Re: [Haskell-cafe] Locking, unsafePerformIO and bolt-on thread safety.
My first thought was to create all of the lookup table lazily, and create a pure top level binding for it. Something like: lookupTable :: [Int] lookupTable = map (\x - unsafePerformIO (create_lookup_table x) `seq` x) [1..] Then on a calculation you would index into this list and pass the result as the last argument to perform_math. However, I'm not sure how evaluation of thunks works with multiple threads; it might be possible that this will occasionally execute create_lookup_table twice. I found this paper [1] which suggests (in 3.5) that it does indeed, and they suggest a primitive (justOnce :: a - a) to prevent it. So I guess this won't work, unless things have changed since 2005. Erik [1] http://research.microsoft.com/en-us/um/people/simonpj/papers/parallel/multiproc.pdf On Tue, May 10, 2011 at 02:45, Jason Dusek jason.du...@gmail.com wrote: A friend is making bindings to a C library that offers some fast math operations. The normal way to use the library is like this: int a = ...; int b = ...; int c = ...; int d = ...; int x = ...; int m, n; create_lookup_table(x); m = perform_math(a, b, x); n = perform_math(c, d, x); We see that the lookup table for x must be created before we can perform math in the field/ring/what-have-you defined by x. Once we have created the table, though, we're done. My friend would like to create a pure interface to this library. One thought was to write an interface to perform_math that checked if the table was created, created it if not, and did all this while locking an MVar so that no other instance could be called at the same time, trashing the table. Doing this behind unsafePerformIO would seem to be the ticket. We end up with an implementation like this: module FastMath where import Control.Concurrent import Foreign import Foreign.C foreign import ccall create_lookup_table :: CInt - IO () foreign import ccall perform_math :: CInt - CInt - CInt - IO CInt masterLock = unsafePeformIO (newMVar [CInt]) safe_perform_math a b x = do list - takeMVar masterLock toPut - if not (x `elem` list) then do create_lookup_table x return (x:list) else return list result - perform_math a b x putMVar masterLock toPut return result performMath a b x = unsafePerformIO (safe_perform_math a b x) This does not compile but I think it gets the point across. Is this approach safe? The unsafePerformIO in conjunction with locking has me worried. -- Jason Dusek () ascii ribbon campaign - against html e-mail /\ www.asciiribbon.org - against proprietary attachments ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Template Haskell reified type.
Can you give a concrete example? There is code in GHC that is supposed to produce TupleT and ListT! Simon | -Original Message- | From: haskell-cafe-boun...@haskell.org [mailto:haskell-cafe-boun...@haskell.org] On | Behalf Of Serguey Zefirov | Sent: 09 May 2011 14:43 | To: haskell | Subject: [Haskell-cafe] Template Haskell reified type. | | Language.Haskell.TH.Type contains, among others, two constructors: | TupleT Int and ListT. | | I can safely construct types using them, but reification returns ConT | GHC.Tuple.(,) and ConT GHC.Types.[] respectively. | | This is not fair asymmetry, I think. | | Also, it took purity from one of my functions while I debugged that | problem. I had to make it into Q monad. ;) | | ___ | Haskell-Cafe mailing list | Haskell-Cafe@haskell.org | http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Template Haskell reified type.
