- Haskell-Cafe - Haskell.org

yi-editor for emacer
by Junior White 15 Apr '13

15 Apr '13

Hi Cafe, I'm glad to announce my fork of yi-editor. As a emacer, I made yi-editor more emacs like, including the following change: 1. ido-mode like file find and buffer find 2. support more color in vty 3. automatic search tags file in parents's directory 4. change some keymap The following step to have a try: 1. clone : git clone https://github.com/onlyu/yi.git 2. build : ./yi/yi.sh --rebuild 3. run : ./yi/yi.sh Thanks for have a test, and thanks yi-editor, now I combine my favourite editor (emacs) and language (haskell) together. Apologize for my noisy!

2 1

Optimizing queries in Haskell
by Jan Stolarek 15 Apr '13

15 Apr '13

Dear list, list comprehensions and SQL-like generalized comprehensions can be used to write queries in Haskell. Does anyone know of any work focused on optimizing such queries? A quick google didn't show up anything meaningful. Janek

2 1

[Announcement] Sparse matrix Conjugate Gradient Solver
by Levent Erkok 15 Apr '13

15 Apr '13

I'm happy to announce the first release of conjugateGradient, implementing the Conjugate Gradient algorithm for solving linear systems of equations over sparse matrices: http://hackage.haskell.org/package/conjugateGradient The conjugate gradient algorithm only applies to the cases when the input matrix is symmetric and positive definite. See: http://en.wikipedia.org/wiki/Conjugate_gradient_method The advantage of this method is that it can handle really large sparse systems quite well, when other direct methods (such as LU decomposition) are just not practical due to algorithmic complexity. Such large and sparse systems naturally arise in engineering applications, such as in ASIC placement algorithms and when solving partial differential equations. Bug reports, feedback, and improvements are always welcome. -Levent.

2 1

Building the Haskell Platform in Linux
by Daniel Díaz Casanueva 15 Apr '13

15 Apr '13

Hi cafe! Probably you all know how to do this, but I myself found confused when building the Haskell Platform in Linux for my first time. I was using Linux for my first time too! The first problem I encountered was to decide what linux packages install to make the ./configure successful in both GHC binary distribution and the Haskell Platform. So I collected the names of the minimum set of packages that you need to have installed before starting with GHC and the Platform in a small blog post: http://deltadiaz.blogspot.com/2013/04/haskell-platform-from-source-in-linux… If I would have to start all over again, forgetting what I have learned so far, I would fine this list very useful! This thought is what brought me here to make it public. Who knows, maybe I am saving somebody of some google searches and trials and errors. With my best intentions, Daniel Díaz. -- E-mail sent by Daniel Díaz Casanueva let f x = x in x

2 3

multivariate normal distribution in Haskell?
by Bas de Haas 14 Apr '13

14 Apr '13

Dear List, I’m implementing a probabilistic model for recognising musical chords in Haskell. This model relies on a multivariate normal distribution. I’ve been searching the internet and mainly hackage for a Haskell library to do this for me, but so far I’ve been unsuccessful. What I’m looking for is a Haskell function that does exactly what the mvnpdf function in matlab does: http://www.mathworks.nl/help/stats/multivariate-normal-distribution.html Does anyone know a library that can help me out? Thanks. Kind regards, Bas de Haas -- dr. W. Bas de Haas Department of Information and Computing Sciences Utrecht University E: W.B.deHaas(a)uu.nl T: +31 30 253 5965 I: http://www.uu.nl/staff/WBdeHaas/

3 2

Re: [Haskell-cafe] <package>-inplace is shadowed by package <package>-<hexstring>
by Niklas Hambüchen 14 Apr '13

14 Apr '13

Hi, I just got the same thing with attoparsec GIT: Preprocessing benchmark 'benchmarks' for attoparsec-0.10.4.0... Building benchmark benchmarks... creating dist/build/benchmarks creating dist/build/benchmarks/benchmarks-tmp /home/niklas/opt/haskell-7.4/bin/ghc --make -fbuilding-cabal-package -O -odir dist/build/benchmarks/benchmarks-tmp -hidir dist/build/benchmarks/benchmarks-tmp -stubdir dist/build/benchmarks/benchmarks-tmp -i -idist/build/benchmarks/benchmarks-tmp -ibenchmarks -idist/build/autogen -Idist/build/autogen -Idist/build/benchmarks/benchmarks-tmp -optP-include -optPdist/build/autogen/cabal_macros.h -hide-all-packages -package-conf dist/package.conf.inplace -package-id base-4.5.1.0-66f22db3dfcd87541c9c7e50e7095d26 -package-id bytestring-0.9.2.1-503e91bb155301fdb1956cb5c26ce6e9 -package-id criterion-0.6.2.1-5bc7e5a96c8208948366b8e3ea536e68 -package-id deepseq-1.3.0.0-c26e15897417ecd448742528253d68f6 -package-id parsec-3.1.3-771f99c8818551756b6f2ec3e86ab039 -package-id text-0.11.2.3-db61832d0c4660614c4ceff234ed4abb -package-id attoparsec-0.10.4.0-inplace -XHaskell98 benchmarks/Benchmarks.hs -o dist/build/benchmarks/benchmarks <command line>: cannot satisfy -package-id attoparsec-0.10.4.0-inplace: attoparsec-0.10.4.0-inplace is shadowed by package attoparsec-0.10.4.0-c391286d724823eaea3d4278acc0acc0 (use -v for more information) I have no clue what's going on!

