- Haskell-Cafe - Haskell.org

Re: [Haskell-cafe] Why so many strings in Network.URI, System.Posix and similar libraries?
by Jason Dusek 12 Mar '12

12 Mar '12

2012/3/11 Thedward Blevins <thedward(a)barsoom.net>: > On Sun, Mar 11, 2012 at 13:33, Jason Dusek <jason.dusek(a)gmail.com> wrote: > > The syntax of URIs is a mechanism for describing data octets, > > not Unicode code points. It is at variance to describe URIs in > > terms of Unicode code points. > > This claim is at odds with the RFC you quoted: > > 2. Characters > > The URI syntax provides a method of encoding data, presumably for the sake > of identifying a resource, as a sequence of characters. The URI characters > are, in turn, frequently encoded as octets for transport or presentation. > This specification does not mandate any particular character encoding for > mapping between URI characters and the octets used to store or transmit > those characters. > > (Emphasis is mine) > > The RFC is specifically agnostic about serialization. I generally agree that > there are a lot of places where ByteString should be used, but I'm not > convinced this is one of them. Hi Thedward, I am CC'ing the list since you raise a good point that, I think, reflects on the discussion broadly. It is true that intent of the spec is to allow encoding of characters and not of bytes: I misread its intent, attending only to the productions. But due to the way URIs interact with character encoding, a general URI parser is constrained to work with ByteStrings, just the same. The RFC "...does not mandate any particular character encoding for mapping between URI characters and the octets used to store or transmit those characters..." and in Section 1.2.1 it is allowed that the encoding of may depend on the scheme: In local or regional contexts and with improving technology, users might benefit from being able to use a wider range of characters; such use is not defined by this specification. Percent-encoded octets (Section 2.1) may be used within a URI to represent characters outside the range of the US-ASCII coded character set if this representation is allowed by the scheme or by the protocol element in which the URI is referenced. It seems possible for any octet, 0x00..0xFF, to show up in a URI, and it is only after parsing the scheme that we can say whether the octet belongs there are not. Thus a general URI parser can only go as far as splitting into components and percent decoding before handing off to scheme specific validation rules (but that's a big help already!). I've implemented a parser under these principles that handles specifically URLs: http://hackage.haskell.org/package/URLb Although the intent of the spec is to represent characters, I contend it does not succeed in doing so. Is it wise to assume more semantics than are actually there? The Internet and UNIX are full of broken junk; but faithful representation would seem to be better than idealization for those occasions where we must deal with them. I'm not sure the assumption of "textiness" really helps much in practice since the Universal Character Set contains control codes and bidi characters -- data that isn't really text. -- Jason Dusek pgp // solidsnack // C1EBC57DC55144F35460C8DF1FD4C6C1FED18A2B

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ANNOUNCE: freesect-0.0.5
by Ras Far 12 Mar '12

12 Mar '12

Hi, I'm pleased to announce my first package, freesect, which is a Haskell syntax extension to generalise sections. Please visit the homepage http://www.fremissant.net/freesect for more information. The package is also available on Hackage. Some previous discussion occurred on the haskell-cafe thread http://www.mail-archive.com/haskell-cafe@haskell.org/msg97643.html It's been an exhilarating experience! Kind Regards, Andrew Seniuk (rasfar on #haskell)

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ANNOUNCE : Leksah 0.12
by Hamish Mackenzie 12 Mar '12

12 Mar '12

Source is in Hackage and https://github.com/leksah OS X Binary Installers http://leksah.org/packages/leksah-0.12.0.3-ghc-7.0.4.dmg http://leksah.org/packages/leksah-0.12.0.3-ghc-7.4.1.dmg Windows Binary Installers http://leksah.org/packages/leksah-0.12.0.3-ghc-6.12.3.exe http://leksah.org/packages/leksah-0.12.0.3-ghc-7.0.3.exe http://leksah.org/packages/leksah-0.12.0.3-ghc-7.0.4.exe http://leksah.org/packages/leksah-0.12.0.3-ghc-7.4.1.exe Changes to the last release include: * Support for GHC 7.2 and 7.4 * Better handling of navigation from text panes * Addition of a Files pane * Support for "cabal test" * Better printer for cabal files (when Leksah is built with Cabal >1.10) * Better candy support for literal Haskell * Syntax highlighting for quasi-quoted hamlet, julius and cassius (DSLs used in Yesod) * Several bug fixes and optimizations Thanks to Sanny Sanoff for improving some of the keyboard navigation and symbol searching among other things. Thanks to Harald Jagenteufel and Stephan Fortelny we have basic source control integration (git,svn) in a repo branch, but it is not part of this release. We hope to merge this in soon. Work has been progressing on a major restructuring of Leksah to make it a modular plugin based system from the ground up. It is a big task and there is still more to do. Unfortunately this has meant we have spent less time adding features.

