November 2011 - Haskell-Cafe

doctest: Interpreter exited with an error: ExitFailure 127
by informationen 16 Nov '11

16 Nov '11

Hi, i have upgraded to doctest version 0.4.1. Now when i try to run the example from the webpage, i get: doctest: Interpreter exited with an error: ExitFailure 127 What's wrong here and how can i fix it? Kind regards Chris This is the content of Fib.hs: module Fib where -- | Compute Fibonacci numbers -- -- Examples: -- -- >>> fib 10 -- 55 -- -- >>> fib 5 -- 5 fib 0 = 0 fib 1 = 1 fib n = fib (n - 1) + fib (n - 2) main = do print $ fib 4

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Tutorial/slides on pretty-printing combinators?
by Sean Leather 16 Nov '11

16 Nov '11

Do you know of any tutorial or slides from a talk on one of the pretty-printing libraries? It could be on Text.PrettyPrint.HughesPJ or uulib or any other, similar library. I'm thinking of developing slides for a course, and I'm looking for sources of inspiration. Regards, Sean

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Re: [Haskell-cafe] Amazon AWS storage best to use with Haskell?
by dokondr 16 Nov '11

16 Nov '11

On Mon, Oct 31, 2011 at 6:50 PM, John Lenz <lenz(a)math.uic.edu> wrote: > CouchDB works great, although I decided to go with SimpleDB since then it > is amazon's problem to scale and allocate disk and so forth, which I like > better. For couchdb, you can use my package couchdb-enumerator on hackage. > > > Regarding CouchDB. So far I have my records keyed by Id and stored in Data.Map which I serialize to text file. Using Data.Map functions I do many operations with these records including mapping functions over keys and values, accumulation, lookup, intersection, union etc. When I move this data to CouchDB and start using couchdb-enumerator to work with it, how natural will it be to implement all these functions that I use from Data.Map? Or maybe it makes more sense to store my serialized Data.Map as a blob in CouchDB? And do not use views or similar CouchDB / SimpleDB interfaces at all? Just retrieve necessary blob and deserialize it to Data.Map, update and then store modified blob to CouchDB again? It would be great if somebody had time to implement Data.List, Data.Map, etc on top of generic NoSQL DB interface with specific instances for CouchDB, SimpleDB, etc.

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Dutch National FP Day 2012
by Sean Leather 16 Nov '11

16 Nov '11

(Sent on behalf of Doaitse Swierstra) Despite some last minute changes to the planning we are happy to announce that the next Dutch functional programming day will take place on January 6, 2012, at the university campus "De Uithof" of Utrecht University. In case you want to give a presentation please send title, speaker and abstract to doaitse(a)swierstra.net before Dec 1. We will collect the proposals and try to make an interesting program out of it. Further details will be placed on the site: http://www.cs.uu.nl/wiki/FPDag2012 Best, hoping to see you all, Doaitse

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How to Create Programming Language with Haskell?
by Shogo Sugamoto 16 Nov '11

16 Nov '11

Hi,Cafe. I want to create my own Programming Language with Haskell, and I learn how to do it. I read: WikiBooks of "Write Yourself a Scheme in 48 Hours", "Real World Haskell" of Chapter "Using Parsec", Source of "HJS", Book of "Introduction of Functional Programming Using Haskell". Ok,What is another good source creating my own Programming Language with Haskell? Thanks :) esehara

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(no subject)
by Benjamin L. Russell 16 Nov '11

16 Nov '11

http://elikat.com/blogs/wp-content/plugins/index1.php

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Re: [Haskell-cafe] A Mascot
by heathmatlock 15 Nov '11

15 Nov '11

On Tue, Nov 15, 2011 at 7:06 PM, Ivan Lazar Miljenovic < ivan.miljenovic(a)gmail.com> wrote: > Ummmmm.... do we _really_ need a mascot? I don't think a programming community every really needs a mascot, just nice to have. > And no offence to your > artistic abilities, but even if we did, I don't see how a lamb relates > to Haskell :/ > > The lamb is a play on lambda calculus. -- Heath Matlock +1 256 274 4225

