- Haskell - Haskell.org

sweet bananas, lenses, and other miscellaneous brackets
by Vivian McPhail 25 Sep '05

25 Sep '05

Hi, Just as we can define infix operators as syntactic sugar, could we not also have a similar mechanism for programmable fancy brackets? There could be a keyword for the bracket declaration and a function definition, in this way ana- and catamorphisms, Template Haskell-like syntax, and set notation could become a regular feature of the language. I am more interested in the general idea than the syntax of this specific example: \begin{code} bracket (( _ )) :: a -> Ana a bracket (| _ |) :: a -> Cata a bracket [ _ | _ |] :: Char -> b -> Splice -- or whatever bracket {[ _ , .. ]} :: [a] -> SList a ((( _ ))) :: a -> Ana a (( x )) = Ana x ((| _ |)) :: a -> Cata a (| x |) = Cata x ([ _ | _ |]) :: Char -> b -> Splice [ c | t |] = case c of b -> doC t d -> doD t -- or whatever -- the idea of this bracket is to create a user-defined list-type structure -- {[ "the" , "lambda" , "calculus" ]} -- would have the value -- (SCons "the" (SCons "lambda" (SCons "calculus" SEmpty))) ({[ _ , .. ]} :: [a] -> SList a {[ [] ]} = sempty {[ x:xs ]} = scons x {[ xs ]} \end{code} Any thoughts? Vivian

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RE: [Haskell] Object-Orientation and Haskell
by Ralf Lammel 24 Sep '05

24 Sep '05

> Define a type A such that for any type B you can define > > up :: B -> A > down :: A -> Maybe B > > such that > > down . up = Just > > You can do this quite easily in Java or C++, mutatis mutandis. You can't > do this in Haskell, I don't think. You can't actually do this in > O'Haskell either, it seems the O' essentially amounts to syntactic sugar. You can't even do this in OCaml. However, in OOHaskell you can. >From the TOC of the OOHaskell paper http://homepages.cwi.nl/~ralf/OOHaskell/ 5.4 Casts based on dynamics 50 5.5 Casts based on unions 51 The second technique may add something to this discussion here. We use a sort of intersection-type encoding (also reminiscent of TICs). Thanks, Ralf

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Object-Orientation and Haskell
by Ashley Yakeley 24 Sep '05

24 Sep '05

Here's a simple test for object orientation (for some reasonable definition): Define a type A such that for any type B you can define up :: B -> A down :: A -> Maybe B such that down . up = Just You can do this quite easily in Java or C++, mutatis mutandis. You can't do this in Haskell, I don't think. You can't actually do this in O'Haskell either, it seems the O' essentially amounts to syntactic sugar. You can do a weaker form of this with Haskell's Dynamic, where you only have to deal with Bs that are instances of Typeable. But even with that, note that Dynamic/Typeable/TypeRep are a bit messy, with instances for Typeable defined for a wide range of known types. An alternative approach would be to identify your "B" within "A" not per-B but per-(up,down). This would allow for instance separate (up,down) for the same B such that down1 . up2 = Nothing down2 . up1 = Nothing Of course this can be done with Dynamic too, by defining dummy types. But it's ugly. A better extension is something like extensible data-types. This allows a type to be defined as "open", which can later be extended by disjoint union. Here's a sample syntax that achieves my OO test: module P where data A = .. module Q where import P A |= MkB B up = MkB down (MkB b) = Just b down _ = Nothing Actually, it is possible to define Dynamic in this way. Here's a naive attempt: data Dynamic = .. class Typeable' a where toDyn :: a -> Dynamic fromDynamic :: Dynamic -> Maybe a -- for each type... Dynamic |= MkBool Bool instance Typeable' Bool where toDyn = MkBool fromDynamic (MkBool b) = Just b fromDynamic _ = Nothing This attempt however doesn't allow easy creation of Typeable1, Typeable2 etc. A better way is to use type-constructor parameters: data Dynamic0 (f :: * -> *) = .. data Dynamic1 (g :: (* -> *) -> *) = .. type Dynamic = Dynamic0 Identity data Type a = MkType type TypeRep = Dynamic0 Type class Typeable0 a where toDyn0 :: f a -> Dynamic0 f fromDynamic0 :: Dynamic0 f -> Maybe (f a) class Typeable1 p where toDyn1 :: g p -> Dynamic1 g fromDynamic1 :: Dynamic1 g -> Maybe (g p) data Compose p q a = MkCompose (p (q a)) data Compose1 d0 f p = MkCompose1 (d0 (Compose f p)) Dynamic0 f |= MkDynamic1 (Dynamic1 (Compose1 Dynamic0 f)) unDynamic1 :: Dynamic0 f -> Maybe (Dynamic1 (Compose1 Dynamic0 f)) unDynamic1 (MkDynamic1 xx) = Just xx unDynamic1 _ = Nothing instance (Typeable1 p,Typeable0 a) => Typeable0 (p a) -- toDyn0 :: f (p a) -> Dynamic0 f toDyn0 = MkDynamic1 . toDyn1 . MkCompose1 . toDyn0 . MkCompose -- fromDynamic0 :: Dynamic0 f -> Maybe (f (p a)) fromDynamic0 dyn = do dcdf <- unDynamic1 dyn (MkCompose1 dcfp) <- fromDynamic1 dcdf (MkCompose fpa) <- fromDynamic0 dcfp return fpa -- for each type Dynamic0 f |= MkInt (f Int) instance Typeable0 Int where toDyn0 = MkInt fromDynamic0 (MkInt fi) = Just fi fromDynamic0 _ = Nothing Dynamic1 g |= MkMaybe (g Maybe) instance Typeable1 Maybe where toDyn1 = MkMaybe fromDynamic1 (MkMaybe gm) = Just gm fromDynamic1 _ = Nothing I submit that this is "hairy" rather than "ugly", but I suspect the Type-Constructors Of Unusual Kind (TCOUKs) get even hairier for Typeable2, Typeable3 etc... -- Ashley Yakeley, Seattle WA

