Re: [Haskell-cafe] Chordify, a new web startup using Haskell
Congratulations! Keep up the good work, especially in using Haskell at a commercial level :) Bye! Alfredo On 18 January 2013 07:34, Alp Mestanogullari alpmes...@gmail.com wrote: That's awesome, works like a charm on the samples I've tried it on! Cheers to the Chordify team, I will use it and give any useful feedback if I have any. On Fri, Jan 18, 2013 at 12:07 AM, José Pedro Magalhães j...@cs.uu.nlwrote: Hi all, I'd like to introduce Chordify http://chordify.net/ [1], an online music player that extracts chords from musical sources like Soundcloud, Youtube or your own files, and shows you which chord to play when. Here's an example song: http://chordify.net/chords/passenger-let-her-go-official-video-passengermusic The aim of Chordify is to make state-of-the-art music technology accessible to a broader audience. Behind the scenes, Chordify uses the HarmTrace Haskell package to compute chords from audio. I've been working on this project with a couple of colleagues for a while now, and recently we have made the website public, free to use for everyone. We do not use Haskell for any of the frontend/user interface, but the backend is entirely written in Haskell (and it uses pretty advanced features, such as GADTs and type families [3]). We're particularly interested in user feedback at this stage, so if you're interested in music and could use an automatic chord transcription service, please try Chordify! Cheers, Pedro [1] http://chordify.net/ [2] http://hackage.haskell.org/package/HarmTrace [3] José Pedro Magalhães and W. Bas de Haas. Functional Modelling of Musical Harmony: an Experience Report. In Proceedings of the 16th ACM SIGPLAN International Conference on Functional Programming (ICFP'11), pp. 156–162, ACM, 2011. http://dreixel.net/research/pdf/fmmh.pdf ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Alp Mestanogullari ___ 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] Chordify, a new web startup using Haskell
Is it possible to play the generated chords as a melody by itself, without the original music over it? 2013/1/18 Alfredo Di Napoli alfredo.dinap...@gmail.com Congratulations! Keep up the good work, especially in using Haskell at a commercial level :) Bye! Alfredo On 18 January 2013 07:34, Alp Mestanogullari alpmes...@gmail.com wrote: That's awesome, works like a charm on the samples I've tried it on! Cheers to the Chordify team, I will use it and give any useful feedback if I have any. On Fri, Jan 18, 2013 at 12:07 AM, José Pedro Magalhães j...@cs.uu.nlwrote: Hi all, I'd like to introduce Chordify http://chordify.net/ [1], an online music player that extracts chords from musical sources like Soundcloud, Youtube or your own files, and shows you which chord to play when. Here's an example song: http://chordify.net/chords/passenger-let-her-go-official-video-passengermusic The aim of Chordify is to make state-of-the-art music technology accessible to a broader audience. Behind the scenes, Chordify uses the HarmTrace Haskell package to compute chords from audio. I've been working on this project with a couple of colleagues for a while now, and recently we have made the website public, free to use for everyone. We do not use Haskell for any of the frontend/user interface, but the backend is entirely written in Haskell (and it uses pretty advanced features, such as GADTs and type families [3]). We're particularly interested in user feedback at this stage, so if you're interested in music and could use an automatic chord transcription service, please try Chordify! Cheers, Pedro [1] http://chordify.net/ [2] http://hackage.haskell.org/package/HarmTrace [3] José Pedro Magalhães and W. Bas de Haas. Functional Modelling of Musical Harmony: an Experience Report. In Proceedings of the 16th ACM SIGPLAN International Conference on Functional Programming (ICFP'11), pp. 156–162, ACM, 2011. http://dreixel.net/research/pdf/fmmh.pdf ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Alp Mestanogullari ___ 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 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] resources for learning Hindley-Milner type inference for undergraduate students
Dear Haskellers, could somebody recommend me study materials for learning Hindley-Milner type inference algorithm I could recommend to undergraduate students? The original paper is harder to understand, I'm looking for something more didactic. The students are familiar with the lambda calculus, natural deduction and System F. Thanks for help, Petr Pudlak ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] resources for learning Hindley-Milner type inference for undergraduate students
