at 12:22 PM, Carter Schonwald carter.schonw...@gmail.com wrote: i believe that a valid idiom is to define a class C that has no functions, but requires any instance to also be of type classes A and B, so that you can write: C a = blah rather than (A a,B a)= blah, though I don't know how often such is used in practice the same idea should apply more generally to multiparam type classes I've done this. It's handy not only for reducing class context noise, but also keeping implementation details from leaking out the interface. It looks funny when some function randomly requires its parameter to be Storable just because somewhere down the line someone else needs it, and it's awkward when a whole interface requires the same 4 typeclasses on every function. Of course, if you want to write a new type that can be passed, you do need to implement those classes, so from the point of view of that user it's not an implementation detail. But from the point of view of someone just passing in data, not writing their own instances, it's awkward to have to keep writing a random bunch of class contexts that reflect the implementation of a function and may break if that implementation changes. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Unicode pretty-printing
Hi all, I've been considering using Haskell for my natural language processing project. Due to its nature, it has much to do with Unicode. Unfortunately, Haskell escapes UTF8 characters. I've been able to output these strings via System.IO.UTF8.putStrLn (though I wish it was less painful), but still there are two problems. First, I want to pretty-print not only strings, but any structures made of lists and algebraic data types. Their 'show' calls string's 'show' which escapes all UTF8 symbols. The second problem is that I'm not the only one who wants to output the structures. For example, I want to have tests which check that certain operations produce certain natural language strings. So, I considered using HUnit for that. When its assertEqual fails, it displays the expected versus actual data, which is fine. But, of course, it doesn't know anything about Unicode, and I can't read escaped strings very well to understand what exactly has failed. I really don't want to write yet another unit test framework only for the sake of UTF8. Is there any way to make Haskell display values containing Unicode strings in a readable way? Peter ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Unicode pretty-printing
gromopetr: Hi all, I've been considering using Haskell for my natural language processing project. Due to its nature, it has much to do with Unicode. Unfortunately, Haskell escapes UTF8 characters. I've been able to output these strings via System.IO.UTF8.putStrLn (though I wish it was less painful), but still there are two problems. First, I want to pretty-print not only strings, but any structures made of lists and algebraic data types. Their 'show' calls string's 'show' which escapes all UTF8 symbols. How about a Pretty class for unicode text: http://hackage.haskell.org/package/text That might be easy to write. displays the expected versus actual data, which is fine. But, of course, it doesn't know anything about Unicode, and I can't read escaped strings very well to understand what exactly has failed. I really don't want to write yet another unit test framework only for the sake of UTF8. Is there any way to make Haskell display values containing Unicode strings in a readable way? Via a new pretty class, similar to Show, but rendering Text values. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Fwd: Semantics of iteratees, enumerators, enumeratees?
On 26/08/2010, Daniel Fischer daniel.is.fisc...@web.de wrote: [...] Well, I just gave an example where one would want chunking for reasons other than performance. That iteratees don't provide the desired functionality is a different matter. [...] In the case of hashing, wouldn't it be more reasonable to consider iterators over streams of fixed (or at least predictable) sized chunks (where a set of chunks can themselves be chunked), with the chunking behaviour being given by another iteratee over the original stream? It seems to me that one of the major points of iteratees is to provide an abstraction from the kind of chunking irrelevant to the parsing logic, otherwise I fail to see any difference (at least relevant to chunking) to plain strict IO. I'm not particularly well read on anything here, so I could just totally miss what is going on, in which case I apologise. //Tilo Wiklund ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] On to applicative
I'm looking at a discussion of Either (as functor) here: http://learnyouahaskell.com/making-our-own-types-and-typeclasses#the-functor-typeclass instance Functor (Either a) where fmap f (Right x) = Right (f x) fmap f (Left x) = Left x And this line in Data.Either Functor (Either a) but no fmap defined here. How come? Michael ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Support for lock-free/wait-free programming?
