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X11 package
by Don Stewart 07 Oct '07

07 Oct '07

I've taken over maintainership of the X11 package, as we need it for xmonad. The previous maintainer was libraries@. Let me know if you've any problems with this. -- Don

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Proposal: Fix abstract unix sockets (#1699)
by Lennart Kolmodin 05 Oct '07

05 Oct '07

Hi, I've added proposal #1699 to fix abstract unix sockets on Linux for the network library. The patch is so far only tested under Linux (2.6.15), but should not affect Windows or other OSes which does not have AUS. >From the darcs patch comment: Abstract Unix Socket paths begin with a zero, are not zero terminated and needs accurate socklen calculation. Thus this patch, on linux: * Calculates the exact size of sockaddr. * Pokes sockaddr correctly wrt aus. Also, due to much more socklen usage: * Switch Network.Socket to use CSockLen instead of CInt. * Cleanup surrounding code. Cheers, Lennart Kolmodin -- "The only thing that interferes with my learning is my education." -- Albert Einstein

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Control.Monad, Control.Applicative vs. Data.Foldable, Data.Traversable
by Henning Thielemann 01 Oct '07

01 Oct '07

What is the reason for some of the standard type classes being in 'Data' folder and some in 'Control'? Since, say 'Reader' is a monad, an applicative thing, an arrow and an instance of other classes - why is it located in Control.Monad? Why not Data.Reader? I find it reasonable to have a directory for concrete data types and one directory for classes. Currently I cannot see, why the Reader data type is in Monad, Monad is in Control, but Foldable class is in Data, together with List, Tree and other concrete data types.

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Suitable new name for Dimensional library
by Björn Buckwalter 29 Sep '07

29 Sep '07

All, For quite a while[1] now I've been wanting to change the name of my Dimensional library[2]. The library blurb is: "Dimensional is a library providing data types for performing arithmetic with physical quantities and units. Information about the physical dimensions of the quantities/units is embedded in their types and the validity of operations is verified by the type checker at compile time. The boxing and unboxing of numerical values as quantities is done by multiplication and division with units. The library is designed to, as far as is practical, enforce/encourage best practices of unit usage." There are two primary reasons I have been wanting to change the name. Firstly I wanted to move the library from the arbitrary 'Buckwalter.Dimensional' namespace into the standard hierarchy. At Don's suggestion (patch) the library has been moved to the 'Numeric.Dimensional' namespace and if no-one objects it will remain under 'Numeric'. Secondly, I feel that "Dimensional" is to vague and ambiguous, in particular it could just as well refer to dimensions in the linear algebra sense as physical dimensions. I'd like a more specific and perhaps less pretentious name for the library. This is where I would appreciate some feedback as to what would be appropriate. Some suggestions are: - Numeric.Units - Numeric.PhysicalUnits - Numeric.PhysicalDimensions - Numeric.SI - Numeric.SIUnits - Numeric.Units.Static (While the library isn't limited to SI units or even the SI dimensions they are the main focus and default export.) Personally I like 'Numeric.Units' (it emphasizes that units are the key to interacting with the library) but I'd love to get a second, third and fourth opinion! Thanks, Bjorn Buckwalter [1] http://www.haskell.org/pipermail/haskell/2006-December/018993.html [2] http://dimensional.googlecode.com

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Re: Suitable new name for Dimensional library
by Björn Buckwalter 28 Sep '07

28 Sep '07

On 9/28/07, Isaac Dupree <isaacdupree(a)charter.net> wrote: > >> I don't remember, is it possible for modules that import yours, to > >> define arbitrary new units of their own? > > > > Yes, e.g. "nauticalMile = prefix 1.852 (kilo meter)". > > I mean a new dimension, like "prettyness" measured in "Emilys", for example. Ah, yes. The 'Extensible' module makes it relatively easy to add a new base dimension on top of the seven SI base dimensions. The 'CGS' module demonstrates how to replace the SI with another system altogether. Both of these should be considered experimental, however. -Bjorn

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Re: Suitable new name for Dimensional library
by Isaac Dupree 28 Sep '07

28 Sep '07

Björn Buckwalter wrote: > On 9/28/07, Isaac Dupree <isaacdupree(a)charter.net> wrote: >> Björn Buckwalter wrote: >>> There are two primary reasons I have been wanting to change the name. >>> >>> Firstly I wanted to move the library from the arbitrary >>> 'Buckwalter.Dimensional' namespace into the standard hierarchy. At >>> Don's suggestion (patch) the library has been moved to the >>> 'Numeric.Dimensional' namespace and if no-one objects it will remain >>> under 'Numeric'. >> seems fine to me >> >>> Secondly, I feel that "Dimensional" is to vague and ambiguous, in >>> particular it could just as well refer to dimensions in the linear >>> algebra sense as physical dimensions. >> They are somewhat related. But indeed your library only deals with >> specific named dimensions... >> >>> I'd like a more specific and >>> perhaps less pretentious name for the library. This is where I would >>> appreciate some feedback as to what would be appropriate. Some >>> suggestions are: >>> >>> - Numeric.Units >>> - Numeric.PhysicalUnits >>> - Numeric.PhysicalDimensions >>> - Numeric.SI >>> - Numeric.SIUnits >>> - Numeric.Units.Static >>> >>> (While the library isn't limited to SI units or even the SI dimensions >>> they are the main focus and default export.) >>> >>> Personally I like 'Numeric.Units' (it emphasizes that units are the >>> key to interacting with the library) but I'd love to get a second, >>> third and fourth opinion! >> perhaps: Numeric.Units.SI exports the SI units... but then it's not >> obvious what to do with the other exports (Dimensionless etc.) - >> Numeric.Units I guess? > > Normal usage would be: > > import qualified Prelude > import Numeric.Units.Prelude > import Numeric.Units.NonSI (poundMass) > > The Prelude replacement includes all SI units. > >> I don't remember, is it possible for modules that import yours, to >> define arbitrary new units of their own? > > Yes, e.g. "nauticalMile = prefix 1.852 (kilo meter)". I mean a new dimension, like "prettyness" measured in "Emilys", for example. > >> Is the module's API good enough (or unlikely enough to be duplicated or >> significantly changed) to use a clean name -- or are we not supposed to >> be worrying about that because of namespace separation by package? I'm >> a little confused here, but I think it doesn't matter if our >> infrastructure is good enough? > > I don't foresee any changes to the API. I'm rather happy with it > though I haven't gotten much feedback from others. The library isn't > haskell98 though, indeed it is GHC6.6+ only. Not sure whether that > should be a concern. > > I'd also like to think all this doesn't matter if our infrastructure > is good enough, but are we there yet? I don't know. > Thanks, > Bjorn >