2013/1/18 Petr P petr@gmail.com: Dear Haskellers, could somebody recommend me study materials for learning Hindley-Milner type inference algorithm I could recommend to undergraduate students? The original paper is harder to understand, I'm looking for something more didactic. The students are familiar with the lambda calculus, natural deduction and System F. I think I really liked Cardelli's paper Basic Polymorphic Typechecking, 1987 HTH, Thu ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: hgdbmi 0.2, GDB Machine Interface
Hi Alexander, On Thu, Jan 17, 2013 at 10:17:33PM +0100, Alexander Bernauer wrote: I am happy to announce the second release of hgdbmi, a Haskell implementation of the GDB Machine Interface. Nice project! :) PS: This is my first serious Haskell package. If you see something that you consider odd, I might have done this simply because I didn't know better. I would appreciate if you would let me know in such a case. Looking at the function names: have you got a c programming background? Instead of using these prefixes you could put the functions into separate modules. If the interface depends on the GDB version, than it could make sense to encode the GDB version into the module name, something like: Gdbmi.V7_4.Commands Greetings, Daniel ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] resources for learning Hindley-Milner type inference for undergraduate students
I also agree that Cardelli paper is great. It was also very useful for me to follow Python implementation provided in the following blog post: http://www.smallshire.org.uk/sufficientlysmall/2010/04/11/a-hindley-milner-type-inference-implementation-in-python/ I found it useful to investigate in Python debugger how various terms were interpreted. You may also find useful implementations in Scala and Perl: http://dysphoria.net/2009/06/28/hindley-milner-type-inference-in-scala/ http://web.archive.org/web/20050911123640/http://www.cs.berkeley.edu/~nikitab/courses/cs263/hm.html Also, I have plans to read Typing Haskell in Haskell by Mark Jones and Practical type inference for arbitrary-rank types by Simon Peyton-Jones et. al. They are also related here, but not directly. -- Best Regards, Anton Dergunov Пятница, 18 января 2013, 11:12 +01:00 от Vo Minh Thu not...@gmail.com: 2013/1/18 Petr P petr@gmail.com : Dear Haskellers, could somebody recommend me study materials for learning Hindley-Milner type inference algorithm I could recommend to undergraduate students? The original paper is harder to understand, I'm looking for something more didactic. The students are familiar with the lambda calculus, natural deduction and System F. I think I really liked Cardelli's paper Basic Polymorphic Typechecking, 1987 HTH, Thu ___ 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] ANN: crypto-pubkey: all your public key crypto algorithms belong to us.
On Tue, Jan 15, 2013 at 03:27:29PM +0100, Ertugrul Söylemez wrote: Vincent Hanquez t...@snarc.org wrote: Yes, the performance are terrible in term of integers. As the library is specific to public key algorithm, i just can't reasonable work on 64 bits integer :-), and multiprecision integers is the only way to go. I'm on-and-off working on some mutable mpi library to be able to define pure function that do the necessary stuff (i.e. expmod, mulmod, etc..) I'm hoping this could be reasonably competitive with a C mpi library, but time will tell. It's a waste of time. In my benchmarks Haskell Integer outperformed equivalent (sane) C implementations using GMP's mpz_* interface. You would be reinventing GMP's mpn_* interface and a custom memory manager to be able to match the speed of Integer. I don't plan to match (or outperform) the speed of integer for simple operations. My experiment is about overtaking haskell's Integer in composite operations (mainly for non naive expmod) by operating with mutable integers and direct access to the representation (the second point is somewhat what Daniel is doing using integer-gmp). One valid way to solve this problem, would be to export more GMP function to haskell without wrapping them for referencial transparency. However the GMP dependencies is not always welcome and the integration of GMP is slightly special (primops), which is why i'm not taking this course of action. The things that were slower than equivalent C code were not related to Integer, but mostly to data structures like Set in my case, which was the motivation for me to write the 'quickset' library. AFAIK, Haskell's Integer expmod algorithms have no way to rival with real world implementation of expmod, which make all pubkey operations quite slow compare to their C friends. There's also the question of timing security with a pure GCed interface. -- Vincent ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: MFlow 0.2
