Re: [Haskell-cafe] ANNOUNCE: Data.IVar 0.1
lrpalmer: Several very elegant FRP approaches are emerging, most visibly FRP.Reactive, which rely on blocking on multiple variables at once, continuing when the *first* of them is available. . . inside an unsafePerformIO, so the beautiful STM orElse solution is not available. The current solution is to race threads against each other, and have the one that finishes first kill the other one. This is implemented, for example, in Data.Unamb. However, our empirical tests have shown that the GHC scheduler is not *quite* good enough to handle this efficiently, and ends up introducing too much latency and nondeterminacy. Cool! Does you IVar implementation have anything in common with previous proposals for things called IVar (or say, 'ports', http://www.cse.unsw.edu.au/~chak/haskell/ports/)? What's the background for this abstraction? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: Data.IVar 0.1
On Wed, Oct 8, 2008 at 12:20 AM, Don Stewart [EMAIL PROTECTED] wrote: lrpalmer: Several very elegant FRP approaches are emerging, most visibly FRP.Reactive, which rely on blocking on multiple variables at once, continuing when the *first* of them is available. . . inside an unsafePerformIO, so the beautiful STM orElse solution is not available. The current solution is to race threads against each other, and have the one that finishes first kill the other one. This is implemented, for example, in Data.Unamb. However, our empirical tests have shown that the GHC scheduler is not *quite* good enough to handle this efficiently, and ends up introducing too much latency and nondeterminacy. Cool! Does you IVar implementation have anything in common with previous proposals for things called IVar (or say, 'ports', http://www.cse.unsw.edu.au/~chak/haskell/ports/http://www.cse.unsw.edu.au/%7Echak/haskell/ports/ )? Yes, I picked up the name from haskell-cafe discussions a while back. Various forms have been popping in and out of the reactive libraries. I hadn't seen ports before. What's the background for this abstraction? So like I said, I'm not too sure, I just stole the name and vague idea from discussions about it. As is easily noticed from the jive above, it's motivated by the continuous barrage of suboptimal FRP libraries. While I'm working on reactive from the top down, this is the beginning of one I have planned, taking baby steps from the bottom up (and it'll likely get incorporated into reactive too). Luke ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: Data.IVar 0.1
forkIO $ threadDelay 1000 writeIVar iv' my spoon is too big writeIVar iv' i am a banana -- throws error IVar written twice Nice Don Hertzfeldt reference. ;) If this means nothing to you, here's the animated film from whence this came: http://www.youtube.com/watch?v=MuOvqeABHvQ Sean ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Hoogle? [Stacking monads]
On Tue, Oct 7, 2008 at 7:09 PM, Andrew Coppin
[EMAIL PROTECTED] wrote:
For my current troubles, it would be really useful if there were some
program that you could feed some source code to, and it would tell you what
the inferred types of each subexpression are. (Ideally it would be nice if
you could use this on fragments that don't typecheck; being able to see what
types are being inferred where could help explain why the type checker is
unhappy, and ultimately where you went wrong. But I'm not sure how you could
present the internal state in a digestible way.) I don't know if anybody has
ever attempted such a tool...?
There is such a tool, it's called ghci :)
It just takes a bit of massaging to do what you want:
... some module code ...
{-
function_that_does_not_typecheck = some_expression
-}
function_that_does_not_typecheck = error force typechecker to be happy
For now lets assume that you are curious about the type of the subexpression
f some_func [a..b]
where f, a, and b are locally bound.
Then
ghci :set -fglasgow-exts
ghci :t (?f some_func [?a .. ?b])
Here's an example:
Prelude :t ?f map [?a .. ?b]
?f map [?a .. ?b] :: forall t a b t1.
(Enum t1,
?b::t1,
?a::t1,
?f::((a - b) - [a] - [b]) - [t1] - t)
= t
This tells you the types the variables have to have, and the type of
the expression.
Judicious use of (undefined :: type_signature) can also help.
