November 2002 - Haskell

first stab at -ffunction-sections
by William Lee Irwin III 17 Nov '02

17 Nov '02

This could be an artifact of the -j64 (BTW, has anyone else noticed the makefiles can only keep 5 or 6 cpus busy at a time much of the time, and often less?). gcc -O -ffunction-sections -c Text/Regex/Posix_hsc.c -o Text/Regex/Posix_hsc.o Text/ParserCombinators/Parsec/Pos.hs:15: failed to load interface for `Prelude': Bad interface file: /mnt/h/tmp/ghc5-5.04/build-stage1/libraries/base/Prelude.hi does not exist Action: openFileEx Reason: No such file or directory File: /mnt/h/tmp/ghc5-5.04/build-stage1/libraries/base/Prelude.hi make[4]: *** [Text/ParserCombinators/Parsec/Pos.o] Error 1 make[4]: *** Waiting for unfinished jobs.... GHC/PrimopWrappers.hs:2: failed to load interface for `GHC.Base': Bad interface file: /mnt/h/tmp/ghc5-5.04/build-stage1/libraries/base/GHC/Base.hi does not exist Action: openFileEx Reason: No such file or directory File: /mnt/h/tmp/ghc5-5.04/build-stage1/libraries/base/GHC/Base.hi GHC/PrimopWrappers.hs:2: Failed to find interface decl for `GHC.Base.eqString' from module `GHC.Base' GHC/PrimopWrappers.hs:2: Failed to find interface decl for `GHC.Base.unpackCStringUtf8#' from module `GHC.Base' GHC/PrimopWrappers.hs:2: Failed to find interface decl for `GHC.Base.unpackFoldrCString#' from module `GHC.Base' GHC/PrimopWrappers.hs:2: Failed to find interface decl for `GHC.Base.unpackCString#' from module `GHC.Base' make[4]: *** [GHC/PrimopWrappers.o] Error 1 make[3]: *** [all] Error 1 make[3]: Leaving directory `/mnt/h/tmp/ghc5-5.04/build-stage1/libraries' make[2]: *** [all] Error 1 make[2]: Leaving directory `/mnt/h/tmp/ghc5-5.04/build-stage1' make[1]: *** [build-stage1] Error 2 make[1]: Leaving directory `/mnt/h/tmp/ghc5-5.04' make: *** [stamps/build-stamp] Error 2 debuild: fatal error at line 456: dpkg-buildpackage failed!

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RFC822 date strings vs. current practice
by William Lee Irwin III 17 Nov '02

17 Nov '02

These don't appear to actually show up as mailers commonly format them: e.g.: Cc: linux-kernel(a)vger.kernel.org, trivial(a)rustcorp.com.au From: Olaf Dietsche <olaf.dietsche%23list.linux-kernel(a)t-online.de> To: Chris Wedgwood <cw(a)f00f.org> Subject: Re: [PATCH] 2.5.47: strdup() Date: Sun, 17 Nov 2002 02:37:27 +0100 The implementation in Time.lhs appears to follow the RFC to the letter, which doesn't match current practice. The following appears to match current practice somewhat more closely: genDate = do t <- getClockTime c <- toCalendarTime t let gmtOff = ctTZ c `div` 36 let gmtSgn = gmtOff >= 0 let gmtAbs = abs gmtOff let hrStr = (if gmtOff < 0 then "-" else "+") ++ (if gmtAbs < 10 00 then "0" else "") ++ show gmtAbs return $ (formatCalendarTime defaultTimeLocale "%a, %_d %b %Y %H :%M:%S " c) ++ hrStr

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Running out of memory in a simple program
by Magnus Lindberg 15 Nov '02

15 Nov '02

{- Hi! I have a problem with monads. When a monadic function calls itself many times (see below) Hugs and GHCi runs out of memory/stack, and I can't see why. This is my program (well, I've kind of sipmlified it a lot :): -} newtype M a = M (Int -> (a,Int)) instance Monad M where return x = M $ \i -> (x,i) M f >>= k = M $ \i -> let (x,i2) = f i M f2 = k x in f2 i2 inc 0 = return () inc n = do inc'; inc (n-1) where inc' = M $ \i -> ((), i+1) runM :: M () -> IO () runM (M m) = print (m 0) -- in print i run n = runM (inc n) -- crashes for large n !! {- Shouldn't `run n' work for any n? But if I use n over 20 000 (or something) Hugs says "error: couldn't retreive enough memory when garabae-collecting" (or something), and other times Windows 2000 says "unknown software exception 0xc000000fd at 0x00040ec01". I tested to add "continuation passing style" (I don't really know what I should do) but that didn't work either. Does anyone have an idea of what the error is and what I should do / not do? Best regards, Magnus Lindberg -}

