Re: [Haskell-cafe] What is -

: it is desugared as described elsewhere in the thread and in the Report. HTH, Jochem -- Jochem Berndsen | joc...@functor.nl ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Re: [web-devel] Google Summer of Code: BlazeHTML RFC

On 05/29/2010 08:05 PM, Gregory Collins wrote: Matt Parkermoonmaster9...@gmail.com writes: Q3: Which HTML version would you preferably use? HTML 5. google summer of code should be about pushing the new and exciting. Yes, definitely, this should be the default IMO. +1 -- Jochem

Re: [Haskell-cafe] MultiParamTypeClasses, FunctionalDependencies and FlexibleInstances using GHCi

but a type class), they need not be of the same type (e.g., 3 could be of type Integer, and 4 of type Double). Jochem -- Jochem Berndsen | joc...@functor.nl ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo

Re: [Haskell-cafe] and [] = True; or [] = False

. Cheers, Jochem -- Jochem Berndsen | joc...@functor.nl ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Rank-2 polymorphism and overloading

:: forall a. Eq a = a - a - Bool z = y g :: (Bool, Bool) g = (f x, f z) -- note the use of z here instead of y Jochem -- Jochem Berndsen | joc...@functor.nl ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman

Re: [Haskell-cafe] Are there any female Haskellers?

that. My other hobby is evolution and evolutionary psichology. I really recommend to learn about it. Could you point us to any evidence that supports your assumption that there are sexual differences in mathematical abilities? Thanks, Jochem -- Jochem Berndsen | joc...@functor.nl

Re: [Haskell-cafe] Bytestrings and [Char]

the same thing as a sequence of Unicode bytes when you use UTF8. What is a Unicode byte? Cheers, Jochem -- Jochem Berndsen | joc...@functor.nl ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell

Re: [Haskell-cafe] stuck with a sample of programming in haskell

, Jochem -- Jochem Berndsen | joc...@functor.nl ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Linguistic hair-splitting

multiplication is not a group. (The only invertible elements of this monoid are 1 and -1.) Now, here's the question: Is is correct to say that [3, 5, 8] is a monad? In what sense would this be a monad? I don't quite get your question. Cheers, Jochem -- Jochem Berndsen | joc...@functor.nl

Re: [Haskell-cafe] Linguistic hair-splitting

Luke Palmer wrote: On Wed, Jan 27, 2010 at 11:39 AM, Jochem Berndsen joc...@functor.nl wrote: Now, here's the question: Is is correct to say that [3, 5, 8] is a monad? In what sense would this be a monad? I don't quite get your question. I think the question is this: if m is a monad

Re: [Haskell-cafe] Design question, HTML for GUIs?

access control provided by the OS on multi-user machines (i.e., other users working on the same machine can connect to localhost:8080 too). This might or might not be a concern for you. Regards, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里.com

Re: [Haskell-cafe] Review request for my permutations implementation

Data.List. HTH, regards, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] lawless instances of Functor

Steffen Schuldenzucker wrote: data Foo a = Foo a instance Functor Foo where fmap f (Foo x) = Foo . f . f $ x I think this doesn't typecheck. Cheers, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里.com ___ Haskell-Cafe mailing

Re: [Haskell-cafe] powering of new types

literal wherever your program expects a Double, Int, Integer, and so on. This includes your own type. You have probably defined fromInteger = Scalar for your type. Cheers, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里.com ___ Haskell-Cafe

Re: [Haskell-cafe] Pattern matching, and bugs

'good guy' who think he's robin hood if he can 'hack' the server ) is an every day reality. You should validate your data in any case. You may even turn a DoS attack into a real security problem with your solution. Cheers, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里.com

[Haskell-cafe] Re: [Haskell] ANN: readline-statevar-1.0.1.0

nerds ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Re: [Haskell] ANN: readline-statevar-1.0.1.0

Jochem Berndsen wrote: nerds This was a friend of mine trying to be funny. Apologies, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo

Re: [Haskell-cafe] Haskell-Newbie and Char-Function

result in output f. You might want to use the functions ord and chr from Data.Char, and the mod function from the Prelude. Regards, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http

Re: [Haskell-cafe] Mystery operator?

)) ([],[]) This works but can't find (~) operator anywhere. Please explain or site a reference. This is called a lazy pattern. See: http://www.haskell.org/tutorial/patterns.html section 4.4 Cheers, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里.com

Re: [Haskell-cafe] hackage is down.

to compromise the system. Cheers, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] hackage is down.

On Sun, Nov 01, 2009 at 07:58:00AM -0600, Thomas Hartman wrote: http://hackage.haskell.org Hackage is down currently, I am seeding the torrent by mauke from IRC on http://mauke.ath.cx/tmp/2009-10-19-hackage-archive.torrent Cheers, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里

Re: [Haskell-cafe] x - String

. Cheers, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] is proof by testing possible?

