February 2002 - Glasgow-haskell-users

RE: i368-pc-os2-emx port
by Simon Marlow 20 Feb '02

20 Feb '02

> > One thing I could try would be to see if I can get a version > of GHC to run > under ODIN (ODIN is a Win32 API implementation under OS/2). > Do you think > this would be helpful? Or would it lead me down the path of making an > OS/2 complier that produced Windows Executables (that would be bad). I don't know enough about ODIN to be able to usefully comment, apart from to say that extra layers of translation generally add extra layers of complication (we've had no end of trouble with cygwin/mingw on Win32), and in this case you'd be going through 2 layers (mingw + ODIN) which could well be more trouble than it's worth. On the other hand, you'd need something like mingw for OS/2 - does such a beast exist? Cheers, Simon

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Re: i368-pc-os2-emx port
by Albert Lai 20 Feb '02

20 Feb '02

"Simon Marlow" <simonmar(a)microsoft.com> writes: > On the other hand, you'd need something like mingw for OS/2 - does > such a beast exist? The substring "emx" refers to an OS/2 version of gcc and libraries that make OS/2 look really like Unix from the programmer's point of view. (It probably even pre-dates cygwin.) I have two encouraging stories to tell. First, for a school assignment, I wrote an OpenGL program on emx, then ported it to school's Solaris+Mesa ten minutes before the deadline --- where porting meant removing "#include <os2.h>". Second, I wrote a program that used tcpip sockets on Unix, then merely recompiled it on emx to use it on OS/2 as well.

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Re: Congrats to Mandrake
by Albert Lai 20 Feb '02

20 Feb '02

ketil(a)ii.uib.no (Ketil Z. Malde) writes: > I'm not sure what the point would be, if they are in the > distributions anyway? Isn't it better to install them by apt-get or > up2date or whatever? (In fact, I had almost thought manually > downloading packages a thing of the past, but then the IT department > insisted on Red Hat) If I, a developer, wrote a program, and some distributions included it (while others didn't), I would want to acknowledge and thank them in public. If I, a potential customer choosing among Linux distributions, liked to use a program, and I saw on the program home page that so-and-so distributions included the program, I would arrange my preference accordingly. If I, an absent-minded user, heard about some great program from my friends, and saw on the program home page which distributions included it, I might realize "Gosh, *my* distribution CD already has it!" and save some download and install effort. Remember, I am absent-minded, so I wouldn't know what's on my CD unless someone stick it on my face. :) I probably don't need hyperlinks; I just need to know if my distribution includes it or not.

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RE: Importing a reference to a non-function entity.
by Simon Marlow 20 Feb '02

20 Feb '02

> What is the politically correct way using the FFI and ghc5.03 > (which I have just managed to compile from > CVS) to import an externally defined object (not a function)? > I have a source file containing the line > > foreign label "default_options" defaultOptions :: CString.CString > > for which ghc5.03 complains about "Warning: foreign > declaration uses deprecated non-standard syntax", > but which works anyway. However in my attempt to be a good > little ghc user, I try instead > > foreign import "default_options" defaultOptions :: CString.CString > > (after deciphering with difficulty the Postscript version of > the FFI document on this screen) but > still get the deprecated warning. Then I try > > foreign import ccall "default_options" defaultOptions :: > CString.CString I believe you meant to say foreign import ccall "&default_options" defaultOptions :: CString.Cstring :-) (see the latest FFI addendum at http://www.cse.unsw.edu.au/~chak/haskell/ffi/) Cheers, Simon

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RE: Data constructors and pattern matching
by Simon Marlow 20 Feb '02

20 Feb '02

> It seems to me that it might be very useful for a module to export the > pattern matching operators for a datatype without exporting the > constructors. Suppose we have > > data A = X {a::Int, b::Float} > > And we want to maintain the invariant that b is a floating-point > representation of a. So normally we would have to use a completely > abstract datatype, and provide constructors and destructors. But in > this case, it would actually make sense to provide the > pattern-matching > operator X, but not the data constructor X. So I think it > would be good > to separate these in the module export syntax. What's wrong with module M (A, a, b) where { ... } ? Simon

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Re: Congrats to Mandrake
by Ashley Yakeley 20 Feb '02

20 Feb '02

At 2002-02-20 00:19, Ketil Z. Malde wrote: >I'm not sure what the point would be, if they are in the >distributions anyway? Actually for me I'm more interested in someone keeping up with the GHC versions with debs. I'm not so worried about where they put them. But actually I just noticed that 5.02.2 is in Debian sid. Thanks to Michael Weber for doing this... -- Ashley Yakeley, Seattle WA

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Re: Congrats to Mandrake
by Ashley Yakeley 20 Feb '02

20 Feb '02

At 2002-02-19 14:13, Duncan Coutts wrote: >So what I mean is, can we have links to more binaries than just Red Hat? >Debian, Mandrake, FreeBSD. (I know these's SuSE) Seconded. If someone would do a 5.02.2 deb, that would be very useful... -- Ashley Yakeley, Seattle WA

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Congrats to Mandrake
by Duncan Coutts 19 Feb '02

19 Feb '02

All, I think that Mandrake deserve thanks for (reasonably) consistently including both hugs and ghc in their Linux distro *as standard*. This could significantly help Haskell takeup amongst the unwashed masses. :-) There should probably be a link on the ghc download page to the mdk binaries. The hugs download page just links directly to the mdk rpmfind pages. http://rpmfind.net/linux/rpm2html/search.php?query=ghc&submit=Search+...&sy… http://rpmfind.net//linux/RPM/cooker/contrib/RPMS/ghc-5.02.2-2mdk.i586.html Duncan

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RE: Strictness information?
by Ashley Yakeley 19 Feb '02

19 Feb '02

At 2002-02-19 09:21, Simon Peyton-Jones wrote: >'V' means 'eValuates'. So your function is strict in both arguments. >It's intended to be internal compiler stuff which is while it's not >properly documented, I'm afraid. I'd quite like to see intelligible .hi files that look like Haskell, even if they are autogenerated... -- Ashley Yakeley, Seattle WA

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Data constructors and pattern matching
by David Feuer 19 Feb '02

19 Feb '02

It seems to me that it might be very useful for a module to export the pattern matching operators for a datatype without exporting the constructors. Suppose we have data A = X {a::Int, b::Float} And we want to maintain the invariant that b is a floating-point representation of a. So normally we would have to use a completely abstract datatype, and provide constructors and destructors. But in this case, it would actually make sense to provide the pattern-matching operator X, but not the data constructor X. So I think it would be good to separate these in the module export syntax. Note: You can get this with views, but it's more clunky that way. David Feuer

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