Re: [Haskell-cafe] Basic question....

- Ursprüngliche Nachricht - Von: rodrigo.bonifacio [EMAIL PROTECTED] Datum: Freitag, August 17, 2007 3:11 pm Betreff: [Haskell-cafe] Basic question Hi all. I want to create the following polymorphic type (EnvItem) that we can apply two functions (envKey and envValue). I tried

Re: [Haskell-cafe] Re: [Haskell] Announce: generating free theorems, online and offline

legibility. In general, there are some other corners where one could beneficially improve the amount of simplifications done. But my most important point was to get *correct* statements out of the tool. Overzealous simplification can easily compromise this aim (see above). Ciao, Janis. -- Dr. Janis

Re: [Haskell-cafe] Re: [Haskell] Announce: generating free theorems, online and offline

[EMAIL PROTECTED] wrote: G'day. Quoting Janis Voigtlaender [EMAIL PROTECTED]: Hmm, but I can easily define an instance of Eq that does not satisfy this invariant. And I want the generated free theorem to be true for any legal Haskell program. I would think that if x == y isn't the same

[Haskell-cafe] Class invariants/laws

be wrong. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

[Haskell-cafe] Class invariants/laws

be that it checks as well that we have implemented at *most* a minimal set of operations. Otherwise, we are back to the point where I can implement both (==) and (/=), and in a way that the supposed invariant is broken. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto

[Haskell-cafe] Re: [Haskell] ANNOUNCE: Lazy SmallCheck 0.1

. Suggestions, experiences and bug reports are welcome! Matthew. ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED

Re: [Haskell-cafe] Class invariants/laws

Ryan Ingram wrote: On 10/18/07, Janis Voigtlaender [EMAIL PROTECTED] wrote: Yes, but that's a problem of the Arrow library writer, not of GHC. The compiler will never check a RULE. I'm going to disagree a bit here; it's not the problem of the Arrow library writer at all, it's the problem

Re: [Haskell-cafe] Class invariants/laws

assumes any laws to hold for any type classes. If the programmer tricks the compiler by providing wrong RULES in source files, it's the programmers problem and fault. It's like using unsafePerformIO. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL

Re: [Haskell-cafe] Class invariants/laws

. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Why is this strict in its arguments?

@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell

Re: [Haskell-cafe] Implementation of the Floyd-Warshall algorithm

(embedded in Haskell) is very much like the above self-referential array idea. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http

Re: [Haskell-cafe] Memoizing longest-common-subsequence

, it would then be less straightforward to apply subsequent optimizations (like strictifying and unboxing), as the details of the implementation would be hidden inside their DSL. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED

Re: [Haskell-cafe] a bunch of newbie questions

, and are implemented in GHC, for example. They are just approximative, and cannot be exact by computability reasons. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell

Quantification in free theorems (Was: [Haskell-cafe] Exercise in point free-style)

here, not globally. That is not reflected in the other version above. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org

[Haskell-cafe] Re: Quantification in free theorems

general relational free theorem (prior to the specialization to functions), which is also supported in Sascha's system. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list

Re: [Haskell-cafe] Re: evaluate vs seq

, Guerrini, ...). Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Expressing seq

of http://wwwtcs.inf.tu-dresden.de/~voigt/seqFinal.pdf Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman

seq does not preclude parametricity (Re: [Haskell-cafe] IO is not a monad)

seq's supposed destruction of parametricity (as in all or nothing) as an argument in weighing this decision. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe

Re: seq does not preclude parametricity (Re: [Haskell-cafe] IO is not a monad)

Janis Voigtlaender wrote: Lennart Augustsson wrote: There is a good reason seq cannot be defined for functions in the pure lambda calculus... It doesn't belong there. :) How about the same argument for general recursion? As in: There is a good reason (typability) that fixpoint combinators

Re: seq does not preclude parametricity (Re: [Haskell-cafe] IO is not a monad)

Janis Voigtlaender wrote: Janis Voigtlaender wrote: Lennart Augustsson wrote: There is a good reason seq cannot be defined for functions in the pure lambda calculus... It doesn't belong there. :) How about the same argument for general recursion? As in: There is a good reason

Re: seq does not preclude parametricity (Re: [Haskell-cafe] IO is not a monad)

. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Who started 42, and when?

the reference to the Great Question of ... Everything). So unless Douglas Adams wrote some Haskell papers I am not aware of, the original question is still open ;-) Happy weekend... Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED

[Haskell-cafe] Re: [Haskell] Mailing List Archive: Search Broken?

prior to November 2007, and from 2008. Too bad... Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo

Re: [Haskell-cafe] Re: [Haskell] Mailing List Archive: Search Broken?

