- Glasgow-haskell-users

GHC version 5.02.2 is available
by Julian Seward (Intl Vendor) 12 Jan '02

12 Jan '02

The (Interactive) Glasgow Haskell Compiler -- version 5.02.2 ============================================================== We are pleased to announce a new patchlevel release of the Glasgow Haskell Compiler (GHC), version 5.02.2. 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, Alpha(OSF) and Win32 are also available, or will appear shortly. 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 5.02.2 ====================== Some important bugfixes: - fix for the long-standing "oversize heap-check" bug - networking library fixes: now works on Windows again - GHC's memory requirements should be improved over 5.02.1, especially when using --make. and many other minor fixes. 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/latest/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: State Transformer
by Albert Lai 12 Jan '02

12 Jan '02

> > testfunc = do > > r <- newSTRef ('x',0) > > foo r > > bar r > > (c,n) <- readSTRef r > > return n Jorge Adriano <jadrian(a)mat.uc.pt> writes: > Yeap, I could do it like this myself :) > The whole problem is with passing the 'r' as a parameter, which is precisly > what I'm trying to avoid. I agree with you. My work-around is then to define foo and bar locally to testfunc, in the scope of r: testfunc = do r <- newSTRef ('x',0) let foo = do (c,n) <- readSTRef r writeSTRef r ('a', n+1) bar = do (c,n) <- readSTRef r writeSTRef r (c,n+2) foo bar (c,n) <- readSTRef r return n But if this looks like unsatisfactory (it does to me, too), perhaps you have to go back to DIY monads. DIY monads are good when: you fix the state variables, you don't want to mention them in subprogram parameters. The ST monad is good when: you create more state variables on the fly, you use mutable arrays, you don't want to write your own monad and put/get commands.

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Re: State Transformer
by Ashley Yakeley 12 Jan '02

12 Jan '02

At 2002-01-11 06:18, Jorge Adriano wrote: >The whole problem is with passing the 'r' as a parameter, which is precisly >what I'm trying to avoid. You could always pass it implicitly (using -fglasgow-exts): -- testfunc = do r <- newSTRef ('x',0) (do foo bar with ?ref = r) (c,n) <- readSTRef r return n foo :: (Num a,?ref :: STRef s (Char,a)) => ST s () foo = do (c,n) <- readSTRef ?ref writeSTRef ?ref ('a', n+1) bar :: (Num a,?ref :: STRef s (t,a)) => ST s () bar = do (c,n) <- readSTRef ?ref writeSTRef ?ref (c,n+2) tryTestFunc = runST testfunc -- Curiously, GHC isn't smart enough to infer the types of foo and bar by itself. -- Ashley Yakeley, Seattle WA

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Re: State Transformer
by Jan-Willem Maessen 12 Jan '02

12 Jan '02

Theodore Norvell <theo(a)cs.ubc.ca> asks: > Jorge's question raised a question in my mind. The IOExts > module has many of the same features as the ST module, why > are there two ways to do the same thing? Is the ST module > only there for legacy purposes? The ST monad provides safer encapsulation of mutable references. We can prove that references which escape a particular instance of ST are never side effected. See the paper "Lazy Functional State Threads": http://www.cse.ogi.edu/~jl/Papers/stateThreads.ps This allows us to construct functions which are certain to present a functional face to the world, but use mutation internally. In this respect, ST is actually "better" than IO, albeit less well-supported. -Jan-Willem Maessen [Note that the above paper presents the version of ST contained in the LazyST library these days (if my memory serves me right). The arguments about encapsulation apply in either case.]

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Re: State Transformer
by Albert Lai 11 Jan '02

11 Jan '02

I will just translate your example from Norvell's DIY state monad to GHC's ST monad. As you noticed, GHC's ST monad begins with an "empty" state and you use some commands to add state variables as you go. This means the translation is not straightforward. I hope you still get the gist of it. Your hunch is correct: Norvell's applyST becomes GHC's runST. Your example uses two state variables: a Char and an Int, paired up as a tuple. Below, I use one state variable of type (Char,Int) for that, as hinted by your first attempt at the translation. foo and bar will each need to take a parameter --- the reference to the state variable, due to the reference business. testfunc = do r <- newSTRef ('x',0) foo r bar r (c,n) <- readSTRef r return n foo r = do (c,n) <- readSTRef r writeSTRef r ('a', n+1) bar r = do (c,n) <- readSTRef r writeSTRef r (c,n+2) tryTestFunc = runST testfunc