Alberto G. Corona wrote: Hello. haskellers and, specially, web developpers. This is the second version of MFlow, a deep-first effort in the development of a platform for web applications at the higher level, by including as much haskell magic as possible. It is at the same time experimental and intended to be used in industry. I believe that haskell will not have its chance in the Web if it does not bring unique advantages and challenging paradigms beyond speed and type safety. Deep-first means that the effort is more in the addition higher level features rather than in being complete and bug free, with the conviction that feedback from real usage at the highest level is the best guide for development. Rather than to mimic other platforms in other languages, MFlow is as Haskell'ish as possible, and introduces new approaches like statefulness, event sourcing, back-execution, composable, active, self contained widgets and persistent STM. All of them collaborate to create a high level environment for web programming. This release adds bidings for WAI, blaze-html, stateful AJAX, active widgets, requirements, content management, multilanguage and URLs to pages inside stateful procedures. The package: [http://hackage.haskell.org/package/MFlow The entry in my blog, with the announcement and the philosophy behind http://haskell-web.blogspot.com.es/2013/01/announce-mflow-02.html For some reason, your blog posts are not displayed in my browser (Chrome). I block all cookies and I'm using adblock, though. Best regards, Heinrich Apfelmus -- http://apfelmus.nfshost.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: MFlow 0.2
Heinrich Apfelmus apfel...@quantentunnel.de wrote: For some reason, your blog posts are not displayed in my browser (Chrome). I block all cookies and I'm using adblock, though. Blogger.com blogs often need JavaScript to display anything at all. Greets, Ertugrul -- Not to be or to be and (not to be or to be and (not to be or to be and (not to be or to be and ... that is the list monad. signature.asc Description: PGP signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] resources for learning Hindley-Milner type inference for undergraduate students
Dnia piątek, 18 stycznia 2013, Petr P napisał: for learning Hindley-Milner type inference algorithm I could recommend to undergraduate students? The original paper is harder to understand, I'm looking for something more didactic. The students are familiar with the lambda calculus, natural deduction and System F. Perhaps chapters on H-M from Appel's Modern compiler implementation in C/Java would be good? Janek ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Chordify, a new web startup using Haskell
On Fri, Jan 18, 2013 at 2:09 PM, Thiago Negri evoh...@gmail.com wrote: Is it possible to play the generated chords as a melody by itself, without the original music over it? Super work! I was meaning to ask something similar -- can we get out something of the music that chordify has reverse engineered -- maybe midi maybe musicxml? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] resources for learning Hindley-Milner type inference for undergraduate students
On Fri, Jan 18, 2013 at 5:49 PM, Jan Stolarek jan.stola...@p.lodz.plwrote: Dnia piątek, 18 stycznia 2013, Petr P napisał: for learning Hindley-Milner type inference algorithm I could recommend to undergraduate students? The original paper is harder to understand, I'm looking for something more didactic. The students are familiar with the lambda calculus, natural deduction and System F. What is the current opinion of Mark Jones Typing haskell in haskell? http://web.cecs.pdx.edu/~mpj/thih/TypingHaskellInHaskell.html [Note This is to add to the question more than the answer] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] resources for learning Hindley-Milner type inference for undergraduate students
There is a summary paper by Sunil Kothari and James L. Cladwell covering the algorithms M, J and W with informal presentations plus code available in Ocaml. Paper is on Citeseer, code is available from Sunil Kothari's home page. Martin Grabmueller has a tutorial implementation of algorithm W in Haskell: http://www.grabmueller.de/martin/www/pub/pub.en.html On 18 January 2013 10:06, Petr P petr@gmail.com wrote: Dear Haskellers, could somebody recommend me study materials for learning Hindley-Milner type inference algorithm I could recommend to undergraduate students? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: hgdbmi 0.2, GDB Machine Interface
Hi Daniel thank you for your feedback. On Fri, Jan 18, 2013 at 11:22 AM, Daniel Trstenjak daniel.trsten...@gmail.com wrote: Looking at the function names: have you got a c programming background? Instead of using these prefixes you could put the functions into separate modules. Although I do have some background in C programming, these naming schemes are not my idea. Instead the function names match the names of the corresponding GDB/MI commands. I thought it would make sense to use these names for ease of reference. Given this, would you still prefer them being grouped in separate modules? If the interface depends on the GDB version, than it could make sense to encode the GDB version into the module name, something like: Gdbmi.V7_4.Commands Gdbmi.Commands is not the only module that depends on the GDB version. GDB/MI is in general still evolving and GDB's compliance with the documentation keeps on changing on all levels. So I would have to maintain all hgdbmi modules for each GDB version. Do you think this makes sense and is worth the effort? Greetings, Alex ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] regular expression sub-expression matching
