April 2006 - Haskell - Haskell.org

Haskell' status & summary
by Isaac Jones 22 Apr '06

22 Apr '06

Greetings! I'll try to update the Haskell community periodically on the status of the Haskell' language standard. As mentioned previously, we are currently focusing on two topics, concurrency and the class system. If you feel that you have anything important to contribute to those topics, now is the time to review the proposals, join in the Haskell' mailing list and let us know what you know! Stephanie Weirich has posted a summary of the class system discussion here: http://hackage.haskell.org/trac/haskell-prime/wiki/ClassSystem Stephanie says: This page is important because it lists all of the proposals not related to MPTCs as well as trying to capture the big picture about where we stand with respect to MPTCs. I've been trying to not duplicate text that appears elsewhere in the wiki, but just provide a consistent picture of the state of the discussions on the mailing list. Please take a look at this page and help me fill it out. In particular, 've been trying to take a pulse of where we stand on some of these issues, and some of you may not agree! Tell me if I'm off the wall. Also, I've (mostly) concentrated on issues that have tickets, so I may have missed some issues that were only discussed in the mailing list. Please let me know if there is anything I've forgotten. Simon Marlow has posted a summary of the concurrency discussion here: http://hackage.haskell.org/trac/haskell-prime/wiki/Concurrency Simon says: I have tried to summarise the various points that have arisen during the discussion. If anyone feels they have been mis-paraphrased, or I have forgotten something, please feel free to edit, or send me some text for inclusion. I don't want to include long gobs of text in here, though: just summarise the main points, and if necessary link to relevant mailing list posts. Thanks, Simon & Stephanie for keeping things moving forward! peace, isaac

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(HS)XML queries via SYB3-like generic transformations
by oleg＠pobox.com 21 Apr '06

