- Haskell - Haskell.org

RE: Haskell98 undefinedness
by Simon Peyton-Jones 13 Sep '01

13 Sep '01

Personally I think this is ok, and it's compatible with the relaxed story about cumulative imports. I don't propose to change this unless there are yells. | So, it's not considered an error if you do something | like | | module A ( B(C), ...some other stuff..., B(D) ) where | ... | data B = C | D | | but C and D is exported. Is the extra flexibility of | allowing duplicates really worth it? Simon

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RE: Application letters at the Haskell workshop: suggestion
by brk＠jenkon.com 13 Sep '01

13 Sep '01

This is an area of grave concern for me. I am still quite new to Haskell, so perhaps I should wait until others have spoken, but I'll go ahead anyway. I certainly don't mean to offend anyone, so please bear with me. Speaking as an 'industrial' programmer who gave a 30-minute application presentation at the International Python Conference earlier this year, I have to say that I wouldn't even think of submitting a paper to a Haskell workshop. Why? Because the feel of Haskell in general and Haskell conferences in particular is relentlessly academic, and I doubt I'd have anything to say that would be appreciated in such a context. *This does not mean* that I'm dismissing Haskell as "only" an academic exercise, quite the contrary. I think Haskell is a beautiful language in many ways, and a useful one. It is sometimes difficult for me to formulate problems in a purely functional way as opposed to a mixed style like Ocaml or Dylan, but in general once I've succeeded in doing so I find the program that I've written more elegant than the program I would have written in another language. I think I speak for the majority of 'industrial' programmers when I say Haskell is a very difficult language to approach. I believe a great deal of this difficulty stems from lack of documentation. It is common practice in the Haskell community to write some code, write a paper, and consider one's work done. While this is entirely reasonable for research projects, it is not reasonable to later wonder why more people aren't making use of that library. This applies not only to libraries, but also to experimental language features. If anyone needs examples, I've plenty to provide, but I'll not include them here because I don't want anyone to think I'm "blaming" them for this situation. This approach is entirely suitable for the majority of Haskell users today, who seem to me to be very bright people, mostly in academia, though there seem to be a few compiler writers and so on. However, it won't do if people want Haskell to have broader acceptance. Haskell concepts can be difficult for imperative programmers to grasp at first, but the larger issue is that people have to work *hard* to find the information they need. People without a deep and abiding interest in programming languages and their design (such as myself) will not go through the trouble to become familiar with lambda calculus, denotational semantics, and category theory just to learn a language they're not likely to get paid for anytime soon. But remember, the primary documentation of Haskell is currently research papers, which are largely composed of the aforementioned mathematics. The lack of *coherent* documentation describing everything you need to know to write a significant application in Haskell is breathtaking. I have a stack of Haskell papers more than six inches thick at my house, and I do have a good book, but collectively they're less useful to a beginner in the language than, say O'Reilly's _Learning Python_, especially when followed up with _Programming Python_. I'm actually thinking about keeping notes about my learning process so that I could eventually write such a book for Haskell. So I think Haskell is unlikely (in its current state) to attract many people who would develop applications that would be interesting to the people who go to Haskell workshops. I for one would like to see that situation change. I would suggest (if you couldn't guess :-)) that improving documentation and making the documentation more accessible to people with less mathematical background would be excellent places to start. After that's taken care of, (IMHO) a standard (and *maintained*) cross-platform GUI, standard (and *maintained*) database access facilities, and strong Unicode support would more than pay for themselves in terms of increased interest in the language. As an aside, very few contributed packages will build on windows machines (or rely on antiquated versions of Hugs or something), which also doesn't help acceptance. Please take these comments in the spirit they're offered, I'm only trying to help Haskell achieve the status I think it deserves. Bryn > -----Original Message----- > From: S.J.Thompson(a)ukc.ac.uk [SMTP:S.J.Thompson@ukc.ac.uk] > Sent: Wednesday, September 12, 2001 2:04 AM > To: haskell(a)haskell.org > Subject: Application letters at the Haskell workshop: suggestion > > > A thought to dicscuss for next year's Haskell > workshop. This is the second year running that > there have been no submissions accepted in the > `application letters' category for the Haskell > workshop. It seems that this comes from the > fact that these are not getting the same grades > as submissions focussed on more theoretical aspects > of Haskell and functional programming. That's a shame, > since it means that information of value to many users > of the language are not going into the public record. > > A suggestion: why not have a poster session at the next > workshop? This is used at many conferences for shorter > papers, work in progress, implementation aspects and the like. > The advantage of this over ten minute, ad hoc, talks is that > the posters (or poster abstracts) form part of the formal > proceedings and are thus available to the community for > reference. This is, of course, particularly valuable in the > case of applications, when it's useful to find out what one can > re-use, as well as seeing what might be problematic about > existing tools and libraries. > > How would a poster session work? People submit abstracts, > and then bring posters (plus laptops for demos etc. if they > wish) to the meeting. These are displayed over tea/coffee breaks, > or indeed a separate time could be devoted to them. > > I'd be interested to hear what others think; maybe there's a > better way of getting the application-oriented material into > the workshop? > > Simon Thompson > > > _______________________________________________ > Haskell mailing list > Haskell(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell

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RE: Haskell98 undefinedness
by Simon Peyton-Jones 12 Sep '01

12 Sep '01

Yes, it's the same as exporting just B(..) or B(C). I guess I should try to make this clearer. S | -----Original Message----- | From: Sigbjorn Finne [mailto:sof@galconn.com] | Sent: 11 September 2001 20:31 | To: haskell(a)haskell.org | Subject: Haskell98 undefinedness | | | What's the meaning of | | module A (B, B(..)) where { data B = C }; | | Is or isn't C exported? i.e., the H98 report is silent | about what it means to have entity duplicates in | an export list, possibly with different 'visibility' | modifiers. | | --sigbjorn | | | | _______________________________________________ | Haskell mailing list | Haskell(a)haskell.org http://www.haskell.org/mailman/listinfo/haskell |

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Tab "\t" character behaviour in (Win)Hugs/ghc
by Rijk-Jan van Haaften 12 Sep '01

12 Sep '01

Hello, Recently, Craig Delehanty discovered that there is a difference in behaviour of putStr "a\tb" between Hugs and WinHugs (see comp.lang.functional). Hugs interprets it as a alignment character: >putStr "a\tb" "a b" > (7 spaces) but in WinHugs, it is always the same as 8 spaces: >putStr "a\tb" "a b" > (8 spaces) What does the language definition say about this? What is the behaviour of ghc/ghci? Rijk-Jan

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Application letters at the Haskell workshop: suggestion
by S.J.Thompson＠ukc.ac.uk 12 Sep '01

12 Sep '01

A thought to dicscuss for next year's Haskell workshop. This is the second year running that there have been no submissions accepted in the `application letters' category for the Haskell workshop. It seems that this comes from the fact that these are not getting the same grades as submissions focussed on more theoretical aspects of Haskell and functional programming. That's a shame, since it means that information of value to many users of the language are not going into the public record. A suggestion: why not have a poster session at the next workshop? This is used at many conferences for shorter papers, work in progress, implementation aspects and the like. The advantage of this over ten minute, ad hoc, talks is that the posters (or poster abstracts) form part of the formal proceedings and are thus available to the community for reference. This is, of course, particularly valuable in the case of applications, when it's useful to find out what one can re-use, as well as seeing what might be problematic about existing tools and libraries. How would a poster session work? People submit abstracts, and then bring posters (plus laptops for demos etc. if they wish) to the meeting. These are displayed over tea/coffee breaks, or indeed a separate time could be devoted to them. I'd be interested to hear what others think; maybe there's a better way of getting the application-oriented material into the workshop? Simon Thompson

