Re: [Haskell-cafe] Printing call site for partial functions
Michael Snoyman mich...@snoyman.com writes:
I had a bug in a site of mine[1] for a few weeks, where it would just print:
Prelude.head: empty list
It took a long time to track down the problem
+1: I've been arguing this for something like ten years :-)
One half-baked quasi-solution is to use:
#define head (\xs - case xs of { (x:_) - x ; _ - error(head: empty list
at++__FILE__++show __LINE__)})
Downsides are that it depends on CPP, and, CPP being a C preprocessor,
it doesn't blend well with lines with single apostrophes on them (e.g.:
head x')
-k
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Re: [Haskell-cafe] Printing call site for partial functions
On Mon, 30 Apr 2012 10:31:01 +0200, Ketil Malde ke...@malde.org wrote:
One half-baked quasi-solution is to use:
#define head (\xs - case xs of { (x:_) - x ; _ - error(head: empty
list at++__FILE__++show __LINE__)})
Downsides are that it depends on CPP, and, CPP being a C preprocessor,
it doesn't blend well with lines with single apostrophes on them (e.g.:
head x')
-k
There is a Haskell solution: cpphs[0], you can invoke this preprocessor by
specifying the flags
-cpp -pgmPcpphs -optP--cpp
for GHC.
Regards,
Henk-Jan van Tuyl
[0] http://hackage.haskell.org/package/cpphs
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http://members.chello.nl/hjgtuyl/tourdemonad.html
Haskell programming
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[Haskell-cafe] Hong Kong Haskell hackathon - call for participation
Hi everybody, if you are in or around Hong Kong in May and want to play, please check out this: http://www.haskell.org/haskellwiki/HkHac2012 Otherwise, any wider circulation or suggestion of channels / university people / companies that I should invite directly is welcome. cheers, Matthias ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] ANN: Portackage - a hackage portal
Great work! Thanks. Does it include only packages without executables ? Eg I see hledger-lib but not the hledger or gist packages. It would be nice to have all of hackage there. Best - Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: hflags-0.1, a command line flags library similar to Google's gflags
Hello,
I would like to announce the release of HFlags, a command line flags
library that makes it very easy to define and use flags.
The API is similar to Google's gflags, here is a very simple example
program:
-=-
#!/usr/bin/env runhaskell
{-# LANGUAGE TemplateHaskell #-}
import HFlags
defineFlag name Indiana Jones Who to greet.
defineFlag r:repeat (3 + 4 :: Int)
Number of times to repeat the message.
main = do remainingArgs - $(initHFlags Simple program v0.1)
sequence_ $ replicate flags_repeat greet
where
greet = putStrLn $ Hello
++ flags_name
++ , very nice to meet you!
-=-
As you can see, we have TemplateHaskell functions to help with the
definition (and initialization) of the flags, and the values themselves
are pure, no need for being in the IO monad to use the value of the
flags.
Also, the initHFlags function automagically gathers all the flags
defined anywhere in the whole program, so if a library defines flags,
you don't have to mention it in the main, but the user will still be
able to set those flags too.
More details behind this design and more example can be found in the
following post: http://blog.risko.hu/2012/04/ann-hflags-0.html
Comments and criticism is welcome.