-- ryan
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RE: [Haskell-cafe] Darcs / Git
Yes, I've used SSH key. Didn't think it would be different with a password. It really is! :-) Thanks Neil On 7 Oct 2008, at 20:19, Mitchell, Neil wrote: I use darcs on Windows every day and it works well. The only problem is that it is not very usable if you access your repository via SSH and the authentication is via password. Why not? It worked fine for me. It's never worked for me, I always get a frozen darcs trying to read a password, but not from my console. If you connect with an SSH key its more secure and less typing - it's a better way to go. Thanks Neil = = = = = = = = == Please access the attached hyperlink for an important electronic communications disclaimer: http://www.credit-suisse.com/legal/en/disclaimer_email_ib.html = = = = = = = = == ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe == Please access the attached hyperlink for an important electronic communications disclaimer: http://www.credit-suisse.com/legal/en/disclaimer_email_ib.html == ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] [hmatrix] build error
Hi, looks like I hit a bug, but I'm not sure which software it belongs to, gcc, ghc or atlas? -- error doing runhaskell Setup build -- Preprocessing library hmatrix-0.4.1.0... /usr/bin/ld: dist/build/Numeric/GSL/Special/Internal_hsc_make: hidden symbol `__powidf2' in /usr/lib/gcc/x86_64-unknown-linux-gnu/4.3.2/libgcc.a(_powidf2.o) isreferenced by DSO /usr/bin/ld: final link failed: Nonrepresentable section on output collect2: ld returned 1 exit status linking dist/build/Numeric/GSL/Special/Internal_hsc_make.o failed command was: /usr/bin/ghc -optl-lgsl -optl-llapack dist/build/Numeric/GSL/Special/Internal_hsc_make.o -o dist/build/Numeric/GSL/Special/Internal_hsc_make -- error doing runhaskell Setup build -- I believe `__powidf2' is a internal symbol in gcc and it is hidden. The system is archlinux x86_64 and the software I used are atlas-lapack 3.8.2-1 gcc 4.3.2-1 Using built-in specs. Target: x86_64-unknown-linux-gnu Configured with: ../configure --prefix=/usr --enable-shared --enable-languages=c,c++,fortran,objc,obj-c++,treelang --enable-threads=posix --mandir=/usr/share/man --infodir=/usr/share/info --enable-__cxa_atexit --disable-multilib --libdir=/usr/lib --libexecdir=/usr/lib --enable-clocale=gnu --disable-libstdcxx-pch --with-tune=generic Thread model: posix gcc version 4.3.2 (GCC) ghc 6.8.2-2 [(Project name,The Glorious Glasgow Haskell Compilation System) ,(Project version,6.8.2) ,(Booter version,6.8.2) ,(Stage,2) ,(Interface file version,6) ,(Have interpreter,YES) ,(Object splitting,YES) ,(Have native code generator,YES) ,(Support SMP,YES) ,(Unregisterised,NO) ,(Tables next to code,YES) ,(Win32 DLLs,) ,(RTS ways, debug thr thr_p thr_debug) ,(Leading underscore,NO) ] I googled but no useful information. Best, Xiao-Yong -- c/*__o/* \ * (__ */\ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [hmatrix] build error
Xiao-Yong Jin [EMAIL PROTECTED] writes: Hi, looks like I hit a bug, but I'm not sure which software it belongs to, gcc, ghc or atlas? -- error doing runhaskell Setup build -- Preprocessing library hmatrix-0.4.1.0... /usr/bin/ld: dist/build/Numeric/GSL/Special/Internal_hsc_make: hidden symbol `__powidf2' in /usr/lib/gcc/x86_64-unknown-linux-gnu/4.3.2/libgcc.a(_powidf2.o) isreferenced by DSO /usr/bin/ld: final link failed: Nonrepresentable section on output collect2: ld returned 1 exit status linking dist/build/Numeric/GSL/Special/Internal_hsc_make.o failed command was: /usr/bin/ghc -optl-lgsl -optl-llapack dist/build/Numeric/GSL/Special/Internal_hsc_make.o -o dist/build/Numeric/GSL/Special/Internal_hsc_make -- error doing runhaskell Setup build -- It might be a problem of atlas. With Intel's MKL, it builds fine. -- c/*__o/* \ * (__ */\ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Functional dependencies and incoherent instances
Hi,
Im trying to overload a multiplication operator for scalars and vectors,
but keep running into the error message Functional dependencies
conflict. What I think is going on is that the dependency check doesn't
work with incoherent (or overlapping) instances. In the example below,
the two instances of Mult are overlapping. What I want is the vector
version to be used for vectors and the scalar version used for numbers,
even if a vector-type is an instance of the Num-class (I believe
-fallow-incoherent-instances would make that kind of choise for me,
right?).
Im using the Visual Studio plugin Visual Haskell, and thus GHC version
6.6. Otherwise I think associated types might have worked better for
this...
Regards
Tobias Bexelius
{-# OPTIONS_GHC -fglasgow-exts -fallow-undecidable-instances
-fallow-incoherent-instances #-}
data V2 a = V2 a a
class Vec v a where
dot :: v a - v a - a
instance Num a = Vec V2 a where
V2 a1 a2 `dot` V2 b1 b2 = a1*b1+a2*b2
class Mult a b c | a b - c where
(*.) :: a - b - c
instance (Num x) = Mult x x x where (*.) = (*)
instance (Vec a x) = Mult (a x) (a x) x where (*.) = dot
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[Haskell-cafe] OT: Haskell desktop wallpaper?
This morning I got tired of my desktop wallpaper (one that ships with Debian's Gnome packages). Typing haskell desktop wallpaper yeilded a lot of links to wallpapers with Colleen Haskell, while she's a beautiful lady it wasn't exactly what I was hoping to find. Hence this email. Where can I find some nice wallpapers inspired by Haskell, or maybe even created by Haskell code? Oh yes, wallpapers related to XMonad would do, I suppose ;-) /M -- Magnus Therning(OpenPGP: 0xAB4DFBA4) magnus＠therning．org Jabber: magnus＠therning．org http://therning.org/magnus identi.ca|twitter: magthe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Type classes question
Ryan Ingram ryani.spam at gmail.com writes:
[...]
Here's another possible solution:
newtype AsFunctor s a = AF { fstream :: (s a) }
instance (Stream f) = Functor (AsFunctor f) where
fmap f (AF s) = AF (fmapStreamDefault f s)
Now to use fmap you wrap in AF and unwrap with fstream.
None of the existing solutions are really satisfactory, unfortunately.