I turned out that it is in ghc 6.12. The same code in ghc 7.0.1 works just fine, Reification produces TupleT and ListT. I just rechecked it. I forgot that I use 6.12. Sorry about that. 2011/5/10 Simon Peyton-Jones simo...@microsoft.com: Can you give a concrete example? There is code in GHC that is supposed to produce TupleT and ListT! Simon | -Original Message- | From: haskell-cafe-boun...@haskell.org [mailto:haskell-cafe-boun...@haskell.org] On | Behalf Of Serguey Zefirov | Sent: 09 May 2011 14:43 | To: haskell | Subject: [Haskell-cafe] Template Haskell reified type. | | Language.Haskell.TH.Type contains, among others, two constructors: | TupleT Int and ListT. | | I can safely construct types using them, but reification returns ConT | GHC.Tuple.(,) and ConT GHC.Types.[] respectively. | | This is not fair asymmetry, I think. | | Also, it took purity from one of my functions while I debugged that | problem. I had to make it into Q monad. ;) | | ___ | Haskell-Cafe mailing list | Haskell-Cafe@haskell.org | http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Those damned parentheses
Eitan Goldshtrom wrote: f p = putStrLn $ (show (Main.id p)) ++ - message received Brandon S Allbery KF8NH wrote: f p = putStrLn $ (show $ Main.id p) ++ = message received wren ng thornton w...@freegeek.org wrote: f p = putStrLn $ show (Main.id p) ++ - message received f p = putStrLn $ (show . Main.id) p ++ - message received f p = putStrLn $ ((show . Main.id) p) ++ - message received f p = putStrLn $ (show . Main.id $ p) ++ - message received f p = putStrLn ((show . Main.id $ p) ++ - message received) etc. I think the clearest way to write it is: f = putStrLn . (++ - message received) . show . Main.id Not because it happens to be point-free, but because it is the combinator approach. You apply functions one after the other, each with its own simple meaning and purpose. If I were to describe to someone in words what this function does, I would say something like: Apply Main.id, turn it into a string, tack a message onto the end, and print it. So why not write it that way in Haskell? One of the nicest features of Haskell is that the combinator approach is often so natural. Regards, Yitz ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Those damned parentheses
On 10 May 2011, at 08:30, Yitzchak Gale wrote: If I were to describe to someone in words what this function does, I would say something like: Apply Main.id, turn it into a string, tack a message onto the end, and print it. So why not write it that way in Haskell? Why not indeed ? (--) = flip (.) f = Main.id -- show -- (++ = message received) -- putStrLn ;-) One of the nicest features of Haskell is that the combinator approach is often so natural. :-) :-) Regards, Yitz ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe Andrew Butterfield Tel: +353-1-896-2517 Fax: +353-1-677-2204 Foundations and Methods Research Group Director. School of Computer Science and Statistics, Room F.13, O'Reilly Institute, Trinity College, University of Dublin http://www.cs.tcd.ie/Andrew.Butterfield/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Crypto-api performance
On Tue, May 3, 2011 at 22:05, Johan Brinch brin...@gmail.com wrote: Does anyone have experience with the crypto-api package? It seems to define a nice common API for block ciphers, hash functions and prng's. However, I get very low performance using it. I ran its benchmark on a NOP block cipher, where encryptBlock k = id, and it's still very slow. After expanded the included block cipher benchmark (which uses ECB) to include CBC and CTR I got the following: ECB: 30 MB/s -- somewhat slow CBC: 12 MB/s -- very slow CTR: 4 MB/s -- why is adding a counter so bad? Have anyone else benchmarked this and if so with what results? Are there any other high level crypto API? Here's my benchmark code for CTR (easily modified to use ECB/CBC): https://gist.github.com/954093 And here's my patched Benchmark/Crypto.hs: https://gist.github.com/954099 Package in question: http://hackage.haskell.org/package/crypto-api Would there be anything wrong / really ugly in simply pushing those small bottlenecks into C code? Stuff like xor'ing two bytestrings or generating a block of incremental IV's (for CTR mode)? -- Johan Brinch ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Those damned parentheses
On 10 May 2011 09:47, Andrew Butterfield andrew.butterfi...@cs.tcd.ie wrote: Why not indeed ? (--) = flip (.) f = Main.id -- show -- (++ = message received) -- putStrLn -- () :: Category cat = cat a b - cat b c - cat a c import Control.Category ( () ) f = Main.id show (++ - message received) putStrLn ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Those damned parentheses
Andrew Butterfield wrote: Why not indeed ? Roel van Dijk wrote: import Control.Category ( () ) f = Main.id show (++ - message received) putStrLn Indeed, I agree. I sometimes do that, too, when I want to emphasize the idea of applying tools one after the other. But most often I just use traditional function composition notation. That reminds us of the connection with mathematical functions. It also raises less eyebrows when other people read my code and see ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] An update on ICFP'11 in Tokyo (September 18-24, 2011)