Gabriel Wicke wi...@wikidev.net writes: On Tue, 17 Aug 2010 01:09:41 -0400, Gregory Collins wrote: Hello all, Does GHC expose any primitives for things like atomic compare-and-swap? I can't seem to find anything in the docs. Hello Gregory, I have recently published experimental and low-level FFI bindings to GCC's atomic primitives including CAS as 'bits-extras' on Hackage [1]. Instances for Int and Word types are included. This is likely lower-level than what you are after, but might still be handy for experimentation. On OSX libgcc_s is only supplied as a dynamic library, which GHC doesn't seem to be able to link with. Any ideas would be appreciated. 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] On to applicative
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 8/28/10 20:43 , michael rice wrote: I'm looking at a discussion of Either (as functor) here: http://learnyouahaskell.com/making-our-own-types-and-typeclasses#the-functor-typeclass instance Functor (Either a) where fmap f (Right x) = Right (f x) fmap f (Left x) = Left x And this line in Data.Either Functor (Either a) but no fmap defined here. How come? Historical accident, to wit: Haskell 98 minimally defined Either in the Prelude, so in practice we get the basic definitions (Either itself and its Functor and Monad instances) from the Prelude and other utility functions from Data.Either. - -- brandon s. allbery [linux,solaris,freebsd,perl] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.10 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkx5sq4ACgkQIn7hlCsL25WA+QCeKUOuNN4kUpci9fH6BcFZ5WqG bX8AoIBImpWLoxVz7kcwVIuHycYR/v5G =EaIs -END PGP SIGNATURE- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Support for lock-free/wait-free programming?
Gregory Collins g...@gregorycollins.net writes: Gabriel Wicke wi...@wikidev.net writes: On Tue, 17 Aug 2010 01:09:41 -0400, Gregory Collins wrote: Hello all, Does GHC expose any primitives for things like atomic compare-and-swap? I can't seem to find anything in the docs. Hello Gregory, I have recently published experimental and low-level FFI bindings to GCC's atomic primitives including CAS as 'bits-extras' on Hackage [1]. Instances for Int and Word types are included. This is likely lower-level than what you are after, but might still be handy for experimentation. On OSX libgcc_s is only supplied as a dynamic library, which GHC doesn't seem to be able to link with. Any ideas would be appreciated. It works with this patch: -- Remove cc-options field from .cabal; the flags given don't work on OSX diff --git a/bits-extras.cabal b/bits-extras.cabal --- a/bits-extras.cabal +++ b/bits-extras.cabal @@ -42,8 +42,6 @@ --CC-Options: -O3 -fomit-frame-pointer -march=native -Wall -- Try link-time optimization (inlining) with gcc 4.5: -- CC-Options: -fomit-frame-pointer -march=native -Wall -flto -CC-Options: -fomit-frame-pointer -march=native -Wall -Extra-Libraries: gcc_s Include-Dirs: cbits Install-Includes: bitops-gcc.h atomic-bitops-gcc.h Extensions: ForeignFunctionInterface -- 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] Re: Hackage on Linux
Andrew Coppin wrote: On Linux, if I do, say, cabal install zlib, it falls over and tells me it can't find the zlib headers. So I go install them, rerun the command, and it works. On Windows, I issue the same command and it falls over and says that autoconf doesn't exist. It doesn't even *get* to the part where it looks for header files! You are trying to build code that is designed on and for Linux. As such it will probably work on all variants of Linux, Mac OSX and a majority of Unix variants (after installation of the required GNU tools). Unsurprisingly it does work on windows because windows because windows does just about everything differently to the Linux and the rest of the world does it. Interestingly, even though everybody claims that it's impossible to support C bindings on Windows, gtk2hs has managed it somehow. If you try to built it, it complains that it can't find the GTK+ headers. Go install those, add them to the search path, and suddenly it builds just fine. No problems with it. Go figure... The reason that works is probably because whoever released it had a windows machine available and took the time to make it work. In general, code written on and for Linux/Unix is not going compile with little problem on most Unix-style OSes and close to zero chance of compiling without siginficant work on windows. How about hoping that Linux and Mac devs are going to realise that Windows doesn't have some of the problems that people claim it does? The problems I claim windows has with respect to