August 2001 - Haskell

Re: ANN: ports 0.3.3 "Autumn Sun"
by Marcin 'Qrczak' Kowalczyk 29 Aug '01

29 Aug '01

Wed, 29 Aug 2001 15:21:22 +1000, Manuel M. T. Chakravarty <chak(a)cse.unsw.edu.au> pisze: > Hmm, I had an application where I absolutely wanted to kill > it (ie, prevent it from surviving by registering a signal > handler). But I agree, in general you probably want a > sigTERM. So, I guess we need an additional argument here. I still think that it's enough to have sigTERM here (would be some other default method of killing on non-POSIX systems) *and* the ability to reach pids of processes for direct manipulation. -- __("< Marcin Kowalczyk * qrczak(a)knm.org.pl http://qrczak.ids.net.pl/ \__/ ^^ SYGNATURA ZASTÊPCZA QRCZAK

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Re: ANN: ports 0.3.3 "Autumn Sun"
by Marcin 'Qrczak' Kowalczyk 29 Aug '01

29 Aug '01

Tue, 28 Aug 2001 18:30:21 +1000, Manuel M. T. Chakravarty <chak(a)cse.unsw.edu.au> pisze: > It now has experiemental support for process management. IMHO processes should not be killed using killProcess (sigKILL). Better use softwareTermination (sigTERM). -- __("< Marcin Kowalczyk * qrczak(a)knm.org.pl http://qrczak.ids.net.pl/ \__/ ^^ SYGNATURA ZASTÊPCZA QRCZAK

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Re: ANN: C->Haskell 0.9.9 "Blue Ginger"
by Marcin 'Qrczak' Kowalczyk 29 Aug '01

29 Aug '01

Tue, 28 Aug 2001 00:39:13 +1000, Manuel M. T. Chakravarty <chak(a)cse.unsw.edu.au> pisze: > I am pleased to announce version 0.9.9 "Blue Ginger" of the > C interface generator C->Haskell. gtk+hs doesn't compile under ghc-5.01 because of "library" "function" pairs in foreign imports which are no longer supported. -- __("< Marcin Kowalczyk * qrczak(a)knm.org.pl http://qrczak.ids.net.pl/ \__/ ^^ SYGNATURA ZASTÊPCZA QRCZAK

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RE: Numeric literals: Haskell 98
by Simon Peyton-Jones 28 Aug '01

28 Aug '01

Mark Caroll points out that the Haskell 98 Numeric library should be able to read the numbers "Infinity" and "NaN", which can be printed by formatRealFloat. So I propose the following ammendment to the Numeric library: Page 16, Section 4, Numeric library. In the definition of readFloat, after "... (k,t) <- readExpr s]" add ++ [ (0/0, t) | ("NaN",t) <- lex r] ++ [ (1/0, t) | ("Infinity",t) <- lex r] However, the Haskell language report seems to say that it's optional for a Haskell implementation to actually support NaNs and Inifinity. I don't propose to change this, though it's a bit unsatisfactory because one can't rely on it. I'm proposing the above change to the Numeric library just for consistency: if 'show' can print "Infinitity" (and it can), then 'read' should be able to read it. Thanks, Mark. Simon | -----Original Message----- | From: Mark Carroll [mailto:mark@chaos.x-philes.com] | Sent: 27 August 2001 20:40 | To: haskell-cafe(a)haskell.org | Subject: Numeric literals | | | Today's other question has to do with numeric literals. How | do I write literals for interesting IEEE values, e.g. | | Prelude> x | Infinity | Prelude> :type x | Double | Prelude> (read "Infinity") :: Double | *** Exception: Ratio.%: zero denominator | Prelude> | | ...? | | If I'm just missing something obvious in the standard | documentation, please feel free to just give me a citation. | I've already tried sections 2.5 and 6.4.1 of the Haskell | Report, etc. though. | | Thanks. | | -- Mark | | | _______________________________________________ | Haskell-Cafe mailing list | Haskell-Cafe(a)haskell.org | http://www.haskell.org/mailman/listinfo/haskell-cafe |

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ANN: ports 0.3.3 "Autumn Sun"
by Manuel M. T. Chakravarty 28 Aug '01

28 Aug '01

There is a new version of the Haskell Ports Library available at http://www.cse.unsw.edu.au/~chak/haskell/ports/ It now has experiemental support for process management. You can create a process that gets its stdin from a lazy string and pumps its stdout and stderr into two ports. There are a couple of combinators that facilitate Unix-pipe-like behaviour and you can wait for the exit code of a subprocess in a single Haskell thread without blocking all the others. It's all quite a hackery and still pretty experimental, but as the subprocess management question did come up a couple of times recently, I thought I share what I have at the moment with the rest of you. Cheers, Manuel PS: This requires GHC as it relies on preemptive concurrency, exceptions, and the POSIX libs.