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Haskell-platform and ghc 7.4
by G 11 Mar '12

11 Mar '12

Am new to haskell, but one thing I wanted to try out was the performance of an app in haskel. Having issues getting it to compile under ghc 7.0.4. The owner recommend trying to upgrade to 7.2/7.4 I see a warning that the haskell-platform isn't compatible with with 7.4.1, or so my homebrew install says. Can it be made to compile ?? Can I remove the haskell-platform and then install the dev tools from the haskell-platform via cabal etc once I have moved to 7.4.x etc ? Thanks

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network-conduit proxy
by grant 11 Mar '12

11 Mar '12

I am trying to get a proxy working using the network-conduit package on windows. So I send a request to port 5002 and that gets forwarded to another port 5000 where I have a simple echo server running. I made a stab at it, but get intermittent send errors after the first connection Here is the code: {-# OPTIONS -Wall #-} import Data.Conduit import Data.Conduit.Network import Network (withSocketsDo) import Control.Monad.IO.Class (liftIO) import Control.Monad.Trans.Resource main::IO () main = withSocketsDo $ runTCPClient (ClientSettings 5000 "localhost") $ \src1 sink1 -> do liftIO $ print "in tcpclient section" liftIO $ withSocketsDo $ runTCPServer (ServerSettings 5002 Nothing) $ \src sink -> do liftIO $ print "in tcpserver section" _ <- liftIO $ runResourceT $ resourceForkIO $ do src1 $$ sink return () src $$ sink1 Thanks for any help, Grant

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haskell platform - mac lion - installation error
by Peter 11 Mar '12

11 Mar '12

Hello - I'm a new user, having some trouble installing the Haskell Platform (2011.4.0.0 64bit.pkg) on a Macbook Pro (10.7.3). I installed Xcode 4.3.1 (4E1019), then the Haskell Platform. When I double-click on the Platform package icon, I get an installation dialogue with an error message reading "Developer Tools Missing - Please install Xcode developer tools first." Are Xcode developer tools something distinct from Xcode itself? I'm mystified by this error message. Any assistance would be greatly appreciated - thank you.

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Haskell Java interoperability
by bartosz＠fpcomplete.com 11 Mar '12

11 Mar '12

I looked on haskell.org for solutions to Haskell/Java interop, but there doesn't seem to be any current project. What is the status of Lambada or its progeny (I asked Erik Meijer, but he lost track of it). Which project is closest to maturity? --Bartosz

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ANNOUNCE: diagrams 0.5
by Brent Yorgey 09 Mar '12

09 Mar '12

I am pleased to announce the release of version 0.5 of diagrams [1], a full-featured framework and embedded domain-specific language for declarative drawing. Check out the gallery [2] for examples of what it can do! [1] http://projects.haskell.org/diagrams [2] http://projects.haskell.org/diagrams/gallery.html Highlights of this release include: - A new diagrams-contrib [3] package of user-contributed modules, which so far contains code for tree drawing, Apollonian gaskets, planar tilings, "wrapped" layout, and turtle graphics. - Experimental support for animation, built on top of the new active [4] library. - Numerous small additions and improvements, including more general rounded rectangle shapes and better text support. - Much better performance in some common situations, such as laying out a very long list of diagrams using 'cat' and related combinators. - Added support for GHC 7.4. See the release notes [5] for complete details, and the diagrams wiki [6] for help migrating code from 0.4 to 0.5 (changes should be minimal). [3] http://hackage.haskell.org/package/diagrams%2Dcontrib [4] http://hackage.haskell.org/package/active [5] http://projects.haskell.org/diagrams/releases.html [6] http://www.haskell.org/haskellwiki/Diagrams/Migrate0.5 Try it out ---------- For the truly impatient: cabal install gtk2hs-buildtools cabal install diagrams Diagrams is supported under GHC 6.12, 7.0, 7.2, and 7.4. However, getting cairo to build can be tricky on some platforms; see the diagrams wiki [8] for more information and workarounds regarding specific platforms. (A new native SVG backend is in the works, targeted for the 0.6 release.) To get started with diagrams, read the quick tutorial [9], which will introduce you to the fundamentals of the framework. For those who are even less impatient but want to really dig in and use the power features, read the user manual [10]. [7] http://projects.haskell.org/gtk2hs/development/#development [8] http://www.haskell.org/haskellwiki/Diagrams [9] http://projects.haskell.org/diagrams/tutorial/DiagramsTutorial.html [10] http://projects.haskell.org/diagrams/manual/diagrams-manual.html Get involved ------------ Subscribe to the project mailing list [11], and/or come hang out in the #diagrams IRC channel on freenode.org for help and discussion. Make some diagrams. Fix some bugs [12]. Submit your cool examples for inclusion in the gallery or your cool code for inclusion in the diagrams-contrib package! [11] http://groups.google.com/group/diagrams-discuss [12] http://code.google.com/p/diagrams/issues/list Happy diagramming! Brought to you by the diagrams team: - Peter Hall - Ian Ross - Michael Sloan - Ryan Yates - Brent Yorgey with contributions from: - Sam Griffin - Claude Heiland-Allen - John Lato - Vilhelm Sjoberg - Luite Stegeman - Kanchalai Suveepattananont - Scott Walck

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ANNOUNCE: string-conversions-0.1
by Sönke Hahn 09 Mar '12

09 Mar '12

Hi all! string-conversions is a very simple package to facilitate dealing with different string types. It provides a simple type class that allows you to convert between values of different string types. It also provides type synonyms for these string types. Supported types are: - String - Strict ByteString - Lazy ByteString - Strict Text - Lazy Text http://hackage.haskell.org/package/string-conversions Any comments welcome. Cheers, Sönke

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If you'd design a Haskell-like language, what would you do different?
by Robert Clausecker 09 Mar '12

09 Mar '12

Image you would create your own language with a paradigm similar to Haskell or have to chance to change Haskell without the need to keep any compatibility. What stuff would you add to your language, what stuff would you remove and what problems would you solve completely different? Thanks in advance for all answers, yours Robert Clausecker

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