compiling and installing FOSS: a) No standard place to find C include files. b) No standard place to find libraries. c) No standard way to find if common open source libraries are installed and where. d) Missing common unix tools like bash. awk, sed, grep, make, autoconf, automake, libtool, pkg-config etc. Ideally for installing open source libraries the tools used should be the same as the ones used on Linux/Unix where they originated. My obviously all desktops are Windows was not meant to be entirely serious. But it's not exactly a revelation to state that Windows has much greater penetration in the desktop market than either Linux or indeed Mac OS. Linux is much more popular now than it used to be (e.g., I can remember when you had to wear open-toed sandals and eat lentil burgers in order to run Linux), but it's not yet anywhere near the level of popularity of Windows. Your assessment is valid for user desktops but highly questionable for developer desktops. 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
Re: [Haskell-cafe] Re: Hackage on Linux
Hmm, Sunday morning reply before caffeine. Erik de Castro Lopo wrote: Andrew Coppin wrote: On Linux, if I do, say, cabal install zlib, it falls over and tells me it can't find the zlib headers. So I go install them, rerun the command, and it works. On Windows, I issue the same command and it falls over and says that autoconf doesn't exist. It doesn't even *get* to the part where it looks for header files! You are trying to build code that is designed on and for Linux. As such it will probably work on all variants of Linux, Mac OSX and a majority of Unix variants (after installation of the required GNU tools). Unsurprisingly it does work on windows because windows because windows ^not does just about everything differently to the Linux and the rest of the world does it. Interestingly, even though everybody claims that it's impossible to support C bindings on Windows, gtk2hs has managed it somehow. If you try to built it, it complains that it can't find the GTK+ headers. Go install those, add them to the search path, and suddenly it builds just fine. No problems with it. Go figure... The reason that works is probably because whoever released it had a windows machine available and took the time to make it work. In general, code written on and for Linux/Unix is not going compile Remove 'not' in the line above. with little problem on most Unix-style OSes and close to zero chance of compiling without siginficant work on windows. 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
Re: [Haskell-cafe] On to applicative
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 8/28/10 22:15 , michael rice wrote: Prelude fmap (*2) l interactive:1:0: No instance for (Functor (Either Integer)) arising from a use of `fmap' at interactive:1:0-10 Possible fix: add an instance declaration for (Functor (Either Integer)) In the expression: fmap (* 2) l In the definition of `it': it = fmap (* 2) l Prelude Huh. I understood it to be defined in the Prelude, but didn't check. Looks like it's now in Control.Monad.Instances (a relatively new module). Confusing - -- brandon s. allbery [linux,solaris,freebsd,perl] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.10 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkx5yW0ACgkQIn7hlCsL25VpMACeJR2GVmy1XvOMLtze7s0z3jaZ t5sAnirMJhfh4ZYdMzJBdPbdUs8s166L =OXTs -END PGP SIGNATURE- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On to applicative
Thanks, Brandon. Michael --- On Sat, 8/28/10, Brandon S Allbery KF8NH allb...@ece.cmu.edu wrote: From: Brandon S Allbery KF8NH allb...@ece.cmu.edu Subject: Re: [Haskell-cafe] On to applicative To: michael rice nowg...@yahoo.com Cc: haskell-cafe@haskell.org Date: Saturday, August 28, 2010, 10:43 PM -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 8/28/10 22:15 , michael rice wrote: Prelude fmap (*2) l interactive:1:0: No instance for (Functor (Either Integer)) arising from a use of `fmap' at interactive:1:0-10 Possible fix: add an instance declaration for (Functor (Either Integer)) In the expression: fmap (* 2) l In the definition of `it': it = fmap (* 2) l Prelude Huh. I understood it to be defined in the Prelude, but didn't check. Looks like it's now in Control.Monad.Instances (a relatively new module). Confusing - -- brandon s. allbery [linux,solaris,freebsd,perl] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.10 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkx5yW0ACgkQIn7hlCsL25VpMACeJR2GVmy1XvOMLtze7s0z3jaZ t5sAnirMJhfh4ZYdMzJBdPbdUs8s166L =OXTs -END PGP SIGNATURE- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