21 Apr '06

This message demonstrates SYB3-like generic term processing for transformations and selections from (HS)XML-like documents. Our running example is an HSXML document that includes Haskell sample code, which is to be formatted specially. Moreover, we wish to guarantee that the sample code is syntactically and type-correct. Furthermore, we wish to evaluate expressions in the context of the code -- and include the result in the rendered HTML document. The present message is inspired by the example posted by shelarcy(a)gmail.com on the Haskell list, Mar 25, 2006, and benefited from discussions with shelarcy(a)gmail.com. We show a quite non-trivial generic term processing: extracting textual data from a particular subterm. The subterm in question is identified by its type; as there may be several occurrences of subterms of a given type, we further identify the desired subterm by its content (i.e., a string label). Some of the extracted strings must be concatenated, while the others must be kept distinct -- depending on their occurrences within terms of a particular type. Thus our extraction has both static aspects (i.e., type-directed) as well as dynamic ones (i.e., guards). We should point out that in HSXML, the notions of the element type (in the sense of the XML Recommendation) and of the Haskell data type coincide. Our generic term processing is like SYB3 in spirit, but different in implementation. In particular, we do not require a GHC extension of recursive instances, although this point is moot here as HSXML so far has had no recursive datatypes. Like SYB3, we do need overlapping instances to specify generic term processing, which the user can later override for particular types of terms. Our HSXML transformations are like SXSLT, SXML pre-post-order transformations described in http://pobox.com/~oleg/ftp/Scheme/xml.html#SXSLT only more modular. The complete code discussed in the present message is in the file sample-code.hs included in the (updated) archive http://pobox.com/~oleg/ftp/Haskell/HSXML.tar.gz Here's our running example: > test_haskell = > (document > (head > [meta_tag [description "Haskell"]]) > (body > [h1 "Haskell examples"] > [h2 "The first sample code"] > [hcode "sample1" > "module Main where" > "fact n = product [1..n]" > ] > [hcode "sample2" > [[thide "module Main where"]] > [[thcode "fix f = f $" [[em "fix f"]]]] > "fact self n = if n <= 0 then 1 else n * (self (n-1))" > ] > [p "the result:" [[thrunh test_haskell "sample2" > "show $ fix fact 5"]]] > )) It includes two pieces of Haskell code, gabelled "sample1" and "sample2". The sample code is comprised of lines, which may include formatting annotations such as 'em' to emphasize certain parts of code. Some other lines of code, like module declarations, can be hidden in rendering for the sake of clarity. We may wish to extract a particular piece of code from the HSXML document, with formatting annotations removed. For example, we may wish to type-check that code, and evaluate some expressions in its context. We may want to do that while we render the HSXML document into HTML. For instance, [[thrunh test_haskell "sample2" "show $ fix fact 5"]], when rendered on a particular formatter, will extract "sample2", evaluate the expression "show $ fix fact 5" in its context, and insert the result in the rendered HTML document: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd"> <html> <head> <meta name="description" content="Haskell"></head> <body bgcolor="#FFFFFF"> <h1>Haskell examples</h1> <h2>The first sample code</h2> <pre> > module Main where > fact n = product [1..n]</pre> <pre> > fix f = f $ <em>fix f</em> > fact self n = if n <= 0 then 1 else n * (self (n-1))</pre> <p>the result: <code>show $ fix fact 5</code> is 120</p> </body> </html> To accomplish evaluation during rendering, we do invoke a Haskell system (runghc). To render Haskell code in a particular way, we define a new HSXML context, CT_hcode, and provide for interpretation of the text data and elements in that context: > -- Rendering of Strings in the HCODE context. > instance Render (HW CT_hcode String) where > render (HW str) = emit "\n> " >> emit str > > -- `Transparent' grouping of inline elements into one > -- hcode element > -- This is an administrative element > newtype THCODE a = THCODE a deriving Show > thcode x = build (as_hcode . HW . THCODE . rev'apppend HNil) nil_inline x > > -- An THCODE element is rendered as one string > instance RenderInline b => Render (HW CT_hcode (THCODE b)) where > render (HW (THCODE b)) = emit "\n> " >> (render_inline False b > >> return ()) Of a particular interest is SYB3-like generic processing for extracting sections of HSXML document. Just like in SYB3, the generic term processing code naturally splits into three distinct modules. In sample-code.hs file however, all three `modules' are placed within one file, for convenience. Again, our processing is SYB3 is spirit only -- but not in the implementation. The first part of the library defines the class Dat and its instances for term types of interest. This part of the library depends exclusively on the structure of terms -- irrespective of operations one may wish to perform on terms. > class Dat gctx a where > gmapq :: ([gctx] ->w) -> a -> w We also define a class of generic functions, identified by labels. We don't provide any instances of this class here. > class FN label a where > fn :: a -> label Unlike SYB3, Dat is not a subclass of any class (cf. the SAT class in SYB3). Thus the dictionary for Dat does not depend on other dictionaries. Furthermore, the function gmapq has _no_ higher-rank type. The type gctx is the label that identifies a particular generic function to apply. Within this part of the library, we treat gctx as an (abstract) type variable. Here are a few instances of the Dat class > instance Dat gctx (HW ctx String) where > gmapq u _ = u [] > instance Dat gctx HNil where > gmapq u _ = u [] > instance (FN gctx a, FN gctx b) => Dat gctx (HCons a b) where > gmapq u (HCons a b) = u [fn a, fn b] > -- Instances of Dat for more specific containers > instance (FN gctx h, FN gctx b) => Dat gctx (HW ctx (Document h b)) where > gmapq u (HW (Document h b)) = u [fn h, fn b] > > instance (FN gctx h) => Dat gctx (HW ctx (Head h)) where > gmapq u (HW (Head h)) = u [fn h] As we can see, all the instances are quite regular and could well be automatically derived (e.g., via DrIFT). The second part of the generic term traversal library defines generic functions, irrespective of the structure of the types to which they may apply. Here we define a traversal function to extract a part of the term according to some criterion (to be specified later by the user of the library) > class ExtractD a r where > extractd :: a -> r > newtype EXD r = EXD{unEXD :: r} We use EXD in two ways. First, we use its type as a label to select the proper instance of FN. Second, we use EXD to encapsulate the result type. So, we can select the proper instance of generic function based on the argument type and the result type. The following `registers' ExtractD to be a generic `function'. > instance ExtractD a r => FN (EXD r) a where fn = EXD . extractd That's all there is to the second part of the library. Incidentally, none of the previous parts needed overlapping instances. Finally, we wish to instantiate the ExtractD function to extract all strings from a part of the term that has the type (HW CT_block (HCode b)) and which has the desired label (given as a string): First we define a generic extraction, which applies to any term type: > instance Dat (EXD (String->[String])) a > => ExtractD a (String->[String]) where > extractd a label = gmapq (concatMap (\x -> unEXD x $ label)) a This traversal rule obviously does nothing but propagating accumulated strings. To get any result we need to define specific extraction rules. In our case, we have to find the HCode sub-term of the desired label and extract all strings from it: > instance ExtractC b => > ExtractD (HW CT_block (HCode b)) (String->[String]) where > extractd (HW (HCode label b)) label' = > if label == label' > then extractc b > else [] -- otherwise, ignore the whole block Here extractc is yet another generic function, which extracts the string content from terms and returns the array of lines. The following is the entire definition. A three-line boiler-plate: > class ExtractC a where extractc :: a -> [String] > newtype EXC = EXC{unEXC :: [String]} > instance ExtractC a => FN EXC a where fn = EXC . extractc General extraction instance, which only propagates what other instances might have produced: > instance Dat EXC a => ExtractC a where > extractc a = gmapq (concatMap unEXC) a Specific instances: > instance ExtractC (HW ctx String) where > extractc (HW str) = [str] > instance ExtractC b => ExtractC (HW CT_hcode (THIDE b)) where > extractc (HW (THIDE b)) = [concat $ extractc b] > instance ExtractC b => ExtractC (HW CT_hcode (THCODE b)) where > extractc (HW (THCODE b)) = [concat $ intersperse " " (extractc b) ]