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Second CfP: International Conference on Test and Proofs (TAP 2012), Next Deadline: 2011-12-14
by Achim D. Brucker 15 Nov '11

15 Nov '11

(Apologies for duplicates) ************************************************* **** Less than one month until the deadline *** **** for submitting abstract to TAP 2012 *** ************************************************* CALL FOR PAPERS Full and short Research Paper, Industrial Expierence Papers, Tool Papers Abstract submission: Dec 14, 2011, Paper submission Dec 21, 2012 6th INTERNATIONAL CONFERENCE ON TEST AND PROOFS (TAP 2012) http://lifc.univ-fcomte.fr/tap2012/ May 31 - June 1, 2012, Prague, Czech Republic Part of the TOOLS Federated Conferences 2012 http://tools2012.fit.cvut.cz/ The TAP conference is devoted to the convergence of proofs and tests, to the application of techniques from both sides and their combination for the advancement of software quality. Test and Proof seem to be contradictory techniques: if you have proved your program to be correct, it is fruitless to comb it for bugs; and if you are testing it, that is surely a sign that you have given up on any hope to prove its correctness. Accordingly, proofs and tests have, since the onset of software engineering research, been pursued by distinct communities. However, the development of both approaches lead to the discovery of common issues and to the realization that each may need the other. The emergence of model checking has been one of the first signs that contradiction may yield to complementarity. Further evidence give test data generation techniques from models or programs which boil down to constraint resolution techniques for relatively large formula; the advent of powerful SMT solvers have therefore powered new testing techniques. Finally, since formal, proof-based verification is costly, testing invariants and background theories can be helpful to detect errors early and to improve cost effectivity. Summing up, in the past few years an increasing number of research efforts have encountered the need for combining proofs and tests, dropping earlier dogmatic views of incompatibility and taking instead the best of what each of these software engineering domains has to offer. The TAP conference aims to bring together researchers and practitioners working in the converging fields of testing and proving, and will offer a generous allocation of papers, panels and informal discussions. Topics of interest cover theory definitions, tool constructions and experimentations and include (other topics related to TAP are welcome): - Transfer of concepts from testing to proving (e.g., coverage criteria) and from proving to testing - Program proving with the aid of testing techniques - New problematics in automated reasoning emerging from specificities of test generation - Verification and testing techniques combining proofs and tests - Generation of test data, oracles, or preambles by deductive techniques such as: theorem proving, model checking, symbolic execution, constraint logic programming - Model-based testing and verification - Generation of specifications by deduction - Automatic bug finding - Debugging of programs combining static and dynamic analysis - Formal frameworks - Tool descriptions and experience reports - Case studies combining tests and proofs - Applying combination of test and proof techniques to new application domains such as validating security procotols or vulnerability detection of programs Important Dates: ================ Abstract submission: December 14, 2011 Paper submission: December 21, 2011 Notification: March 2, 2012 Camera ready version: March 19, 2012 TAP conference: May 31 - June 1, 2012 (to be confirmed) TOOLS conferences (TOOLS, ICMT, SC, TAP): May 29 - June 01, 2012 Conference Chairs: Bertrand Meyer Program Chairs: Achim D. Brucker and Jacques Julliand Program Committee (to be extended): =================================== Nazareno Aguirre, Bernhard K. Aichernig, Paul Ammann, Dirk Beyer, Nikolaj Bjorner, Robert Clarisó, Marco Comini, Catherine Dubois, Gordon Fraser, Angelo Gargantini, Alain Giorgetti, Patrice Godefroid, Martin Gogolla, Arnaud Gotlieb, Reiner Hähnle, Bart Jacobs, Thierry Jéron, Gregory Kapfhammer, Nikolai Kosmatov, Victor Kuliamin, Karl Meinke, Jeff Offutt, Holger Schlingloff, T.H. Tse, Margus Veanes, Luca Viganò, Burkhart Wolff, Fatiha Zaidi Submission: =========== Please submit your papers via http://lifc.univ-fcomte.fr/tap2012/. TAP 2012 will accept two types of papers: - Research papers: full papers with at most 16 pages in LNCS format (pdf), which have to be original, unpublished and not submitted elsewhere. - Short contributions: work in progress, (industrial) experience reports or tool demonstrations, position statements; an extended abstract with at most 6 pages in LNCS format (pdf) is expected. Accepted papers will be published in the Springer LNCS series and will be available at the conference. The contents of previous TAP proceedings is available at: http://www.informatik.uni-trier.de/~ley/db/conf/tap/ -- Dr. Achim D. Brucker, SAP Research, Vincenz-Priessnitz-Str. 1, D-76131 Karlsruhe Phone: +49 6227 7-52595, Fax: +49-6227 78-50502, http://www.brucker.ch