) is equivalent to looping, except that calling error is pragmatically speaking better: it is nicer to the caller of your function (they/you get to see a somewhat more descriptive error message instead of 100% CPU without any results). Regards, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里.com

Re: [Haskell-cafe] type inference question

= (\ (f :: forall a. a - a) - f f True) id Cheers, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] I read somewhere that for 90% of a wide class of computing problems, you only need 10% of the source code in Haskell, that you would in an imperative language.

that's what he is used to. This may or may not be true. It would be interesting to see some research on this. Without that, I think we cannot decide either way. Cheers, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里.com ___ Haskell-Cafe

Re: [Haskell-cafe] convert a list of booleans into Word*

. zipWith (*) (map (2^) [0..]) I'd turn this into sum . zipWith (*) (iterate (2*) 1) , but it's probably not very important. Regards, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http

Re: [Haskell-cafe] Haskell for Physicists

seminar (if any) and even if they are in Spanish (nothing is impossible for man with a dictionary) And what if they're in Portuguese? ;) Cheers, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里.com ___ Haskell-Cafe mailing list Haskell-Cafe

Re: [Haskell-cafe] yi-editor: Duplicate instance declarations

. This means that you either have to downgrade data-accessor, or trash out the Category instance in Yi/Prelude.hs line 182. FYI: I had the same problem this morning. Using data-accessor 0.2.0.2 worked. Regards, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里.com

Re: [Haskell-cafe] Problem on existential type.

the ExistentialTypes extension. This declares a so-called existential type, see the wiki for details, http://www.haskell.org/haskellwiki/Existential_types . Note that the second occurrence of GridWidget defines a data constructor, not a type constructor. Cheers, Jochem -- Jochem Berndsen | joc

Re: [Haskell-cafe] Get data from HTML pages

, in the way described above? To parse HTML documents, I've had success with TagSoup in the past. You can take a look at the HTTP package to download the HTML from the server. Both packages are available from Hackage. HTH, Jochem -- Jochem Berndsen | joc...@functor.nl

Re: [Haskell-cafe] Leaner Haskell.org frontpage

with the maximum number of menu items you should use. There is of course a limit, but there is no reason to limit it to 7+-2. Cheers, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http

Re: [Haskell-cafe] Haskell Platform on Ubuntu

, there has been a lot of activity on the debian-haskell mailing list lately (debian-hask...@lists.debian.org) so there will probably some progress quite soon! (Not sure if it will be in time for Ubuntu 9.10 though). Cheers, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB

Re: [Haskell-cafe] ORM for haskell?

, this is undefined? I have done something similar as you, except that I filled the related field with an unsafePerformIO fetching the related data from the database. Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing

Re: [Haskell-cafe] Monoid wants a (++) equivalent

operator. I totally agree. (+) is too asymmetric for my taste, like (=) and (*) it suggests asymmetry between the arguments. (++) is symmetric and suggests an associative operator to me. -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe

Re: [Haskell-cafe] Another question about unsafePerformIO

'unsafePerformIO' will work, but a better idea might be to understand why your solver has IO in its type signature. Is this because of FFI calls? You can remove IO in FFI calls if they are free from side effects as well. Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB

Re: [Haskell-cafe] Using unsafePerformIO safely

of clean, pure code, and impure code in the IO monad (your main function, which can be pretty small in your case). To avoid boilerplate, you can use the Writer monad, for example, but others may have better suggestions. Kind regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB

Re: [Haskell-cafe] coding standard question

to somebody who reads your code (including yourself) that this omission was intentional. The same holds for other warnings (although I sometimes am annoyed by the shadowing warnings, I agree :). My default is to start developing, then adding -Wall -Werror and make it compile again. Regards, -- Jochem

Re: [Haskell-cafe] Code walking off the right edge of the screen

the same about exceptions, but they are a necessary evil ;-). Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] ANNOUNCE: hyena

, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Haskell - string to list isusses, and more

of it :) Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Haskell - string to list isusses, and more

, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Haskell - string to list isusses, and more

Deniz Dogan wrote: 2009/6/14 Jochem Berndsen joc...@functor.nl: Toby Miller wrote: caps1 s = all (\x - isUpper (head x)) (words s) This seems fine, but you need to check that words never returns a list containing the empty string (otherwise `head' will fail). Is there any such case? I

Re: [Haskell-cafe] Haskell - string to list isusses, and more

string all words start with an uppercase letter, don't they? (If it's True, you can even remove this clause, and let the other one take care of the rest.) Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell

Re: Fwd: [Haskell-cafe] curious about sum

] 5050 so the garbage collector do the job in freeing the consumed part of the list This is correct; the function you defined is equivalent to foldl' in Data.List, if I'm not mistaken. Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB

Re: [Haskell-cafe] curious about sum

be nonstrict. Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] curious about sum

Deniz Dogan wrote: 2009/6/13 Jochem Berndsen joc...@functor.nl: Keith Sheppard wrote: Is there any reason that sum isn't strict? I can't think of any case where that is a good thing. Prelude sum [0 .. 100] *** Exception: stack overflow It is useful if the (+) is nonstrict; although I

Re: [Haskell-cafe] curious about sum

Daniel Fischer wrote: Am Samstag 13 Juni 2009 17:00:36 schrieb Jochem Berndsen: Deniz Dogan wrote: 2009/6/13 Jochem Berndsen joc...@functor.nl: Keith Sheppard wrote: Is there any reason that sum isn't strict? I can't think of any case where that is a good thing. Prelude sum [0 .. 100

