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darcs patch: Data.List.sort: force elements from start to end.
by Bertram Felgenhauer 16 Jan '08

16 Jan '08

Hi, the patch below is a trivial change to the merge helper function of Data.List.sort. Its effect is that the first argument of merge is evaluated before the second argument instead of vice versa. I think it's obviously correct. Also, sort is necessarily strict in the whole list, so there can be no loss of laziness. Rationale: The change helps to avoid a stack overflow in the common case where each element of a list depends on the previous one. Examples for such lists are '[1..]' or uses of 'iterate f' where f is a strict function. I believe this case is far more common than the opposite case where each element of the list depends on the next one, so the patch below is an improvement. See also http://thread.gmane.org/gmane.comp.lang.haskell.cafe/30598 Bertram Wed Nov 21 11:14:58 CET 2007 Bertram Felgenhauer <int-e(a)gmx.de> * Data.List.sort: force elements from start to end. this prevents a stack overflow on sort (take 10^6 [1..])

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Re: Copyright for readline/editline packages
by Thorkil Naur 14 Jan '08

14 Jan '08

Hello, Indeed an interesting question. Although I am no licensing expert, I guess that the intention of the GPL is that if you copy the Haskell readline code which is under the GPL and modify it, then the result will also be under the GPL. Independent development is a possibility, unless you can get hold of the copyright holder. Best regards Thorkil On Saturday 12 January 2008 01:19, Judah Jacobson wrote: > Hi all, > > As mentioned before, I'm putting together an editline package which > will provide a subset of the APIs from the readline package, but be > BSD-compatible since it links against libedit. > > The licensing for the readline package itself is a little strange -- > it's licensed under the GPL (because it links with libreadline), but > there's no copyright holder information; and Readline.hsc from that > package lists "Copyright: (c) unknown". > > I'd like to put the Haskell editline package under BSD3, but most of > the code will be copied verbatim from the readline package. How > should this be attributed/copyrighted? > > Thanks, > -Judah > _______________________________________________ > Libraries mailing list > Libraries(a)haskell.org > http://www.haskell.org/mailman/listinfo/libraries >

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can't build plugins-1.0 with ghc-6.9
by Valery V. Vorotyntsev 14 Jan '08

14 Jan '08

Hi, (The message below contains bunch of "preformatted" sections. I hope it's still readable, otherwise, please, let me know.) My quest is to install lambdabot (for the sake of offline `@hoogle' and `@pl' commands), and the one depends on `plugins'. 1) plugins.cabal should be updated ---------------------------------- A patch to .cabal file[1] is needed to get rid of config-time warning[2] and resolve build-time errors[3]. [1] vvv:~/src/plugins-1.0$ diff -u plugins.cabal{.orig,} --- plugins.cabal.orig 2008-01-06 22:23:44.657177486 +0200 +++ plugins.cabal 2008-01-06 22:25:45.160728537 +0200 @@ -33,6 +33,6 @@ src/Language/Hi/hschooks.c includes: Linker.h extensions: CPP, ForeignFunctionInterface -Build-Depends: base, Cabal, haskell-src +Build-Depends: base, Cabal, haskell-src, array, containers, directory, random, process ghc-options: -Wall -O -fasm -funbox-strict-fields -fno-warn-missing-signatures -hs-source-dir: src +hs-source-dirs: src [2] vvv:~/src/plugins-1.0$ runhaskell Setup configure --prefix=$HOME --user Warning: The field "hs-source-dir" is deprecated, please use "hs-source-dirs" Configuring plugins-1.0... [...] [3] vvv:~/src/plugins-1.0$ runhaskell Setup build Preprocessing library plugins-1.0... Building plugins-1.0... src/Language/Hi/Binary.hs:90:7: Could not find module `Data.Array.Base': it is a member of package array-0.1, which is hidden 2) it doesn't build with Cabal-1.3.2 ------------------------------------ `InstalledPackageInfo' is a type alias in GHC's Cabal[4], not a data constructor; `plugins' library[5] gets confused[6]. [4] vvv:~/src$ diff -u cabal-1.2.2.0/Distribution/InstalledPackageInfo.hs ghc/libraries/Cabal/Distribution/InstalledPackageInfo.hs --- cabal-1.2.2.0/Distribution/InstalledPackageInfo.hs 2007-11-01 17:02:35.000000000 +0200 +++ ghc/libraries/Cabal/Distribution/InstalledPackageInfo.hs 2007-12-17 17:53:21.691532864 +0200 @@ -46,7 +46,7 @@ -- This module is meant to be local-only to Distribution... module Distribution.InstalledPackageInfo ( - InstalledPackageInfo(..), + InstalledPackageInfo_(..), InstalledPackageInfo, ParseResult(..), PError(..), PWarning, emptyInstalledPackageInfo, parseInstalledPackageInfo, @@ -72,8 +72,8 @@ -- ----------------------------------------------------------------------------- -- The InstalledPackageInfo type -data InstalledPackageInfo - = InstalledPackageInfo { +data InstalledPackageInfo_ m + = InstalledPackageInfo_ { -- these parts are exactly the same as PackageDescription package :: PackageIdentifier, license :: License, @@ -87,8 +87,8 @@ category :: String, -- these parts are required by an installed package only: exposed :: Bool, - exposedModules :: [String], - hiddenModules :: [String], + exposedModules :: [m], + hiddenModules :: [m], importDirs :: [FilePath], -- contain sources in case of Hugs libraryDirs :: [FilePath], hsLibraries :: [String], @@ -107,9 +107,11 @@ } deriving (Read, Show) -emptyInstalledPackageInfo :: InstalledPackageInfo +type InstalledPackageInfo = InstalledPackageInfo_ String + +emptyInstalledPackageInfo :: InstalledPackageInfo_ m emptyInstalledPackageInfo - = InstalledPackageInfo { + = InstalledPackageInfo_ { package = PackageIdentifier "" noVersion, license = AllRightsReserved, copyright = "", [5] vvv:~/src/plugins-1.0$ sed -n 64,66p src/System/Plugins/PackageAPI.hs updImportDirs f pk@(InstalledPackageInfo { importDirs = idirs }) = pk { importDirs = f idirs } updLibraryDirs f pk@(InstalledPackageInfo { libraryDirs = ldirs }) = [6] vvv:~/src/plugins-1.0$ runhaskell Setup build Preprocessing library plugins-1.0... Building plugins-1.0... [ 1 of 24] Compiling System.Plugins.Process ( src/System/Plugins/Process.hs, dist/build/System/Plugins/Process.o ) [ 2 of 24] Compiling System.Plugins.Parser ( src/System/Plugins/Parser.hs, dist/build/System/Plugins/Parser.o ) [ 3 of 24] Compiling System.Plugins.ParsePkgConfCabal ( src/System/Plugins/ParsePkgConfCabal.hs, dist/build/System/Plugins/ParsePkgConfCabal.o ) [ 4 of 24] Compiling System.Plugins.PackageAPI ( src/System/Plugins/PackageAPI.hs, dist/build/System/Plugins/PackageAPI.o ) src/System/Plugins/PackageAPI.hs:64:20: Not in scope: data constructor `InstalledPackageInfo' src/System/Plugins/PackageAPI.hs:66:21: Not in scope: data constructor `InstalledPackageInfo' I would like to hear your suggestions. Should I try harder[7] installing Cabal-1.2.2.0? Or is this a bug of GHC's Cabal? In this case I've just reported it. :) [7] vvv:~/src/cabal-1.2.2.0$ runhaskell Setup configure --prefix=$HOME --user Configuring Cabal-1.2.2.0... Setup: At least the following dependencies are missing: base <3, filepath -any vvv:~/src/cabal-1.2.2.0$ runhaskell Setup configure --prefix=$HOME --user -f small_base Configuring Cabal-1.2.2.0... Setup: At least the following dependencies are missing: base >=3, pretty -any, directory -any, old-time -any, process -any, containers -any, filepath -any vvv:~/src/cabal-1.2.2.0$ ghc-pkg list /home/vvv/lib/ghc-6.9.20080104/package.conf: Cabal-1.3.2, array-0.1, base-3.0, bytestring-0.9, containers-0.1, directory-1.0, filepath-1.1, (ghc-6.9.20080104), haskell98-1.0.1, hpc-0.5, old-locale-1.0, old-time-1.0, packedstring-0.1, pretty-1.0, process-1.0, random-1.0, readline-1.0.1, rts-1.0, template-haskell-2.2, unix-2.2 /home/vvv/.ghc/i386-linux-6.9.20080104/package.conf: X11-1.4.1, binary-0.4.1, haskell-src-1.0.1.1, mtl-1.1.0.0, network-2.1.0.0, parsec-2.1.0.0, xmonad-0.5, xmonad-contrib-0.5 Thanks a lot. Happy hacking! -- vvv