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ANNOUNCE: FPS - FastPackedStrings 0.2
by dons＠cse.unsw.edu.au 20 Apr '06

20 Apr '06

I'm pleased to announce version 0.2 of FPS, the fast, packed string library for Haskell. FPS allows you to have time and space efficient arrays of bytes accessed via a List interface, along with fast IO on those strings. FPS is, in particular, suited for heavy duty string and IO projects. It is also useful for applications that must pass strings back and forward from C. Version 0.2 features a number of improvements over v0.1. * Its faster! * There is a richer interface. * More support for converting between C, Addr# and Haskell strings. (in particular, there are 0-copy functions to create FPS strings from Addr# and to create CStrings from FPS') Get it here: Homepage: http://www.cse.unsw.edu.au/~dons/fps.html Interface: http://www.cse.unsw.edu.au/~dons/fps/Data.FastPackedString.html FTP: ftp://ftp.cse.unsw.edu.au/pub/users/dons/fps/fps-0.2.tar.gz darcs: darcs get --partial http://www.cse.unsw.edu.au/~dons/code/fps Cheers, Don ------------------------------------------------------------------------ Here are benchmarking results for 20M strings, for versions 0.1 and 0.2 of FPS, compared against Simon Marlow's prototype packedstring code, the current Data.PackedString library and traditional [Char] functions. Functions that are only provided by FPS (such as the various CString routines) are not tested. Key: FPS2 = Fast Packed String v2 FPS1 = Fast Packed String v1 SPS = Simon Marlow's packedstring prototype PS = Data.PackedString [a] = [Char] ~ = unchanged from FPS2 - = no function exists ! = stack or memory exhaustion Size of test data: 21256k Time in seconds. FPS2 FPS1 SPS PS* [a] ++ 0.078 ~ ! ! 1.288 length 0.000 ~ 0.000 0.000 0.131 pack 0.345 2.043 0.502 0.337 - unpack 1.596 ~ 1.630 7.445 - compare 0.000 ~ 0.000 0.000 0.000 index 0.000 ~ 0.000 0.000 0.000 map 2.664 4.283 2.917 4.813 7.286 filter 0.282 0.482 2.805 0.954 0.305 take 0.000 ~ 0.000 0.024 0.005 drop 0.000 ~ 0.000 11.768 0.130 takeWhile 0.000 ~ 1.498 0.000 0.000 dropWhile 0.000 ~ 1.985 8.447 0.130 span 0.000 ~ 9.289 11.144 0.131 break 0.000 ~ 9.383 11.268 0.133 lines 0.421 ~ 1.114 1.367 2.790 unlines 0.121 ~ ! ! 10.950 words 2.115 3.202 2.128 5.644 4.184 unwords 0.058 ~ ! ! 1.305 reverse 0.024 4.606 12.997 13.018 1.622 concat 0.029 ~ 12.701 11.459 1.163 cons 0.016 3.094 2.064 8.358 0.131 snoc 0.017 1.536 - - - empty 0.000 ~ 0.000 0.000 0.000 head 0.000 ~ 0.000 0.000 0.000 tail 0.000 ~ 0.000 14.490 0.130 last 0.000 ~ - - 0.143 init 0.000 ~ - - 1.147 inits 5.350 - - - ! tails 6.634 - - - 1.136 intersperse 0.034 4.590 - - 10.517 concatMap ! - - - 1.131 any 0.000 ~ - - 0.000 all 0.000 ~ - - 0.000 sort 14.380 15.773 - - ! maximum 0.024 ~ - - 0.183 minimum 0.025 ~ - - 0.185 replicate 0.008 ~ - - 0.053 elem 0.000 ~ 1.490 0.001 0.000 find 0.278 0.366 - - 0.000 elemIndex 0.000 ~ - - 0.000 elemIndicies 4.192 ~ - - 0.314 * Note that it is not possible to directly read a string larger than 1M into a Data.PackedString (due to a space leak). Instead you need to use packString

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ANN: Debian From Scratch 0.99.0
by John Goerzen 20 Apr '06

20 Apr '06

Here's why I'm sending a copy of this announcement to the Haskell list: The tool that generates these ISO images (dfsbuild) is written in Haskell (having been ported from OCaml). The generated ISO images also contain full, working GHC and Hugs environments. -------------------------------------------------------------- Debian From Scratch (DFS) is a single, full rescue CD capable of working with all major filesystems, LVM, software RAID, and even compiling a new kernel. The DFS ISO images also contain a small Debian mirror subset that lets you use cdebootstrap, along with the other utilities on the CD, to perform a manual, "Gentoo-like" installation. It also serves as an excellent rescue CD, with a full compliment of filesystem tools, backup/restore software, and a development environment complete enough to build your own kernels. DFS also refers to dfsbuild, the tool that generates DFS images. dfsbuild is available as a Debian package. dfsbuild is designed to make it trivial to build your own custom DFS images. You can have your own set of Debian packages on your images, your own kernels, etc. Unlike many other systems, you can go from the example dfs.cfg to a customized DFS build in just a few minutes, even if you've never used dfsbuild before. Today I am announcing the availability of DFS 0.99.0 images for i386/amd64 and dfsbuild 0.99.0. dfsbuild is available in sid and (hopefully shortly) testing. My DFS ISOs are available from http://people.debian.org/~jgoerzen/dfs/ DFS is not a separate distribution. DFS images *are* Debian. What you get when you boot a DFS CD is etch (or whatever you built your own images with), with a few minor tweaks to make it run from CD-ROM. These are the major changes since the previous incarnation of DFS: * Entire program rewritten from scratch. Ported from OCaml to Haskell, with some Busybox scripts. * DFS now supports Debian initramfs kernels out of the box. It continues to support kernels with enough drivers statically compiled to load the CD. * Switched from apt-move to reprepro for the generation of the on-CD mini Debian mirror, saving space on the generated image. * DFS images now use (and require) udev. 2.4.x kernels are no longer supported. * CD-ROM autodetection via /sys. * My DFS images are now built with testing (etch). * My DFS images now come with multiple versions of GCC, plus development environments for C, Java, Perl, Haskell, Pyton, OCaml, shell, and tcl. * My DFS images now come with various version-control programs: CVS, darcs, bzr, subversion, git, cogito, arch2darcs, tailor, etc. * Numerous additions of other packages to the DFS images; full list at [1]. My DFS images now contain 575 packages. * My DFS images now built with etch, and come with enough .debs to cdebootstrap sarge, etch, or sid (assuming sid is stable enough at this time) * My DFS images continue to be able to cdebootstrap either an i386 or amd64 system. A more comprehensive list of DFS features is available at [2]. [1] http://people.debian.org/~jgoerzen/dfs/pkglist-0.99.0_i386.txt [2] http://people.debian.org/~jgoerzen/dfs/html/intro.html#FEATURES