Re: [Haskell-cafe] exporting Data.ByteString functions via FFI

If I replace ByteString with the ordinary String, the above programs can be compiled and linked. Can someone tell me what I did wrong here? Add -package bytestring to the ghc command line options. I believe that adding --make also may work. Regards, -- Jochem Berndsen | joc...@functor.nl

Re: [Haskell-cafe] How to compile base?

separately. GHC 6.10.1 ships with base-4.0.0.0, later versions in the 6.10.x series may have a somewhat later version. Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http

Re: [Haskell-cafe] Convert IO Int to Int

, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Problem with Data.Map

as Map to shorten the notation. HTH, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Problem with Data.Map

you to write Data.Map.Map everywhere instead of just 'Map'. Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Problem with Data.Map

michael rice wrote: I don't understand your response. I copied the imports from Hoogles Data.Map page. What should the imports be? Michael The imports are fine, but instead of 'fromList' you should use 'Map.fromList' or 'Data.Map.fromList'. Regards, -- Jochem Berndsen | joc...@functor.nl

Re: [Haskell-cafe] GSoC update: sneak peek at the live heap profiler

. Seems pretty cool :) Will this graph be interactive during the run of the program? (I tried to comment on the web page -- however, it didn't let me. Firefox 3.0 on Debian) Cheers, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe

Re: [Haskell-cafe] measure a function in ghci

profiling. Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Function Returning Type?

. Please someone point me in the right direction. Thanks. Just rationals :: Integer - String suffices. (Without the argument 'n'.) This makes sense, since rationals has type Integer. rationals n has type String. (But you still cannot declare that in toplevel that way.) Regards, -- Jochem Berndsen

Re: [Haskell-cafe] Function Returning Type?

Jochem Berndsen wrote: This makes sense, since rationals has type Integer I meant Integer - String obviously. Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http

Re: [Haskell-cafe] ANN: TxtSushi 0.1

already cabalized the code, so it should suffice to upload it. Cheers -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Data.Map.Map Pattern Matching

patterns, but they are a bit more advanced.) I'm not sure what you are trying to accomplish, could you elaborate? Cheers, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org

Re: [Haskell-cafe] Main function error

applebiz89 wrote: main :: IO () main = do doFilmsInGivenYear films main You pass as argument to 'doFilmsInGivenYear' the value 'films', which is not defined. Instead, I think you meant 'testDatabase'. All the best, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB

Re: [Haskell-cafe] is value evaluated?

that this yields False the 101st Fibonacci number True but this violates referential transparency. Cheers, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman

Re: [Haskell-cafe] parse error on input `'

with a capital or a : (colon). So changing your definition into data Graph a b = Empty | Context a b : Graph a b will work. If you want you can define () = (:) and use the symbol for constructing graphs (not in pattern matches though). HTH, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB

Re: [Haskell-cafe] Not in scope

Haskell is bringing the message Not in scope: data constructor `:' Why is that so? This works for me. Are the definitions in the same file? Otherwise, you will need to import your definition. All the best, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB

Re: [Haskell-cafe] want to upgrade to 6.10.1 ghc

://www.haskell.org/ghc Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Link errors

ideas on how to fix this? I am using GHC version 6.10.1 on Windows XP. Did you use --make ? Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo

Re: [Haskell-cafe] Partial pattern matching

be the type of firstCoord? Typically, you'd use data Pair a b = P { firstCoord :: a , secondCoord :: b } or firstCoord (P x _) = x secondCoord (P _ y) = y Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB

Re: [Haskell-cafe] cabal-install 0.6.2 does not bootstrap with ghc-6.10.1 debian distribution

having to install zlib1g-dev using the package manager, aptitude install zlib1g-dev should suffice. If this was not the problem, please post the exact error message so we can figure out what's going wrong. Regards, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB

Re: [Haskell-cafe] ANN: The Typeclassopedia, and request for feedback

://www.cis.upenn.edu/~byorgey/papers/typeclassopedia-draft-090216.pdf Also see my blog post for a bit more info: http://byorgey.wordpress.com/2009/02/16/the-typeclassopedia-request-for-feedback/ This is really great! Thanks for doing this. Regards, -- Jochem Berndsen | joc...@functor.nl GPG

Re: [Haskell-cafe] lazy evaluation is not complete

? For efficiency reasons? It's a pity because a parallel-outermost strategy would be complete. (*) is strict in both arguments for Int. If you want to avoid this, you could do newtype X = X Int and write your own implementation of (*) that is nonstrict. -- Jochem Berndsen | joc...@functor.nl GPG

Re: [Haskell-cafe] Happstack 0.1 Released!

/HAppS/msg/d128331e213c1031 . The Happstack project is intended to continue development. For more details, see http://happstack.com/faq.html . -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http

[Haskell-cafe] ANN: Hasim, discrete event simulation in Haskell

. Regards, -- Jochem Berndsen | [EMAIL PROTECTED] GPG: 0xE6FABFAB signature.asc Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe