October 2007 - Libraries

!! for Data.Stream
by Conal Elliott 24 Oct '07

24 Oct '07

I see that (!!) for Data.Stream has arguments reversed, compared to !! on lists. The Haddock comment, however, suggests otherwise. Is the argument reversal intended? - Conal >From Data.Stream: -- | @xs !! n@ returns the element of the stream @xs@ at index -- @n@. Note that the head of the stream has index 0. -- -- /Beware/: passing a negative integer as the first argument will cause -- an error. (!!) :: Int -> Stream a -> a (!!) n (Cons x xs) | n == 0 = x | n > 0 = (!!) (n - 1) xs | otherwise = error "Stream.!! negative argument"

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Let's do ListT right, finally
by Yitzchak Gale 23 Oct '07

23 Oct '07

Hi Ian, thanks for responding to my plea! I am renaming this thread and moving it to libraries. Please respond there. I wrote: >> http://haskell.org/haskellwiki/ListT_done_right >> and not the broken implementation that comes with mtl. >> (Finally fixed in 6.8? Please?) Ian Lynagh wrote: > If you want to propose that mtl switches to a different definition of > ListT then please see > http://www.haskell.org/haskellwiki/Library_submissions OK, then. This is a major rewrite of this module. So let me open up the topic for discussion even before posting a submission. Do we need to worry about breaking code? Not very much, I suspect. That "monad" really is broken - it's not a monad at all. The problem and its solution have been well known for years. I personally tried using the "standard" ListT for a while, just because it's the standard. Until I ran into enough problems that I finally slapped my forehead and said "forget it". But just in case: Is there anyone reading this who would be hurt by this change and opposes it? Should we provide a more gradual deprecation path (what is it)? Thanks, Yitz

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Bumping "extralib" library versions
by Duncan Coutts 23 Oct '07

