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Problem with package consistency on Hackage
by Antoine Latter 10 Oct '08

10 Oct '08

Folks, I'm not sure who to email about this, but hopefully someone on the cafe knows: On the machine which builds the Hackage packages the 'binary' package is built against 'bytestring-0.9.1.2', however the package I just uploaded gets built against 'bytestring-0.9.1.3' which leades to typecheck failures (the ByteStrings I get from the 'binary' package are not the same as all the other ByteStrings). See: http://hackage.haskell.org/packages/archive/uuid/1.0.0/logs/failure/ghc-6.8 If I wait will Hackage eventually become consistent? How does this work? Thanks, Antoine

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ANNOUNCE: darcs 2.1.0 (corrected!)
by Eric Kow 10 Oct '08

10 Oct '08

This is a correction to my previous announcement. I had misgrepped the ChangeLog. There are only 20 bug fixes and 7 new features since 2.0.2. Sorry! ====== Hi all, I am delighted to announce the release of darcs 2.1.0, available at http://darcs.net/darcs-2.1.0.tar.gz What has changed? ----------------- This version provides over 20 bug fixes and 7 new features since darcs 2.0.2. The most notable changes are: * Defaulting to darcs-2. The darcs initialize command now creates darcs-2 format repositories by default. This change will make the the improved conflict handling and merging semantics from darcs 2 available to more users. Note that no action is required on your part. Darcs will continue working with all pre-existing repositories. You can explicitly request an old-fashioned repository if needed. * Better HTTP support. Dmitry Kurochkin has refined our HTTP support and fixed several http-related bugs from darcs 2.0.2. There is also an experimental --http-pipelining feature you can enable on the command line (or in your defaults file) for faster downloading. Note: --http-pipelining is enabled by default for libwww, and also for libcurl 7.19.1 (not yet released at the time of this writing) * Repository correctness. David Roundy has resolved a longstanding 'pending patch' regression (originally reported on 2008-02). Needless to say the offending case has been moved to our regression testing suite See the attached ChangeLog for more details. What should I do? ----------------- Upgrade! Binary versions should be available shortly, either from your favourite package distributor or by third party contributors. Other than installing the new darcs, no action is required on your part to perform this upgrade. Darcs 2, including this particular version, is 100% compatible with your pre-existing repositories. If you have not done so already, you should consider using the hashed repository format in place of your current old-fashioned repositories. This format offers greater protection against accidental corruption, better support for case insensitive file systems. It also provides some very nice performance features, including lazy fetching of patches and a global cache (both optional). If darcs 1 compatibility is not a concern, you could also upgrade your repositories all the way to the darcs 2 format. In addition to the robustness and performance features above, this gives you the improved merging semantics and conflicts handling that give darcs 2 its name. More details about upgrading to darcs 2 here: http://wiki.darcs.net/index.html/DarcsTwo What comes next? ---------------- We will now be shifting to a time based release model, with the next darcs release planned for January 2009. For the next release of darcs, we will be focusing on optimising darcs's day to day performance issues. We want darcs to fetch repositories as fast as it possibly can over a network, and we especially want to rehabilitate known slow commands like darcs annotate. We believe that a few simple and practical changes can really improve the darcs experience for most users. Think you can help? We would love to hear from you. In fact, the first darcs hacking sprint (25-26 October) is fast approaching! We have three venues available: Brighton, Paris and Portland and everybody is invited to come hack. See http://wiki.darcs.net/index.html/Sprints for details. Thanks everybody, and enjoy! -- Eric Kow <http://www.nltg.brighton.ac.uk/home/Eric.Kow> PGP Key ID: 08AC04F9

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compiling ghc-6.8.3: unrecognized command line option "-fconfigure-option=" (SOLVED)
by Poor Yorick 10 Oct '08

