September 2007 - Libraries

hsql-1.7 with ghc-6.8
by Johannes Waldmann 27 Sep '07

27 Sep '07

something seemed to have changed in cabal (compiling hsql-1.7 with ghc version 6.8.0.20070921) HSQL/MySQL$ runhaskell Setup.lhs configure -p -O Setup.lhs:8:33: Module `Distribution.Simple.Utils' does not export `rawSystemVerbose' (same: http://hackage.haskell.org/packages/archive/hsql-mysql/1.7/log ) is there a workaround? -- -- Johannes Waldmann -- Tel/Fax (0341) 3076 6479/80 -- ---- http://www.imn.htwk-leipzig.de/~waldmann/ -------

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RFC: Extended version-range descriptions for Cabal
by Thomas Schilling 25 Sep '07

25 Sep '07

Hi librarians, I'd like to propose a an extension to Cabal's dependency description syntax. Cabal currently supports version range descriptions using the unary operators >, >=, <, <=, ==, and binary operators && and ||. This can lead to rather awkward descriptions of common version ranges, for example, base >= 1 && < 2 and could lead to subtle errors like base > 1 && < 2 or base >= 1 && <= 2 I therefore propose two extensions. Both are just syntactic sugar. (1) Wildcards: 1.* ~~> >= 1 && < 2 in general m.n.o.* ~~> >= m.n.o && < m.n.(o+1) Note, that the translation is not ">= 1.0 && < 2", because that would exclude version "1", as [1] < [1,0] == True. (2) Ranges: 1 - 2.1 ~~> >= 1 && <= 2.1 in general m - n ~~> >= m && <= n If the upper limit is supposed to be exclusive, this can be combined with (1): 1 - 2.0.* ~~> >= 1 && < 2.1 A possible alternatve syntax (subsuming both (1) and (2)) could be: [1, 2.1] ~~> >= 1 && <= 2.1 [1, 2.1) ~~> >= 1 && < 2.1 Although this syntax is closer to mathematical notation, I prefer the former for it is more explicit and more similar to common conventions used in other languages/package systems (an less scary scary to non-math-aficiados). I'd like include this into Cabal-1.2 which is scheduled with the next ghc release, so it can fearlessly be used when getting packages ready for GC 6.8.1. Please comment/vote. Thanks, / Thomas

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Cont as Monoid
by Conal Elliott 23 Sep '07

23 Sep '07

I'd like to see the following addition to Control.Monad.Cont in mtl: instance Monoid r => Monoid (Cont r a) where mempty = Cont mempty m `mappend` m' = Cont (runCont m `mappend` runCont m') What's the process for suggesting, discussing, and making such changes? Cheers, - Conal

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darcs patch: Add dropped STM invariants functions
by shelarcy 21 Sep '07