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Build error with network/snap w/win7 haskell platform
by Adam Turoff 15 Nov '11

15 Nov '11

I'm trying to build snap-0.6 on win7/x64 with the current 64-bit haskell platform. I have the mingw compilers from the platform in $PATH, and I can get the network and snap-server modules to build. But snap-0.6 fails: [18 of 31] Compiling Snap.Snaplet.Internal.Types ( src\Snap\Snaplet\Internal\Types.hs, dist\build\Snap\Snaplet\Internal\Types.o ) Loading package ghc-prim ... linking ... done. ... Loading package murmur-hash-0.1.0.4 ... linking ... done. Loading package parsec-3.1.2 ... linking ... done. Loading package network-2.3.0.7 ... linking ... ghc.exe: unable to load package `network-2.3.0.7' ghc.exe: C:\Users\aturoff\AppData\Roaming\cabal\network-2.3.0.7\ghc-7.0.3\HSnetwork-2.3.0.7.o: unknown symbol `_acceptNewSock' cabal.exe: Error: some packages failed to install: snap-0.6.0.2 failed during the building phase. The exception was: ExitFailure 1 Any ideas? The platform comes with network-2.3.0.2, but cabal insists on upgrading it. Is there some way to force cabal to use the version that came with the platform instead? Specifying network==2.3.0.2 as a dependency just rebuilds it as a user package. Thanks, -- Adam

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deepseq-1.2.0.1 missing Data.Map instance
by Henry Laxen 15 Nov '11

15 Nov '11

Dear Group, Today I tried to compile snap 0.6 with ghc 7.2, (using virthualenv, which is GREAT by the way) and got the following error somewhere along the way got a message about aeson-native requires deepseq-1.1.0.2 but I had deepseq-1.2.0.1 installed. So I unpacked aeson-native-0.3.3.1 in my virthualenv and changed the build-depends to just deepseq which caused: Configuring aeson-native-0.3.3.1... Preprocessing library aeson-native-0.3.3.1... Building aeson-native-0.3.3.1... [2 of 6] Compiling Data.Aeson.Types ( Data/Aeson/Types.hs, dist/build/Data/Aeson/Types.o ) Data/Aeson/Types.hs:196:22: No instance for (NFData Object) arising from a use of `rnf' Possible fix: add an instance declaration for (NFData Object) In the expression: rnf o In an equation for `rnf': rnf (Object o) = rnf o In the instance declaration for `NFData Value' cabal: Error: some packages failed to install: aeson-native-0.3.3.1 failed during the building phase. The exception was: ExitFailure 1 A little investigating and I discovered that instance (NFData k, NFData a) => NFData (Data.Map.Map k a) where rnf = rnf . Data.Map.toList is in deepseq-1.1.0.2 but not in deepseq-1.2.0.1. Adding it back got aeson-native-0.3.3.1 and later snap-0.6 to compile just fine. So I guess my question is: Is there a reason that the map instance was removed from deepseq-1.2.0.1, and can we please put it back in? Thanks. Best wishes, Henry Laxen

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