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Euro-Par 2003, Topic 10 (CfP)
by Ch. A. Herrmann 15 Nov '02

15 Nov '02

Dear Haskellers, many of you are using Haskell as a tool for developing parallel programs, are working on parallelizing Haskell compilers, language extensions, or interfaces. If you are involved in parallel programming, I'd strongly encourage you to submit a paper to Topic 10 of Euro-Par 2003. It'll be a good forum to present your work. Apologies if you receive multiple copies of this message. ----------------------------------------------------------------------- ****************************************************** *** *** *** CALL FOR PAPERS *** *** Submission Deadline: February 9, 2003 *** *** *** *** EURO-PAR 2003 Topic 10 *** *** Parallel Programming: Models, Methods and *** *** Programming Languages *** *** *** *** Klagenfurt, Austria *** *** August 26-29, 2003 *** *** *** *** http://europar-itec.uni-klu.ac.at/ *** *** *** ****************************************************** Description This topic provides a forum for the presentation of the latest research results and practical experience in the development of parallel programs. Advances in algorithmic and programming models, design methods, languages, and interfaces are needed to produce correct, portable parallel software with predictable performance on different parallel and distributed architectures. The topic emphasises results that improve the process of developing high-performance programs, including high-integrity programs that are scalable with both problem size and complexity. Of particular interest are novel techniques by which parallel software can be assembled from reusable parallel components without compromising efficiency. Related to this is the need for parallel software to adapt, both to available resources and to the problem being solved. Where appropriate, contributions should demonstrate quantitative performance results in support of their claims, and address applications not adequately handled by well-established approaches. Focus * Languages, libraries and interfaces for different parallel programming models (e.g. data-parallelism, task-parallelism, functional, object-oriented, logic, component-based etc.). * Implementation and optimisation techniques for innovative parallel languages and programming models (e.g. threads, dataflow, tiling, skeletons, declarative languages, and generalised data-parallel approaches, etc.). * Performance models and their integration into the design of efficient parallel algorithms and programs (e.g. BSP, LogP, CGM, N-half and their alternatives, cost calculi and static performance prediction, profile-driven approaches). * Parallel programming paradigms and tools, their comparison and integration (e.g. data-parallel vs. task-parallel, coordination programming, performance analysis and debugging). * Methodological aspects of developing, optimizing and validating parallel programs (formalisms, semantics, specification, design, transformations, verification, etc.). * Software engineering for parallel and distributed systems (design patterns, portability, robustness, standardization, etc.). * Systematic approaches and programming models to support effective program development in grid environments. * Domain-specific parallel libraries and languages (e.g. for simulation, irregular and unstructured meshes, computational geometry, etc.). ----------------------------------------------------------------------- KEY DATES November 8, 2002 First call for papers February 9, 2003 Final date for submissions May 1, 2003 Notification of acceptance July 15, 2003 Early registration deadline ----------------------------------------------------------------------- PC COMMITTEE Global Chair Prof. José C. Cunha New University of Lisbon, Portugal Email: jcc(a)di.fct.unl.pt Vice Chairs Dr. Marco Danelutto University of Pisa, Italy Email: marcod(a)di.unipi.it Prof. Peter H. Welch University of Kent, United Kingdom Email: P.H.Welch(a)ukc.ac.uk Local Chair Dr. Christoph Herrmann Universität Passau, Germany Email: herrmann(a)fmi.uni-passau.de ----------------------------------------------------------------------- SUBMISSION DETAILS Authors are requested to submit their papers by using our submission site http://europar-itec.uni-klu.ac.at/submission.html (please indicate TOPIC 10). The site will open not later than at the beginning of January 2003. All accepted papers will be available at the conference in the proceedings published by Springer-Verlag in the LNCS series. ----------------------------------------------------------------------- MISSION STATEMENT EURO-PAR Euro-Par is the annual series of international conferences dedicated to the promotion and advancement of all aspects of parallel and distributed computing. Euro-Par 2003 will represent 19 topics in the categories of hardware, software, algorithms and applications. The conference normally attracts more than 300 participants coming from universities, research centres and industry. ---------------------------------------------------------------------- We are looking forward to receiving your paper submissions. Best regards -- Dr. Christoph Herrmann Teaching and Research Assistant University of Passau, Germany http://www.fmi.uni-passau.de/~herrmann

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Re: Time library underspecified
by George Russell 15 Nov '02

15 Nov '02

The TimeExts library probably does most of what you want. I really ought to Haddockify the comments some time . . .