Given the fairly recent severe earthquake and tsunami in Japan, you may wonder how this affects the preparations for ICFP'11 in Tokyo. Luckily, Tokyo was significantly less affected by these saddening events than the regions further north. In fact, the situation in Tokyo is almost back to normal, after only two months, with another four months until ICFP. Moreover, all major embassies have in the meantime lifted their travel advisories for the Tokyo metropolitan region (while they still maintain active advisories for some other regions.) Our local organisational team has completed major parts of the preparations and recently summarised the most important facts on a local information page for ICFP'11: http://www.biglab.org/icfp11local/index.html The main conference site is at http://www.icfpconference.org/icfp2011/ We are looking forward to seeing you in Tokyo in September! Manuel Chakravarty Zhenjiang Hu (General Chairs of ICFP'11) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Those damned parentheses
Andrew Butterfield wrote: Why not indeed ? Roel van Dijk wrote: import Control.Category ( () ) f = Main.id show (++ - message received) putStrLn Indeed, I agree. I sometimes do that, too, when I want to emphasize the idea of applying tools one after the other. But most often I just use traditional function composition notation. That reminds us of the connection with mathematical functions. It also raises less eyebrows when other people read my code - some people immediately panic when they see an import from Control.Category or Control.Arrow. :) Regards, Yitz ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Hackage build failure
Hi, Is there something wrong with the Hackage build system? It fails to build BNFC-meta: http://hackage.haskell.org/package/BNFC-meta It complains about a missing dep even though it (the dependency) has been built successfully. Also the dependencies are exactly the same as in the previous version (which configures fine but fails to build because of some bug in HsColor). Regards Jonas ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Crypto-api performance
On Tue, May 10, 2011 at 09:47, Johan Brinch brin...@gmail.com wrote: Stuff like xor'ing two bytestrings or generating a block of incremental IV's (for CTR mode)? I don't particularly like the notion of XOR on a bytestring. The bytestring is not a number and it does not make much sense to bitwise xor such a string. I'd rather have a type specifically tailored for doing crypto-style computations and then use it. Such that the underlying implementation can be repa, bytestring, supermegavectorizationistic, or something completely different. -- J. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] ANN: syntactic-0.1
2011-05-10 15:31, Heinrich Apfelmus skrev: I'm also unhappy about some of the boilerplate. For instance, have a look at the function goE in compileAccumB (line 210), it's just a generic applicative traversal through the data type. Most likely, this boilerplate could be simplified using syntactic. Hm, does the boilerplate get removed or only simplified? I was hoping that one could use a completely generic traversal; but is that actually the case? I was using careful wording :) I think the traversal can be completely generic. But syntactic brings its own (constant) overhead, so I felt the word remove might be too strong. On closer inspection, I'm discovering another issue, namely the need for the Typeable class. This is quite unfortunate, because it would mean that I won't be able to make an API built on type classes like Functor or Applicative. Some discussion on that can be found at the end of http://apfelmus.nfshost.com/blog/2011/04/24-frp-push-driven-sharing.html Hm... The only reason (afair) for having Typeable constraints in the tree was that my code motion transform (not yet released) needs to move around nodes in a way that the type checker is not happy with. But as long as my algorithm is correct, the type casts will actually always succeed. So it might be possible to use unsafeCoerce directly and get rid of Typeable. There might also be ways to make Typeable optional... I will look into this. So, it looks like I can't make use of syntactic at the moment. Then again, my library is probably one of the strongest tests of expressivity for endeavors like syntactic , so that's fine. Another example of similar difficulty would be D. Swierstra's recent parser/grammar combinators that can handle left-recursive grammars. Once syntactic can deal with those, you're the king! :) Thanks for the tip! It would be interesting to try out these libraries for real, if only for the sake of getting to know the practical limits of syntactic. But my focus is currently on the Feldspar implementation, so I probably won't have time for things like this in a (long) while. / Emil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Hackage build failure
On Tue, May 10, 2011 at 10:46:53AM +0200, Jonas Almström Duregård wrote: Is there something wrong with the Hackage build system? It fails to build BNFC-meta: http://hackage.haskell.org/package/BNFC-meta It complains about a missing dep even though it (the dependency) has been built successfully. Also the dependencies are exactly the same as in the previous version (which configures fine but fails to build because of some bug in HsColor). happy-meta is one of those packages that won't build again after you clean them (it has files under dist/build to work around a bug in Happy). Fixed now. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Those damned parentheses