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Proposal: Add --with-libedit flag to the readline package
by Judah Jacobson 14 Jan '08

14 Jan '08

It would be useful for the readline package to support compiling against the libedit library (which provides a subset of the readline APIs): - libedit is available by default on OS X. - since libedit is BSD-licensed, there are no problems statically linking ghc with it. (This may be useful on Windows.) I propose adding a --with-libedit flag to the readline autoconf script. Without that flag, the package will behave exactly as before, refusing to link against libedit. With that flag, the following behavior occurs: - GNUreadline.framework (OS X - only) is ignored, if present - We try to link with -lreadline, and don't fail if readline is actually libedit. - If it is libedit, we #ifdef out all of the functions not supported by libedit. (these are generally low-level APIs not needed by most applications, including ghci.) Otherwise, if we're linking against GNU readline, we support all the available APIs. Suggested deadline: Jan. 23, 2008. A patch is attached to the trac ticket: http://hackage.haskell.org/trac/ghc/ticket/2028 Thoughts? -Judah

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Copyright for readline/editline packages
by Judah Jacobson 12 Jan '08

12 Jan '08

Hi all, As mentioned before, I'm putting together an editline package which will provide a subset of the APIs from the readline package, but be BSD-compatible since it links against libedit. The licensing for the readline package itself is a little strange -- it's licensed under the GPL (because it links with libreadline), but there's no copyright holder information; and Readline.hsc from that package lists "Copyright: (c) unknown". I'd like to put the Haskell editline package under BSD3, but most of the code will be copied verbatim from the readline package. How should this be attributed/copyrighted? Thanks, -Judah

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PROPOSAL: Some more 'Applicative' combinators
by Iavor Diatchki 11 Jan '08

11 Jan '08

Hello, I propose that we add the following combinators to the 'Control.Applicative' module: skipMany :: (Alternative f) => f a -> f () skipMany p = skipSome p <|> pure () skipSome :: (Alternative f) => f a -> f () skipSome p = p *> skipMany p endBy :: (Alternative f) => f a -> f b -> f [a] endBy p s = many (p <* s) endBy1 :: (Alternative f) => f a -> f b -> f [a] endBy1 p s = some (p <* s) sepBy :: (Alternative f) => f a -> f v -> f [a] sepBy p s = sepBy1 p s <|> pure [] sepBy1 :: (Alternative f) => f a -> f v -> f [a] sepBy1 p s = (:) <$> p <*> many (s *> p) Any objections? Deadline for discussion is 2 weeks from now, which would be the 20th of Jan. -Iavor

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Proposal: new version of getModificationTime
by Felix Martini 11 Jan '08

11 Jan '08

Hello all, Function getModificationTime in System.Directory returns ClockTime. ClockTime is part of the old-time package. The (new) time package has UTCTime, so i propose a new version of getModificationTime that returns UTCTime instead. I am not sure what a good name for the new version would be, perhaps getModificationUTCTime? Regards, Felix

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Announcement: Typeful [x]html combinators -- pre-release 0
by Jon Fairbairn 10 Jan '08