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Re: State Transformer
by Albert Lai 11 Jan '02

11 Jan '02

Theodore Norvell <theo(a)cs.ubc.ca> writes: > Jorge's question raised a question in my mind. The IOExts > module has many of the same features as the ST module, why > are there two ways to do the same thing? Is the ST module > only there for legacy purposes? My user view is that I appreciate the presence of both. When I write a pure function that can be implemented efficiently in imperative programming, I want the ST monad to support mutable variables. E.g., to implement "f n returns a list of all primes between 2 and n", I want to use a mutable array and hide it. When I write an I/O-bound routine that can be implemented conveniently with state variables, I want the IO monad to support mutable variables. Now my grief is that I cannot write a subprogram with state variables and have it reused in ST and IO. Fortunately I can write a subprogram with mutable arrays and have it reused in ST and IO, so I can write "sort a given array"; but I cannot write "increment a given integer variable". Of course, you can tell me to use mutable arrays of length 1 to simulate mutable variables. Fine!

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Re: FFI
by Ronald Legere 11 Jan '02

11 Jan '02

Mark, I have tried several of the available methods. Greencard works pretty well for most things, but these days I use straight ffi (with CForeign libs that come with ghc) and code it myself. It turned out to be a lot less difficult then I imagined to marshall simple structures and arrays back and forth. CHeers! > From: Mark Conway Wirt <mark(a)ArsConcero.org> > To: glasgow-haskell-users(a)haskell.org > Subject: FFI > __________________________________________________ Do You Yahoo!? Send FREE video emails in Yahoo! Mail! http://promo.yahoo.com/videomail/

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ghc-5.03 release candidate installer available (win32)
by Sigbjorn Finne 10 Jan '02

10 Jan '02

In preparation for a ghc-5.03 snapshot release, a test installer for Win32 platforms is now available: http://www.galois.com/~sof/ghc-503.msi (*) Size: 25.1 Mb. Please let me know if you run into any problems with it. thanks, --sigbjorn btw, Mike Thomas deserves a special mention for very helpful (and quick) feedback on the ghc-5.02.2 RC installer. Feedback that has been used to improve both the 5.02.2 and 5.03 installer setups. * - This installer relies on the Windows Installer runtime to operate. If, after having downloaded the above file, double-clicking on the MSI file doesn't start up the installer, the likely cause is that you don't have the runtime installed on your machine. Redistributables of the runtime can be downloaded from Microsoft: * http://www.microsoft.com/downloads/release.asp?releaseid=32831 (Windows 95,98 and ME version) * http://www.microsoft.com/downloads/release.asp?releaseid=32832 (Windows NT and 2000 version). Try installing the appropriate version before double-clicking again on the GHC installer.

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ghc-5.02.2 release candidate installer available (win32)
by Sigbjorn Finne 09 Jan '02

09 Jan '02

In preparation for the upcoming release of 5.02.2, I've made available a test installer for Win32 platforms, in the hope that any packaging glitches can be caught before it's too late. The installer is available via http://www.galois.com/~sof/ghc-502-2.msi (*) It's big: 21.7 Mb. Please let me know if you run into any problems with it (or not). thanks, --sigbjorn * - This installer relies on the Windows Installer runtime to operate. If, after having downloaded the above file, double-clicking on the MSI file doesn't start up the installer, the likely cause is that you don't have the runtime installed on your machine. Redistributables of the runtime can be downloaded from Microsoft: * http://www.microsoft.com/downloads/release.asp?releaseid=32831 (Windows 95,98 and ME version) * http://www.microsoft.com/downloads/release.asp?releaseid=32832 (Windows NT and 2000 version). Try installing the appropriate version before double-clicking again on the GHC installer.

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Re: GHC Poll: scope in GHCi
by cwitty＠newtonlabs.com 09 Jan '02

09 Jan '02

"Simon Marlow" <simonmar(a)microsoft.com> writes: > Ok, so in general a 'scope' can be constructed by combining: > > 1. the full top-level scope from zero or more *interpreted* modules > 2. the exports of zero or more modules (interpreted or compiled) > 3. any temporary bindings made on the command line I'd like to suggest one more thing that it would be nice to have in scope. I would like every loaded module to be imported "qualified" into the scope. (In fact, I would prefer if this were the default, although I suppose it might be useful to have a way to turn it off.) Carl Witty

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