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Survery of Setup.hs with Cabal-1.2
by Duncan Coutts 27 Sep '07

27 Sep '07

This is a survey of the problems in updating to Cabal-1.2. (This is independent of the problems in updating to GHC-6.8, though of course many people will encounter both at the same time.) I've compiled The Setup.(l)hs scripts of all 248 packages (394 package-version pairs) on hackage with the new Cabal-1.2 library. Of those, the Setup scripts from 20 packages fail to compile (there are 31 package-version pairs). 4 more compile but with warnings. I've categorised the failures by their cause & remedy: ------------------------------ There are several packages which currently use custom code in the Setup.hs script that can now be replaced entirely by using the new configurations feature. They are doing things like picking the dependencies based on the ghc version or the operating system. This is exactly what configurations are for. These packages can then use the "build-type: Simple" and the trivial Setup.hs script. cabalmdvrpm-0.0.1 cabalrpmdeps-0.0.3 HDBC-odbc-1.0.1.0 hslogger-1.0.2 MissingH-0.18.2 tar-0.1 unix-compat-0.1 hsql-odbc-1.7 (actually does compile but with a warning) ------------------------------ A similar case is using code to run an external program to discover the correct build flags for a package. In general this still needs to use custom code but in the common case of using the "pkg-config" program we can take advantage of the pkg-config support in Cabal-1.2 and again get away with using the build-type: Simple and the trivial Setup.hs script. hsql-sqlite3-1.7 ------------------------------ An API change in the "UserHook" hooks interface that affected many Setup scripts was that the result type was changed from IO ExitCode to just IO (). Then instead of returning codes all over the place (which were not being consistently checked) we now use IO exceptions instead. So Setup scripts which used to return ExitSuccess can now return () and ExitFailure n can be replaced by exitWith (ExitFailure n). debian-1.0 hburg-1.0 YamlReference-0.1 to 0.5 ------------------------------ There are a number of packages where the Setup script makes extensive use of the internal API of Cabal's default build system. I'll mention each one briefly: fenfire-0.1: needs updating to use new PreProcessor abstraction. Can drop the local def of c2hs pre-processor as this hack is no longer required in the minimum version of c2hs that Cabal supports (and it probably would no longer work anyway). lhs2tex-1.12: requires significant work. It makes use of the Program abstraction and system for managing installation dirs both of which have changed significantly. hsql-mysql-1.7, hsql-postgresql-1.7: requires significant work. can be simplified by using the cabal api effectively and using configurations. These both call external config programs to find the right build flags. I posted an update to hsql-mysql-1.7 the other day as an example. alex-2.1.0, happy-1.16: requires significant work (though already done in darcs versions). Again these used the internal Program abstraction which changed significantly. yi-0.2, hint-0.1: These both try to find ghc's libdir. The both could be significantly simplified by doing things in the 'proper' way which is to use the HookedBuildInfo stuff rather than writing little .ghc-libdir files. xmobar-0.3.1-0.7: The Setup.hs for this package completely re-implements the haddock command to customise the way docs are generated for executables. This is no longer necessary in Cabal-1.2 as it provides the features required. So the Setup.hs can be replaced with default and use build-type: Simple. ------------------------------ Packages for which Setup.hs compiles with a warning with Cabal-1.2: These three packages add a feature that was missing in Cabal-1.1.6 but is now present in Cabal-1.2. They add a --ghc-option= and --configure-option= flag to the configure command. Cabal-1.2 implements this generically for all programs that it knows about (and the programs it knows about can be extended by the Setup script). So again, these can use build-type: Simple and the trivial Setup script. cgi-3001.1.3 filepath-1.0 X11-1.2.2 One immediate cause of problems is Setup scripts importing Distribution.PreProcess, Distribution.Program which have moved under Distribution.Simple. I could add re-exports for both as I did for Distribution.Setup however both modules have changed significantly so any Script that actually uses these modules needs changing anyway, so theres no particular advantage to providing a module re-export crutch. I might make module Distribution.Simple.Utils export rawSystemVerbose again since some scripts use it. Though all those that do have other problems as well. So overall that's not too bad. Less than 10% of the hackage packages are affected by the significant internal changes in Cabal-1.2. Of those, only 9 packages need significant work to update their Setup scripts and 12 others can eliminate their custom Setup code completely using new features in Cabal-1.2. The remaining 3 need only minor changes. Duncan

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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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