Calvin Smith wrote: On 02/14/2008 11:13 PM, Janis Voigtlaender wrote: Don Stewart wrote: voigt: I always use gmane, via: http://news.gmane.org/search.php?match=haskell The problem with this is that when searching through gmane, and selecting a single message with a hit, one gets only

Re: [Haskell-cafe] Re: [Haskell] Mailing List Archive: Search Broken?

apfelmus wrote: Janis Voigtlaender wrote: when searching through gmane, and selecting a single message with a hit, one gets only to see that message without its context thread. At least I could not find out a way to switch from the found message to the thread in which it occurred

Re: [Haskell-cafe] Unboxed arrays

suggests that nothing is happening ... -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Unboxed arrays

Andrew Coppin wrote: Janis Voigtlaender wrote: Google - http://research.microsoft.com/~simonpj/papers/ndp/ I don't think the above suggests that nothing is happening ... The latet thing on that page is dated over a year ago. Well, if you expect monthly updates... -- Dr. Janis

Re: [Haskell-cafe] How can I represent 4x4 map in haskell

/Homework_help -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] How can I represent 4x4 map in haskell

, of making this more generic, rather than inventing your own Quadruple. Probably they are overkill for your goal.) Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell

Re: [Haskell-cafe] Function Precedence

of putting g x in brackets. You can get the same behavior with f . g $ x if you mislike brackets. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http

Re: [Haskell-cafe] FW: Haskell

. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Re: FW: Haskell

apfelmus wrote: Janis Voigtlaender wrote: Loup Vaillant wrote: Thanks to some geniuses (could someone name them?), we have type classes and higher order types in Haskell (and even more). As far as names go: for type classes, of course Wadler, but also Blott and Kaes

Re: [Haskell-cafe] Re: FW: Haskell

Loup Vaillant wrote: By higher order types, I meant the type of runST (ST monad), or dpSwich (in yampa). I meant things like (forall a, a- b) - a - b That's then usually called higher-rank polymorphic types, just in case you need more keywords for literature search ;-) -- Dr. Janis

[Haskell-cafe] PhD or PostDoc opening in Dresden, Germany

with any further questions. Please also forward to potentially interested students. The closing date for applications is 15th May 2008. Best wishes, Janis Voigtlaender -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED

[Haskell-cafe] Call for Contributions - Haskell Communities and Activities Report, May 2008 edition

hours (provided we have your valid email address). Please modify that template, rather than using your own version of the old entry as a template. Don't worry about writing correct LaTeX, we will be able to handle your file. Please don't use HTML or even DOC. -- Dr. Janis Voigtlaender http

[Haskell-cafe] REMINDER: Haskell Communities and Activities Report

in plain text or LaTeX format. More information can be found in the original Call for Contributions at http://www.haskell.org/pipermail/haskell/2008-April/020378.html We look forward to receiving your contributions. Thanks a lot, Andres and Janis. -- Dr. Janis Voigtlaender http

Re: [Haskell-cafe] Short circuiting and the Maybe monad

= n = \a - f a = \b - g b = h you get only one: *Main foo' Nothing' match Nothing' For a way to obtain such improvements automatically, and without touching the code, you may want to look into http://wwwtcs.inf.tu-dresden.de/~voigt/mpc08.pdf Ciao, Janis. -- Dr. Janis Voigtlaender http

Re: [Haskell-cafe] Re: Control.Exception.evaluate - 'correct definition' not so correct

Ariel J. Birnbaum wrote: (considering undefined as equivalent to const undefined, which iirc was the definition of _|_ for function types). What am I missing? undefined /= const undefined in Haskell, due to seq. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto

Re: [Haskell-cafe] one-way monads

. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

[Haskell-cafe] ANNOUNCE: Haskell Communities and Activities Report (14th ed., May 2008)

their report, but maybe we can increase our coverage of all that is going on in the community. Feel free to circulate this announcement further in order to reach people who might otherwise not see it. Enjoy! Andres Loeh and Janis Voigtlaender hcar at haskell.org -- Dr. Janis Voigtlaender http

Re: [Haskell-cafe] automatically deriving Map and Filter on datatypes etc.

for theory of containers. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Lambda and closures in PHP -- could someone please comment?

at someone/something you have three pointing back at yourself. Well, at least not this finger... -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http

Re: [Haskell-cafe] Lambda and closures in PHP -- could someone please comment?