23 Oct '07

All, There is unfortunately some synchronisation between ghc releases and the releases of various common libraries, the so-called "extralibs" collection. So I'd like to look briefly at what the version numbers of theses packages should be. It is important that we do increase the version numbers if there are changes since the last releases. In cases where the package's HEAD repo is maintained somewhere other than darcs.haskell.org/packages/$pkg that we do not break the version scheme used by the package maintainer. The current set of "extralibs" packages is: ALUT arrows cgi fgl GLUT haskell-src HGL html HUnit mtl network ObjectIO OpenAL OpenGL parallel parsec QuickCheck regex-base regex-compat regex-posix stm time X11 xhtml For each one I'd like to identify where the HEAD repo is, what the last released version was, what the current version number in the darcs version is, if there are any changes since that release and if so what the new release number ought to be. These version number bumps are based on existing versioning practise for these libraries rather than the proposed package versioning policy. http://haskell.org/haskellwiki/Package_versioning_policy#Version_numbers I have also listed for each package what the next version number would be under the proposed package versioning policy.They are marked as "PVP next version". If you think I've got any of these details wrong, please say so. ========== ALUT HEAD repo: http://darcs.haskell.org/packages/ALUT Released version: 2.0.1 (in ghc-6.6.1 extralibs tarball) Current version: 2.0.1 Changes since release: minor build system changes Suggested next version: 2.0.2 PVP next version: 2.0.1.1 ========== arrows HEAD repo: http://darcs.haskell.org/packages/arrows Released version: 0.3 (on hackage) Current version: 0.3 Changes since release: none Suggested next version: not needed PVP next version: not needed Notes: The latest version of this package depends on Stream which is not currently in the extralibs collection. This anomaly will need to be sorted out. ========== cgi HEAD repo: http://darcs.haskell.org/packages/cgi Released version: 3001.1.5 (on hackage) Current version: 3001.1.5 Changes since release: comments and build system changes Suggested next version: 3001.1.6 PVP next version: 3001.1.5.1 Notes: requires .cabal changes to build with older base versions ========== fgl HEAD repo: http://darcs.haskell.org/packages/fgl Released version: 5.4.1 (in ghc-6.6.1 extralibs tarball) Current version: 5.4.1 Changes since release: build system changes Suggested next version: 5.4.2 PVP next version: 5.4.1.1 Notes: requires .cabal changes to build with older base versions ========== GLUT HEAD repo: http://darcs.haskell.org/packages/GLUT Released version: 2.1.1 (in ghc-6.6.1 extralibs tarball) Current version: 2.1.1 Changes since release: build system changes Suggested next version: 2.1.2 PVP next version: 2.1.1.1 ========== haskell-src HEAD repo: http://darcs.haskell.org/packages/haskell-src Released version: 1.0.1 (in ghc-6.6.1 extralibs tarball) Current version: 1.0.1 Changes since release: build system and portability changes (same api) Suggested next version: 1.0.2 PVP next version: 1.0.1.1 Notes: requires .cabal changes to build with older base versions ========== HGL HEAD repo: http://darcs.haskell.org/packages/HGL Released version: 3.1.1 (in ghc-6.6.1 extralibs tarball) Current version: 3.1.1 Changes since: build system changes Suggested next version: 3.1.2 PVP next version: 3.1.1.1 Notes: requires .cabal changes to build with older base versions ========== html HEAD repo: http://darcs.haskell.org/packages/html Released version: 1.0.1 (in ghc-6.6.1 extralibs tarball) Current version: 1.0.1 Changes since: build system changes Suggested next version: 1.0.2 PVP next version: 1.0.1.1 ========== HUnit HEAD repo: http://darcs.haskell.org/packages/HUnit Released version: 1.1.1 (in ghc-6.6.1 extralibs tarball) Current version: 1.1.1 Changes since: some code changes, not obvious if api changed Suggested next version: 1.1.2 PVP next version: 1.1.2 ========== mtl HEAD repo: http://darcs.haskell.org/packages/mtl Released version: 1.0.1 (in ghc-6.6.1 extralibs tarball) Current version: 1.0.1 Changes since: added more module re-exports and docs Suggested next version: 1.0.2 PVP next version: 1.0.2 Note: does not build with ghc-6.4.x as base-1.0 ========== network HEAD repo: http://darcs.haskell.org/packages/network Released version: 2.0.1 (in ghc-6.6.1 extralibs tarball) Current version: 2.0.1 Changes since: IPV6 support added, api extended not changed Suggested next version: 2.0.2 PVP next version: 2.0.2 Note: needs a patch to build with ghc-6.4.x and base-1.0 ========== ObjectIO HEAD repo: http://darcs.haskell.org/packages/ObjectIO Released version: 1.0.1 (in ghc-6.6.1 extralibs tarball) Current version: 1.0.1 Changes since: Setup.hs changes only Suggested next version: 1.0.2 PVP next version: 1.0.1.1 ========== OpenAL HEAD repo: http://darcs.haskell.org/packages/OpenAL Released version: 1.3.1 (in ghc-6.6.1 extralibs tarball) Current version: 1.3.1 Changes since: build system changes Suggested next version: 1.3.2 PVP next version: 1.3.1.1 ========== OpenGL HEAD repo: http://darcs.haskell.org/packages/OpenGL Released version: 2.2.1 (in ghc-6.6.1 extralibs tarball) Current version: 2.2.1 Changes since: build system changes Suggested next version: 2.2.2 PVP next version: 2.2.1.1 ========== parallel HEAD repo: http://darcs.haskell.org/packages/parallel Released version: none Current version: 1.0 Changes since: n/a Suggested next version: 1.0 PVP next version: 1.0 Note: cannot build with older ghc/base versions