- Glasgow-haskell-users

Top-level bindings for unlifted types
by Neil Mitchell 28 Nov '07

28 Nov '07

Hi, The following program: ------------------------------------------- {-# OPTIONS_GHC -fglasgow-exts #-} module Test() where import GHC.Base test = realWorld# ----------------------------------------- gives the error message: Top-level bindings for unlifted types aren't allowed: { test = realWorld# } Changing to test _ = realWorld# works fine. The question is why are these bindings disallowed? Reading the "Unboxed values as first class citizens" paper I can't see it listed as a restriction. Thanks Neil

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single-stepping and infinite recursion
by Wolfgang Jeltsch 27 Nov '07

27 Nov '07

Hello, please consider the following program: main = putChar 'A' >> main I load this into GHCi, enter :step main, followed by :step and a second :step. Although I would expect to get the As in the output step by step, GHCi now hangs inside the infinite loop. Is this intentional? To me, this seems rather weird. I wanted to use GHCi’s debugger to find the reason for an infinite recursion but from my experience it looks as if this might not be possible. :-( Best wishes, Wolfgang

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Profiling bugs in 6.8.1 and 6.6.1
by Daniel Fischer 26 Nov '07

26 Nov '07

Hello, first let me remark that 6.8.1 is really remarkable, compiles faster and produces faster executables than 6.6.1. However, I have a problem with profiling, the time is always reported as 0.00 secs: Sun Nov 25 22:58 2007 Time and Allocation Profiling Report (Final) p28Master +RTS -P -hb -sstderr -RTS MMDataA total time = 0.00 secs (0 ticks @ 20 ms) total alloc = 1,313,421,840 bytes (excludes profiling overheads) although it took more than 15 seconds: INIT time 0.00s ( 0.00s elapsed) MUT time 16.10s ( 16.41s elapsed) GC time 10.76s ( 11.16s elapsed) RP time 0.00s ( 0.00s elapsed) PROF time 0.00s ( 0.00s elapsed) EXIT time 0.00s ( 0.00s elapsed) Total time 26.86s ( 27.57s elapsed) Could that be caused by commenting out the lines ifeq "$(GhcThreaded)" "YES" SRC_HC_OPTS += -threaded endif in compiler/Makefile.ghcbin ? I did that because if I build ghc with -threaded, the times reported with :set +s in ghci are rubbish (I have a linux 2.4.20 kernel, and the threads don't support process-wide times; and no, I'm not likely to upgrade, SuSE 8.2 is the only OS that ever worked properly for me). If that's the cause, too bad, I'll have to revert to 6.4.2 for profiling :( In 6.6.1, -O2 and -prof -auto-all don't work together well, I have a programme where that combination of options results in an instant wrong output, while the combinations -prof -auto-all -O1 -prof -auto-all -O2 -prof lead to the correct output calculated in 10 to 13 seconds. If you're interested in that bug, I could send you the code, it's short enough. Thanks, Daniel

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docon soft announcement
by Serge D. Mechveliani 25 Nov '07

25 Nov '07

Software Announcement. The Algebraic Domain Constructor DoCon, Version 2.11 is available at http://www.botik.ru/pub/local/Mechveliani/docon/ (Russian site), ftp.botik.ru/pub/local/Mechveliani/docon/ (same site), http://www.haskell.org/docon/distrib/ (USA site) It works under ghc-6.8.1 and 6.6.1. The difference to the previous release of 2.10 is only a couple of minor bug fixes in installation. ----------------- Serge Mechveliani mechvel(a)botik.ru

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First Call for Papers TFP 2008, The Netherlands
by Peter Achten 23 Nov '07