On 10/05/2011 08:30 AM, Yitzchak Gale wrote: I think the clearest way to write it is: f = putStrLn . (++ - message received) . show . Main.id You're serious?? If I were to describe to someone in words what this function does, I would say something like: Apply Main.id, turn it into a string, tack a message onto the end, and print it. So why not write it that way in Haskell? Hmm, I suppose. OTOH, this breaks if you want to insert several items into a string. For example, f x y z = putStrLn (X = ++ show x ++ , Y = ++ show y ++ , Z = ++ show z) (Fortunately, here a simple call to ($) will fix you up nicely.) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Crypto-api performance
On Tue, May 10, 2011 at 11:14, Jesper Louis Andersen jesper.louis.ander...@gmail.com wrote: On Tue, May 10, 2011 at 09:47, Johan Brinch brin...@gmail.com wrote: Stuff like xor'ing two bytestrings or generating a block of incremental IV's (for CTR mode)? I don't particularly like the notion of XOR on a bytestring. The bytestring is not a number and it does not make much sense to bitwise xor such a string. I'd rather have a type specifically tailored for doing crypto-style computations and then use it. Such that the underlying implementation can be repa, bytestring, supermegavectorizationistic, or something completely different. Well, the need for extracting the underlying char pointer to call the c function does limit possible abstraction of the data structure somewhat. Of course, one could make a type class providing unpack/pack functions for extracting the pointer and rebuilting the Haskell value. Of course, this was never meant as part as anything, but a low level crypto lib for high level crypto libs to use. It's not meant for regular usage. -- Johan Brinch ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Asynchronous Arrows need Type Specialization - Help!
Responding to a very stale thread here... Scott Turner 2hask...@pkturner.org writes: And indeed, a channel carrying a sum type corresponds much more closely to a pair of channels than does a channel carrying pairs. I certainly agree with the slogan a stream of pairs is not the same as a pair of streams. However I don't think sums are correct either -- if you have backpressure the behavior is very different. Suppose I have two incoming streams, one of type A and one of type B, and (for simplicity) the producers providing these streams do not communicate with each other in any way. I can decide not to consume any values of type B until I receive at least one value of type A. Now replace my pair of streams with a single stream of (Either A B). In order to consume a (Left A) I might have to consume a bunch of (Right B)'s first; the fact that I have consumed them can be detected by the B-producer and may influence its behavior in a manner I did not intend. Even if this is acceptable, there's another problem: I need an unbounded amount of storage for all those B's -- so this solution won't work in any sort of hardware design or embedded situation. Paul L nine...@gmail.com writes: Peter Gammie suggested use of Adam Megacz's Generalized Arrows, which would avoid this problem by use of an opaque product type that can only be converted to a pair by an explicit operation (i.e. 'synch :: a (b**c) (b,c)' for opaque product type (**)). I'm still debating whether to take this approach. Yes, this is one of the situations where you need the generalized part of generalized arrows; see the blurb in the first paragraph on page 6 [1]. If you look at the corresponding multi-level language, the type of synch's input (pair-of-streams) is additive conjunction [2] and its output type (stream-of-pairs) is multiplicative conjunction; both of these are distinct from Fudgets' additive disjunction (stream-of-sums). Sadly GHC does not support substructural types, so there's little chance of these sorts of things being supported in the GHC-based flattener. - a [1] http://arxiv.org/abs/1007.2885 [2] http://en.wikipedia.org/wiki/Linear_logic#The_resource_interpretation ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Cairo package broken on Windows, or am I cooking it wrong?
Hello, After a moderate struggle with getting gtk2hs to install on Windows, I tried to install Chart and got a linker message saying _cairo_image_surface_get_data was missing. After another struggle I figured that if I launch ghci -lcairo-2 then everything works fine. I tried patching cairo.cabal by adding this line: extra-libraries: cairo-2 and reinstalling cairo. This helped, I could install Chart without problems. My question is: Should this line be added to cairo.cabal, or should everything have worked fine in some other magical way, but did not, because of some other error? How can I diagnose what's wrong? How is cabal install generally supposed to find that a dll is needed, if I don't write it down in the extra-libraries field? -- Eugene Kirpichov Principal Engineer, Mirantis Inc. http://www.mirantis.com/ Editor, http://fprog.ru/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Work on Collections Processing Arrows?
