- Haskell-Cafe - Haskell.org

async simplify code
by grant weyburne 06 Jul '14

06 Jul '14

Hi Cafe, Is there any way to simplify this async code to somehow merge the withAsync code into the STM code? Looking at the code for tstABorCD it is not easy to see that it is really just (A&&B)||(C&&D). Here is the code: http://lpaste.net/106945 Thanks for any pointers, Grant

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Restarting doc build on hackage
by Erik Hesselink 05 Jul '14

05 Jul '14

Hi cafe, Does anyone know if there is a way to restart a documentation build on hackage? We have a package where the documentation failed to build due to a dependency lacking upper bounds. That has recently been fixed (using the new in-place cabal file editing feature), and we'd like to get documentation for our package now. Is there any way to do this (apart from uploading a new version without changes)? Erik

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Signal Processing Library
by Vivian McPhail 05 Jul '14

05 Jul '14

Hi, There is also a signal processing package on Hackage [1] which performs auto_correlation. FFT is has been moved from hmatrix to hmatrix-gsl [2]. Hope this helps. Cheers, Vivian [1] http://hackage.haskell.org/package/hsignal <http://hackage.haskell.org/package/hstatistics> [2] http://hackage.haskell.org/package/hmatrix-gsl <http://hackage.haskell.org/package/hstatistics> Date: Fri, 4 Jul 2014 10:19:51 -0700 > From: Jeremy Wright <jeremy(a)codestrokes.com> > To: "haskell-cafe(a)haskell.org" <haskell-cafe(a)haskell.org> > Subject: [Haskell-cafe] Signal Processing Library > Message-ID: <BAY179-W29288B298009D61A9BC5A2B9000(a)phx.gbl> > Content-Type: text/plain; charset="iso-8859-1" > > Hello: > > I'm working on my Master's Thesis, and I need a signal processing library > that can compute FFTs and autocorrelation on discrete data. Doesn't anyone > have experience with such a package in Haskell? I appreciate your time. > > Sincerely, > Jeremy Wright > >

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How to state semantics in denotational design?
by Hans Höglund 05 Jul '14

05 Jul '14

Dear all, This may seem a strange question due to my unfamiliarity with formal semantics, but bear with me. I am trying to apply denotational design principles to my library music-score, and often find myself writing down semantics of data structures in pseudo-Haskell such as > type Duration = Double > type Time = Point Duration > type Span = Time^2 > type Note a = (Span, a) The actual implementation of the data structures may or may not be identical to the semantics. For example, it makes sense to implement Span as (Time^2) or (Time x Duration), as these types are isomorphic. My question is basically: 1) Is my approach (using pseudo-Haskell) a sound way to state denotational semantics? 2) How can I state semantics (in code and/or documentation), and be sure that my implementation follow the semantics? I understand that the correctness of the implementation w.r.t. to the semantics can be verified using manual proofs, which worries me as I want to be able to refactor the semantics and be make sure that the implementation is still correct without having to repeat all the proofs. Is there a "trick" to encode the semantics in actual Haskell and have the type system and/or QuickCheck do the verification for me? Or am I misunderstanding the concept of denotational design? Sincerly, Hans - Hans Höglund Composer, conductor and developer hans [at] hanshoglund.se hanshoglund.com https://twitter.com/hanshogl https://soundcloud.com/hanshoglund http://github.com/hanshoglund

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Signal Processing Library
by Jeremy Wright 04 Jul '14

04 Jul '14

Hello: I'm working on my Master's Thesis, and I need a signal processing library that can compute FFTs and autocorrelation on discrete data. Doesn't anyone have experience with such a package in Haskell? I appreciate your time. Sincerely, Jeremy Wright

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New Functional Programming Job Opportunities
by Functional Jobs 04 Jul '14

04 Jul '14

Here are some functional programming job opportunities that were posted recently: Developer / DevOps Engineer at Klarna http://functionaljobs.com/jobs/8721-developer-devops-engineer-at-klarna Cheers, Sean Murphy FunctionalJobs.com

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How to deal with dependency bounds for an application
by Alois Cochard 04 Jul '14