as it exposes modules provided by base-2.x. ========== parsec HEAD repo: http://darcs.haskell.org/packages/parsec Released version: 2.0 (hackage and ghc-6.6.1 extralibs tarball) Current version: 2.0 Changes since: api additions (extended, not changed) Suggested next version: 2.0.1 PVP next version: 2.0.1 ========== QuickCheck HEAD repo: http://darcs.haskell.org/QuickCheck 1.x repo: http://darcs.haskell.org/packages/QuickCheck Released version: 1.0.1 (in ghc-6.6.1 extralibs tarball) Current version: 1.0.1 Changes since: build system Suggested next version: 1.0.2 PVP next version: 1.0.1.1 Note: we seem to be including QuickCheck 1.x rather than 2.x. ========== regex-base HEAD repo: http://darcs.haskell.org/packages/regex-unstable/regex-base 0.72 repo: http://darcs.haskell.org/packages/regex-base Released version: 0.72 (in ghc-6.6.1 extralibs tarball) 0.92 (on hackage) Current version: 0.72 (in ghc-6.8 extralibs) 0.92 (upstream) Changes since: build system changes Suggested next version: 0.72.1 PVP next version: 0.72.0.1 Note: we seem to be including regex-base 0.72 when the latest upstream version is 0.92. ========== regex-compat HEAD repo: http://darcs.haskell.org/packages/regex-unstable/regex-compat 0.71 repo: http://darcs.haskell.org/packages/regex-compat Released version: 0.71 (hackage and ghc-6.6.1 extralibs tarball) 0.90 (on hackage) Current version: 0.71 (in ghc-6.8 extralibs) 0.90 (upstream) Changes since: trivial code change and build system changes Suggested next version: 0.71.1 PVP next version: 0.71.0.1 Note: Setup.lhs needs fixing to be trivial. Again, we seem to be including regex-base 0.71 when the latest upstream version is 0.90. ========== regex-posix HEAD repo: http://darcs.haskell.org/packages/regex-unstable/regex-posix 0.72 repo: http://darcs.haskell.org/packages/regex-posix Released version: 0.71 (hackage and ghc-6.6.1 extralibs tarball) 0.91 (on hackage) Current version: 0.72 (in ghc-6.8 extralibs) 0.91 (upstream) Changes since: compatible code changes and build system changes Suggested next version: 0.72.1 PVP next version: 0.72.0.1 Note: will need patching to build with base-2.0. Again, we seem to be including regex-base 0.72 when the latest upstream version is 0.91. ========== stm HEAD repo: http://darcs.haskell.org/packages/stm Released version: 2.1 (hackage and ghc-6.6.1 extralibs tarball) Current version: 2.1 Changes since: two new new functions and build system changes Suggested next version: 2.1.1 PVP next version: 2.1.1 Note: will not currently build with base-2.0. It's not clear if this is a problem, or if stm is tightly tied to the base/ghc version anyway. ========== time HEAD repo: http://darcs.haskell.org/packages/time Released version: 1.1.1 (in ghc-6.6.1 extralibs tarball) Current version: 1.1.1 Changes since: minor behaviour changes (bug fixes) Suggested next version: 1.1.2 PVP next version: 1.1.2 ========== X11 HEAD repo: http://darcs.haskell.org/packages/X11 Released version: 1.2.3 (on hackage) Current version: 1.2.3 Changes since: none Suggested next version: not needed PVP next version: not needed ========== xhtml HEAD repo: http://darcs.haskell.org/packages/xhtml Released version: 3000.0.2 (in ghc-6.6.1 extralibs tarball) Current version: 3000.0.2 Changes since: minor build system changes Suggested next version: 3000.0.3 PVP next version: 3000.0.2.1 Additionally, there are some core libs that could be usable with older versions of other libs, like base and so could be used with older releases of ghc or other implementations: bytestring Cabal filepath haskell98 readline unix Win32 ========== bytestring HEAD repo: http://darcs.haskell.org/bytestring Released version: 0.9 (on hackage) Current version: 0.9 Changes since: none Suggested next version: not needed PVP next version: not needed ========== Cabal HEAD repo: http://darcs.haskell.org/cabal Released version: 1.2.1 (on hackage) Current version: 1.2.1 Changes since: some minor changes Suggested next version: 1.2.2 PVP next version: 1.2.2 ========== filepath HEAD repo: http://darcs.haskell.org/packages/filepath 1.1 repo: http://darcs.haskell.org/ghc-6.8/packages/filepath Released version: 1.0 (on hackage) Current version: 1.1 Changes since: api additions, bug fixes Suggested next version: 1.1 PVP next version: 1.0.1 Note: filepath head branch is marked as version 1.0 while the version included with ghc-6.8 is marked as 1.1. ========== haskell98 HEAD repo: http://darcs.haskell.org/packages/haskell98 Released version: 1.0 (hackage and ghc-6.6.1 extralibs tarball) Current version: 1.0.1 Changes since: build system changes Suggested next version: ??? PVP next version: 1.0.0.1 Note: If the version number identifies the api to some degree, then the H98 api never changes so it's version number should never increment, except in the micro revision for build system changes. ========== readline HEAD repo: http://darcs.haskell.org/packages/readline Released version: 1.0 (ghc-6.6.1 extralibs tarball) Current version: 1.0.1 Changes since: api additions, build system changes Suggested next version: 1.0.1 PVP next version: 1.0.1 ========== unix HEAD repo: http://darcs.haskell.org/packages/unix Released version: 2.1 (ghc-6.6.1 extralibs tarball) Current version: 2.2 Changes since: many api additions Suggested next version: 2.2 PVP next version: 2.1.1 Note: will not currently build with base-2.0. ========== Win32 HEAD repo: http://darcs.haskell.org/packages/Win32 Released version: 2.1 (hackage and ghc-6.6.1 extralibs tarball) Current version: 2.1.1 Changes since: api additions Suggested next version: 2.1.1 PVP next version: 2.1.1 Note: will not currently build with base-2.0. Duncan