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Implementing forward refs in monadic assembler and interpreter
by Mike Gunter 15 Nov '02

15 Nov '02

I need to implement an assembler and interpreter for a simple instruction set. For example, this code \begin{code} compute112 = do { zero r1 ; zero r2 ; addi r2 3 -- loop three times ;topLoop <- label ; addi r1 4 ; addi r2 (-1) -- decrement loop counter ; brPositive r2 topLoop ; add r1 100 } \end{code} would result in register r1 having a value 112. Without forward branches, the implementation is reasonably straightforward. The assembler can use a Monad with state and writer capabilities. The interpreter can use a continuation monad to implement branches and a state monad for the machine state. However, forward branches make things harder. I'd like to be able to write something along the lines of: \begin{code} compute12 = mdo { zero r1 ; zero r2 ; addi r2 3 -- loop three times ;topLoop <- label ; addi r1 4 ; addi r2 (-1) -- decrement loop counter ; brPositive r2 topLoop ; mov r3 r1 ; addi r3 (-10) -- !!! Forward branch: ; brPositive r3 out -- if r1 > 10 don't add 100 ; add r1 100 ;out <- label } \end{code} but it's not clear to me how to implement it. I'd be willing to accept a somewhat less clean version (for instance, with more cumbersome forward references.) Any help would be greatly appreciated. thanks, mike

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ANNOUNCE: Chameleon version 02-11
by Martin Sulzmann 15 Nov '02

15 Nov '02

Chameleon is a Haskell-style language which provides a flexible overloading mechanism based on Constraint Handling Rules (CHRs). The latest version comes with a type debugger. Our approach handles Hindley/Milner types with Haskell style overloading (including advanced features such as functional dependencies etc.) For more details check out http://www.comp.nus.edu.sg/~sulzmann/chr/publications.html for papers describing Chameleon, http://www.comp.nus.edu.sg/~sulzmann/chameleon/ for the latest release including a number of examples. Cheers, Martin

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Time library underspecified
by Peter Thiemann 14 Nov '02

14 Nov '02

Did anyone try to use the standard Time library that comes with Haskell for a serious purpose? I wanted to, but came across the problem that the TimeDiff data type is underspecified. For example, what is the official way to convert a TimeDiff value into seconds? The problematic parts are: * how many days for one tdYear (365, 366) * how many days for one tdMonth (28,29,30,31) * how many seconds for one tdMin (given the presence of leap seconds)^(1) Actually, once the absolute reference of the TimeDiff is lost, then it is impossible to recover leap years and leap seconds, so TimeDiff better had to account for them somehow. I suppose, the best would be to just have diffClockTimes return the number of seconds as an Integer. Since Simon PJ has finished editing the library report, who's now in charge of keeping track of problems with it and perhaps writing a commentary in cases such as this? Cheers -Peter (1) for this one, there is reasonable consensus. for example the ISO 8601 standard (representation of dates and times) defines minute=60 seconds, hour=60 minutes, day=24 hours. However, this leads to the strange(?) situation that the difference between 1998-12-31T12:00:00 and 1999-01-01T12:00:00 is 1 day and one second. (There was a leap second on that night 1998 December 31 23h 59m 59s 1998 December 31 23h 59m 60s 1999 January 01 0h 0m 0s see http://tycho.usno.navy.mil/leap.html)

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Re: storing to a file
by Ferenc Wagner 14 Nov '02

14 Nov '02

Johan Steunenberg <johan.steunenberg(a)openknowledge.de> writes: > how to store a Double, or any non-char, to a file. I can give you a general advice: store it in ASCII format via show, unless you have *VERY* strong reasons against it. Yes, it results in bigger files (but you can compress them), and slower (what compression makes even worse) but you gain easy view/edit and compatibility. I couple of years ago I was very fond of binary formats... Feri.

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ANNOUNCE: rsa-haskell 1.0.0
by David Sankel 13 Nov '02

13 Nov '02

rsa-haskell 1.0.0 ================= This is an announcement for a version 1.0.0 of the rsa-haskell library/tools. Description: rsa-haskell is a haskell implementation of the RSA algorithm. It contains simple programs that are useful for encrypting/decrypting anything that can be piped from STDIN/STDOUT. rsa-haskell also has an easy-to-use rsa and number theory library. For more information and download: http://www.electronconsulting.com/rsa-haskell/ Please email comments, bugs, etc. to camio(a)yahoo.com. David J. Sankel __________________________________________________ Do you Yahoo!? U2 on LAUNCH - Exclusive greatest hits videos http://launch.yahoo.com/u2

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