21 Sep '07

DarcsURL: http://darcs.haskell.org/ghc-6.8/packages/stm MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="=_" --=_ Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Thu Sep 20 21:56:33 =93=8C=8B=9E (=95W=8F=80=8E=9E) 2007 shelarcy <shelarc= y(a)gmail.com> * Add dropped STM invariants functions --=_ Content-Type: text/x-darcs-patch; name="add-dropped-stm-invariants-functions.dpatch" Content-Transfer-Encoding: quoted-printable Content-Description: A darcs patch for your repository! New patches: [Add dropped STM invariants functions shelarcy <shelarcy(a)gmail.com>**20070920125633] { hunk ./Control/Monad/STM.hs 27 + always, + alwaysSucceeds, } Context: [fix this test some more... Simon Marlow <simonmar(a)microsoft.com>**20070903133837] = [Add a dep on array Ian Lynagh <igloo(a)earth.li>**20070805200603] = [conc052 test is broken for profc/profasm (trac #1547) Ian Lynagh <igloo(a)earth.li>**20070718130955] = [Skip conc063 when fast Ian Lynagh <igloo(a)earth.li>**20070717114245 It's failing, but in a way that looks valid to me, so stop it tripping up the validate script. ] = [Fix test conc053: Don't use pattern sigs gratuitously Ian Lynagh <igloo(a)earth.li>**20070717014902] = [-fglasgow-exts is required due to type signature in pattern Simon Marlow <simonmar(a)microsoft.com>**20070607101102] = [--configure-option and --ghc-option are now provided by Cabal Ross Paterson <ross(a)soi.city.ac.uk>**20070604115937] = [Remove Makefile and package.conf.in (used in the old GHC build system) Ian Lynagh <igloo(a)earth.li>**20070524145834] = [Move STM-specific tests from testsuite/tests/ghc-regress/concurrent/should= _run Simon Marlow <simonmar(a)microsoft.com>**20070517090102] = [Follow Cabal changes in Setup.*hs Ian Lynagh <igloo(a)earth.li>**20070418121347] = [Fix -Wall warnings Ian Lynagh <igloo(a)earth.li>**20070411005022] = [Add missing case in removePrefix Ian Lynagh <igloo(a)earth.li>**20070411002558] = [parse (but don't pass on) options for ./configure Ian Lynagh <igloo(a)earth.li>**20070406153749] = [make Setup suitable for building the libraries with GHC Ian Lynagh <igloo(a)earth.li>**20061112214731] = [turn off TMVar and TMChan for non-GHC Ross Paterson <ross(a)soi.city.ac.uk>**20070401210122] = [fix typo in comment Ross Paterson <ross(a)soi.city.ac.uk>**20070401210044] = [Add missing modules to the .cabal file Ian Lynagh <igloo(a)earth.li>**20070401203812] = [Add documentation for TMVar. Spencer Janssen <sjanssen(a)cse.unl.edu>**20061211074318] = [Add documentation for TChan Spencer Janssen <sjanssen(a)cse.unl.edu>**20061211071201] = [TAG 6.6 release Ian Lynagh <igloo(a)earth.li>**20061011124740] = [TAG Version 2.1 Ian Lynagh <igloo(a)earth.li>**20061009114914] = [Bump version number Ian Lynagh <igloo(a)earth.li>**20061009114909] = [Add comment simonpj(a)microsoft.com**20061124101835] = [add boilerplate Setup.hs Ross Paterson <ross(a)soi.city.ac.uk>**20060928231526] = [Add Control.Concurrent.STM.TArray to the exposed modules of the STM packag= e (I'm assuming it's supposed to be exposed!) simonpj(a)microsoft.com**20060925152624] = [sequential implementation of revised semantics of catchSTM Ross Paterson <ross(a)soi.city.ac.uk>**20060904172921 = (This module is not used by GHC) ] = [bump version to 2.0 Simon Marlow <simonmar(a)microsoft.com>**20060811152819] = [update following changes to MArray Simon Marlow <simonmar(a)microsoft.com>**20060810100940] = [add Control.Monad.STM to package.conf.in Bertram Felgenhauer <int-e(a)gmx.de>**20060619073302] = [factor out a Control.Monad.STM module Ross Paterson <ross(a)soi.city.ac.uk>**20060615133443] = [offer a subset of the interface to sequential implementations Ross Paterson <ross(a)soi.city.ac.uk>**20060613142751] = [TAG Initial conversion from CVS complete John Goerzen <jgoerzen(a)complete.org>**20060112154138] = Patch bundle hash: f81215a5d844090ca64b07a034e40c2d89ba73d1 --=_-- .