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Proposal: Add &&& and *** to Data.Tuple
by Josef Svenningsson 23 Oct '07

23 Oct '07

Hi all, It is becoming increasingly popular to import Control.Arrow just to get access to the functions &&& and *** specialized to the function arrow. I propose to add the specialized version of these two functions to Data.Tuple which is more logical thing to import if you wish to have functions operating on tuples. I have chosen the same fixities for these operators as in Control.Arrow. I have deliberately chosen not to include any tests. These functions are so simple that eye-balling them beats any other method of verification, at least in my opinion. Some suggestions for better documentation of &&& would be very welcome. Proposal period: 2 weeks. Deadline October 1st. I haven't been able to create a ticket for this proposal. I'm unsure what the problem is, maybe trac and Firefox doesn't work so well together. No matter what I've tried (logging as both myself and as guest) trac tells me that I don't have the permission to create a ticket whenever I submit it. If someone would be willing to create a ticket for this proposal I would be grateful. Cheers, /Josef

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Re[2]: System.Win32.Types to base library?
by Bulat Ziganshin 23 Oct '07

23 Oct '07

Hello Felix, Tuesday, October 23, 2007, 1:24:08 AM, you wrote: >> NO, because this will lead again to non-upgradability hell. other >> libraries will need to import these types from different places >> depending on GHC version where they are runned > Ok, so how about a new module in base for Windows API error handling? > E.g. a Foreign.C.Error.Win32 module which resembles Foreign.C.Error. it will raise the same problem. imho, it's better to redefine as much as possible in other libs, or just reexport `base` types/functions via additional libs -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com

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Data.Stream conflict
by Conal Elliott 21 Oct '07

21 Oct '07

The "arrows" and "Stream" package both provide a Data.Stream module. I'd like to use the latter, which is much more filled out, but ghc is finding and choosing the former. Are there mechanisms for resolving this kind of conflict? - Conal

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Data encoding library
by Magnus Therning 20 Oct '07