David Barbour dmbarb...@gmail.com writes: I've a preliminary model, using Adam Megacz's Generalized Arrows, of the form: Hey, neat. Actually, this sounds more like the generalized arrow version of arrowized FRP's switch and par (Section 2.6 of [1]). I'd been meaning to figure out the GArrow version of those but never got around to it. ArrowApply would give me a dynamic amount of processing, but seems excessively expressive. Yes, that's overkill and would rule out the applications where implementing ArrowApply is impossible. class (GArrow a (**) u c) = GArrowMap a (**) u c where mapA :: a d r - a (c d) (c r) class (GArrow a (**) u) = GArrowUnion a (**) u c where union :: a ((c r) ** (c r)) (c r) class (GArrowMap a (**) u c) = GArrowJoin a (**) u c where join :: a d (c r) - a (c d) (c r) I like these; I think you're on the right track. The last one reminds me of concatMap. class (GArrowDrop a (**) u) = GArrowMap_ a (**) u c where mapA_ :: a d u - a (c d) u I don't think you want to ask for a GArrowDrop instance here -- if you've got that, you might as well just ignore the argument and say: mapA_ = \x - ga_drop Perhaps what you want is gac_drop :: a (c u) u ... which is a bit like ga_cancell and ga_cancelr, but for a whole collection rather than one input at a time. By the way, I've started [2] using type families for the aggregate GArrow classes like GArrowSTLC. This greatly reduces the syntactic noise in the types -- you only have one type parameter instead of four. The price is that a single type can't be an instance of these classes in more than one way (see Section 3.6.1 of [3] for why this is important). I tend to think of type classes in terms of dictionary-passing (like in Coq), so I often get myself into trouble in situations where I know which dictionary to pass, but can't get Haskell's instance inference to do what I want. I welcome suggestions on ways to improve the user-friendliness of the GArrow classes -- there are probably a bunch of cool Haskell type class tricks I ought to be using but don't know about. In my own case, 'c' might be representing an asynchronous or distributed, reactive collection, so the ability to restrict expressiveness is important for performance. Certainly. The multiplicative disjunction [4] of linear logic is the binary version of this: (A \bindnasrepma B) is sort of like an A and a B in geographically distant locations; if you have a (Int \bindnasrepma Int) you have two Int's, but in order to (for example) add them together you must use some sort of communication primitive to get them both to the same place. It sounds like you want a sort of collection version of multiplicative disjunction. I bet Data Paralell Haskell's parallel array type-former (([::]) :: * - *) would be an instance of this class. - a [1] http://dx.doi.org/10.1145/581690.581695 [2] http://git.megacz.com/?p=ghc-base.git;a=commitdiff;h=47c002441ab30c48 [3] http://arxiv.org/pdf/1007.2885v2 [4] http://en.wikipedia.org/wiki/Linear_logic#The_resource_interpretation ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] parsing currency amounts with parsec
* Eric Rasmussen ericrasmus...@gmail.com [2011-05-09 15:07:57-0700] Hi everyone, I am relatively new to Haskell and Parsec, and I couldn't find any articles on parsing numbers in the following format: You could read hledger[1] sources for inspiration: it's written in Haskell and contains some (quite generic) currency parsing. [1]: http://hledger.org/ -- Roman I. Cheplyaka :: http://ro-che.info/ Don't worry what people think, they don't do it very often. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Proposal to incorporate Haskell.org
Hello everyone. The haskell.org committee[1], in the interest of the long-term stability of the open source Haskell community infrastructure, has decided to incorporate haskell.org as a legal entity. This email outlines our recommendation, and seeks input from the community on this decision. The committee's proposal is that haskell.org incorporate as an entity under the Software Freedom Conservancy umbrella organization (the same group that Darcs joined recently): http://sfconservancy.org/ If we proceed with this move, haskell.org will be a legal entity, and registered as a non-profit, allowing us to more directly accept (US tax-deductible) donations, and to invest in assets that benefit the Haskell open source community. We welcome your feedback on the proposal attached below. -- Don Stewart (on behalf of the Haskell.org committee) = A proposal for the incorporation of Haskell.org = In recent years, haskell.org has started to receive assets, e.g. money from Google Summer Of Code, donations for Hackathons, and a Sparc machine for use in GHC development. We have also started spending this money: in particular, on hosting haskell.org itself. There is also interest in running fundraising drives for specific things such as Hackathon sponsorship and hosting fees. However, haskell.org doesn't currently exist as a legal entity, meaning that these assets have had to be held on our behalf by other entities, such as Galois and various universities. This