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ANNOUNCE: GHC 6.4.1 binary package for Mac OS X
by Wolfgang Thaller 23 Sep '05

23 Sep '05

My GHC 6.4.1 packages for Mac OS X are finally ready. Mac OS X 10.3.9 (Panther) and 10.4.x (Tiger) ==== http://www.uni-graz.at/imawww/haskell/GHC-6.4.1.pkg.zip This is an installer package that will install a full version of GHC with GHCi, profiling, dynamic linking, double-clickable icons and HTML documentation on Mac OS X 10.3.9 or later. Darwin/PPC 8.x and Mac OS X 10.4 (Tiger) ==== http://www.uni-graz.at/imawww/haskell/ghc-6.4.1dyn-powerpc-apple- darwin.tar.bz2 This is a standard unix-style binary package with GHCi, profiling, dynamic linking and HTML docs. It requires Mac OS X 10.4 (Tiger) and libreadline.5.0.dylib. The readline library is expected to be installed in /usr/local/lib, but you can change those expectations using the following command: install_name_tool -change /usr/local/lib/libreadline.5.0.dylib /some/ new/path/libreadline.5.0.dylib ghc-6.4.1/lib/powerpc-apple-darwin/ ghc-6.4.1 Enjoy, Wolfgang

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*** ICFP '06 CALL FOR WORKSHOP PROPOSALS ***
by Matthias Blume 23 Sep '05