/listinfo/haskell-cafe -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Interesting feature

. Obviously, people on the Curry list will know more about the details... Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org

Re: [Haskell-cafe] data Color3 a = Color3 !a !a !a

-VertexSpec.html#v%3AColor3 !a !a !a http://cvs.haskell.org/Hugs/pages/libraries/OpenGL/Graphics-Rendering-OpenGL-GL-VertexSpec.html#t%3AColor3 In short, http://haskell.org/onlinereport/decls.html#strictness-flags -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED

Re: [Haskell-cafe] Associative Commutative Unification

to the book Term Rewriting and all That by Baader and Nipkow. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

[Haskell-cafe] Prime time for Haskell

It is really just a short discussion, but Haskell STM is featured in an article of this month's Communications of the ACM: http://doi.acm.org/10.1145/1364782.1364800 -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED

Re: [Haskell-cafe] Prime time for Haskell

Jon Harrop wrote: On Sunday 13 July 2008 10:00:49 Janis Voigtlaender wrote: It is really just a short discussion, but Haskell STM is featured in an article of this month's Communications of the ACM: http://doi.acm.org/10.1145/1364782.1364800 Is the article freely available anywhere

[Haskell-cafe] 2nd Call For Papers: APLAS 2009 (Korea, Dec 14-16, 2009)

=== CALL FOR PAPERS The Seventh Asian Symposium on Programming Languages and Systems (APLAS 2009) Seoul, December 14-16, 2009

[Haskell-cafe] Re: [Haskell] International Summer School on Advances in Programming Languages (precedes ICFP'09)

Note that potential participants in the below summer school should pre-register their interest *now*. The organizers need that information to go ahead with the planning. Matthew Fluet (ICFP Publicity Chair) wrote: International Summer School on Advances in Programming Languages

Re: [Haskell-cafe] conflicting variable definitions in pattern

? Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:vo...@tcs.inf.tu-dresden.de ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Bidirectional programming in Haskell

, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:vo...@tcs.inf.tu-dresden.de ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

[Haskell-cafe] ANNOUNCE: Haskell Communities and Activities Report (16th ed., May 2009)

our coverage of all that is going on in the community. Feel free to circulate this announcement further in order to reach people who might otherwise not see it. Enjoy! Janis Voigtlaender hcar at haskell.org -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:vo...@tcs.inf.tu

[Haskell-cafe] HaL4: Haskell-Meeting in Germany, 12th June 2009

Hi all, If you are anyway near Halle/Saale in June, be sure not to miss out on: http://iba-cg.de/hal4.html We have already close to 50 registered participants, so expect a very lively meeting. See you there? (Late registration still possible.) Ciao, Janis. -- Dr. Janis Voigtlaender http

Re: [Haskell-cafe] HaL4: Haskell-Meeting in Germany, 12th June 2009

Janis Voigtlaender wrote: Hi all, If you are anyway near Halle/Saale in June, be sure not to miss out on: I meant anywhere near, of course :-) And even if you are not anyway or anywhere near, you might still want to come just for the occasion :-) -- Dr. Janis Voigtlaender http

[Haskell-cafe] PEPM'10 - First Call for Papers

=== CALL FOR PAPERS ACM SIGPLAN 2010 Workshop on Partial Evaluation and Program Manipulation (PEPM'10) Madrid, January 18-19, 2010 (Affiliated with POPL'10)

Re: [Haskell-cafe] shadowing keywords like otherwise

like so: otherwise = True Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:vo...@tcs.inf.tu-dresden.de ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] shadowing keywords like otherwise

otherwise as a variable. But you do not use that variable in that branch. Hence the warning: Swish/HaskellRDF/SwishCommands.hs:304:12: Warning: Defined but not used: `otherwise' This has nothing to do with someone else shadowing the definition of otherwise. Ciao, Janis. -- Dr. Janis

Re: [Haskell-cafe] ANN: Hayoo! beta 0.4

decreased in some areas? I am pretty sure that a week ago or so I could use Hayoo to find sumP :: Num a = [:a:] - a from GHC.PArr. Now, that result does not turn up anymore. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:vo...@tcs.inf.tu-dresden.de

Re: [Haskell-cafe] Laziness enhances composability: an example

Bulat Ziganshin wrote: Hello Cristiano, Thursday, July 9, 2009, 4:55:09 PM, you wrote: the best known example is chessmate implementation in Wadler's why functional programming matter Aeh, ... Wadler's - Hughes' -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:vo

Re: [Haskell-cafe] Why is there no Zippable class? Would this work?

deriver for Zippable instances, so you don't have to write the above instance definition yourself. The implementation is by Joachim Breitner. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:vo...@tcs.inf.tu-dresden.de