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ANN: C->Haskell 0.9.9 "Blue Ginger"
by Manuel M. T. Chakravarty 27 Aug '01

27 Aug '01

I am pleased to announce version 0.9.9 "Blue Ginger" of the C interface generator C->Haskell. Among bug fixes, the system includes the following features wrt to the previous release: * Sizeof hooks (to compute the size of C types in Haskell) * Local prefix for enum hooks * Pointer hooks (abstract pointers, foreign pointers, and stable pointer) * Support for parametrised pointers * Extended documentation including a description of all binding hooks * Deriving option for enum hooks * Adapted to GHC 5.0 This release greatly benefitted from code contributions by Armin Sander and Axel Simon. Moreover, a number of people have been very helpful in reporting and, in some cases, fixing bugs. Thanks guys! More information as well as source and binary packages are available from http://www.cse.unsw.edu.au/~chak/haskell/c2hs/ Happy Hacking! Manuel

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Aldor, Cayenne
by S.D.Mechveliani 27 Aug '01

27 Aug '01

Lennart Augustsson responded recently about Aldor and Cayenne systems and on the possibility of proofs in these languages. Aldor www page shows the following among other Projects: > Mathematical libraries > * Atypical > Authors: Simon Thompson, James Beaumont, John Shackell, Leonid > Timochouk > The aim of the project is to integrate into Aldor a capability > for reasoning. The logic is embedded into the types of Aldor by > means of a modified version of Aldor's dependent types. > [..] This looks similar to what was being developed with Cayenne. ----------------- Serge Mechveliani mechvel(a)botik.ru

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Re: 2 points about language
by Marcin 'Qrczak' Kowalczyk 24 Aug '01

24 Aug '01

Thu, 23 Aug 2001 15:02:28 +0400, S.D.Mechveliani <mechvel(a)math.botik.ru> pisze: > I wrote in the BAL paper that meaningful standard algebraic > categories (classes) may, in principle, help the compiler to > optimize programs using the properties related to the category > names (associativity, commutativity ...). How the compiler could take advantage of them? -- __("< Marcin Kowalczyk * qrczak(a)knm.org.pl http://qrczak.ids.net.pl/ \__/ ^^ SYGNATURA ZASTÊPCZA QRCZAK

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Re: 2 points on language. Continuing
by cwitty＠newtonlabs.com 24 Aug '01

24 Aug '01

"D. Tweed" <tweed(a)cs.bris.ac.uk> writes: > On a purely pragmatic note ( :-) ) these optimisations can't necessarily > be safely used in three of the four most common cases, namely Int, Float > and Double because of the restricted range of intermediates. While the programmer can't necessarily change ((p-q)+p) to (2*p-q) in the case of Int, the compiler usually can. The compiler can know that on the target machine, Int operations wrap on overflow in the typical way, in which case that's an entirely safe optimization. By the way, are there any Haskell systems where Int does not wrap on overflow? Carl Witty

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Aldor, Cayenne
by S.D.Mechveliani 24 Aug '01

24 Aug '01

To my >> (1) it is desirable to accommodate such features of Aldor language >> as types as values and dependent types Alastair David Reid <reid(a)cs.utah.edu> writes > You should take a look at Lennart Augustsson's Cayenne: > > http://www.cs.chalmers.se/~augustss/cayenne/index.html > > > In the fullness of time, it'd be useful to hear back from you: > > What parts of Cayenne (that Haskell lacks) are useful for your system? > Which parts are a problem? > Which parts are of no use for what you're trying to do? First, download Aldor. It says it is coming within several weeks, but it is also available (as commercial) from-within Axiom. And try to program in Aldor and in Cayenne the above example with Zmod(n), or similar, compute something for such domain, try other simple mathematical examples, and see, which programs _look more natural_ and which of them fail. Aldor has a large non-standard library - Axiom. Probably, this can be considered as certain guarantee for Aldor fitness. Cayenne has not such confirmation. After I reach Aldor, I could try to provide you with examples - if you ask of this. Year or two ago I dealt with Cayenne. Sent a couple of questions and notes. Then Cayenne people silenced. Probably, got tired to answer to silly newbie's questions (there were 3-4 letters). And I quitted, because was not able to work with this version of program. It behaved so, that I doubted whether it is going to grow into a needed tool. Regards, ----------------- Serge Mechveliani mechvel(a)botik.ru

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