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Re: Haskell report (August release)
by Marcin 'Qrczak' Kowalczyk 12 Sep '01

12 Sep '01

Thu, 23 Aug 2001 10:00:35 -0700, Simon Peyton-Jones <simonpj(a)microsoft.com> pisze: > Please check it out. My plan is that if I hear nothing for a month, > I'll freeze it. Otherwise I'll iterate. I'll send some minor issues in September (much less than before it seems). Please wait... -- __("< Marcin Kowalczyk * qrczak(a)knm.org.pl http://qrczak.ids.net.pl/ \__/ ^^ SYGNATURA ZASTÊPCZA QRCZAK

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Re: The future of Haskell discussion
by Marcin 'Qrczak' Kowalczyk 12 Sep '01

12 Sep '01

Wed, 12 Sep 2001 11:00:38 +0100, Olaf Chitil <olaf(a)cs.york.ac.uk> pisze: > Mark Shields: Lightweight Modules for Haskell > Shortly stated that he is working on a new module system and would like > every interested person to join. I'm interested. How to join? -- __("< Marcin Kowalczyk * qrczak(a)knm.org.pl http://qrczak.ids.net.pl/ \__/ ^^ SYGNATURA ZASTÊPCZA QRCZAK

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Haskell98 undefinedness
by Sigbjorn Finne 11 Sep '01

11 Sep '01

What's the meaning of module A (B, B(..)) where { data B = C }; Is or isn't C exported? i.e., the H98 report is silent about what it means to have entity duplicates in an export list, possibly with different 'visibility' modifiers. --sigbjorn

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LOPSTR 2001 - Submission Deadline Extension
by Fabio Fioravanti 11 Sep '01

11 Sep '01

___________________________________________________________________________ Our apologies if you receive multiple copies. ___________________________________________________________________________ CALL FOR PAPERS LOPSTR 2001 11th International Workshop on Logic-based Program Synthesis and Transformation http://www.iasi.rm.cnr.it/~adp/lopstr01_cfp.html Paphos, Cyprus, November 28 - 30, 2001 The deadline for abstract submission has been extended to: *** September 24th, 2001. Invited Speaker: Natarajan Shankar, SRI, Menlo Park, CA, USA, "Generating Efficient Code from Logic". The following is a non-exhaustive list of topics: specification analysis component-based software development synthesis optimization software architectures verification composition design patterns and frameworks transformation reuse specialization applications Any other information is available at: http://www.iasi.rm.cnr.it/~adp/lopstr01_cfp.html ============================================================================

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Re: H98: Ix class
by Marcin 'Qrczak' Kowalczyk 11 Sep '01

11 Sep '01

Tue, 11 Sep 2001 09:16:11 -0400, Jan-Willem Maessen <jmaessen(a)alum.mit.edu> pisze: > Just to clarify, do we still require identities (1) and (3) below > (pasted from the Library report and numbered)? That is, is range > obliged to yield its results in strict index order? [This rules out > Ix instances that do, e.g., blocked iteration unless the array itself > is also re-blocked. Reblocking the array itself is arguably a good > idea, but may not be what we expect...] > > 1) range (l,u) !! index (l,u) i == i -- when i is in range > 2) inRange (l,u) i == i `elem` range (l,u) > 3) map index (range (l,u)) == [0..rangeSize (l,u)] The current implementation of Array in ghc iterates relies on them. It iterates either over array elements in the stored order or over range, whichever is more convenient for efficient implementation of the particular operation. For example elems is described in Haskell 98 as [a!i | i <- indices a], but ghc just picks elements in the stored order without computing index values or bounds checking. -- __("< Marcin Kowalczyk * qrczak(a)knm.org.pl http://qrczak.ids.net.pl/ \__/ ^^ SYGNATURA ZASTÊPCZA QRCZAK

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