[Haskell-cafe] PEPM'10 - Call for Papers (Deadline: 6 Oct 09) - Invited Speakers announced

=== CALL FOR PAPERS ACM SIGPLAN 2010 Workshop on Partial Evaluation and Program Manipulation (PEPM'10) Madrid, January 18-19, 2010 (Affiliated with POPL'10)

Re: [Haskell-cafe] Trouble with non-exhaustive patterns

with this. BTW, you might want to have this kind of discussion at [EMAIL PROTECTED] instead. See the announcement: http://thread.gmane.org/gmane.comp.lang.haskell.general/16345 Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED

Re: [Haskell-cafe] Optimizing 'sequence'

Don Stewart wrote: If you can demonstrate the required laziness/strictness properties are identical, looks like a nice idea. I think they are not identical, as something along Antoine's second example demonstrates. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto

Re: [Haskell-cafe] Re: Optimizing 'sequence'

/704350.html)? -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Re: Optimizing 'sequence'

or not your = is lazy. For then proving that hypothesis, the paper (and probably other papers it cites) also provides some techniques that might be of use to you. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED

Re: [Haskell-cafe] Online Real World Haskell, problem with Sqlite3 chapters

-- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Haskell and Java

Bulat Ziganshin wrote: Is there a a Haskell to Java compiler that's already ready to use? CAL Just in case this answer was a bit cryptic for the original poster... What Bulat means is the following: http://labs.businessobjects.com/cal/ -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu

[Haskell-cafe] piping to system call

, and then calling system (cmd ++ temp) Of course, without actually creating that temporary file and having to clean it up afterwards. Does such a system' exist? Thanks, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED

Re: [Haskell-cafe] piping to system call

Marc Weber wrote: On Tue, Sep 23, 2008 at 01:37:56PM +0200, Janis Voigtlaender wrote: Hi, assume I have a program taking input from stdin. How do I call it from Haskell while feeding to it a string as input. Sure, have a look at http://hackage.haskell.org/packages/archive/process/1.0.0.0

Re: [Haskell-cafe] piping to system call

Jules Bean wrote: Marc Weber wrote: On Tue, Sep 23, 2008 at 01:37:56PM +0200, Janis Voigtlaender wrote: Hi, assume I have a program taking input from stdin. How do I call it from Haskell while feeding to it a string as input. Sure, have a look at http://hackage.haskell.org/packages

Re: [Haskell-cafe] Hmm, what license to use?

Manlio Perillo wrote: When I compare GPL and MIT/BSD licenses, I do a simple reasoning. Suppose a doctor in a battle field meet a badly injuried enemy. Should he help the enemy? I'm so glad I don't understand this ;-) -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto

Re: [Haskell-cafe] Hmm, what license to use?

Thomas Davie wrote: On 26 Sep 2008, at 12:12, Janis Voigtlaender wrote: Manlio Perillo wrote: When I compare GPL and MIT/BSD licenses, I do a simple reasoning. Suppose a doctor in a battle field meet a badly injuried enemy. Should he help the enemy? I'm so glad I don't understand

[Haskell-cafe] Call for Contributions - Haskell Communities and Activities Report, November 2008 edition

, but it might be dropped if it is older than a year, to give more room and more attention to projects that change a lot. Do not resend complete entries if you have not changed them. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED

[Haskell-cafe] Haskell on mobile platforms

/gmane.comp.lang.haskell.cafe/45967 Thanks, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] What I wish someone had told me...

attitude. Such people need to stop acting like five year old children. Not that it has much to do with the debate, but the attitude you complain about is the exact opposite of the attitude of any five year old children that *I* know (well, my son primarily ;-). -- Dr. Janis Voigtlaender http

Re: [Haskell-cafe] List as input

: main *** Outstanding context : (Read b, Show b, Ord b) The compiler doesn't know what kind of list you are trying to read, sort, and print. Try something like: (l::[Int]) - readLn in the penultimate line. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto

Re: [Haskell-cafe] What is this function?

- scramble x part. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

[Haskell-cafe] REMINDER: Haskell Communities and Activities Report

format. More information can be found in the original Call for Contributions at: http://www.haskell.org/pipermail/haskell/2008-October/020651.html I look forward to receiving your contributions. Thanks a lot, Janis (current editor) -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de

Re: [Haskell-cafe] Why 'round' does not just round numbers ?

) - 0.5 - (round to integer) - 1 but 0.45 - (round to integer) - 0 That is of course true (and was the topic of heated discussion with my fourth grade math teacher), but does not explain 2.5 - 2. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED

Re: [Haskell-cafe] Why 'round' does not just round numbers ?