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MVar API - modifyMVar
by Jules Bean 21 Sep '07

21 Sep '07

The MVar API is a bit inconsistent with the IORef one, and it catches me out every time. We have: modifyIORef :: IORef a -> (a->a) -> IO () which takes a nice pure modification function, and yet modifyMVar has a slightly weird Kleisli type: modifyMVar :: MVar a -> (a -> IO (a, b)) -> IO b which not only moves the modification into the IO monad but also permits returning an auxiliary value. One has only to browse the source of Chan to see that this function is useful, but I do think it's a surprising default. Then there is the _ version. So, we currently have: modifyMVar :: MVar a -> (a -> IO (a, b)) -> IO b modifyMVar_ :: MVar a -> (a -> IO a) -> IO () I suggest that the following would be more consistent with the normal conventions for _ and M: modifyMVar :: MVar a -> (a -> a) -> IO () modifyMVarM :: MVar a -> (a -> IO (a, b)) -> IO b modifyMVarM_ :: MVar a -> (a -> IO a) -> IO () ...however, that would break currently working code. If that seems to painful, then please at least supply some form of MVar a -> (a -> a) -> IO (), under whatever name seems suitable. Jules PS : Dear moderator : I subscribed and reposted, you may have a copy of this in your moderation queue too.

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Add Data.Eq.equating to match Data.Ord.comparing?
by Paul Johnson 20 Sep '07

20 Sep '07

I recently wanted to group a list of pairs by the second item in the pairs. So I tried writing > x = groupBy (comparing snd) pairs But this threw a type error because groupBy expects its first argument to return a Bool and comparing returns an Ordering. So I had to write > x = groupBy ((== EQ) . comparing snd) pairs Which is clunky. What I needed was a function in Data.Eq such as > equating :: Eq a => (b -> a) -> b -> b -> Bool This could be generalised to a function such as > pairWise :: (b -> b -> c) -> (a -> b) -> a -> a -> c > pairWise pair project x y = pair (project x) (project y) Then we can write > comparing = pairWise compare > equating = pairWise (==) Should I submit a patch to add this? And is "pairWise" the right name? Paul.

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Re: Building haddock docs with Cabal from .lhs sources
by Adrian Hey 19 Sep '07

19 Sep '07

Ketil Malde wrote: > On Wed, 2007-09-19 at 12:13 +0100, Adrian Hey wrote: > >>> 2. even with the base.haddock etc files in the right places, haddock >>> still doesn't find them. !? > >> This problem seems to have been fixed with the 6.8 release candidate. >> Unfortunately there still seems to be another, in that the resulting >> links are broken (no "file://" prefix). I don't know which bit of >> s/w is at fault here though. > > I wonder if this is something you really want - isn't it better to > generate relative links (i.e. for accessing in a differently mounted > file system, or via a different protocol - HTTP, say)? I guess that's a possibility, I don't really know what the issues are, but as long as clicking on a link takes me to the right place instead of a browser error I'll be happy :-) Regards -- Adrian Hey

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cpphs and C++-style comments
by Ross Paterson 19 Sep '07

19 Sep '07

Recent versions of cpphs also strip // comments in --strip mode, which causes problems with preprocessing Data.Array.Base, where (//) is an operator. It's necessary to strip C comments from that file, because it includes MachDeps.h, and that includes ghcautoconf.h, which being generated by autoconf has lots of C-style comments. (Though gcc's cpp strips them too -- I'm not sure how this ever worked.)

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Building haddock docs with Cabal from .lhs sources
by Alistair Bayley 19 Sep '07