leads to tricky situations, with no-one being sure who should decide how the haskell.org assets can be used. To solve these problems, we propose that haskell.org applies to become a member project of the Software Freedom Conservancy (SFC) http://conservancy.softwarefreedom.org/. The SFC is a non-profit organization that provides free financial and administrative services to open source projects. Additionally, it has 501(c)(3) status, meaning donations from the US are tax-deductible. The SFC would hold haskell.org's money and other assets, and would be able to accept donations on behalf of haskell.org. The haskell.org committee, as described here [2], will make decisions on spending assets and other decisions related to governing the non-profit. Before proceeding, we are inviting input from the community in the form of specific objections or queries regarding the plan. We've tried to answer some of the most likely questions: Q: Does this mean that my Haskell project must now be covered by a copyleft licence such as GPL? A: No, but Haskell projects using haskell.org resource should use an Open Source licence http://www.opensource.org/licenses/alphabetical. Q: Will it still be possible to use community.h.o to host non-open-source material, such as academic papers? A: An overall minority of such content, as is the current situation, is not a problem. Q: Will it still be possible to have job ads on the haskell.org mailing lists and website? A: Yes. Q: Will this affect our ability to host the Haskell Symposium http://www.haskell.org/haskell-symposium/ and Industrial Haskell Grouphttp://industry.haskell.org/ webpages within haskell.org? A: No. Q: What will be the relationship between haskell.org and other organizations such as the Haskell Symposium and Industrial Haskell Group? A: Those organisations will continue to exist as separate entities. Q: If an umbrella non-profit organisation The Haskell Foundation was created, would haskell.org be able to join it? A: Yes. It's likely that in such a scenario, the Haskell Foundation would become the owner of the haskell.org domain name, with the cost divided between the members. The entity that is part of the SFC would be renamed community.haskell.org in order to avoid confusion. [1]: http://www.haskell.org/haskellwiki/Haskell.org_committee [2]: http://www.haskell.org/haskellwiki/Haskell.org_committee#Operation ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Modeling the performance of a non-trivial software app
Hi, I was wondering if it would be a good idea to model a software app's performance using Haskell. The idea is a little abstract in my mind right now. I'll try and illustrate it with an example - Let's say, I want to model a web app - to, model it, I could think of the following entities - 1. One or more clients and as many connections (essentially bandwidth of each connection) 2. A Load balancer ( and bandwidths to the webservers) 3. Bunch of webservers (and bandwidths to the database server) 4. A database server Using the model, I could generate performance characteristics and figure out if database is the bottleneck or not ... if so, what level of sharding would be useful etc Is there already a wheel I am trying to re-invent? Has anyone attempted this? Regards, kashyap ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Proposal to incorporate Haskell.org
Q: Does this mean that my Haskell project must now be covered by a copyleft licence such as GPL? A: No, but Haskell projects using haskell.org resource should use an Open Source licence http://www.opensource.org/licenses/alphabetical. Should == must? Would this apply to everything on Hackage? Thanks for clarifying, Tom ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Modeling the performance of a non-trivial software app
On 05/11/2011 07:55 AM, C K Kashyap wrote: Hi, I was wondering if it would be a good idea to model a software app's performance using Haskell. The idea is a little abstract in my mind right now. I'll try and illustrate it with an example - Let's say, I want to model a web app - to, model it, I could think of the following entities - 1. One or more clients and as many connections (essentially bandwidth of each connection) 2. A Load balancer ( and bandwidths to the webservers) 3. Bunch of webservers (and bandwidths to the database server) 4. A database server Using the model, I could generate performance characteristics and figure out if database is the bottleneck or not ... if so, what level of sharding would be useful etc Is there already a wheel I am trying to re-invent? Has anyone attempted this? Regards, kashyap ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe Sometimes it is possible to write the corresponded model. Then the model can be simulated to receive the performance characteristics. Much depends on that how precise the model is. The keywords are Discrete Event Simulation (DES) and Theory of Queue. It may require some maths. I wrote a small library called Aivika[1]. Perhaps it might be helpful. David [1]http://hackage.haskell.org/package/aivika ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Proposal to incorporate Haskell.org