Code: http://github.com/errge/hflags
Examples: https://github.com/errge/hflags/tree/master/examples
Hackage: http://hackage.haskell.org/package/hflags
Best regards,
Gergely Risko
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Re: [Haskell-cafe] [Haskell] ANN: Portackage - a hackage portal
First let me mention, there is now a complete modules tree with API links (in a very preliminary state), at http://fremissant.net/portackage/modules.php and the package view is still http://fremissant.net/portackage On Mon, Apr 30, 2012 at 11:35 AM, Simon Michael si...@joyful.com wrote: Great work! Thanks. Does it include only packages without executables ? Eg I see hledger-lib but not the hledger or gist packages. It would be nice to have all of hackage there. Simon, thank you. And, yes, as a temporary measure, I elided the packages that expose no modules, to try to tame the slowness a bit. I could provide them on a similar, separate page, until figure out some optimisations. Derek, if you're reading, sorry if I seemed defensive there before. :) Okay, this bagel is screaming Eat Me!!... Kind Reg'ds, Andrew On Mon, Apr 30, 2012 at 11:35 AM, Simon Michael si...@joyful.com wrote: Great work! Thanks. Does it include only packages without executables ? Eg I see hledger-lib but not the hledger or gist packages. It would be nice to have all of hackage there. Best - Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] ANN: Portackage - a hackage portal
...and the binary packages (those exposing no modules) are now up at http://fremissant.net/portackage/binary.php Not nice to have them in a separate table, but for now that's the case. :( So the three links in summary: module tree: http://fremissant.net/portackage/modules.php library packages: http://fremissant.net/portackage/binary.php other packages: http://fremissant.net/portackage/portackage.php On Mon, Apr 30, 2012 at 1:42 PM, Andrew Seniuk ras...@gmail.com wrote: First let me mention, there is now a complete modules tree with API links (in a very preliminary state), at http://fremissant.net/portackage/modules.php and the package view is still http://fremissant.net/portackage On Mon, Apr 30, 2012 at 11:35 AM, Simon Michael si...@joyful.com wrote: Great work! Thanks. Does it include only packages without executables ? Eg I see hledger-lib but not the hledger or gist packages. It would be nice to have all of hackage there. Simon, thank you. And, yes, as a temporary measure, I elided the packages that expose no modules, to try to tame the slowness a bit. I could provide them on a similar, separate page, until figure out some optimisations. Derek, if you're reading, sorry if I seemed defensive there before. :) Okay, this bagel is screaming Eat Me!!... Kind Reg'ds, Andrew On Mon, Apr 30, 2012 at 11:35 AM, Simon Michael si...@joyful.com wrote: Great work! Thanks. Does it include only packages without executables ? Eg I see hledger-lib but not the hledger or gist packages. It would be nice to have all of hackage there. Best - Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] ANN: Portackage - a hackage portal
Oops, the three links in summary are: module tree: http://fremissant.net/portackage/modules.php library packages: http://fremissant.net/portackage/portackage.php other packages: http://fremissant.net/portackage/binary.php ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Darcs home page updated
With 2.8 released, I felt Darcs deserves better presentation. After surveying other VCS sites I worked on an update to our home page layout and content over the last few days, with review and input from #darcs, and it went live last night. It's far from perfect but I hope it's a good step forward. Thanks for the input, and have at it: http://darcs.net -Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Darcs home page updated
On Mon, 30 Apr 2012 12:27:57 -0700, Simon Michael si...@joyful.com said: Simon With 2.8 released, I felt Darcs deserves better presentation. After Simon surveying other VCS sites I worked on an update to our home page Simon layout and content over the last few days, with review and input from Simon #darcs, and it went live last night. It's far from perfect but I hope Simon it's a good step forward. Thanks for the input, and have at it: Simon http://darcs.net Hi, that looks good, thanks. Here are some ideas : - The purple color of titles is not very attractive, changing it to something more saturated would make it look fresher. - the purple color rounded box is not very attractive either :) - there is a video right on the first page, good ! Unfortunatly, it is not showing darcs but its cousin. Also, the title is why do we continue to develop ... [camp], which isn't the most positive approach one can expect on a start page - the compact tutorial is great, I love it. It deserves more poish. For inspiration, one can have a look at this website for example : http://gembundler.com/ - underlined links looks a bit 90's. You can add a simple css rule to choose an other color and remove the underline (though it is good practice to set it on mouseover) cheers, -- Paul ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Darcs home page updated