Bulat Ziganshin bulat.ziganshin at gmail.com writes:
http://haskell.org/haskellwiki/OOP_vs_type_classes may be useful
Many thanks to you both for the clarification and pointers.
cheers,
Roly
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Re: [Haskell-cafe] ANNOUNCE: Data.IVar 0.1
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On Oct 8, 2008, at 7:28 AM, Jake Mcarthur wrote: I'm attaching one of the more well-known variants in case anybody is interested, although to be honest I can't remember which one was actually the best as I have moved on from this approach. I just looked back over it. I had forgotten how far from the original idea I had gone. Perhaps this would be better with a different name now. - - Jake -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.8 (Darwin) iEYEARECAAYFAkjsqI4ACgkQye5hVyvIUKm/dQCfbzNfeTZTzmPQa6a2ZwGkqlbp ZZUAn2V5NrX1zR549EsEm8Oj5psU4fl6 =8vsl -END PGP SIGNATURE- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] OT: Haskell desktop wallpaper?
2008/10/8 Magnus Therning [EMAIL PROTECTED]: This morning I got tired of my desktop wallpaper (one that ships with Debian's Gnome packages). Typing haskell desktop wallpaper yeilded a lot of links to wallpapers with Colleen Haskell, while she's a beautiful lady it wasn't exactly what I was hoping to find. Hence this email. Where can I find some nice wallpapers inspired by Haskell, or maybe even created by Haskell code? It shouldn't be too difficult to generate some wallpapers. Look at the examples included with the Diagrams package [1]. You could take the Ford circles and have different coloured circles at every startup. You could even have a range of palettes depending on season ;-) [1]: http://code.haskell.org/diagrams/example/examples.html Cheers, D ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: I'll do USB in Haskell - tips?
Looking for Posix Linux API, I found www.linux-usb.org. It has a lot (I think all I need) to start in Linux. Does anyone knows where can I find related information for Windows, so I can start without writing something that would be difficult to support there? Best, Maurício Hello, I am also interested in SCSI, PCI, etc. (...) Maybe Marco should talk to the people doing the Linux implementation for the Posix API and see how viable that API is before spending a year for nothing. Or Marco maybe you can be a trailblazer and come up with a better Posix/Win32 USB APIquo t; and implement in Haskell? ;^) Very kind regards, Vasili ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Call for Contributions - Haskell Communities and Activities Report, November 2008 edition
Dear Haskellers, so much has happened in the Haskell world in the past months. Therefore, I would very much like to collect contributions for the 15th edition of the Haskell Communities Activities Report http://www.haskell.org/communities/ Submission deadline: 31 October 2008 (please send your contributions to [EMAIL PROTECTED], in plain text or LaTeX format) This is the short story: * If you are working on any project that is in some way related to Haskell, please write a short entry and submit it. Even if the project is very small or unfinished or you think it is not important enough -- please reconsider and submit an entry anyway! * If you are interested in any project related to Haskell that has not previously been mentioned in the HCA Report, please tell me, so that I can contact the project leaders and ask them to submit an entry. * Feel free to pass on this call for contributions to others that might be interested. More detailed information: The Haskell Communities Activities Report is a bi-annual overview of the state of Haskell as well as Haskell-related projects over the last, and possibly the upcoming six months. If you have only recently been exposed to Haskell, it might be a good idea to browse the May 2008 edition -- you will find interesting topics described as well as several starting points and links that may provide answers to many questions. Contributions will be collected until the submission deadline. They will then be compiled into a coherent report that is published online as soon as it is ready. As always, this is a great opportunity to update your webpages, make new releases, announce or even start new projects, or to talk about developments you want every Haskeller to know about! Looking forward to your contributions, Janis (current editor) FAQ: Q: What format should I write in? A: The best format is a LaTeX source file, adhering to the template that is available at: http://haskell.org/communities/11-2008/template.tex There is also a LaTeX style file at http://haskell.org/communities/11-2008/hcar.sty that you can use to preview your entry. If you do not know LaTeX, then use plain text. If you modify an old entry that you have written for an earlier edition of the report, you should have received your old entry as a template already (provided I have your valid email address). Please modify that template, rather than using your own version of the old entry as a template. Do not worry about writing correct LaTeX, I will be able to handle your file. Please do not use HTML or even DOC. Q: Can I include images? A: Yes, you are even encouraged to do so. Please use .jpg format, then. Q: How much should I write? A: Authors are asked to limit entries to about one column of text. This corresponds to approximately one page, or 40 lines of text, with the above style and template. A general introduction is helpful. Apart from that, you should focus on recent or upcoming developments. Pointers to online content can be given for more comprehensive or ``historic'' overviews of a project. Images do not count towards the length limit, so you may want to use this opportunity to pep entries up. There is no minimum length of an entry! The report aims at being as complete as possible, so please consider writing an entry, even if it is only a few lines long. Q: Which topics are relevant? A: All topics which are related to Haskell in some way are relevant. We usually had reports from users of Haskell (private, academic, or commercial), from authors or contributors to projects related to Haskell, from people working on the Haskell language, libraries, on language extensions or variants. We also like reports over distributions of Haskell software, Haskell infrastructure, books and tutorials on Haskell. Reports on past and upcoming events related to Haskell are also relevant. Finally, there might be new topics we do not even think about. As a rule of thumb: if in doubt, then it probably is relevant and has a place in the HCAR. You can also ask the editor. Q: Is unfinished work relevant? Are ideas for projects relevant? A: Yes! You can use the HCAR to talk about projects you are currently working on. You can use it to look for other developers that might help you. You can use it to write ``wishlist'' items for libraries and language features you would like to see implemented. Q: If I do not update my entry, but want to keep it in the report, what should I do? A: Tell the editor that there are no changes. The old entry will be reused in this case, but it might be dropped if it is older than a year, to give more room and more attention to projects that change a lot. Do not resend complete entries if you have not changed them. -- Dr. Janis
RE: [Haskell-cafe] Functional dependencies and incoherent instances
Yeah, I realized that.