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lhs2TeX: lazy pattern "~" formatting
by Conal Elliott 20 Apr '06

20 Apr '06

Does anyone have a nice way to format the "~" of a lazy pattern in lhs2TeX? I use %format ~ = "{} ^\sim " but the result isn't as pretty as I'd like. For one thing, no space is inserted before the "~" after a lambda, "do", or whatever. Thanks, - Conal

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Call for Contributions - HC&A Report (May 2006 edition)
by Andres Loeh 19 Apr '06

19 Apr '06

Dear Haskellers, it is nearly time for the tenth edition of the ================================================================ Haskell Communities & Activities Report http://www.haskell.org/communities/ Submission deadline: 12 May 2006 (please send your contributions to hcar at haskell.org, in plain ASCII or LaTeX format) ================================================================ This is the short story: * If you are working on any project that is in some way related to Haskell, write a short entry and submit it to the me. * If you are interested any project related to Haskell that has not previously been mentioned in the HC&A Report, please tell me, so that I can contact the project leaders and ask them to submit an entry. * Feel free to pass on this call for contributions to others that might be interested. More detailed information: The Haskell Communities & Activities Report is a bi-annual overview of the state of Haskell as well as Haskell-related projects over the last, and possibly the upcoming 6 months. If you have only recently been exposed to Haskell, it might be a good idea to browse the November 2005 edition -- you will find interesting topics described as well as several starting points and links that may provide answers to many questions. Contributions will be collected until the middle of May. They will be compiled into a coherent report which will appear sometime near the end of May. As always, this is a great opportunity to update your webpages, make new releases, announce of even start new projects, or to point at some developments you want every Haskeller to see! As the purpose of the report is to collect recent or current activities, I encourage you to update all existing summaries and reports. I will probably drop any topics that have not had any activity for the past year, i.e., since May 2005, but I would very much prefer you to present an updated description of the topic. Of course, new entries are more than welcome. Reports should generally be kept brief and informative, ranging from a few sentences to a few hundred words, to keep the whole report reasonably sized. Looking forward to your contributions, Andres (current editor) ----------------------------------- topics New suggestions for current hot topics, activities, projects, etc. are welcome - especially with names and addresses of potential contacts, but here is a non-exclusive list of likely topics (see also http://www.haskell.org/communities/topics.html ): General Haskell developments Haskell implementations Haskell extensions Standardization (Haskell', ...) Documentation Libraries Papers and Books Feedback Summaries of discussions in specialist mailing lists Conference reports Community activities Other Haskell information channels (TMR, Sequence, HWN, ...) Announcements Everything that's new or has had new releases Ongoing projects Reports on what's happening behind the scenes Confirmations that projects are still maintained Calls for contributions and contributors Tutorials Tools and Applications Released and unreleased Haskell applications Tools useful for Haskell programmers Experiences with using Haskell for a project Commercial uses of Haskell Even if your topic is not listed in this list, there's a good chance it has a place in the Report. Please get in touch with me. If you want to see an entry that hasn't been there in the past, but you are not the maintainer of the project, then please encourage the maintainers to write an entry/update, or ask permission to write the entry yourself. -------------------------- what should I write? That depends on your topic, but as a general rule, it shouldn't take you long. A simple sentence or two about your use of Haskell could go into the "Individual Haskellers" section. If you're a company, or if you're working on a project using Haskell as the implementation language, a paragraph on that could go into the "Applications" section. A typical summary report about a tool/library/project/application/... would be between 1 and 3 paragraphs of ASCII text (what's it about? major topics and results since the last report? current hot topics? major goals for the next six months?) plus pointers to material for further reading (typically to a home page, or to mailing list archives, specifications and drafts, implementations, meetings, minutes, ...). Browsing through previous editions should give you a good idea of the variety of possibilities, ranging from very brief to extensive. For those who prefer templates to fill in, the report is edited in LaTeX, and an entry template might look something like this: \begin{hcarentry}{(MYSTUFF)} \report{(MY NAME)} \status{(PROJECT STATUS IN ONE LINE)} \participants{(PARTICIPANTS OTHER THAN MYSELF)}% optional \makeheader Put the text here. What's following are suggestions for the content of an entry. (WHAT IS IT?) (WHAT IS ITS STATUS? / WHAT HAS HAPPENED SINCE LAST TIME?) (CAN OTHERS GET IT?) (WHAT ARE THE IMMEDIATE PLANS?) \FurtherReading \url{(PROJECT URL)} \end{hcarentry} This template and a style file to preview your document are available at http://haskell.org/communities/05-2006/template.tex http://haskell.org/communities/05-2006/hcar.sty