On 04/30/12 15:27, Simon Michael wrote: With 2.8 released, I felt Darcs deserves better presentation. After surveying other VCS sites I worked on an update to our home page layout and content over the last few days, with review and input from #darcs, and it went live last night. It's far from perfect but I hope it's a good step forward. Thanks for the input, and have at it: http://darcs.net Maybe use some other repo for the hello world example? $ darcs get http://darcs.net darcs is too many darc. Using darcs to check out darcs and commit a file named darcs.cabal just conflates too many things unnecessarily. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Darcs home page updated
Thanks for the feedback Paul (and Michael), all such is very useful. Maybe I'll try Django-green... :) - there is a video right on the first page, good ! Unfortunatly, it is not showing darcs but its cousin. Also, the title is why do we continue to develop ... [camp], which isn't the most positive approach one can expect on a start page It does discuss both camp and darcs. I meant to say the following: I was happy to be able to use Ian Lynagh's video, which I have always felt strikes a very good tone - technical, concise, grounded and energising. I like listening to it. Thanks Ian! Also, there isn't a lot out there to work with. Please let me know if I'm missing something else good. - the compact tutorial is great, I love it. It deserves more poish. For inspiration, one can have a look at this website for example : Good to hear, I have scheduled more polish. - underlined links looks a bit 90's. You can add a simple css rule to choose an other color and remove the underline (though it is good practice to set it on mouseover) Oh I thought underline had come back in. Ok done. A few more notes trimmed from the original mail: - I've tried to emphasise the relative simplicity Darcs offers. I think this is a true strength and our biggest value proposition. (Aside: I think Haskell is another true strength, but a less obvious one, currently not mentioned.) - You may notice my very swift description of patch dependencies. Though we are used to thinking of patch deps as painful, I think the text is a fair and accurate high-level description for newcomers. The video gives a little more insight. - Like some other sites (I liked Mercurial's best), we have quick start examples right on the front page. This grew a bit long, but how handy to be able to jump to darcs.net and instantly see how to get stuff done.. and its basically *all you need to know* to use Darcs, correct me if I'm wrong. - The colours are a bit anaemic. Needs more red and dark tones. The dark pres I tried gave less contrast.. - I use and occasionally hack on Alex Suraci's darcsden repo-hosting app. You can see my dev repo and changes at http://joyful.com/darcsden/simon/darcs-sm , and you might even be able to register, fork, show previews and send pull requests there - testers welcome. Perhaps one day this could be on darcs.net, or a reliable funded darcsden.com, or something. Best - Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] twitter election on favorite programming language
Hello, A twitter election on favorite programming language was held in Japan and it appeared that Heskell is No. 10 loved language in Japan. :-) http://twisen.com/election/index/654 Regards, --Kazu ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: HandsomeSoup-0.3: CSS selectors for HXT
Because I had the methods written for network and http already (this is just old code of mine I'm open-sourcing), and I didn't want to bother with reading the source for hxt-curl or hxt-http (since neither has documentation and I'm not convinced that they can do exactly what I want). If you feel strongly about hxt-curl or hxt-http I would love to hear why! I'm not opposed to using those instead. Adit On Fri, Apr 27, 2012 at 1:30 AM, Yves Parès yves.pa...@gmail.com wrote: Why do you make your own overlay to download files via HTTP? HXT has backends (hxt-http or hxt-curl) to do that. Le 27 avril 2012 04:16, aditya bhargava bluemangrou...@gmail.com a écrit : *Homepage:* http://egonschiele.github.com/HandsomeSoup *On Hackage:* http://hackage.haskell.org/package/HandsomeSoup *Blurb:* HandsomeSoup is the library I wish I had when I started parsing HTML in Haskell. It is built on top of HXT and adds a few functions that make is easier to work with HTML. Most importantly, it adds CSS selectors to HXT. The goal of HandsomeSoup is to be a complete CSS2 parser for HXT (it is very close to this right now). -- adit.io ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- adit.io ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