But heres where I would like the undecidable incoherent instances to kick in,
i.e. as long as I haven't got any NumVec instances GHC should be able to choose
only one of the Mult instances. Or do I have too much faith in the
-fallow-incoherent-instances flag now? :/
I would like to be able to write something like
instance (Vec a x, -Num (a x)) = Mult (a x) (a x) x where (*.) = dot
where -Num (a x) means that (a x) must not be an instance of Num. Can I express
this in some way?
Regards
Tobias
-Original Message-
From: Joel Björnson [mailto:[EMAIL PROTECTED]
Sent: den 8 oktober 2008 15:50
To: Tobias Bexelius
Cc: haskell-cafe@haskell.org
Subject: Re: [Haskell-cafe] Functional dependencies and incoherent instances
Hi,
On Wed, Oct 8, 2008 at 2:31 PM, Tobias Bexelius [EMAIL PROTECTED] wrote:
Hi,
Im trying to overload a multiplication operator for scalars and
vectors, but keep running into the error message Functional
dependencies conflict. What I think is going on is that the
dependency check doesn't work with incoherent (or overlapping)
instances. In the example below, the two instances of Mult are
overlapping. What I want is the vector version to be used for vectors
and the scalar version used for numbers, even if a vector-type is an
instance of the Num-class (I believe -fallow-incoherent-instances
would make that kind of choise for me, right?).
Im using the Visual Studio plugin Visual Haskell, and thus GHC version
6.6. Otherwise I think associated types might have worked better for
this...
{-# OPTIONS_GHC -fglasgow-exts -fallow-undecidable-instances
-fallow-incoherent-instances #-}
data V2 a = V2 a a
class Vec v a where
dot :: v a - v a - a
instance Num a = Vec V2 a where
V2 a1 a2 `dot` V2 b1 b2 = a1*b1+a2*b2
class Mult a b c | a b - c where
(*.) :: a - b - c
instance (Num x) = Mult x x x where (*.) = (*) instance (Vec a x) =
Mult (a x) (a x) x where (*.) = dot
According to the definition of Mult the parameter 'c' from above should be
uniquely determined by a pair of types 'a' and 'b'. Now, lets say we have a
type NumVec that instantiates both the Vec class and the Num as in
instance Num (NumVec a) where
instance Vec NumVec a where
Then according to the instance declaration
instance (Num x) = Mult x x x where ...
(NumVec a) (NumVec a) (NumVec a) instantiates the class. On the other hand
looking at the instance declaration:
instance (Vec a x) = Mult (a x) (a x) x where ...
(NumVec a) (NumVec a) a , is also an instance why the fun dep (a b -
c) is violated.
Regards,
Joel
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[Haskell-cafe] Simple Table Update
Hi, I'd like to create a new list based on an original list, using information from a second (symbol) list. That second list should be updated as each element in the new list is added. I've been using map a lot, but that's not an option here, and I'm having trouble obtaining a good recursive structure for my function. The minimal fixpus function below shows the problem. I have sts on both sides of the : list construct, but I'd like the second sts to be a version modified by the where (singular) function, fixpu. fixpus :: [ProgUnit] - [ProgUnitSymbolTable] - [ProgUnit] fixpus [] _ = [] fixpus (pu:pus) sts = fixpu pu sts : fixpus pus sts where fixpu pu sts = pu (Below) I tried making fixpu return a tuple, and then use fst, snd and let, but I think it looks strange. I know it's quite basic, but I'd like a strong foundation for what's likely to become a medium-scale project. Can anyone offer advice? fixpus :: [ProgUnit] - [ProgUnitSymbolTable] - [ProgUnit] fixpus [] _ = [] fixpus (pu:pus) sts = let a = (fixpu pu sts) in fst a : fixpus pus (snd a) where fixpu pu sts = (pu,sts ++ [(,[])]) Regards, Paul ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] monadic parser with Happy and Alex
Timothy Goddard ha scritto: On Sun, 05 Oct 2008 04:05:51 Manlio Perillo wrote: Hi. I have completed a draft of a CSS lexer, using Alex. http://hg.mperillo.ath.cx/haskell/webtools/file/tip/src/CSS/Lexer.x The lexer use the posn wrapper. Now I'm starting to write the parser with Happy, however for the final product I would like to: 1) Be able to do I/O in the lexer, for stylesheets inclusion (@import rule) 2) be able to keep state in the parser (or lexer?), for character transcoding (@charset rule) This should be possible with Happy (and there are some example), however I don't find examples that make use of a lexer written with Alex. Should I write a lexer using only the Alex basic interface (without wrappers)? Thanks Manlio Perillo ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe Hi Manlio, You may be better off separating the parsing from the import process. You would first parse it in to internal data structures (including an option for import) then go through that and replace import statements with the parsed content of those files. Thanks, this seems the best solution. Producing a list which is then consumed by an IO procedure is almost exactly equivalent to threading IO through the entire parser and is a lot tidier, more flexible and should be easier to maintain. Regards Manlio ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] OT: Haskell desktop wallpaper?