10 Oct '08

For anyone who might experience the same problem... Intalling ghc-6.8.3, the following error occurred: make -C libraries all make[1]: Entering directory `/path/to/src/gh c-6.8.3/ghc-6.8.3/libraries' rm -f -f stamp/configure.library.*.base base/unbuildable ( cd base && setup/Setup configure \ --enable-library-profiling --enable-split-objs \ --prefix=/NONEXISTANT \ --bindir=/NONEXISTANT \ --libdir=/NONEXISTANT \ --libsubdir='$pkgid' \ --libexecdir=/NONEXISTANT \ --datadir=/NONEXISTANT \ --docdir=/NONEXISTANT \ --htmldir=/NONEXISTANT \ --interfacedir=/NONEXISTANT \ --with-compiler=../../compiler/stage1/ghc-inplace \ --with-hc-pkg=../../utils/ghc-pkg/ghc-pkg-inplace \ --with-hsc2hs=../../utils/hsc2hs/hsc2hs-inplace \ --with-ld=/path/to/bin/ld \ --haddock-options="--use-contents=../index.html \ --use-index=../doc-index.html" \ --configure-option='--prefix=/path/to/ghc-6.8.3' --configure-option='CC=gcc -m32' --configure-option='LDFLAGS=-Wl,-rpath,/path/to/lib -Wl,-rpath,/path/to/lib64 -Wl,--enable-new-dtags -L/path/to/lib -L/path/to/lib64 --configure-option=' --configure-option='CPPFLAGS=-I/path/to/include --configure-option=' \ --configure-option=--with-cc=gcc ) \ && touch stamp/configure.library.build-profiling-splitting.base || touch base/unbuildable Configuring base-3.0.2.0... configure: WARNING: Unrecognized options: --with-hc, --with-hc-pkg checking for gcc... gcc checking for C compiler default output file name... configure: error: C compiler cannot create executables See `config.log' for more details. config.log showed this: configure:2171: checking for C compiler default output file name configure:2193: gcc -I/path/to/include --configure-option= -Wl,-rpath,/path/to/lib -Wl,-rpath,/path/to/lib64 -Wl,--enable-new-dtags -L/path/to/lib -L/path/to/lib64 --configure-option= conftest.c >&5 cc1: error: unrecognized command line option "-fconfigure-option=" cc1: error: unrecognized command line option "-fconfigure-option=" configure:2197: $? = 1 configure:2235: result: configure: failed program was: | /* confdefs.h. */ | #define PACKAGE_NAME "Haskell base package" | #define PACKAGE_TARNAME "base" | #define PACKAGE_VERSION "1.0" | #define PACKAGE_STRING "Haskell base package 1.0" | #define PACKAGE_BUGREPORT "libraries(a)haskell.org" | /* end confdefs.h. */ | | int | main () | { | | ; | return 0; | } configure:2242: error: C compiler cannot create executables See `config.log' for more details. ## ---------------- ## ## Cache variables. ## ## ---------------- ## ac_cv_env_CC_set=set ac_cv_env_CC_value='gcc -m32' ac_cv_env_CFLAGS_set= ac_cv_env_CFLAGS_value= ac_cv_env_CPPFLAGS_set=set ac_cv_env_CPPFLAGS_value='-I/path/to/include --configure-option=' ac_cv_env_CPP_set= ac_cv_env_CPP_value= ac_cv_env_LDFLAGS_set=set ac_cv_env_LDFLAGS_value='-Wl,-rpath,/path/to/lib -Wl,-rpath,/path/to/lib64 -Wl,--enable-new-dtags -L/path/to/lib -L/path/to/lib64 --configure-option=' ac_cv_env_LIBS_set= ac_cv_env_LIBS_value= ac_cv_env_build_alias_set= ac_cv_env_build_alias_value= ac_cv_env_host_alias_set= ac_cv_env_host_alias_value= ac_cv_env_target_alias_set= ac_cv_env_target_alias_value= ac_cv_prog_ac_ct_CC=gcc ## ----------------- ## ## Output variables. ## ## ----------------- ## CC='gcc' CFLAGS='' CPP='' CPPFLAGS='-I/path/to/include --configure-option=' DEFS='' ECHO_C='' ECHO_N='-n' ECHO_T='' EGREP='' EXEEXT='' GREP='' LDFLAGS='-Wl,-rpath,/path/to/lib -Wl,-rpath,/path/to/lib64 -Wl,--enable-new-dtags -L/path/to/lib -L/path/to/lib64 --configure-option=' LIBOBJS='' LIBS='' LTLIBOBJS='' OBJEXT='' PACKAGE_BUGREPORT='libraries(a)haskell.org' PACKAGE_NAME='Haskell base package' PACKAGE_STRING='Haskell base package 1.0' PACKAGE_TARNAME='base' PACKAGE_VERSION='1.0' PATH_SEPARATOR=':' SHELL='/bin/sh' ac_ct_CC='gcc' bindir='/NONEXISTANT' build_alias='' datadir='/NONEXISTANT' datarootdir='${prefix}/share' docdir='${datarootdir}/doc/${PACKAGE_TARNAME}' dvidir='${docdir}' exec_prefix='NONE' host_alias='' htmldir='${docdir}' includedir='${prefix}/include' infodir='${datarootdir}/info' libdir='/NONEXISTANT' libexecdir='/NONEXISTANT' localedir='${datarootdir}/locale' localstatedir='${prefix}/var' mandir='${datarootdir}/man' oldincludedir='/usr/include' pdfdir='${docdir}' prefix='/path/to/ghc-6.8.3' program_transform_name='s,x,x,' psdir='${docdir}' sbindir='${exec_prefix}/sbin' sharedstatedir='${prefix}/com' sysconfdir='${prefix}/etc' target_alias='' It turned out that trailing whitespace in the LDFLAGS and CPPFLAGS environment variables were causing these problems. see libraries/Makfile: # We rely on all the CONFIGURE_ARGS being quoted with '...', and there # being no 's inside the values. FLAGGED_CONFIGURE_ARGS = $(subst $(space)',\ $(space)--configure-option=',\ $(space)$(CONFIGURE_ARGS)) -- Yorick