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ANNOUNCE: GHC vesrion 6.4.2
by Simon Marlow 19 Apr '06

19 Apr '06

============================================================= The (Interactive) Glasgow Haskell Compiler -- version 6.4.2 ============================================================= The GHC Team is pleased to announce a new patchlevel release of GHC. This release contains a significant number of bugfixes relative to 6.4.1, so we recommend upgrading. Highlights in this release: - Cabal has been upgraded to version 1.1.4. While strictly speaking this breaks our rules about not changing any library APIs in a patchlevel release, it was felt that the Cabal shipped in 6.4.1 was lacking in various ways, and it was more important to provide a Cabal that works with more existing packages. Some distributions of GHC were already supplying an upgraded Cabal by default. With the exception of Cabal, and OpenAL which was also upgraded, all library APIs are identical to 6.4.1. Release notes are here: http://haskell.org/ghc/docs/6.4.2/html/users_guide/release-6-4-2.html How to get it ~~~~~~~~~~~~~ The easy way is to go to the web page, which should be self-explanatory: http://www.haskell.org/ghc/ We supply binary builds in the native package format for many platforms, and the source distribution is available from the same place. Packages will appear as they are built - if the package for your system isn't available yet, please try again later. Background ~~~~~~~~~~ Haskell is a standard lazy functional programming language; the current language version is Haskell 98, agreed in December 1998 and revised December 2002. GHC is a state-of-the-art programming suite for Haskell. Included is an optimising compiler generating good code for a variety of platforms, together with an interactive system for convenient, quick development. The distribution includes space and time profiling facilities, a large collection of libraries, and support for various language extensions, including concurrency, exceptions, and foreign language interfaces (C, whatever). GHC is distributed under a BSD-style open source license. A wide variety of Haskell related resources (tutorials, libraries, specifications, documentation, compilers, interpreters, references, contact information, links to research groups) are available from the Haskell home page (see below). On-line GHC-related resources ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Relevant URLs on the World-Wide Web: GHC home page http://www.haskell.org/ghc/ GHC developers' home page http://hackage.haskell.org/trac/ghc/ Haskell home page http://www.haskell.org/ Supported Platforms ~~~~~~~~~~~~~~~~~~~ The list of platforms we support, and the people responsible for them, is here: http://hackage.haskell.org/trac/ghc/wiki/Contributors Ports to other platforms are possible with varying degrees of difficulty. The Building Guide describes how to go about porting to a new platform: http://www.haskell.org/ghc/docs/latest/html/building/building-guide.html Developers ~~~~~~~~~~ We welcome new contributors. Instructions on accessing our source code repository, and getting started with hacking on GHC, are available from the GHC's developer's site run by Trac: http://hackage.haskell.org/trac/ghc/ Mailing lists ~~~~~~~~~~~~~ We run mailing lists for GHC users and bug reports; to subscribe, use the web interfaces at http://www.haskell.org/mailman/listinfo/glasgow-haskell-users http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs There are several other haskell and ghc-related mailing lists on www.haskell.org; for the full list, see http://www.haskell.org/mailman/listinfo/ GHC developers occasionally hang out on #haskell on IRC, too: http://www.haskell.org/haskellwiki/IRC_channel Please report bugs using our bug tracking system. Instructions on reporting bugs can be found here: http://www.haskell.org/ghc/reportabug