1 0

Invitation to connect on LinkedIn
by Chatura Roche 14 Apr '13

14 Apr '13

LinkedIn ------------ Chatura Roche requested to add you as a connection on LinkedIn: ------------------------------------------ Steve, I'd like to add you to my professional network on LinkedIn. - Chatura Accept invitation from Chatura Roche http://www.linkedin.com/e/-j6322o-hfici7ky-5i/v4h1gXJ8v-XpaSE4KRp1AY1vvMqM3… View profile of Chatura Roche http://www.linkedin.com/e/-j6322o-hfici7ky-5i/rso/115844279/bO7F/name/25907… ------------------------------------------ You are receiving Invitation emails. This email was intended for Steve Severance. Learn why this is included: http://www.linkedin.com/e/-j6322o-hfici7ky-5i/plh/http%3A%2F%2Fhelp%2Elinke… (c) 2012, LinkedIn Corporation. 2029 Stierlin Ct, Mountain View, CA 94043, USA.

1 0

Fwd: [Haskell-beginners] Monad instances and type synonyms
by Christopher Howard 14 Apr '13

14 Apr '13

I asked this question in Haskell-beginners, but I haven't heard anything yet, so I'm forwarding to Cafe. -------- Original Message -------- Subject: [Haskell-beginners] Monad instances and type synonyms Date: Sat, 13 Apr 2013 17:03:57 -0800 From: Christopher Howard <christopher.howard(a)frigidcode.com> Reply-To: The Haskell-Beginners Mailing List - Discussion of primarily beginner-level topics related to Haskell <beginners(a)haskell.org> To: Haskell Beginners <beginners(a)haskell.org> I am playing around with some trivial code (for learning purposes) I wanted to take code: -------- -- SaleVariables a concrete type defined early -- `Adjustment' represents adjustment in a price calculation -- Allows functions of type (a -> Adjustment a) to be composed -- with an appropriate composition function type Adjustment a = SaleVariables -> a -------- And put it into code: -------- instance Monad Adjustment where (>>=) = ... return = ... -------- If I try this, I get code: -------- Type synonym `Adjustment' should have 1 argument, but has been given none In the instance declaration for `Monad Adjustment' -------- But if I give an argument, then it doesn't compile either (it becomes a "*" kind). And I didn't want to make the type with a regular "data" declaration either, because then I have to give it a constructor, which doesn't fit with what I want the type to do. -- frigidcode.com

4 4

Re: [Haskell-cafe] Fwd: [Haskell-beginners] Monad instances and type synonyms
by Chris Wong 14 Apr '13

14 Apr '13

On Sun, Apr 14, 2013 at 5:10 PM, Christopher Howard <christopher.howard(a)frigidcode.com> wrote: > type Adjustment a = SaleVariables -> a > > [...] > > instance Monad Adjustment where > > (>>=) = ... > return = ... Essentially, you can't partially apply type synonyms. I don't recall the exact reasoning, but if this sort of thing was allowed it would probably poke funny holes in the type system. Also, Control.Monad.Instances already supplies a Monad instance for functions (r -> a). So even if that did pass, you'd bump into overlapping instances anyway. Chris > -------- > If I try this, I get > > code: > -------- > Type synonym `Adjustment' should have 1 argument, but has been given none > In the instance declaration for `Monad Adjustment' > -------- > > But if I give an argument, then it doesn't compile either (it becomes a > "*" kind). And I didn't want to make the type with a regular "data" > declaration either, because then I have to give it a constructor, which > doesn't fit with what I want the type to do. > > -- > frigidcode.com > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > -- Chris Wong, fixpoint conjurer e: lambda.fairy(a)gmail.com w: http://lfairy.github.io/

2 1

case switch covering all possible constructor but still fails
by Nathan Hüsken 13 Apr '13

13 Apr '13

Hey, I am trying to fix (or at least get my head around) this: https://github.com/valderman/haste-compiler/issues/27 Which is an issue of the haste haskell->javascript compiler. Doing so I encounter this problem which makes me think I am not understanding something fundamental here (and I believe this not to be haste specific)... OK, the problem is that this code: genAlt :: Bool -> JSVar -> JSVar -> StgAlt -> JSGen Config JSAlt genAlt tailpos scrut res (con, args, used, body) = do construct <- case con of DEFAULT -> return Def LitAlt l -> Cond <$> genLit l DataAlt c | Right tag <- genDataConTag c -> return $ Cond tag _ -> error "Bad data constructor tag generated!" Looking at StgAlt, I conclude that con must be of type AltCon, which is defined like this (from CoreSyn.lhs of the ghc source): data AltCon = DataAlt DataCon | LitAlt Literal | DEFAULT deriving (Eq, Ord, Data, Typeable) What I do not understand: The case switch covers all possibilities of AltCon. So how can this happen? Using trace, the con seemed to have the type "GHC.Integer.Type.S#" in the case of the erro. Thanks! Nathan

3 3