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re: [Haskell-cafe] Functional progarmming at JAOO
by Robert Pickering 10 Oct '08

10 Oct '08

Hi Simon, Thanks for link! I attended JAOO and there were some great talks on programminng langauges, I really enjoyed Guy Steele's introduction to Fortres and Eric Meijer's "Fundamentalist Functional Programming", as well as Anders Hejlsberg's talk, and there were also talks on Scala and F#. I've not been to that many confrences but I all the same I judged this to be a unusally high interester in programming languages for an industrial conference. I got a real fealing that people are much more read to look at "alterative" languages for their projects, I think this can only be good for haskell and the wider FP community in general. Thanks,Robert ---------------------------------------- From: Simon Peyton-Jones <simonpj(a)microsoft.com> Sent: 09 October 2008 20:55 To: "haskell-cafe(a)haskell.org" <haskell-cafe(a)haskell.org> Subject: [Haskell-cafe] Functional progarmming at JAOO Friends Anders Hejlsberg, the chief designer of C# and a very influential person at Microsoft, gave a keynote talk at JAOO Aarhus last week about "Where are programming languages going". Some of you may have mixed feelings about Microsoft but I thought you might still be interested in this talk because he gives a strong plug to functional programming (and F# in particular, although Haskell gets a mention). FP is one of the three major trends he identifies, the others being concurrency and dynamic languages. http://blip.tv/file/1317881 The FP section starts 22 mins in. Simon _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe(a)haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

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Functional progarmming at JAOO
by Simon Peyton-Jones 10 Oct '08

10 Oct '08

Friends Anders Hejlsberg, the chief designer of C# and a very influential person at Microsoft, gave a keynote talk at JAOO Aarhus last week about "Where are programming languages going". Some of you may have mixed feelings about Microsoft but I thought you might still be interested in this talk because he gives a strong plug to functional programming (and F# in particular, although Haskell gets a mention). FP is one of the three major trends he identifies, the others being concurrency and dynamic languages. http://blip.tv/file/1317881 The FP section starts 22 mins in. Simon

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any estimate on when Liskell will be based on GHC 6.8.3, instead of GHC 6.6?
by Benjamin L.Russell 10 Oct '08