Felipe Lessa wrote: On Mon, Oct 27, 2008 at 8:15 AM, Janis Voigtlaender [EMAIL PROTECTED] wrote: That is of course true (and was the topic of heated discussion with my fourth grade math teacher), but does not explain 2.5 - 2. If you round to odd instead of round to even, then 4.5 rounds

Re: [Haskell-cafe] Why 'round' does not just round numbers ?

Janis Voigtlaender wrote: 2.4x - x That's supposed to be 2.4x - 2, of course. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org

Re: [Haskell-cafe] Why 'round' does not just round numbers ?

was taught. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Why 'round' does not just round numbers ?

Felipe Lessa wrote: On Mon, Oct 27, 2008 at 8:30 AM, Janis Voigtlaender [EMAIL PROTECTED] wrote: Well, of course I did not learn to round to odd. I learned to round .5 to above, but not to do repeated rounding. Nobody rounds in passes, of course =). Oh, Mrs. I forgot her name actually

Re: [Haskell-cafe] Why 'round' does not just round numbers ?

Ketil Malde wrote: Janis Voigtlaender [EMAIL PROTECTED] writes: If you round to odd instead of round to even, then 4.5 rounds to 5, Well, of course I did not learn to round to odd. I learned to round .5 to above, but not to do repeated rounding. Since just about every floating point

Re: [Haskell-cafe] Why 'round' does not just round numbers ?

, but another world (politically, pre-'89 ;-). -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Why 'round' does not just round numbers ?

explanation. And yes, the avoiding bias explanation makes sense, but not the this way of rounding makes repeated rounding safe explanation. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing

Re: [Haskell-cafe] Why 'round' does not just round numbers ?

Ketil Malde wrote: Janis Voigtlaender [EMAIL PROTECTED] writes: Since just about every floating point operation involves some sort of loss of precision, repeated rounding is a fact of life. Of course. But that was not the point of the discussion... Well, allow me to contribute

[Haskell-cafe] LAST CALL: Haskell Communities and Activities Report

or LaTeX format. More information can be found in the original Call for Contributions at http://www.haskell.org/pipermail/haskell/2008-October/020651.html I look forward to receiving your contributions. Thanks a lot, Janis (current editor) -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de

Re: [Haskell-cafe] Can't figure out source of race condition when using System.Process

Rafal Kolanski wrote: ..., until I found someone's code snippet online ... and extrapolated from that. Oh yes, I love that kind of programming. Hardly possible in other languages than Haskell. :-) -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED

Re: [Haskell-cafe] Proof that Haskell is RT

you one could prove equivalence. So, to be precise, the question you are interested in cannot even really be asked at the moment. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe

Re: [Haskell-cafe] Re: Type question in instance of a class

and statements about them. The introductory example of the following technical report may be amusing in that respect: http://wwwtcs.inf.tu-dresden.de/~voigt/TUD-FI08-08.pdf Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED

Re: [Haskell-cafe] implementing python-style dictionary in Haskell

. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] varargs zip

deriver (makeZippable) using the derive-package. So no manual boilerplate at all is necessary to use this version of generic zip. (And there is also a tryZipWith.) Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED

Re: [Haskell-cafe] How to use Unicode strings?

Alexey Khudyakov wrote: putStrLn Ну и где этот ваш хвалёный уникод? :-) -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman

Re: [Haskell-cafe] implementing python-style dictionary in Haskell

Ryan Ingram wrote: On Sat, Nov 22, 2008 at 5:33 AM, Janis Voigtlaender [EMAIL PROTECTED] wrote: You can generally make a persistent data structure with the same asymptotic bounds as the ephemeral structure, ... I would be very careful with the generally here. At least, I am not aware

Re: [Haskell-cafe] Re: Type question in instance of a class

Henning Thielemann wrote: On Sat, 22 Nov 2008, Janis Voigtlaender wrote: Definitely. And that surfaces even in quite innocently looking programs and statements about them. The introductory example of the following technical report may be amusing in that respect: http://wwwtcs.inf.tu

Re: [Haskell-cafe] Unique functor instance

;-) Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Unique functor instance

Janis Voigtlaender wrote: Luke Palmer wrote: I've been wondering, is it ever possible to have two (extensionally) different Functor instances for the same type? I do mean in Haskell; i.e. (,) doesn't count. I've failed to either come up with any examples or prove that they all must

Re: [Haskell-cafe] Unique functor instance

since you assumed fmap even x = x ! Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

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