Hello list, I was wondering whether there is a way to do what the following python code does in haskell: import re result = re.compile(M\(([0-9]+),([0-9]+)\) *= *([0-9.eE-]+);).search(M(1,2) = 0.1e-3;) if result: print(result.group(1), result.group(2), result.group(3)) Basically I would like to pattern match parts of a string and return the matches. I have looked at Text.Regex.Posix but (of course I might just not have understood the functions in there properly) it seems as if it does not provide anything like python's re module. Thanks already, nick ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] regular expression sub-expression matching
* Nicolas Bock nicolasb...@gmail.com [2013-01-18 16:25:31-0700] Hello list, I was wondering whether there is a way to do what the following python code does in haskell: import re result = re.compile(M\(([0-9]+),([0-9]+)\) *= *([0-9.eE-]+);).search(M(1,2) = 0.1e-3;) if result: print(result.group(1), result.group(2), result.group(3)) Basically I would like to pattern match parts of a string and return the matches. I have looked at Text.Regex.Posix but (of course I might just not have understood the functions in there properly) it seems as if it does not provide anything like python's re module. Take a look at the regex-applicative package. http://hackage.haskell.org/packages/archive/regex-applicative/0.2.1/doc/html/Text-Regex-Applicative.html Roman ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] regular expression sub-expression matching
Note that Haskell doesn't convert \( to \\( like Python does, so the regex string has been changed. It's not so easy to figure out how to use this library from the documentation because of all the typeclass trickery. h import Text.Regexp.Posix (getAllTextSubmatches, (=~)) h getAllTextSubmatches (M(1,2) = 0.1e-3; =~ M\\(([0-9]+),([0-9]+)\\) *= *([0-9.eE-]+);) :: [String] [M(1,2) = 0.1e-3;,1,2,0.1e-3] If it doesn't match, you'll get an empty list. You can join the tail of the match list together with Data.List.intercalate, and print it out with putStrLn. The if null case would just return (). To demonstrate some of the typeclass trickery going on here, you could ask for the results as an Array with Int indexes of String. h import Text.Regexp.Posix (getAllTextSubmatches, (=~)) h import Data.Array ((!), Array) h let matches = getAllTextSubmatches (M(1,2) = 0.1e-3; =~ M\\(([0-9]+),([0-9]+)\\) *= *([0-9.eE-]+);) :: Array Int String h matches array (0,3) [(0,M(1,2) = 0.1e-3;),(1,1),(2,2),(3,0.1e-3)] h map (matches !) [1..3] [1,2,0.1e-3] -bob On Fri, Jan 18, 2013 at 3:25 PM, Nicolas Bock nicolasb...@gmail.com wrote: Hello list, I was wondering whether there is a way to do what the following python code does in haskell: import re result = re.compile(M\(([0-9]+),([0-9]+)\) *= *([0-9.eE-]+);).search(M(1,2) = 0.1e-3;) if result: print(result.group(1), result.group(2), result.group(3)) Basically I would like to pattern match parts of a string and return the matches. I have looked at Text.Regex.Posix but (of course I might just not have understood the functions in there properly) it seems as if it does not provide anything like python's re module. Thanks already, nick ___ 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
[Haskell-cafe] resources for learning Hindley-Milner type inference for undergraduate students
Petr Pudlak wrote: could somebody recommend me study materials for learning Hindley-Milner type inference algorithm I could recommend to undergraduate students? Perhaps you might like a two-lecture course for undergraduates, which uses Haskell throughout http://okmij.org/ftp/Haskell/AlgorithmsH.html#teval It explained HM type inference in a slightly different way, strongly emphasizing type inference as a non-standard interpretation. The second main idea was relating polymorphism and `inlining' (copying). Type schemas were then introduced as an optimization, to inlining. It becomes clear why it is unsound to infer a polymorphic type for ref []: expressions of polymorphic types are always inlined (conceptually, at least), which goes against the dynamic semantics of reference cells. The lectures also show how to infer not only the type but also the type environment. This inference helps to make the point that `tests' cannot replace typing. We can type check open expressions (and infer the minimal environment they make sense to use in). We cannot run (that is, dynamically check) open expressions. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