10 Jan '08

... or, "whoops! I've writtten another html combinator library." History: I was surprised to find that all the Haskell html generating stuff I've tried allowed one to construct invalid HTML. I thought to myself that this might make an undergraduate project, but then I thought "maybe it's too hard? I'd better write some of it to see how hard it is." After a while I decided that it was probably a bit too big for an undergraduate project, but by that time I'd written too much of it to throw away, and just had to keep going so here it is. I'm announcing it here because I hope the audience is fairly small but discerning, and I'm announcing it at all because I've run out of steam for the moment. This is the first code above the size of a nonce-programme that I've written since I got ill years ago, so don't go too hard on me! I still am ill, so don't expect swift responses either. I'm mainly interested in opinions on the questions below, and in test cases that fail validation. You can get it with darcs get --partial http://homepage.ntlworld.com/jon.fairbairn/Typeful/Text/HTMLs and the documentation (such as it is) is at <http://homepage.ntlworld.com/jon.fairbairn/Typeful/Text/HTMLs/Documentation…> Here's the announcement (which might better be called the release note, except that I'm not sure this counts as a relase). ------ Typeful HTMLs library Library of types and combinators to produce valid xhtml 1.0 (and eventually html 4.01) -- if you use this library (and if it's not faulty), you won't need to run the validator over the output of your code. Types prevent invalid nesting of elements (including the prohibitions of appendix B of the xhtml standard) and ensure an attribute is only passed to elements that has it. Most attributes are given types that reflect their content rather than just being strings (although some are just wrappers around strings for the moment). Includes full set of xhtml character entity names Includes type with names for all IANA-registered character sets. Provides the option of generating output in a choice of character sets (currently with the wide choice of utf_8, us_ascii, latin1 or iso_8859_5 (cyrillic)). Provides the option of generating xhtml without an xml version declaration (to avoid putting IE into quirks mode). It's generated by TemplateHaskell, but otherwise Haskell98. Questions: * I want to add a function to produce HTML 4.01. Unfortunately there are trivial differences (body takes a nonempty list in HTML but an ordinary list in xhtml, and similar). One approach (and the one I'd choose if left to my own devices) would be to restrict the document tree to the common subset, so the types would be constrained by whichever language was the more restrictive in any given case. An alternative would be to transform the xhtml tree by adding empty div elements. Which do people prefer? * Having a monad inside the result types of the *_allowed_in classes complicates the types, complicates programmatic generation of elements and makes some error messages much worse. It wouldn't be necessary if we simply wrote Haskell lists instead of using the +++ operator, ie instead of body << (h1 << ... +++ p << ... +++ p << ...) we had to write body << [h1 << ..., p << ..., p << ...] Admittedly, it is rather more awkward for nonempty lists: ul << (li <<... +++ li<< ... +++ li<<...) would have to be written ul << (li<<... +:[li<<...,li<<...]). Would anyone really be bothered by that? (Either that, or can someone come up with a way of rearranging the types so that +++ works without the monad in the result types of elements?) * What should I do about REQUIRED attributes? Some alternatives are listed in the TODO file. * The preference carrying monad used for Render is backwards; I tried making it go forwards, but the Laziness test programme took about 1.7 times as long to run. I'd like to put some state in there, which can't be done backwards. Can I do this somehow without the performance hit? * This pre release has a very restrictive license (barely falling short of "You may not use this!") My preference is, I think, to release it under LGPL. Is that going to cause people undue grief? -- Jón Fairbairn Jon.Fairbairn(a)cl.cam.ac.uk

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Add 'subsequences' and 'permutations' to Data.List (ticket #1990)
by Twan van Laarhoven 10 Jan '08

10 Jan '08

Hello all, As Thomas Hartman noted in a recent cafe thread [1], haskell 1.3 included the functions 'subsequences' and 'permutations'. I think these functions are quite useful, and I don't know why they were ever removed. This is a proposal to add these two functions to Data.List. The implementation is taken directly from the Haskell 1.3 report [2]. Trac ticket: #1990 Discussion period ends: January 7th (since there is a holiday comming up) Twan [1] http://article.gmane.org/gmane.comp.lang.haskell.cafe/33535 [2] http://haskell.cs.yale.edu/haskell-report/List.html

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Tests in Cabal
by Adrian Hey 10 Jan '08

10 Jan '08

Hello, I've been playing about with the option to add tests to packages and have modified the Setup.hs as follows.. import Distribution.Simple import MyPackage main :: IO () main = defaultMainWithHooks (simpleUserHooks {runTests = myTests}) myTests :: Args -> Bool -> PackageDescription -> LocalBuildInfo -> IO () myTests _ _ _ _ = <whatever> Which I think is the right thing to do if I understand the docs. The first problem I come up against is that in order to do this practically all the modules from the package need compiling by runghc (even during the configure stage presumably). As I guess most people will be using runHaskell/runghc to do this it seems like this will all take quite a bit of time. In my case the process fails completely because the package library files need CPPing and is seems runghc doesn't do this (by default at least). Is this really the way tests are supposed to be included? It doesn't seem workable to me. I wonder if it would be better to just build the lib first (without tests) and then separately build one or more test executables? What does everyone else do about this? Thanks -- Adrian Hey

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