23 Sep '05

ICFP '06 CALL FOR WORKSHOP PROPOSALS The ICFP 2006 ACM SIGPLAN International Conference on Functional Programming will be held in Portland, Oregon from September 18 to September 20, 2006. Proposals for workshops are invited for consideration of ACM SIGPLAN sponsorship and affiliation with ICFP 2006. Affiliated workshops will be held on September 16 and 17 (as well as on September 21, if necessary). The purpose of these workshops is to provide a forum for presenting novel ideas in a less formal and possibly more focused way than at ICFP itself. They may also provide good opportunities for young researchers to present their work to, and to obtain feedback from, a specialized community. The format of each workshop is to be determined by its organizers, but it is expected that each workshop allows ample time for general discussion. The preference is for workshops which span only one day, but other schedules will also be considered. Researchers and practitioners are invited to submit workshop proposals to the ICFP 2006 Workshop Chairs, Matthias Blume and Patricia Johann, via e-mail (icfp06-workshops(a)cs.uchicago.edu) NO LATER THAN NOVEMBER 11, 2005. Submission may be made by e-mail (Postscript, PDF, or ASCII) with "ICFP06 Workshop Submission" in the subject header. Following ACM SIGPLAN's sponsorship procedures, proposals must include: 1. The name of the workshop. 2. A statement of goals for the workshop. 3. The names and addresses of the organizers. 4. The names of potential participants, such as program committee members. (It would be wise to inform your potential comittee members that they have been selected pending SIGPLAN approval.) 5. A description of plans for calls for participation (e.g., calls for papers). 6. The expected number of attendees and planned length of the workshop. 7. A description of plans for publicity. 8. An explanation of any plans for a published proceedings. 9. A description of past versions of the workshop, including dates, organizers, submission and acceptance counts, attendance, sites, registration fees and summary budget information. 10. The URL of the workshop web site. Note that should a proposal be accepted, a final report about the workshop, suitable for publication in SIGPLAN Notices, will be required. Notification of acceptance will be made by DECEMBER 15, 2005. Accepted workshops will be sponsored by SIGPLAN (see http://www.acm.org/sigplan/sigplan_workshop_proposal.htm for more information). A committee chaired by the ICFP 2006 Workshop Chairs and consisting of the ICFP Program and General Chairs and the SIGPLAN Executive Committee will evaluate all proposals. The workshop selection committee members are: * Matthias Blume, TTI-Chicago, Workshop co-Chair for ICFP 2006 * Patricia Johann, Rutgers University, Workshop co-Chair for ICFP 2006 * Julia Lawall, DIKU, Program Chair for ICFP 2006 * John Reppy, University of Chicago, General Chair for ICFP 2006 The maximum number of workshop proposals to be accepted is 6. Any further information needed for preparing a workshop proposal can be obtained by sending email to the workshop chairs (icfp06-workshops(a)cs.uchicago.edu) or consulting the ICFP 2006 web site at http://icfp06.cs.uchicago.edu/.

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RE: [Haskell] reflection/metadata in Haskell?
by Ralf Lammel 23 Sep '05

23 Sep '05

I would rather argue that: - Template Haskell approx. *compile-time* reflection - Scrap your boilerplate II (ICFP 2004) approx. *run-time* reflection - Generic Haskell is effectively a Haskell generator Ralf P.S.: Another way to get *compile-time* reflection in Haskell is of course type-level programming as pioneered by McBride and Hallgreen ... > -----Original Message----- > From: haskell-bounces(a)haskell.org [mailto:haskell-bounces@haskell.org] On > Behalf Of Mads Lindstrøm > Sent: Wednesday, September 21, 2005 11:40 AM > To: haskell(a)haskell.org > Subject: Re: [Haskell] reflection/metadata in Haskell? > ... > I do not know of any Java-like reflection capabilities in Haskell. > However, "Scrap Your Boilerplate" (search google) and Generic Haskell > can do a lot of the same stuff reflection can do in Java. Think of it as > compile-time reflection.

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ANNOUNCE: GHC version 6.4.1
by Simon Marlow 23 Sep '05

23 Sep '05

============================================================= The (Interactive) Glasgow Haskell Compiler -- version 6.4.1 ============================================================= 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, so we recommend upgrading. No library APIs have changed, so code that was working with 6.4 should continue to work with 6.4.1. Release notes are here: http://haskell.org/ghc/docs/6.4.1/html/users_guide/release-6-4-1.html How to get it ~~~~~~~~~~~~~ The easy way is to go to the WWW page, which should be self-explanatory: http://www.haskell.org/ghc/ We supply binary builds in the native package format for various flavours of Linux and BSD, and in Windows Installer (MSI) form for Windows folks. Binary builds for other platforms are available as a .tar.gz which can be installed wherever you want. The source distribution is also 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/ Haskell home page http://www.haskell.org/ comp.lang.functional FAQ http://www.cs.nott.ac.uk/~gmh/faq.html Supported Platforms ~~~~~~~~~~~~~~~~~~~ GHC supports the following platforms in this release: * x86 machines running Windows, common flavours of Linux, FreeBSD, OpenBSD, and NetBSD * x86_64 (aka amd64) machines running Linux * Macs running MacOS X * PowerPC machines running AIX or Linux * Sparc machines running Solaris. Ports to other platforms are possible with varying degrees of difficulty. The Building Guide gives a complete run-down of what ports work and how to go about porting to a new platform: http://www.haskell.org/ghc/docs/latest/html/building/building-guide.html 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/ Please report bugs using our SourceForge page at http://sourceforge.net/projects/ghc/ or send them to glasgow-haskell-bugs(a)haskell.org. GHC users hang out on glasgow-haskell-users(a)haskell.org. Bleeding edge CVS users party on cvs-ghc(a)haskell.org.

