- Glasgow-haskell-users

RE: (strange) huge difference
by Simon Marlow 06 Nov '01

06 Nov '01

> I was surprised when the very simple following program, once > compiled with > GHC-4.08.1, generated a 28.8 Kb file, but when compiled with GHC-5.02 > generated a 436 Kb file. Is this the GHC behavior to be expected? > > fac :: Int -> Int > fac n = product [1..n] > > main :: IO () > main = do > putStrLn "HELLO WORLD" > putStrLn (show (fac 5)) GHC 4.08.1 used shared libraries, which caused no end of problems so we reverted to static linking for 5.02. Cheers, Simon

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(strange) huge difference
by Andre W B Furtado 06 Nov '01

06 Nov '01

I was surprised when the very simple following program, once compiled with GHC-4.08.1, generated a 28.8 Kb file, but when compiled with GHC-5.02 generated a 436 Kb file. Is this the GHC behavior to be expected? fac :: Int -> Int fac n = product [1..n] main :: IO () main = do putStrLn "HELLO WORLD" putStrLn (show (fac 5)) -- Andre

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GHC version 5.02.1 is released
by Julian Seward (Intl Vendor) 05 Nov '01

05 Nov '01

GHC 5.02.1 is available. Currently the source, x86-linux and sparc-solaris tarballs are available. We hope to add binary builds for Win32 and Alpha early next week. -- J The (Interactive) Glasgow Haskell Compiler -- version 5.02.1 ============================================================== We are pleased to announce a new patchlevel release of the Glasgow Haskell Compiler (GHC), version 5.02.1. The source distribution is freely available via the World-Wide Web, under a BSD-style license. See below for download details. Pre-built packages for Linux, FreeBSD, Solaris and Win32 are also available. Haskell is a standard lazy functional programming language; the current language version is Haskell 98, agreed in December 1998. 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, C++, whatever). 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 at http://www.haskell.org/ GHC's Web page lives at http://www.haskell.org/ghc/ What's new in 5.02.1 ====================== Fixed various bugs, some of which caused GHCi to crash or misbehave. Some documentation fixes. Nothing major. What's new in 5.02 ==================== 5.02 incorporates many small refinements and bug fixes over the previous stable release (5.00.2). There are no major changes. - Much improved support for Windows platforms. Binary builds are now entirely freestanding. There's no need to install Cygwin or Mingwin to use it. It's a one-click-install-and-off-you-go story now. - Several small changes to bring GHC into line with the newest Haskell 98 report. - GHCi (the interactive system) now works on Windows. - Partial FFI support in GHCi. At the moment, foreign import (both static and dynamic) is supported on x86 and sparc platforms. - A compacting garbage collector, to try and reduce space use. - Experimental: partial support for hierarchical module names. - Experimental: following heroic hacking by Ken Shan, 5.02 now works on Alpha (Tru64 only). Many 64-bit bugs have been shaken out. At the moment only the batch-mode compiler works -- no GHCi or native code generator yet. We've found and fixed more bugs than you could possibly imagine. A big thank-you to all those who reported bugs in the 5.00.X series. We claim to have fixed almost all reported bugs. In general we've spent a large amount of effort trying to improve the stability of the system relative to 5.00.X. (Famous last words ...) For full details see the release notes: http://www.haskell.org/ghc/docs/5.02/set/release-5-02.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 InstallShield form for Windows folks. Everybody else gets a .tar.gz which can be installed where you want. Once you have the distribution, please follow the pointers in the README file to find all of the documentation about this release. 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 System requirements ===================== To compile programs with GHC, you need a machine with 64+MB memory, GNU C and perl. This release is known to work on the following platforms: * i386-unknown-{linux,freebsd,mingw32} * sparc-sun-solaris2 * alpha-dec-osf3 Ports to the following platforms should be relatively easy (for a wunderhacker), but haven't been tested due to lack of time/hardware: * hppa1.1-hp-hpux{9,10} * i386-unknown-solaris2 * mips-sgi-irix{5,6} * {rs6000,powerpc}-ibm-aix The builder's guide included in distribution gives a complete run-down of what ports work; an on-line version can be found at http://www.haskell.org/ghc/docs/5.02/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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RE: interpreter features
by Simon Peyton-Jones 04 Nov '01

04 Nov '01

| What about my idea? Can't there be a module, say called | *interpreter* which | you can add and remove definitions from on-the-fly? | Something that would put you tighter in the loop. Without | having to go back | to the editor edit stuff, reload from interpreter, choke on | error, see what | went wrong, etc. Just scratch some code on the CLI, see what | you've defined | so far, edit the current module, and evaluate what you want | to. So the CLI would have to have a way to show you what the current "interpreter" module was, and let you edit it. How does that differ from an editor? This smells like a tarpit to me: once you provide a basic editor, everyone will want more features. Better, surely, to use an existing editor? S

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SuSE 7.1 RPMs for ghc-5.02.1
by Ralf Hinze 03 Nov '01