On Tue, May 10, 2011 at 5:44 PM, Don Stewart don...@gmail.com wrote: Hello everyone. The haskell.org committee[1], in the interest of the long-term stability of the open source Haskell community infrastructure, has decided to incorporate haskell.org as a legal entity. This email outlines our recommendation, and seeks input from the community on this decision. The committee's proposal is that haskell.org incorporate as an entity under the Software Freedom Conservancy umbrella organization (the same group that Darcs joined recently): http://sfconservancy.org/ If we proceed with this move, haskell.org will be a legal entity, and registered as a non-profit, allowing us to more directly accept (US tax-deductible) donations, and to invest in assets that benefit the Haskell open source community. We welcome your feedback on the proposal attached below. -- Don Stewart (on behalf of the Haskell.org committee) Keeping -cafe and committee@ on the CC list. Joining the SFC looks like a good alternative to full-on incorporation, and having some sort of legal cover for operations involving money and ownership of infrastructure looks like a good idea. Which assets would move over to the SFC? The domain name? Any sort of hosting could then be leased by the SFC to whomever is doing this now. I'm a bit fuzzy here. They look pretty flexible, and are open to some, none, or all of a project's assets being in the name of the SFC. Antoine = A proposal for the incorporation of Haskell.org = In recent years, haskell.org has started to receive assets, e.g. money from Google Summer Of Code, donations for Hackathons, and a Sparc machine for use in GHC development. We have also started spending this money: in particular, on hosting haskell.org itself. There is also interest in running fundraising drives for specific things such as Hackathon sponsorship and hosting fees. However, haskell.org doesn't currently exist as a legal entity, meaning that these assets have had to be held on our behalf by other entities, such as Galois and various universities. This leads to tricky situations, with no-one being sure who should decide how the haskell.org assets can be used. To solve these problems, we propose that haskell.org applies to become a member project of the Software Freedom Conservancy (SFC) http://conservancy.softwarefreedom.org/. The SFC is a non-profit organization that provides free financial and administrative services to open source projects. Additionally, it has 501(c)(3) status, meaning donations from the US are tax-deductible. The SFC would hold haskell.org's money and other assets, and would be able to accept donations on behalf of haskell.org. The haskell.org committee, as described here [2], will make decisions on spending assets and other decisions related to governing the non-profit. Before proceeding, we are inviting input from the community in the form of specific objections or queries regarding the plan. We've tried to answer some of the most likely questions: Q: Does this mean that my Haskell project must now be covered by a copyleft licence such as GPL? A: No, but Haskell projects using haskell.org resource should use an Open Source licence http://www.opensource.org/licenses/alphabetical. Q: Will it still be possible to use community.h.o to host non-open-source material, such as academic papers? A: An overall minority of such content, as is the current situation, is not a problem. Q: Will it still be possible to have job ads on the haskell.org mailing lists and website? A: Yes. Q: Will this affect our ability to host the Haskell Symposium http://www.haskell.org/haskell-symposium/ and Industrial Haskell Grouphttp://industry.haskell.org/ webpages within haskell.org? A: No. Q: What will be the relationship between haskell.org and other organizations such as the Haskell Symposium and Industrial Haskell Group? A: Those organisations will continue to exist as separate entities. Q: If an umbrella non-profit organisation The Haskell Foundation was created, would haskell.org be able to join it? A: Yes. It's likely that in such a scenario, the Haskell Foundation would become the owner of the haskell.org domain name, with the cost divided between the members. The entity that is part of the SFC would be renamed community.haskell.org in order to avoid confusion. [1]: http://www.haskell.org/haskellwiki/Haskell.org_committee [2]: http://www.haskell.org/haskellwiki/Haskell.org_committee#Operation ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Modeling the performance of a non-trivial software app
Sometimes it is possible to write the corresponded model. Then the model can be simulated to receive the performance characteristics. Much depends on that how precise the model is. The keywords are Discrete Event Simulation (DES) and Theory of Queue. It may require some maths. I wrote a small library called Aivika[1]. Perhaps it might be helpful. David [1]http://hackage.haskell.org/package/aivika Thanks David, I'll check out DES and Aivika. Regards, Kashyap ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
