- Hat - Haskell.org

Re: [Hat] Program Compiles With GHC 6.6 but not Hat
by Tom Cooper 09 Dec '06

09 Dec '06

Olaf said: >This is caused by a limitation of Hat: Hat cannot handle defaulting of >numeric classes. <snip> >In real programs we have hardly ever come across uses of defaulting. > >Ciao, >Olaf Malcolm said: * Implementing type inference is difficult enough that we did not consider the effort worthwhile for the tiny benefit of being able to handle defaulting. Bernie said: a slightly inconvenient problem These assessments depend very much on your point of view. The only proper program I have tried to use hat on required rewriting to get hat to understand it. The program was only ~2k lines of code, and there were 3 different idiosyncrasies of hat which gave problems. The defaulting idiosyncrasy was one of them. I imagine that most people that try hat find it won't understand their code, and give up on it immediately. I am therefore skeptical that this is hardly ever a problem for people even if you 'hardly ever come across' it. I don't remember reading, when I downloaded hat, that it was a beta version, or that I would need to change my code in order for hat to work on it, let alone a systematic description of the changes I would have to make. This made it very difficult to understand the problems I was having, and used a lot of my time, and some other people's too. These three idiosyncrasies, if I recall correctly, required ~20 unwanted changes in my code, so I made a hat version of my code with these alterations, but it is very difficult to keep two parallel versions of a piece of code up to date with each other. For this reason, I didn't find it 'a slightly inconvenient problem'. The existence of a decent debugger/tracer makes a significant difference to the utility of a language; particularly, I think, a lazy language, because the cryptic evaluation order makes print statements in the code less informative. I recently gave a presentation about haskell at my work, and had to significantly tone-down the strength of my recommendation of it because I find haskell code so difficult to debug. At work we use windows (as I do at home), and despite Neil Mitchell's efforts, not enough of the hat tools have been converted to windows to make it worth using them. I didn't find the instructions for using hat via cygwin sufficient for someone with my low level of expertise. It is my personal belief that the lack of a powerful debugger/tracer that works 'straight out of the box', is the major constraint preventing the widespread adoption of haskell. I have no idea how difficult it would be to make hat work on all valid haskell98 code 'out of the box', on windows as well as unix, so I can't criticize anyone for the fact that it doesn't. However, I am strongly opposed the point of view that, for whatever reason, this doesn't really matter. Hat is free to use, and because of this, I feel I shouldn't be whining about problems with it. However, I feel that descriptions of Hat, for example in the communities and activities report, or on the hat website, should contain prominent and frank statements about its current limitations. I feel this is only fair to the readers who are otherwise likely to waste a significant amount of time on hat before they get disillusioned. Tom.