20 Oct '07

I've just created the page http://haskell.org/haskellwiki/Library/Data_encoding (there are no links into it at the moment). Any comments on what I've written there? Are the locations in the hierarchy good? I have code to share if you are interested in commenting on it as well. Just let me know and I'll find a place to put it for public download. /M -- Magnus Therning (OpenPGP: 0xAB4DFBA4) magnus＠therning．org Jabber: magnus．therning＠gmail．com http://therning.org/magnus Windows [n.] A thirty-two bit extension and GUI shell to a sixteen bit patch to an eight bit operating system originally coded for a four bit microprocessor and sold by a two-bit company that can't stand one bit of competition. -- Anonymous USEnet post

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Applicative functor for building C structs with Storable
by Henning Thielemann 19 Oct '07

19 Oct '07

Are there analogons to ByteString's Put and Get Monads to construct and disect binary data in a C struct for exchange with a C program?

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Re: [Haskell] Re: Trying to install binary-0.4
by Simon Marlow 18 Oct '07

18 Oct '07

Several good points have been raised in this thread, and while I might not agree with everything, I think we can all agree on the goal: things shouldn't break so often. So rather than keep replying to individual points, I'd like to make some concrete proposals so we can make progress. 1. Document the version numbering policy. We should have done this earlier, but we didn't. The proposed policy, for the sake of completeness is: x.y where: x changes ==> API changed x constant but y changes ==> API extended only x and y constant ==> API is identical further sub-versions may be added after the x.y, their meaning is package-defined. Ordering on versions is lexicographic, given multiple versions that satisfy a dependency Cabal will pick the latest. 2. Precise dependencies. As suggested by various people in this thread: we change the convention so that dependencies must specify a single x.y API version, or a range of versions with an upper bound. Cabal or Hackage can refuse to accept packages that don't follow this convention (perhaps Hackage is a better place to enforce it, and Cabal should just warn, I'm not sure). Yes, earlier I argued that not specifying precise dependencies allows some packages to continue working even when dependencies change, and that having precise dependencies means that all packages are guaranteed to break when base is updated. However, I agree that specifying precise dependencies is ultimately the right thing, we'll get better errors when things break, There's lots more to discuss, but I think the above 2 proposals are a step in the right direction, agreed? Cheers, Simon

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Linking executables and the library of a Cabal package description
by ramsdell＠mitre.org 18 Oct '07

18 Oct '07

I'm sure this will be an easy question for those on this list. What do you need to add to a Cabal package description so as to allow an executable in the description to be built from the library it also describes? I searched the Cabal documentation many times, but came up empty handed. John $ make runhaskell Setup.hs build Preprocessing library a-1.0... Preprocessing executables for a-1.0... Building a-1.0... [1 of 1] Compiling A ( A.hs, dist/build/A.o ) /usr/bin/ar: creating dist/build/libHSa-1.0.a exec/Main.hs:3:7: Could not find module `A': Use -v to see a list of the files searched for. make: *** [all] Error 1 $ : after cleaning... $ more `find . -type f ` > ../a.txt $ cat ../a.txt :::::::::::::: ./a.cabal :::::::::::::: Name: a Version: 1.0 Build-Depends: base Exposed-Modules: A Executable: b Main-Is: Main.hs Other-Modules: A Hs-Source-Dirs: exec :::::::::::::: ./Setup.hs :::::::::::::: import Distribution.Simple main = defaultMain :::::::::::::: ./Makefile :::::::::::::: SETUP = runhaskell Setup.hs all: if test ! -f .setup-config; then $(SETUP) configure; fi $(SETUP) build Makefile: @echo make $@ %: force $(SETUP) $@ .PHONY: all force :::::::::::::: ./A.hs :::::::::::::: module A where a :: Int a = 3 :::::::::::::: ./exec/Main.hs :::::::::::::: module Main (main) where import A main :: IO () main = print a $ ghc -h ghc-6.6.1: unrecognised flags: -h Usage: For basic information, try the `--help' option. $ uname -a Linux goo 2.6.22.9-91.fc7 #1 SMP Thu Sep 27 23:10:59 EDT 2007 i686 i686 i386 GNU/Linux $

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