On Oct 8, 2008, at 05:12 , Magnus Therning wrote: This morning I got tired of my desktop wallpaper (one that ships with Debian's Gnome packages). Typing haskell desktop wallpaper yeilded a lot of links to wallpapers with Colleen Haskell, while she's a beautiful lady it wasn't exactly what I was hoping to find. Hence this email. Where can I find some nice wallpapers inspired by Haskell, or maybe even created by Haskell code? Haskell-created: http://www.frank-buss.de/haskell/OlympicRings.hs.txt http://hackage.haskell.org/cgi-bin/hackage-scripts/package/nymphaea -- 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: [hmatrix] build error
Hi Xiao-Yong, In i686 Arch linux, with the normal blas and lapack, I need: extra-libraries: gsl lapack blas gslcblas gfortran But using atlas-lapack: extra-libraries: gsl lapack f77blas gslcblas atlas gcc_s I don't know how I found that __powidf2 is in libgcc_s :) I will add these options to hmatrix.cabal. -Alberto Xiao-Yong Jin wrote: Hi, looks like I hit a bug, but I'm not sure which software it belongs to, gcc, ghc or atlas? -- error doing runhaskell Setup build -- Preprocessing library hmatrix-0.4.1.0... /usr/bin/ld: dist/build/Numeric/GSL/Special/Internal_hsc_make: hidden symbol `__powidf2' in /usr/lib/gcc/x86_64-unknown-linux-gnu/4.3.2/libgcc.a(_powidf2.o) isreferenced by DSO /usr/bin/ld: final link failed: Nonrepresentable section on output collect2: ld returned 1 exit status linking dist/build/Numeric/GSL/Special/Internal_hsc_make.o failed command was: /usr/bin/ghc -optl-lgsl -optl-llapack dist/build/Numeric/GSL/Special/Internal_hsc_make.o -o dist/build/Numeric/GSL/Special/Internal_hsc_make -- error doing runhaskell Setup build -- I believe `__powidf2' is a internal symbol in gcc and it is hidden. The system is archlinux x86_64 and the software I used are atlas-lapack 3.8.2-1 gcc 4.3.2-1 Using built-in specs. Target: x86_64-unknown-linux-gnu Configured with: ../configure --prefix=/usr --enable-shared --enable-languages=c,c++,fortran,objc,obj-c++,treelang --enable-threads=posix --mandir=/usr/share/man --infodir=/usr/share/info --enable-__cxa_atexit --disable-multilib --libdir=/usr/lib --libexecdir=/usr/lib --enable-clocale=gnu --disable-libstdcxx-pch --with-tune=generic Thread model: posix gcc version 4.3.2 (GCC) ghc 6.8.2-2 [(Project name,The Glorious Glasgow Haskell Compilation System) ,(Project version,6.8.2) ,(Booter version,6.8.2) ,(Stage,2) ,(Interface file version,6) ,(Have interpreter,YES) ,(Object splitting,YES) ,(Have native code generator,YES) ,(Support SMP,YES) ,(Unregisterised,NO) ,(Tables next to code,YES) ,(Win32 DLLs,) ,(RTS ways, debug thr thr_p thr_debug) ,(Leading underscore,NO) ] I googled but no useful information. Best, Xiao-Yong ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Functional dependencies and incoherent instances
On Wed, Oct 8, 2008 at 2:59 PM, Tobias Bexelius
[EMAIL PROTECTED] wrote:
Or do I have too much faith in the -fallow-incoherent-instances flag now? :/
Overlapping instances are an instance definition-time feature;
incoherent instances only become applicable at the call site for
polymorphic functions in the presence of overlapping instances.
As an example, consider the following overlapping instances:
{-# LANGUAGE OverlappingInstances #-}
class Foo a where foo :: a - Bool
instance Foo a where
foo x = False
instance Foo Integer where
foo x = (x == 3)
test1 :: String - Bool
test1 x = foo x -- uses Foo a instance
test2 :: Integer - Bool
test2 x = foo x -- uses Foo Integer instance
test3 :: a - Bool
test3 x = foo x -- incoherent!
Consider (test3 (3 :: Integer)). This should definitely use the
implementation for instance Foo Integer. But it can't, because test3
doesn't know what type its argument is!
Incoherent instances still allows test3 to compile, but it may choose
the wrong instance. In this case, test3 will use the Foo a
instance no matter what type of argument you pass it.
But the incoherency only arises at a call-site for the class method;
if you take test3 out of this program, the instances are still
overlapping but there is no compile problem (assuming
-foverlapping-instances). If you are getting an error because of an
instance definition, as opposed to a call site, incoherent instances
won't help you.