3 2

First Call for Papers: TFP 2007, New York
by TFP 2007 01 Dec '06

01 Dec '06

CALL FOR PAPERS Trends in Functional Programming 2007 New York, USA April 2-4, 2007 http://cs.shu.edu/tfp2007/ OR http://tltc.shu.edu/tfp2007/ 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. A formal post-symposium refereeing process then selects the best articles presented at the symposium for publication in a high-profile volume. TFP 2007 is co-hosted by Seton Hall University and The City College of New York (CCNY) and will be held in New York, USA, April 2-4, 2007 at the CCNY campus. 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 Articles leading-edge, previously unpublished research work Position Articles on what new trends should or should not be Project Articles descriptions of recently started new projects Evaluation Articles what lessons can be drawn from a finished project Overview Articles 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. Articles on the following subject areas are particularly welcomed: o Dependently Typed Functional Programming o Validation and Verification of Functional Programs o Debugging for Functional Languages o Functional Programming and Security o Functional Programming and Mobility o Functional Programming to Animate/Prototype/Implement Systems from Formal or Semi-Formal Specifications o Functional Languages for Telecommunications Applications o Functional Languages for Embedded Systems o Functional Programming Applied to Global Computing o Functional GRIDs o Functional Programming Ideas in Imperative or Object-Oriented Settings (and the converse) o Interoperability with Imperative Programming Languages o Novel Memory Management Techniques o Parallel/Concurrent Functional Languages o Program Transformation Techniques o Empirical Performance Studies o Abstract/Virtual Machines and Compilers for Functional Languages o New Implementation Strategies o 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 2007 program chair, Marco T. Morazan, at tfp2007(a)shu.edu. SUBMISSION AND DRAFT PROCEEDINGS Acceptance of articles for presentation at the symposium is based on the review of extended abstracts (6 to 10 pages in length) by the program committee. Accepted abstracts are to be completed to full papers before the symposium for publication in the draft proceedings and on-line. Further details can be found at the TFP 2007 website. POST-SYMPOSIUM REFEREEING AND PUBLICATION In addition to the draft symposium proceedings, we intend to continue the TFP tradition of publishing a high-quality subset of contributions in the Intellect series on Trends in Functional Programming. IMPORTANT DATES Abstract Submission: February 1, 2007 Notification of Acceptance: February 20, 2007 Registration Deadline: March 2, 2007 Camera Ready Full Paper Due: March 9, 2007 TFP Symposium: April 2-4, 2007 PROGRAMME COMMITTEE John Clements California Polytechnic State University, USA Marko van Eekelen Radboud Universiteit Nijmegen, The Netherlands Benjamin Goldberg New York University, USA Kevin Hammond University of St. Andrews, UK Patricia Johann Rutgers University, USA Hans-Wolfgang Loidl Ludwig-Maximilians Universität München, Germany Rita Loogen Philipps-Universität Marburg, Germany Greg Michaelson Heriot-Watt University, UK Marco T. Morazán (Chair) Seton Hall University, USA Henrik Nilsson University of Nottingham, UK Chris Okasaki United States Military Academy at West Point, USA Rex Page University of Oklahoma, USA Ricardo Pena Universidad Complutense de Madrid, Spain Benjamin C. Pierce University of Pennsylvania, USA John Reppy University of Chicago, USA Ulrik P. Schultz University of Southern Denmark, Denmark Clara Segura Universidad Complutense de Madrid, Spain Jocelyn Sérot Université Blaise Pascal, France Zhong Shao Yale University, USA Olin Shivers Georgia Institute of Technology, USA Phil Trinder Heriot-Watt University, UK David Walker Princeton University, USA ORGANIZATION Symposium Chair: Henrik Nilsson, University of Nottingham, UK Programme Chair: Marco T. Morazan, Seton Hall University, USA Treasurer: Greg Michaelson, Heriot-Watt University, UK Local Arrangements: Marco T. Morazan, Seton Hall University, USA ************************************************************************************ Dr. Marco T. Morazan TFP 2007 Program Committee Chair http://tltc.shu.edu/tfp2007/ http://cs.shu.edu/tfp2007/

1 0

Program Compiles With GHC 6.6 but not Hat
by Aditya Siram 19 Nov '06

19 Nov '06

The following program compiles and runs on GHC 6.6 but fails to compile with the '-hat' option to hmake. The error message is: **Begin Output** hat-trans HatTest.hs Wrote Hat/HatTest.hs ghc-6.6 -c -package hat -o Hat/HatTest.o Hat/HatTest.hs Hat/HatTest.hs:40:50: Ambiguous type variable `a' in the constraint: `Integral a' arising from use of `htakeodds' at Hat/HatTest.hs:40:50-58 Probable fix: add a type signature that fixes these type variable(s) **End Output** The program source is: import Prelude takeodds xs = [ x | x <- xs, (mod x 2) ==0] main = do { print (takeodds [1 ..7]); } Thanks... Deech _________________________________________________________________ Talk now to your Hotmail contacts with Windows Live Messenger. http://clk.atdmt.com/MSN/go/msnnkwme0020000001msn/direct/01/?href=http://ge…

6 8

Hat-Observe N+M Counter?
by Maik Barz 17 Nov '06

17 Nov '06

Hi, I am wondering if there's no more M+N Counter. In the documentation is an explanation that it shows the number of evaluated and nonevaluated functions when using :info. Is there an option to set this option? I am using hat 2.04 Maik -- Maik Barz Wilhelmplatz 4 - 24116 Kiel www.Barzille.de

3 2

Re: [Haskell-cafe] Newbie; Can't Install Hat From Source
by Malcolm Wallace 16 Nov '06