23 Nov '07

CALL FOR PAPERS TRENDS IN FUNCTIONAL PROGRAMMING 2008 RADBOUD UNIVERSITY NIJMEGEN, THE NETHERLANDS MAY 26-28, 2008 INVITED SPEAKER: PROF. HENK BARENDREGT http://www.st.cs.ru.nl/AFP_TFP_2008/ The symposium on Trends in Functional Programming (TFP) is an international forum for researchers with interests in all aspects of functional programming languages, focusing on providing a broad view of current and future trends in Functional Programming. It aspires to be a lively environment for presenting the latest research results through acceptance by extended abstracts and full papers. A formal post-symposium refereeing process selects the best articles presented at the symposium for publication in a high-profile volume. TFP 2008 is hosted by the Radboud University Nijmegen, The Netherlands, and will be held in the rural setting of Center Parcs “Het Heijderbos”, Heijen (in the vicinity of Nijmegen), The Netherlands. TFP 2008 is co-located with the 6th Int’l. Summer School on Advanced Functional Programming (AFP’08), which is held immediately before TFP’08. SCOPE OF THE SYMPOSIUM The symposium recognizes that new trends may arise through various routes. As part of the Symposium's focus on trends we therefore identify the following five article categories. High-quality articles are solicited in any of these categories: Research: leading-edge, previously unpublished research. Position: on what new trends should or should not be. Project: descriptions of recently started new projects. Evaluation: what lessons can be drawn from a finished project. Overview: summarizing work with respect to a trendy subject. Articles must be original and not submitted for simultaneous publication to any other forum. They may consider any aspect of functional programming: theoretical, implementation-oriented, or more experience-oriented. Applications of functional programming techniques to other languages are also within the scope of the symposium. Contributions on the following subject areas are particularly welcomed: * Dependently Typed Functional Programming * Validation and Verification of Functional Programs * Debugging for Functional Languages * Functional Programming and Security * Functional Programming and Mobility * Functional Programming to Animate/Prototype/Implement Systems from Formal or Semi-Formal Specifications * Functional Languages for Telecommunications Applications * Functional Languages for Embedded Systems * Functional Programming Applied to Global Computing * Functional GRIDs * Functional Programming Ideas in Imperative or Object-Oriented Settings (and the converse) * Interoperability with Imperative Programming Languages * Novel Memory Management Techniques * Parallel/Concurrent Functional Languages * Program Transformation Techniques * Empirical Performance Studies * Abstract/Virtual Machines and Compilers for Functional Languages * New Implementation Strategies * Any new emerging trend in the functional programming area If you are in doubt on whether your article is within the scope of TFP, please contact the TFP 2008 program chairs, Peter Achten and Pieter Koopman, at afp_tfp_2008(a)cs.ru.nl. SUBMISSION AND DRAFT PROCEEDINGS Acceptance of articles for presentation at the symposium is based on the review of full papers (15 pages) and extended abstracts (3 pages) by the program committee. TFP encourages PhD students to submit papers. PhD students may request the program committee to provide extensive feedback on their full papers at the time of submission. Full papers describing work accepted for presentation must be completed before the symposium for publication in the draft proceedings and on-line. Further details can be found at the TFP 2008 website http://www.st.cs.ru.nl/AFP_TFP_2008/. POST-SYMPOSIUM REFEREEING AND PUBLICATION In addition to the draft symposium proceedings, we continue the TFP tradition of publishing a high-quality subset of contributions in the Intellect series on Trends in Functional Programming. IMPORTANT DATES (ALL 2008) Paper Submission: March 3 Notification of Acceptance: March 31 Early Registration Deadline: April 14 Late Registration Deadline: May 5 Camera Ready Symposium: May 5 TFP Symposium: May 26-28 Post Symposium Paper Submission: June 20 Notification of Acceptance: September 7 Camera Ready Revised Paper: September 21 PROGRAMME COMMITTEE Peter Achten (co-chair) Radboud Univ. Nijmegen, NL Andrew Butterfield Trinity College, IE Manuel Chakravarty Univ. of New South Wales, AU John Clements Cal Poly State Univ., USA Matthias Felleisen Northeastern Univ., USA Jurriaan Hage Utrecht Univ., NL Michael Hanus Christian-Albrechts Univ. zu Kiel, DE Ralf Hinze Univ. of Oxford, UK Graham Hutton Univ. of Nottingham, UK Johan Jeuring Utrecht Univ., NL Pieter Koopman (co-chair) Radboud Univ. Nijmegen, NL Shriram Krishnamurthi Brown Univ., USA Hans-Wolfgang Loidl Ludwig-Maximilians Univ.München, DE Rita Loogen Philipps-Univ. Marburg, DE Greg Michaelson Heriot-Watt Univ., UK Marco T. Morazán (symp. chair) Seton Hall Univ., USA Sven-Bodo Scholz Univ. of Hertfordshire, UK Ulrik Schultz Univ. of Southern Denmark, DK Clara Segura Univ. Complutense de Madrid, ES Olin Shivers Northeastern Univ., USA Phil Trinder Heriot-Watt Univ., UK Varmo Vene Univ. of Tartu, EE Viktória Zsók Eötvös Loránd Univ., HU ORGANIZATION Symposium Chair: Marco T. Morazán, Seton Hall University, USA Programme Chair: Peter Achten, Pieter Koopman, Radboud University Nijmegen, NL Treasurer: Greg Michaelson, Heriot-Watt University, UK

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You can now register a trac user for yourself
by Ian Lynagh 22 Nov '07