-- ryan
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Re: [Haskell-cafe] Simple Table Update
Prelude :t Data.List.mapAccumL Data.List.mapAccumL :: (acc - x - (acc, y)) - acc - [x] - (acc, [y]) I'm sure you can fill in the details :) -- ryan 2008/10/8 Paul Keir [EMAIL PROTECTED]: Hi, I'd like to create a new list based on an original list, using information from a second (symbol) list. That second list should be updated as each element in the new list is added. I've been using map a lot, but that's not an option here, and I'm having trouble obtaining a good recursive structure for my function. The minimal fixpus function below shows the problem. I have sts on both sides of the : list construct, but I'd like the second sts to be a version modified by the where (singular) function, fixpu. fixpus :: [ProgUnit] - [ProgUnitSymbolTable] - [ProgUnit] fixpus [] _ = [] fixpus (pu:pus) sts = fixpu pu sts : fixpus pus sts where fixpu pu sts = pu (Below) I tried making fixpu return a tuple, and then use fst, snd and let, but I think it looks strange. I know it's quite basic, but I'd like a strong foundation for what's likely to become a medium-scale project. Can anyone offer advice? fixpus :: [ProgUnit] - [ProgUnitSymbolTable] - [ProgUnit] fixpus [] _ = [] fixpus (pu:pus) sts = let a = (fixpu pu sts) in fst a : fixpus pus (snd a) where fixpu pu sts = (pu,sts ++ [(,[])]) Regards, Paul ___ 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] Functional dependencies and incoherent instances
I think the technique described at http://haskell.org/haskellwiki/GHC/AdvancedOverlap may give you what you want. I've never tried it myself though. / Emil Tobias Bexelius skrev: Yeah, I realized that. But heres where I would like the undecidable incoherent instances to kick in, i.e. as long as I haven't got any NumVec instances GHC should be able to choose only one of the Mult instances. Or do I have too much faith in the -fallow-incoherent-instances flag now? :/ I would like to be able to write something like instance (Vec a x, -Num (a x)) = Mult (a x) (a x) x where (*.) = dot where -Num (a x) means that (a x) must not be an instance of Num. Can I express this in some way? Regards Tobias ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [Haskell] Catching error / making library functions monadic (in failure)
On Wed, 2008-10-08 at 18:07 +0200, Philip K.F. Hölzenspies wrote: I think this is the core problem I have. Really, error should be implemented as fail, rather than vice versa. I see why this doesn't work, because it would type error :: Monad m = String - m a even though the whole idea is that it's typed 'a'. Right, that's exactly why it would not work to give error that type. However error should only be being used for programming errors, not for expected runtime errors. Nonetheless, I would like it if either IO wasn't the only monad allowing catching, or standard functions not only being available with 'error' stuff (like !!, head, etc.). Those functions do have safe counterparts for when you cannot guarantee the pre-condition. It typically involves pattern matching, eg instead of head use: case foo of [] - (x:xs) - Or for !! you could use take or splitAt and pattern matching. If you want more exact analogues of head, !! etc then see Neil's Safe library. If you can report them we can fix them. I think I spoke too soon. The error occur in other libraries' functions, so I unjustly smudged your wonderful gtk2hs work (for which, btw: thanks very, very much). ok :-) To be honest; when I write a library, I also don't assume monadic contexts for stuff that I do in purely functional terms. Sometimes errors occur only in deeply nested code and just putting in error is the easy way out. Especially, libraries that are not intended for industrial strength production code seem to be prone to this type of coding, when they're not already monadic. I think it's not as bad as you suggest. In haskell, error is like unchecked exceptions or assertions in Java. They are for cases that really indicate a programmer error, not for bad input or IO failures. Even these kinds of errors can be caught and contained in a sensible way using exception handlers in IO. For example supposing some web server page handler had some programming error and called a function in a way that violated the pre-condition and called error. That need not kill the entire server. The page handler just needs to catch all exceptions and return a 500 internal server error and write the error out to the logs. So it's actually a reasonably robust way of dealing with the inevitable programmer errors. Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [hmatrix] build error
Alberto Ruiz [EMAIL PROTECTED] writes: Hi Xiao-Yong, In i686 Arch linux, with the normal blas and lapack, I need: extra-libraries: gsl lapack blas gslcblas gfortran But using atlas-lapack: extra-libraries: gsl lapack f77blas gslcblas atlas gcc_s I guess you want cblas instead of gslcblas, since atlas has it. I don't know how I found that __powidf2 is in libgcc_s :) References and bibliography is truly important. I will add these options to hmatrix.cabal. -Alberto Thanks a lot for the excellent work. Xiao-Yong -- c/*__o/* \ * (__ */\ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
RE: [Haskell-cafe] Simple Table Update
It brings tears to my eyes to see such a beautiful function ;) You've hit the nail on the head Ryan. The new version of my second previous code snippet now no longer requires fixpu*, and is: typeCheckAST (Program pus) = Program $ snd $ mapAccumL f [] pus where f st pu = (st ++ [(,[])],pu) Many thanks, Paul -Original Message- From: Ryan Ingram [mailto:[EMAIL PROTECTED] Sent: Wed 08/10/2008 18:03 To: Paul Keir Cc: haskell-cafe@haskell.org Subject: Re: [Haskell-cafe] Simple Table Update Prelude :t Data.List.mapAccumL Data.List.mapAccumL :: (acc - x - (acc, y)) - acc - [x] - (acc, [y]) I'm sure you can fill in the details :) -- ryan 2008/10/8 Paul Keir [EMAIL PROTECTED]: Hi, I'd like to create a new list based on an original list, using information from a second (symbol) list. That second list should be updated as each element in the new list is added. I've been using map a lot, but that's not an option here, and I'm having trouble obtaining a good recursive structure for my function. The minimal fixpus function below shows the problem. I have sts on both sides of the : list construct, but I'd like the second sts to be a version modified by the where (singular) function, fixpu. fixpus :: [ProgUnit] - [ProgUnitSymbolTable] - [ProgUnit] fixpus [] _ = [] fixpus (pu:pus) sts = fixpu pu sts : fixpus pus sts where fixpu pu sts = pu (Below) I tried making fixpu return a tuple, and then use fst, snd and let, but I think it looks strange. I know it's quite basic, but I'd like a strong foundation for what's likely to become a medium-scale project. Can anyone offer advice? fixpus :: [ProgUnit] - [ProgUnitSymbolTable] - [ProgUnit] fixpus [] _ = [] fixpus (pu:pus) sts = let a = (fixpu pu sts) in fst a : fixpus pus (snd a) where fixpu pu sts = (pu,sts ++ [(,[])]) Regards, Paul ___ 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] OT: Haskell desktop wallpaper?