16 Nov '06

"Aditya Siram" <aditya_siram(a)hotmail.com> wrote: > I have been trying to install Hat for the last couple of days but GHC > does not recognize it as a package. I compiled 2.05 from source, but > at the 'make install' step I see this error message: > > Installing hat package for ghc under > /usr/local/lib/hat-2.05/ix86-Linux/ghc-606 > ghc-pkg: cannot find package hat <-----ERROR MESSAGE!!!!! This error message can be safely ignored - it comes from a requirement to support several different versions of ghc, each of which has a different interface to the package manager ghc-pkg. > ghc-pkg: package hat-2.4 is already installed > > /usr/local/lib/ghc-6.6/package.conf: > ... > /home/deech/.ghc/i386-linux-6.6/package.conf: > (hat-2.4) <----ERROR!!! > > For some reason it thinks that hat-2.4 is installed. This is one of a couple of bugs in the 2.05 package. The .cabal file simply had the wrong version number in it. > Bad interface file: > /usr/local/imports/hat-2.05/ghc-606/Hat/PreludeBasic.hi > Something is amiss; requested module hat-2.4:Hat.PreludeBasic > differs from name found in the interface file hat:Hat.PreludeBasic And this is the other bug: the Hat library package was built using "-package-name hat" instead of "-package-name hat-2.05" (as now required by ghc-6.6 and above). I have re-rolled the Hat-2.05 distribution package with these two very minor bugfixes. Please try downloading it again, and re-building. Regards, Malcolm

1 0

Fwd: [Haskell-cafe] Newbie; Can't Install Hat From Source
by Neil Mitchell 16 Nov '06

16 Nov '06

In case any Hat people miss this (pleaes cc Aditya) ---------- Forwarded message ---------- From: Aditya Siram <aditya_siram(a)hotmail.com> Date: Nov 16, 2006 2:00 AM Subject: [Haskell-cafe] Newbie; Can't Install Hat From Source To: haskell-cafe(a)haskell.org Hi all, I have been trying to install Hat for the last couple of days but GHC does not recognize it as a package. I compiled 2.05 from source, but at the 'make install' step I see this error message: **Begin Output** ./configure --install Configuring for hat... [ 2.05 ] Starting with earlier config in targets/ix86-Linux/config.cache [ config: ix86-Linux/ by deech@ubuntu on 15 Nov 2006 ] (but cmdline options have precedence) -------- Looking for already-installed Haskell compilers: Looking for ghc... found 6.6 Looking for nhc98... (not found) Looking for hmake... found 3.13 You said you want to use ghc to build hat. Done. -------- Configuration report for hat. You are going to build hat with: ghc Executables need .exe suffix? no (detected) Testing for the glib library: no (using slower replacement) Installation directories are now created/checked. Install directory root is: /usr/local Hat interface files (.hx) go into: /usr/local/include/hat-2.05 (exists) Array.hx ...... Debug/Trace.hx Installing hat as a ghc package: Installing hat package for ghc under /usr/local/lib/hat-2.05/ix86-Linux/ghc-606 ghc-pkg: cannot find package hat <-----ERROR MESSAGE!!!!! Reading package info from stdin ... done. ghc-pkg: package hat-2.4 is already installed Scripts go into: /usr/local/bin (exists) hat-graph hat-trans hat-tools: hat-stack hat-check hat-observe hat-detect hat-delta hat-view hat-trail hat-anim hat-explore hat-cover black-hat hat-nonterm pretty-hat Executables go into: /usr/local/lib/hat-2.05/ix86-Linux (exists) config hat-anim hat-check hat-cover hat-delta hat-detect hat-explore hat-nonterm hat-observe hat-stack hat-trail hat-trans hat-view black-hat pretty-hat Man pages go into: /usr/local/man/man1 (exists) hat-anim.1 hat-delta.1 hat-detect.1 hat-observe.1 hat-stack.1 hat-trail.1 hat-trans.1 pretty-hat.1 Not (re-)installing html documents Saving current configuration in targets/ix86-Linux/config.cache Done. Please ensure /usr/local/bin is in your PATH variable. **End Of Output** The output of 'ghc-pkg list' is: /usr/local/lib/ghc-6.6/package.conf: Cabal-1.1.6, HUnit-1.1, QuickCheck-1.0, base-2.0, cgi-2006.9.6, fgl-5.2, (ghc-6.6), haskell-src-1.0, haskell98-1.0, html-1.0, mtl-1.0, network-2.0, parsec-2.0, readline-1.0, regex-base-0.71, regex-compat-0.71, regex-posix-0.71, rts-1.0, stm-2.0, template-haskell-2.0, time-1.0, unix-1.0, xhtml-2006.9.13 /home/deech/.ghc/i386-linux-6.6/package.conf: (hat-2.4) <----ERROR!!! For some reason it thinks that hat-2.4 is installed. I tried to run a test program saved in HatTest.hs: import Prelude main = do { print "Hello"; } When I compile it with 'hmake -hat HatTest' I get the following error: hat-trans HatTest.hs Wrote Hat/HatTest.hs ghc-6.6 -c -package hat -o Hat/HatTest.o Hat/HatTest.hs Hat/HatTest.hs:3:0: Bad interface file: /usr/local/imports/hat-2.05/ghc-606/Hat/PreludeBasic.hi Something is amiss; requested module hat-2.4:Hat.PreludeBasic differs from name found in the interface file hat:Hat.PreludeBasic I'm not really sure how to proceed. Any help is appreciated. BTW I get the ghc-package: cannot find package hat when I 'apt-get install' it too. Thanks.. Deech _________________________________________________________________ View Athlete's Collections with Live Search http://sportmaps.live.com/index.html?source=hmemailtaglinenov06&FORM=MGAC01 _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe(a)haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