19 Sep '07

Hello, I'm having a bit of fun trying to get Cabal to make Haddock docs for Takusen. Takusen's sources are a mixture of .lhs (birdtrack), .hs, and .hsc files. .hsc files are preprocessed OK, but the cabal source code for the haddock build action, and also the preprocessor code, seems to deal with .lhs -> .hs as a special case. The normal .lhs -> .hs preprocessor strips comments, which is useless for hadock. I have tried to hook in a custom preprocessor to turn .lhs into .hs (while preserving comments), but this is not triggered because of the hard-coded special cases for .lhs -> .hs. I have resorted to lifting out the entire hadbock function from Distribution.Simple, and modifying it so that it does nothing special for .lhs files. My own .lhs -> .hs transformation runs just before the new haddock hook. Does anyone have a better solution than this? Also, when I finally run haddock, I get this (sorry about the odd formatting, it's a cut-'n'patse from a Windows cmd.exe terminal): C:\haskell\bin\haddock.exe --html --odir=dist\doc\html --title=Takusen-0.7: Data base access library with left-fold interface. Supports PostgreSQL, Oracle, SQLit e. --package=Takusen-0.7 --dump-interface=dist\doc\html\Takusen.haddock --prolog ue=Takusen-0.7-haddock-prolog.txt --use-package=base-2.1.1 --use-package=mtl-1.0 .1 --use-package=time-1.1.1 dist\build\tmp\Database\Enumerator.hs dist\build\tmp \Database\Enumerator.hs dist\build\tmp\Database\Util.hs dist\build\tmp\Database\ Util.hs dist\build\tmp\Database\ODBC\Enumerator.hs dist\build\tmp\Database\ODBC\ Enumerator.hs dist\build\tmp\Database\ODBC\OdbcFunctions.hs dist\build\tmp\Datab ase\Oracle\Enumerator.hs dist\build\tmp\Database\Oracle\Enumerator.hs dist\build \tmp\Database\Oracle\OCIConstants.hs dist\build\tmp\Database\Oracle\OCIConstants .hs dist\build\tmp\Database\Oracle\OCIFunctions.hs dist\build\tmp\Database\Oracl e\OCIFunctions.hs dist\build\tmp\Database\PostgreSQL\Enumerator.hs dist\build\tm p\Database\PostgreSQL\Enumerator.hs dist\build\tmp\Database\PostgreSQL\PGFunctio ns.hs dist\build\tmp\Database\PostgreSQL\PGFunctions.hs dist\build\tmp\Database\ Sqlite\Enumerator.hs dist\build\tmp\Database\Sqlite\Enumerator.hs dist\build\tmp \Database\Sqlite\SqliteFunctions.hs dist\build\tmp\Database\Sqlite\SqliteFunctio ns.hs dist\build\tmp\Database\Stub\Enumerator.hs dist\build\tmp\Database\Stub\En umerator.hs dist\build\tmp\Control\Exception\MonadIO.hs dist\build\tmp\Foreign\C \UTF8.hs dist\build\tmp\Database\InternalEnumerator.hs dist\build\tmp\Database\I nternalEnumerator.hs --hide=Database.InternalEnumerator Warning: cannot use package base-2.1.1: does not exist.y c:/ghc/ghc-6.6.1\html\libraries\base Warning: cannot use package mtl-1.0.1: does not exist.y c:/ghc/ghc-6.6.1\html\libraries\mtl Warning: cannot use package time-1.1.1: does not exist.y c:/ghc/ghc-6.6.1\html\libraries\time Warning: Foreign.C.UTF8: the following names could not be resolved: CChar Word8 CString IO String CStringLen Char Int Ptr <wads of unresolved-name warnings> There are two problems: 1. the library docs bundled with GHC are actually under c:\ghc\ghc-6.6.1\doc\html\libraries, not c:\ghc\ghc-6.6.1\html\libraries. ghc-pjg reports them as in $topdir\html\libraries\base (etc), where I assume $topdir is c:\ghc\ghc-6.6.1. I've copied them up to c:\ghc\ghc-6.6.1\html\libraries to try to keep haddock happy, but as you can see... 2. even with the base.haddock etc files in the right places, haddock still doesn't find them. !? Alistair

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ANN: hstats 0.1
by Marshall Beddoe 19 Sep '07

19 Sep '07

http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hstats-0.1 I've just released hstats, a statistical computing module for the Haskell language. Current functionality includes: mean, median, mode, range, standard/average deviation, variance, iqr, kurtosis, skew, covariance, and correlation. I have plans on adding more rank correlation functions, histograms & chi square tests. darcs repo: http://www.sftank.net/code/hstats -Marshall

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