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Call for Participation (correction): International Conference on Automated Software Engineering 2005
by yunwen＠l3d.cs.colorado.edu 23 Sep '05

23 Sep '05

In the previous CfP(ASE05) I sent, I mixed the titles of keynotes by Dr. Swartout and Dr. Kemmerer. My deep apology to Dr. Swartout and Dr. Kemmerer, as well as to all of you who have to receive and (hopefully not) to delete this email twice. The correct CfP is as follows. --Yunwen Ye, publicity chair of ASE05 ----------------------------------------------------------- Call for Participation 20th IEEE/ACM International Conference on AUTOMATED SOFTWARE ENGINEERING (ASE 2005) November 7-11, 2005 Long Beach, California, USA http://www.ase-conference.org/ ========================================================== Early Registration Deadline: October 7, 2005 Regsitration website: http://www.isr.uci.edu/ase2005/ConferenceRegistration.html ========================================================== The IEEE/ACM International Conference on Automated Software Engineering brings together researchers and practitioners to share ideas on the foundations, techniques, tools, and applications of automated software engineering technology. ASE 2005 features three keynotes, a technical program, four half-day tutorials, four workshops, and a doctoral sympoisum. -------- Keynotes -------- The Power of Software Alfonso Fuggetta CEFRIEL - Politecnico di Milano Virtual Humans: Lessons Learned in Integrating a Large-Scale AI Project William Swartout Institute for Creative Technologies, Univ. of Southern California Designing and Implementing a Family of Intrusion Detection Systems Richard A. Kemmerer University of California, Santa Barbara ----------------- Technical Program ----------------- The technical program includes 28 long papers, 34 short papers, and 4 tool demonstrations on topics such as Validation and Verification, Maintenance and Evolution, Program Understanding, Testing, Code Generation, Configuration Management & Security, Aspect-Oriented Programming, and Software Visualization. --------- Tutorials --------- All four tutorilas are half-day. Bogor: An Extensible Software Model Checking Framework for Domain-Specific Model Checking Robby, Kansas State University, USA Matthew B. Dwyer, University of Nebraska-Lincoln, USA Matthew Hoosier, Kansas State University, USA Learning from Executions: Dynamic Analysis for Program Understanding and Software Engineering Michael Ernst, MIT, USA New Computational Methods for Complex System Construction Christopher Landauer, The Aerospace Corporation, USA Kirstie L. Bellman, The Aerospace Corporation, USA Software Component Models Kung-Kiu Lau, The University of Manchester, UK --------- Workshops --------- Workshop on Specification and Automated Processing of Security Requirements (SAPS '05) http://www.lcc.uma.es/SAPS/ Workshop on Software Security Assurance Tools, Techniques, and Metrics (SSATTM) http://samate.nist.gov/index.php/SSATTM 3rd International Workshop on Traceability in Emerging Forms of Software Engineering (TEFSE 05) http://re.cs.depaul.edu/TEFSE05/ Workshop on Software Certificate Management (SoftCeMent '05) http://ti.arc.nasa.gov/sc05/ ------------------ Doctoral Symposium ------------------ The symposium is closed to public. Only invited students and sympoisum committee will attend. ----------------------- Conference Organization ----------------------- General Chair David Redmiles, University of California, Irvine, USA Program Co-Chairs Tom Ellman, Vassar College, USA Andrea Zisman, City University London, UK Sponsored by IEEE CS, ACM SIGSOFT, ACM SIGART Supported by Institute for Software Research, University of California, Irvine, USA School of Informatics, City University London, UK Donald Bren School of ICS, University of California, Irvine, USA

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RE: [Haskell] cabal/haddock
by Simon Marlow 22 Sep '05

22 Sep '05

On 21 September 2005 10:22, Johannes Waldmann wrote: > What's the current story on cabal and haddock? > I need to run my sources through ghc -cpp > before giving them to haddock. Does cabal support this > (e. g. by directing the ghc -cpp output to dist/src )? Yes, it does. "runhaskell Setup.lhs haddock" will preprocess the Haskell code before running Haddock over it, which is quite convenient since Haddock doesn't know how to do any preprocessing itself. Cheers, Simon

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reflection/metadata in Haskell?
by Srinivas Nedunuri 21 Sep '05

21 Sep '05

I'm sure this question has been asked before, (but unf. the Haskell archives aren't searchable without downloading each month seperately), so I hope nobody minds me asking again. Is there any way to get metadata or reflection capabilities in Haskell? cheers

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