22 Nov '07

Hi all, It is now possible to register a new user account for yourself on the GHC trac. To do so, make sure you are logged out and then click the "register" link at the top-right, or go to this URL: http://hackage.haskell.org/trac/ghc/register Making your own account preferred over using the guest account, as it means we know who to contact if we have a query about a bug report you make, e.g. if we are unable to reproduce it. Thanks Ian

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Windows overlapped IO
by Felix Martini 22 Nov '07

22 Nov '07

I have made a prototype for overlapped IO that works with a modified version of Takano Akio's SSC library. I have been trying to add it to GHC's IO implementation but there are some issues. Instead of file descriptors windows handles are needed. The GHC handle implementation is currently based around fd's and many functions would need a separate windows API version. In some cases there is no simple conversion of existing functionality like the binary/text modes. An additional complication is that Haskell handles can be a lot of things other than files. Finally, a threaded rts is needed for the worker pool that processes the IO completions, so the current single threaded IO support must also remain. So for now i am focusing on testing and improving the prototype with a separate IO library. Best regards, Felix

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ghci changing 'm' to 'g'
by Greg Fitzgerald 22 Nov '07

22 Nov '07

Running 6.8.1 on Windows XP, typing 'main' while ":r" is still processing causes the 'm' in 'main' to morph to a 'g'. > :r [1 of 2] Compiling Language.QidlTypeLibrary.Parser ( Language/QidlTypeLibrary/Parser.hs, interpreted ) Ok, modules loaded: Main, Language.QidlTypeLibrary.Parser. > main <interactive>:1:0: Not in scope: `gain' Thanks, Greg

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[Fwd: Re: suggestion: add a .ehs file type]
by Richard Giraud 22 Nov '07

22 Nov '07

A pre-processor is a great idea. Template Haskell and Cabal make it possible to extend the language by adding all kinds of funky pre-processing (via Cabal hooks) and compile-time calculations. It wouldn't be too difficult to add a package-specific .ehs file type with the desired behavior. I'm currently using this combo to work around the TH limitation of not being able to generate import statements. A Cabal hook looks in a directory to find what .hs files are present, spits out an intermediate file that imports all of these files, and Cabal compiles the generated file into the final program. I think that the biggest limitation of this setup is managing the files if multiple stages of pre-processing are performed. Richard -------- Original Message -------- Subject: Re: suggestion: add a .ehs file type Date: Thu, 22 Nov 2007 10:19:57 +0000 From: Lennart Augustsson <lennart(a)augustsson.net> To: Simon Marlow <simonmarhaskell(a)gmail.com> CC: Alex Jacobson <alex(a)alexjacobson.com>, glasgow-haskell-users(a)haskell.org References: <47434E64.1070206(a)alexjacobson.com> <200711202239.57672.g9ks157k(a)acme.softbase.org> <474354D4.7010307(a)alexjacobson.com> <4743F6B4.9050505(a)gmail.com> <47447B2B.8090206(a)alexjacobson.com> <47454879.8040003(a)gmail.com> Or use a preprocessor that inserts a LANGUAGE pragma. :) On Nov 22, 2007 9:14 AM, Simon Marlow <simonmarhaskell(a)gmail.com <mailto:simonmarhaskell@gmail.com>> wrote: Alex Jacobson wrote: > In any case, I'm pretty sure the correct answer is not 50 language > pragmas with arbitrary spellings for various language features at the > top of each source file. You probably won't like any of these, but there are many ways to avoid writing out all the pragmas at the top of each file. 1. Use Cabal's extensions field. 2. Use CPP MyExtensions.h : {-# LANGUAGE TemplateHaskell, FlexibleInstances, OverlappingInstances, UndecidableInstances, CPP, ScopedTypeVariables, PatternSignatures, GADTs, PolymorphicComponents, FlexibleContexts, MultiParamTypeClasses, DeriveDataTypeable, PatternGuards #-} MyModule.hs: {-# LANGUAGE CPP #-} #include "MyExtensions.h" 3. Use a shell alias alias ghce='ghc -XTemplateHaskell -XFlexibleInstances ...' 4. use a script wrapper for GHC #!/bin/sh exec ghc -XTemplateHaskell -XFlexibleInstances ... $* I'm sure there are more... Cheers, Simon _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users(a)haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users

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if-them_else
by Serge D. Mechveliani 21 Nov '07

21 Nov '07

Dear GHC developers, when compiling the function f x = if x them False else True ghc-8.8.1 reports: " parse error on input `else' ". When there is a large expession after `them', it is sometimes difficult to locate a typo. Why does not it report " parsing if-then-else: cannot find `then' " ? Regards, ----------------- Serge Mechveliani mechvel(a)botik.ru

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