04 Jul '14

Hey, I have wrote a little tool and some people had issues installing it with cabal and had to use "--reorder-goals" to be able to install it [1]. Obviously it's because I have very few dependency bounds (actually near none aside base). I don't have to be convince that it's a bad idea, the motivation for adding bounds are pretty clear... but... I'm not sure how to define them? Should I know what is the lowest possible combination of my dependencies who would compile... because if I'm too strict it might be difficult for some user to install? or maybe I should target as lowest what is in current haskell-platform? I'm looking for some advice and feedback from maintainers. Thanks in advance! [1]: https://github.com/aloiscochard/codex/issues/6 -- *A\ois* http://twitter.com/aloiscochard http://github.com/aloiscochard

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Proposal: New mailing lists -- haskell-jobs & haskell-academia
by Alexander Berntsen 04 Jul '14

04 Jul '14

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 The proposal is simply as follows. 1. Make a list, haskell-jobs. This would be primarily for job postings and looking-for-job posts. A secondary purpose is discussing jobs. E.g. "Anyone know any jobs in the Foo area?", and meta-discussions like "How well does Haskell jobs pay in your experience?". 2. Make a list, haskell-academia. This would be primarily for studentship postings and call for papers. A secondary purpose is discussing academia. E.g. "Anyone know any unis that use Haskell extensively in the Foo area?", and meta-discussions like "How well is Haskell taught at unis in your experience?" The motivation for this is twofold. 1. We get a lot of job postings and studentship postings. Many of these will be ignored by readers, up until they suddenly find themselves looking for a job or studentship. It would be useful if they could then easily filter their email on lists -- or go to the online archives for that specific list. The latter is a big Win, because they needn't even be subscribed in the first place. 2. Job/studentship postings are effectively spam, unless you are actually looking for that kind of information. This proposal will reduce the amount of spam people get. That's always nice. Two weeks should be a satisfactory discussion period. - -- Alexander alexander(a)plaimi.net https://secure.plaimi.net/~alexander -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iF4EAREIAAYFAlO1W6MACgkQRtClrXBQc7Vu1wD/YSAY6AwqzBR74y7zF7OXjaHv 1PwRWglP/hIMOKeI5pAA/iIfvderfxrVLuVwG37ldQ3ar9Xb6+WG1zPfW3vW/PRv =zNvy -----END PGP SIGNATURE-----

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Type-level Nat to Integer
by Gautier DI FOLCO 04 Jul '14

04 Jul '14

Hi all, I'm trying to change type-level Nat to Integer as following: {-# LANGUAGE DataKinds, KindSignatures, GADTs, PolyKinds #-} data Nat = Z | S Nat class NatToInt n where natToInt :: n -> Int instance NatToInt Z where natToInt _ = 0 instance NatToInt (S n) where natToInt = 1 + natToInt (undefined :: n) I understand why it fails (Z and S have not the right kind). How to specify that NatToInt is Nat-specific? Moreover, if you have any advanced explanations/links which could give me a deeper understanding on what going on, I'll take them. Thanks in advance for your help.

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Making the Haskell 2010 report latex repo
by Christopher Done 04 Jul '14

04 Jul '14

The Haskell 2010 report is here: http://darcs.haskell.org/haskell2010-report Also mirrored in git here: git@github.com:hvr/haskell2010-report.git This version doesn't build because it uses old "Char" instead of "Data.Char"-style imports. So my version here: https://github.com/chrisdone/haskell2010-report Fixes that: https://github.com/chrisdone/haskell2010-report/commit/6a773abb7201f4854ba5… But that's as far as I get. Here is what happens when I run $ cd tools; make; cd .. $ cd report; make I get: http://lpaste.net/raw/5699097250156773376 As is typical in the LaTeX, a torrent of uninteresting information is spewed out. Finally, at the end, it says: > (./haskell.ind (./index-intro.tex) > ! Argument of \OT1\" has an extra }. > <inserted text> > \par > l.61 \item |hyperindexformat{\"} > , 51, 73, 107, 112 > ? Does anyone familiar with the language of LaTeX have any idea what's going on? Has anyone successfully been able to build it? If so, please state the exact steps to do so and I will be very grateful. Ciao!

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