Hi, I created a wallpaper from The.Monad.Reader logo. You can find two versions here: http://tonguc.name/images/lambda-1280x800.png http://tonguc.name/images/lambda-1024x768.png Magnus Therning der ki: This morning I got tired of my desktop wallpaper (one that ships with Debian's Gnome packages). Typing haskell desktop wallpaper yeilded a lot of links to wallpapers with Colleen Haskell, while she's a beautiful lady it wasn't exactly what I was hoping to find. Hence this email. Where can I find some nice wallpapers inspired by Haskell, or maybe even created by Haskell code? Oh yes, wallpapers related to XMonad would do, I suppose ;-) /M -- Magnus Therning(OpenPGP: 0xAB4DFBA4) magnus＠therning．org Jabber: magnus＠therning．org http://therning.org/magnus identi.ca|twitter: magthe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- R. Emre Başar İstanbul Bilgi University Department of Computer Science signature.asc Description: Digital signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] synchronous channels in STM
I was wondering if it was possible to implement synchronous channels within STM. In particular, I'd like to have CSP-like send and recv primitives on a channel that each block until the other side arrives to complete the transaction. I think I've convinced myself that it's not possible, but anyone care to differ? cheers, rog. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ghc 6.10 and parsec
Which Parsec is GHC 6.10 going to ship with -- Parsec 2 or Parsec 3? -- _jsn ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] synchronous channels in STM
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 roger peppe wrote: I was wondering if it was possible to implement synchronous channels within STM. In particular, I'd like to have CSP-like send and recv primitives on a channel that each block until the other side arrives to complete the transaction. I think I've convinced myself that it's not possible, but anyone care to differ? This sounds similar to what I once tried for a FRP implementation. I decided that what I was trying to do was impossible (at least without recalculating things all the time whenever something retries), and then constructed an IVar implementation which was working very elegantly (before I decided to change the core ideas behind my FRP implementation). As luck would have it, Luke Palmer recently added his own IVar implementation to Hackage, which you may find a use for. - - Jake -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.9 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkjtMQwACgkQye5hVyvIUKk39QCcDdsFY7z0k2xwkJ/zBK3tVsbT n28An2D9LzUfWiWTpKIU7J7tt/VGs4EB =kQGz -END PGP SIGNATURE- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: [Haskell] ANNOUNCE: SourceGraph-0.1 and Graphalyze-0.3
2008/10/8 Gwern Branwen [EMAIL PROTECTED]: So it'll be fixed for the next release? Cool then; I look forward to seeing my XMC modules' analysis. Yeah, I was planning on making a new release some time this week... and then I somehow accidentally uninstalled just about everything on my system, and have to do a reinstall :s -- Ivan Lazar Miljenovic [EMAIL PROTECTED] IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghc 6.10 and parsec
Jason, If this is representative of what it will be, here's what I have: $ ghc --version The Glorious Glasgow Haskell Compilation System, version 6.10.0.20081007 $ ghc-pkg list parsec /usr/local/lib/ghc-6.10.0.20081007/./package.conf: parsec-2.1.0.1 Paulo On Wed, Oct 8, 2008 at 5:14 PM, Jason Dusek [EMAIL PROTECTED] wrote: Which Parsec is GHC 6.10 going to ship with -- Parsec 2 or Parsec 3? -- _jsn ___ 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] Hoogle? [Stacking monads]
The syntax is for the implicit parameter extension[1]. I think you would write your example as foo (undefined :: Bar x) ?z :: Bar y Then querying the type of that whole expression with :t will list ?z's type in the expression's constraints. (Of course, you should turn off the monomorphism restriction so that ghc doesn't complain if constraints aren't resolved). [1]: http://www.haskell.org/ghc/docs/latest/html/users_guide/other-type-extensions.html#implicit-parameters Reiner On Thu, Oct 9, 2008 at 6:11 AM, Andrew Coppin [EMAIL PROTECTED]wrote: Ryan Ingram wrote: There is such a tool, it's called ghci :) It just takes a bit of massaging to do what you want: ghci :set -fglasgow-exts ghci :t (?f some_func [?a .. ?b]) Here's an example: Prelude :t ?f map [?a .. ?b] ?f map [?a .. ?b] :: forall t a b t1. (Enum t1, ?b::t1, ?a::t1, ?f::((a - b) - [a] - [b]) - [t1] - t) = t This tells you the types the variables have to have, and the type of the expression. Judicious use of (undefined :: type_signature) can also help. Using undefined is already a standard technique for me. But what it doesn't let you do is foo (undefined :: Bar x) (undefined) :: Bar y -- What type is the second argument? I'm curios as to how the example you give actually works - I don't recognise that syntax at all... ___ 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] synchronous channels in STM