03 Nov '01

You can find SuSE 7.1 RPMs for ghc-5.02.1 here http://www.informatik.uni-bonn.de/~ralf/ghc-5.02.1-1.i386.rpm http://www.informatik.uni-bonn.de/~ralf/ghc-prof-5.02.1-1.i386.rpm http://www.informatik.uni-bonn.de/~ralf/ghc-5.02.1-1.src.rpm Have fun, Ralf

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RE: Why is (monad) elegance so costly?
by Simon Peyton-Jones 03 Nov '01

03 Nov '01

| However, my experiments with a simplified lambda-calculus | example shows that (with GHC 5.00) the state monad is | dramatically less efficient than the simple identity monad: | | 4 TIMES SLOWER, and | 7 TIMES MORE MEMORY! | | Is this normal? Acceptable? Am I doing something wrong? I've just measured your program with GHC 5.02. The speed difference seems to be a factor of 2, not 4, though that is still not good. You can see what is going on if you give the flag -ddump-simpl to GHC, and then look for the function Main.eval. You'll see that eval has a shape like eval (Var x) = let ... in \env -> ... eval (Add u v) = let ... in \env -> ... This is bad, because eval is building a function closure for the \env, instead of taking its two arguments together as does simplEval. We'd prefer eval (Var x) env = let ... in ... eval (Add u v) env = let .. in ... Why doesn't GHC do this? Because doing so risks losing sharing. It's possible that you may say let v = eval term in do { v ; v ; v ; v } So you eval the term once, to get a state transformer, and then run that state transformer four times. If the 'env' arg is floated out, the work of the ".." in the above lets would be duplicated. Now *in this case* you aren't (ever) sharing a partial appliation of eval, and GHC could usefully spot this (but it doesn't at the moment). But if eval was exported, so GHC couldn't see all the applications of eval it could no longer do this trick. Maybe we could generate two versions. Another possibility would be to let the programmer give a pragma of some sort. Anyway I hope this helps explain where the costs come from. I'm interested in examples like this because it helps to know what analyses would be useful. Simon

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Student Programming Projects
by Barbara Nostrand 03 Nov '01

03 Nov '01

Hi. Next Semester, I am supposed to teach a short course in Haskell. Can anyone recommend interesting programming projects which can be completed in about a month? I posted this message a while ago and got a few suggestions that sounded like they would maintain student interest. Alas, my disk drive crashed soon thereafter. So if you have given me suggestions before, please do so again. I was particularly intrigued by the suggestions put forth by someone who complained that someone else's suggested projects were too theoretical. We need to try to capture the students' imaginations here and many of them prefer concrete thought to abstract thought. Again. Thank you very much. Barbara Nostrand -- +----------------------------------+----------------------------------+ | Dr. Barbara Nostrand | Department of Computer Science | | Assistant Professor | SUNY College at Potsdam | | Computer Science and Engineering | Potsdam, New York | | (315) 267-2216 | 13676 | +----------------------------------+----------------------------------+ | Ignored domains: bestbiz.net, pop.net, hotmail.com, aibusiness.com | | vdi.net, usa.net, tpnet.pl, myremarq.com | | netscape.net, excite.com, bigfoot.com, public.com | | com.tw, eranet.net, yahoo.com, success.net | | mailcity.com, net.tw, twac.com, netcenter.com | | techie.com, msn.com | +---------------------------------------------------------------------+

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Christmas Shopping and Theatre (optional) break in London from �38.75 pppn!
by Capital Worldwide 02 Nov '01

02 Nov '01

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RE: First class modules (was Existential Typing)
by Simon Peyton-Jones 01 Nov '01

01 Nov '01

| artificial restriction. I think extending the system with | some form of | subtyping between records would be important for a usable | system. Your | paper suggested that you are planning to do this. Any | thoughts on current | ideas in this direction? Yes, we should really say something about this in the paper. A key design choice in our system is to use *nominal* not *structural* typing. The structural choice makes perfect sense, but it leads to complications we don't have (as well as benefits). So we don't have structural subtyping, and it would not be easy to add it. On the other hand, one could add nominal subtyping without too much difficulty: record A = { x,y :: Int } record B <: A = { z :: Int } We have not done that yet, but Mark thinks it would could be done without bad interaction with what we have already. Simon

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RE: problem compiling
by Simon Marlow 01 Nov '01

01 Nov '01

> hello, I installed ok the rpm-packages on linux (Mandrake > 8.1), but when I > try to compile something the following message appears: > > f2.hs:1: > failed to load interface for `Prelude': > Bad interface file: ./Prelude.hi > does not exist > Action: openFile > Reason: No such file or directory > File: ./Prelude.hi > > If I go to the directory /usr/bin (where the binary file ghc > is) and I type > > ghc -c /home/user/file.hs > then the compilation is done without problems. > Does anyone know what I have to do for compiling without > problems in any > folder? > (The directory /usr/bin is my PATH). You probably have a file Prelude.hs in the current directory. The next release of GHC handles this case a little better, but to get going straight away you can just move Prelude.hs out of the way (and any other .hs files in the current directory which match the names of standard libraries). Cheers, Simon

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