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Haskell Reflection
by Oleg Mürk 18 Apr '06

18 Apr '06

Hello, I want to do the following wierd things with arbitrary Haskell program: * Have an IO callback each time a closure is forced * Dynamically load small Haskell expressions that will be executed in the callback * Have access to the syntactic scope of closure being forced in the dynamically loaded expressions * Navigate data graph a'la Java reflection * Test if given closure has been forced I see two ways of doing this: 1) Some Haskell implementation having super-reflective capabilities 2) Doing Haskell program transformation before running it (1) seems doubtful, but I would be more than happy if someone proved me wrong :) As for (2), I would kindly ask the readers of this list for suggestions: * Which program tranformation tool to use. I need to compute syntactic scope of the closures. And I need to know exact line and row numbers of syntactic constructions. Knowing types of expressions of the program being transformed doesn't hurt either. * Most of the features described above are straightforward to implement, but if some of these have been implemented before I would be more than happy to reuse them. In any case I would still need to load dynamically small Haskell expressions. What is the best way to do it? Disclaimer: I am not planning to do application programming using these techniques :) With kind regards, Oleg Mürk

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lhs2TeX-friendly emacs mode?
by Conal Elliott 18 Apr '06

18 Apr '06

Is there a Haskell emacs mode that works well with lhs2TeX? Specifically (a) treating \begin{spec} ... \end{spec} like \begin{code}... \end{code}, and (b) coloring inline code ("|<expr>|)" and maybe inline verbatim ("@<expr>@") as Haskell rather than LaTeX code. - Conal

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6.2.1 for glibc-2.4
by Paul A. Steckler 17 Apr '06

17 Apr '06

[Apologies for the cross-post from Haskell Cafe, but I got no responses there.] I need a Linux ghc 6.2.1 built with glibc-2.4. The existing 6.2.1 RPM, built with glibc-2.3, works mostly OK, but with some programs, the generated executables barf and die on startup. Any suggestions on how to create such a beast? I've tried using ghc 6.4.1, for which there's a Fedora 5 RPM, to build 6.2.1 from source, but all sorts of compile errors occur. On a Linux with glibc-2.3 installed, is there a way to have the ghc build use a different glibc? -- Paul -- Paul Steckler, PhD Tel: +1 503.626.6616 x156 Galois Connections, Inc. Fax: +1 503.350.0833 12725 SW Millikan Way, Beaverton, OR 97005 Email: steck at galois.com

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