I was wondering if it was possible to implement synchronous channels within STM. In particular, I'd like to have CSP-like send and recv primitives on a channel that each block until the other side arrives to complete the transaction. Assuming that retry blocks until something changes, you could associate a channel with a thread that encapsulates the transaction. Somewhat like this? import Control.Concurrent.STM import Control.Concurrent sender write confirm = do atomically $ putTMVar write hi atomically $ takeTMVar confirm putStrLn sender done receiver read = do r - atomically $ takeTMVar read putStrLn $ receiver done: ++r channel read write confirm = atomically $ do w - takeTMVar write putTMVar read w putTMVar confirm () main = do (read,write,confirm) - atomically $ do read - newEmptyTMVar write - newEmptyTMVar confirm - newEmptyTMVar return (read,write,confirm) forkIO (channel read write confirm) forkIO (threadDelay 300 receiver read) threadDelay 500 sender write confirm You might also be interested in http://hackage.haskell.org/cgi-bin/hackage-scripts/package/chp Claus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghc 6.10 and parsec
Aye, I have that as well, but you never know :) -- _jsn ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghc 6.10 and parsec
On Thu, Oct 9, 2008 at 6:14 AM, Jason Dusek [EMAIL PROTECTED] wrote: Which Parsec is GHC 6.10 going to ship with -- Parsec 2 or Parsec 3? I do hope it will be 2. Parsec 3 is significantly slower than 2 in my SQL parser. Cheers, -agentzh ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] parsec 3 parsec 2
Shouldn't hiding the package stop it from causing possible mayhem, yet it be accessible to those packages depending on the new version explicitly ? On Thu, Oct 9, 2008 at 2:53 AM, Jason Dusek [EMAIL PROTECTED] wrote: I recently took a look at the new Yi, and it looks neat but I am hesitant to install it -- it require Parsec 3. What will happen to my system, carefully maintained, if I unleash this new Parsec on my programs and the programs of others? Can I expect total breakage, coexistence or...? -- _jsn ___ 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] synchronous channels in STM
2008/10/9 Claus Reinke [EMAIL PROTECTED]
I was wondering if it was possible to implement synchronous channels
within STM. In particular, I'd like to have CSP-like send and recv
primitives
on a channel that each block until the other side arrives to complete
the transaction.
Assuming that retry blocks until something changes, you could associate
a channel with a thread that encapsulates the transaction. Somewhat like
this?
You don't need an additional channel thread:
module SyncChan (SyncChan, send, recv, newSyncChan) where
import Control.Concurrent.STM
import Control.Monad
import Control.Concurrent
newtype SyncChan a = SC { unSC :: TVar (State a) }
data State a = Ready | Sent a | Received
newSyncChan :: STM (SyncChan a)
newSyncChan = SC `fmap` newTVar Ready
send :: SyncChan a - a - IO ()
send (SC chan) x = do
atomically $ unsafeSend chan x
atomically $ waitReceiver chan
recv :: SyncChan a - STM a
recv (SC chan) = do
s - readTVar chan
case s of
Sent s - writeTVar chan Received return s
_ - retry
unsafeSend chan x = do
s - readTVar chan
case s of
Ready - writeTVar chan (Sent x)
_- retry
waitReceiver chan = do
s - readTVar chan
case s of
Received - writeTVar chan Ready
_- retry
x | f = fmap f x
test b = do
(x,y) - atomically $ liftM2 (,) newSyncChan newSyncChan
forkIO $ join $ atomically $ -- since recv is in STM you can wait on
multiple channels at the same time
(recv x | print)
`mplus`
(recv y | print)
if b
then send x 'a'
else send y 1
as a bonus you can also try to send to the first available among multiple
channels:
(this formulation uses ExistentialQuantification but it's just a
convenience)
data Sending a = forall b. Sending (SyncChan b) b a
sendMulti :: [Sending a] - IO a
sendMulti [] = fail empty
sendMulti xs = do (m,r) - atomically $ msum $ map sending xs
atomically m
return r
sending :: Sending t - STM (STM (), t)
sending (Sending (SC chan) x k) = do
unsafeSend chan x
return (waitReceiver chan,k)
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Re: [Haskell-cafe] parsec 3 parsec 2
I don't know anything about how to do that. Is this a Cabal thing? A GHC package registration thing? -- _jsn ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] parsec 3 parsec 2
ghc-pkg hide {pkg-id}
On Thu, Oct 9, 2008 at 5:53 AM, Jason Dusek [EMAIL PROTECTED] wrote:
I don't know anything about how to do that. Is this a Cabal
thing? A GHC package registration thing?
--
_jsn
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Re: [Haskell-cafe] Simplifying a IsFunction type class using type equality constraints
Corey O'Connor: I recently had a need to use the IsFunction typeclass described by Oleg here: http://okmij.org/ftp/Haskell/isFunction.lhs and am wondering if the use of the TypeCast class can be correctly replaced by a type equality constraint. The IsFunction and TypeCast classes were defined as: data HTrue data HFalse class IsFunction a b | a - b instance TypeCast f HTrue = IsFunction (x-y) f instance TypeCast f HFalse = IsFunction a f -- literally lifted from the HList library class TypeCast a b | a - b, b-a where typeCast :: a - b class TypeCast' t a b | t a - b, t b - a where typeCast' :: t- a-b class TypeCast'' t a b | t a - b, t b - a where typeCast'' :: t- a-b instance TypeCast' () a b = TypeCast a b where typeCast x = typeCast' () x instance TypeCast'' t a b = TypeCast' t a b where typeCast' = typeCast'' instance TypeCast'' () a a where typeCast'' _ x = x I found the use of TypeCast in the IsFunction could be replaced by a type family: class IsFunction a b | a - b instance (f ~ TTrue) = IsFunction (x-y) f instance (f ~ TFalse) = IsFunction a f Yes, that's a fine way of simplifying the definition. In fact, you should also be able to drop the functional dependency in the IsFunction class. Manuel ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