2 1

How does the FFI work?
by Thomas Davie 13 Nov '06

13 Nov '06

I'm having problems with the FFI and GHC 6.6. Namely, I edited one of the tools files (Detect.hs) that contains FFI imports, and now I end up with generalised death when I try to compile. The source compiles fine, but on linking I get: /usr/bin/ld: Undefined symbols: _anySuspect _extendParentSet _findMainUse _newParentSet _nextChild The C and H files are hanging around as they should be. Any ideas what's going on? Bob

2 1

Hat hasn't installed properly
by Thomas Davie 06 Nov '06

06 Nov '06

Something's up with hat-2.05 on my system. It hasn't installed its package correctly. ./configure, make, sudo make install reported no errors, but trying to build using 'hmake -hat' produces this error: hat-trans goodFib.hs Creating directories Hat Wrote Hat/goodFib.hs ghc -c -package hat -o Hat/goodFib.o Hat/goodFib.hs ghc-6.6: unknown package: hat Running ghc-pkg list reveals that no such package is installed: LappyBob:~/Documents/Work/Hat test cases/goodFib tatd2$ ghc-pkg list /usr/local/lib/ghc-6.6/package.conf: Cabal-1.1.6, GLUT-2.0, HGL-3.1, HUnit-1.1, OpenGL-2.1, QuickCheck-1.0, X11-1.1, base-2.0, cgi-2006.9.6, fgl-5.2, (ghc-6.6), haskell-src-1.0, haskell98-1.0, html-1.0, mtl-1.0, network-2.0, parsec-2.0, readline-1.0, regex-base-0.71, regex-compat-0.71, regex-posix-0.71, rts-1.0, stm-2.0, template-haskell-2.0, time-1.0, unix-1.0, xhtml-2006.9.13 Any ideas why the package isn't getting installed correctly? Bob

3 10

trying to get hat-make to swallow my code
by Tom Cooper 26 Oct '06

26 Oct '06

Hello, I've written a haskell program which is not behaving quite as I'd expect. Up till now, I've used Debug.Trace to understand it, but this has become a major pain, and I was hoping to use hat. When I run hat-make on the code, I get thousands of warnings followed by the following errors: ./Hat/EHM2Alt.hs:316:32: Not in scope: `Hat.Ix.grange' ./Hat/EHM2Alt.hs:331:29: Not in scope: `Hat.Ix.gindex' ./Hat/EHM2Alt.hs:342:29: Not in scope: `Hat.Ix.ginRange' Is this enough of a clue to track down what is happening? I'm not sure what other information would be relevant. I'm using GHC on Windows. One of my modules imports Ix, and several of them import Array. Any help would be greatly appreciated. Thanks. Tom.

2 2

2.05
by Thomas Davie 25 Oct '06

25 Oct '06

Malcolm, I'm trying to build hat with ghc 6.6 - I was under the impression that you'd updated it to be compatible, or am I missing something? At the moment I've modified the make files to get rid of the -package {base|lang|util} arguments, but I still get errors re PackedString (because it's been replaced with ByteString for non unicode, and String for unicode). Am I need of rolling back to 6.5, or is there a quick fix? Bob

4 4