10 Oct '08

Recently, I had recommended Liskell to somebody in the thread entitled "Closest statically typed FP "cousin" to Scheme?" (on comp.lang.scheme) (see http://groups.google.se/group/comp.lang.scheme/browse_thread/thread/1fa8fb0…) but then another user replied that a problem with Liskell was that it was based on GHC 6.6, whereas the latest stable version of GHC was 6.8.3 (see http://groups.google.se/group/comp.lang.scheme/msg/a65f73105ef671a1) Does anybody have any estimate on when Liskell will be updated to be based on the current GHC 6.8.3, instead of the old GHC 6.6? I am interested in trying out Liskell myself, but am slightly hesitant because it is based on an older version of GHC. -- Benjamin L. Russell

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Problem (and half solution?) installing cabal-install
by Mauricio 09 Oct '08

09 Oct '08

Hi, After running bootstrap.sh, I got an error related to 'pushd' not beeing available. In fact, when I run 'man sh' I can't find 'pushd' as a command. However, just changing #!/bin/sh to #!/bin/bash (bash do have 'pushd') the installation process went well, except that I got this package versions error: Setup: At least the following dependencies are missing: HTTP >=3000 && <3002, network >=1 && <3 probably when building the executable file itself, since .cabal/lib and .cabal/share were populated with a lot of stuff, but .cabal/bin was not created. Best, Maurício

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Stacking monads
by Andrew Coppin 09 Oct '08

09 Oct '08

Consider the following beautiful code: run :: State -> Foo -> ResultSet State run_and :: State -> Foo -> Foo -> ResultSet State run_and s0 x y = do s1 <- run s0 x s2 <- run s1 y return s2 run_or :: State -> Foo -> Foo -> ResultSet State run_or s0 x y = merge (run s0 x) (run s0 y) That works great. Unfortunately, I made some alterations to the functionallity the program has, and now it is actually possible for 'run' to fail. When this happens, a problem should be reported to the user. (By "user" I mean "the person running my compiled application".) After an insane amount of time making my head hurt, I disocvered that the type "Either ErrorType (ResultSet State)" is actually a monad. (Or rather, a monad within a monad.) Unfortunately, this causes some pretty serious problems: run :: State -> Foo -> Either ErrorType (ResultSet State) run_or :: State -> Foo -> Foo -> Either ErrorType (ResultSet State) run_or s0 x y = do rset1 <- run s0 x rset2 <- run s1 y return (merge rset1 rset2) run_and :: State -> Foo -> Foo -> Either ErrorType (ResultSet State) run_and s0 x y = run s0 x >>= \rset1 -> rset1 >>= \s1 -> run s1 y The 'run_or' function isn't too bad. However, after about an hour of trying, I cannot construct any definition for 'run_and' which actually typechecks. The type signature for (>>=) requires that the result monad matches the source monad, and there is no way for me to implement this. Since ResultSet *just happens* to also be in Functor, I can get as far as run_and s0 x y = run s0 x >>= \rset1 -> fmap (\s1 -> run s1 y) rset1 but that still leaves me with a value of type ResultSet (Either ErrorType (ResultSet State)) and no obvious way to fix this. At this point I am sorely tempted to just change ResultSet to include the error functionallity I need. However, ResultSet is *already* an extremely complicated monad that took me weeks to get working correctly... I'd really prefer to just layer error handling on the top. But I just can't get it to work right. It's soooo fiddly untangling the multiple monads to try to *do* any useful work. Does anybody have any idea how this whole monad stacking craziness is *supposed* to work?

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Libraries in home dir
by Mauricio 09 Oct '08

09 Oct '08

Hi, I want to use a few libraries from hackage and have already download and built them. Can I install those libraries somewhere in my home dir (I want to avoid installing as root) so that ghc can find them? If so, which options should I give to Setup.hs (with main=defaultMain) so that the libraries are going to be copy to that dir? Thanks, Maurício

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how do you deal with mplus?
by Daryoush Mehrtash 09 Oct '08

09 Oct '08

Assuming A, B, C are monadic operation. How do you read the following function: do A 'mplus' B C I expect this to translate to: (A 'mplus' B) >>= C Can I then say it is equivalent to: (A >>=C) mplus (B >>=C) Thanks, Daryoush

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