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installation problems: wx, phooey, checkers
by Jeffrey Brown 01 Dec '14

01 Dec '14

I believe I have wxWidgets installed, because when I go to the demos/ or samples/ subfolders of ~/wxWidgets-3.0.2/build-cocoa-debug/, I can run the apps. Now I want to install the phooey library for Haskell. When I try, I am warned that some things will be broken, so I unregister them and then cabal install them all at once. (The complete output from my session with cabal appears below.) I run cabal from ~/wxWidgets, because that folder contains the files wx-config-inplace.in wx-config.in and I know cabal wants wx-config. The two errors I get: wx-config is not found checkers does not install I am left stumped. Thanks for your help. -------------------- jefferys-mbp:~ jbb$ cd wxWidgets-3.0.2/ jefferys-mbp:wxWidgets-3.0.2 jbb$ cabal install phooey Resolving dependencies... In order, the following would be installed: mtl-1.1.1.1 (latest: 2.2.1) (new version) parsec-3.1.7 (reinstall) changes: mtl-2.2.1 -> 1.1.1.1 reactive-0.5.0.1 (latest: 0.11.5) (new package) wxdirect-0.91.0.0 (reinstall) wxc-0.91.0.0 (new package) wxcore-0.91.0.0 (new package) wx-0.91.0.0 (new package) phooey-2.0.0.1 (new package) cabal: The following packages are likely to be broken by the reinstalls: tidal-0.4.21 network-uri-2.6.0.1 threepenny-gui-0.5.0.0 hmt-0.15 Use --force-reinstalls if you want to install anyway. jefferys-mbp:wxWidgets-3.0.2 jbb$ ghc-pkg unregister tidal jefferys-mbp:wxWidgets-3.0.2 jbb$ ghc-pkg unregister threepenny-gui jefferys-mbp:wxWidgets-3.0.2 jbb$ ghc-pkg unregister network-uri jefferys-mbp:wxWidgets-3.0.2 jbb$ ghc-pkg unregister hmt jefferys-mbp:wxWidgets-3.0.2 jbb$ cabal install tidal network-uri threepenny-gui hmt phooey Resolving dependencies... Configuring checkers-0.1.4... Configuring network-uri-2.6.0.1... Configuring hmt-0.15... Configuring wxc-0.91.0.0... Building network-uri-2.6.0.1... Building checkers-0.1.4... Building hmt-0.15... Failed to install checkers-0.1.4 Last 10 lines of the build log ( /Users/jbb/.cabal/logs/checkers-0.1.4.log ): at src/Test/QuickCheck/Instances/Num.hs:23:12-49 Possible fix: add (Eq a) to the context of the type signature for nonZero :: (Num a, Arbitrary a) => Gen a -> Gen a In the first argument of ‘satisfiesM’, namely ‘(/= 0)’ In the expression: satisfiesM (/= 0) (if (s == 0) then (resize 1 g) else g) In the first argument of ‘sized’, namely ‘(\ s -> satisfiesM (/= 0) (if (s == 0) then (resize 1 g) else g))’ Failed to install wxc-0.91.0.0 Last 10 lines of the build log ( /Users/jbb/.cabal/logs/wxc-0.91.0.0.log ): [1 of 1] Compiling Main ( /var/folders/q1/2_cf13z53tg__sqdk7v8ycgm0000gn/T/wxc-0.91.0.0-41510/wxc-0.91.0.0/Setup.hs, /var/folders/q1/2_cf13z53tg__sqdk7v8ycgm0000gn/T/wxc-0.91.0.0-41510/wxc-0.91.0.0/dist/setup/Main.o ) Linking /var/folders/q1/2_cf13z53tg__sqdk7v8ycgm0000gn/T/wxc-0.91.0.0-41510/wxc-0.91.0.0/dist/setup/setup ... Error: wx-config not found, please install wx-config before installing wxc Installed network-uri-2.6.0.1 Configuring threepenny-gui-0.5.0.0... Building threepenny-gui-0.5.0.0... Installed threepenny-gui-0.5.0.0 Installed hmt-0.15 Configuring tidal-0.4.21... Building tidal-0.4.21... Installed tidal-0.4.21 Updating documentation index /Users/jbb/Library/Haskell/share/doc/index.html cabal: Error: some packages failed to install: checkers-0.1.4 failed during the building phase. The exception was: ExitFailure 1 phooey-2.0 depends on wxc-0.91.0.0 which failed to install. reactive-0.9.3 depends on checkers-0.1.4 which failed to install. wx-0.91.0.0 depends on wxc-0.91.0.0 which failed to install. wxc-0.91.0.0 failed during the configure step. The exception was: ExitFailure 1 wxcore-0.91.0.0 depends on wxc-0.91.0.0 which failed to install.

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Haskell in the "Enterprise"
by gonzaw 01 Dec '14

01 Dec '14

Hi. I've been wondering if there are any plans or projects to bring Haskell to the "enterprise" ecosystem An by this I mean allowing applications made in Haskell (and other languages) to be integrated in a distributed fashion, easily being able to integrate different systems (DBMSs, web services, etc), etc. For example, creating an ESB in Haskell to allow easier integration of distributed applications. We all worked (or know someone who worked) with huge Java/IBM/etc enterprise systems, and know how clunky the experience was. Being able to include Haskell in this ecosystem would be so refreshing. I was also wondering if there is any research going on on how to apply the mathematical concepts and FP principles behind Haskell to these enterprise constructs. For instance, how to apply FP and category theory to Enterprise Application Integration to make scalable, robust and composable systems that are actually easy to use and discover. For example, I always had this idea of having "pure Web Services" and "effectful Web Services" as different protocols that can be used in different ways depending on the service being provided. Or maybe allowing functions to be passed as parameters in web services, by defining a small typed lambda calculus that can be serialized to XML and passed in a SOAP message (with the appropriate interpreters in the client+server). The ideas never went beyond that, but they sparked my interest in this sort of thing. To start somewhere, are there any Haskell libraries with Web Service support? Like a WS client tools (SOAP messaging DSL + WSDL import tool)? Or a haskell library that allows one to provide web services (and maybe provide the WS-* extensions)? -- View this message in context: http://haskell.1045720.n5.nabble.com/Haskell-in-the-Enterprise-tp5761538.ht… Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.

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Kind product
by Gautier DI FOLCO 01 Dec '14

01 Dec '14

Hello all, I have the following code: {-# LANGUAGE NoImplicitPrelude #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE KindSignatures #-} {-# LANGUAGE DataKinds #-} {-# LANGUAGE PolyKinds #-} data Branch = Left | Right type family Product (v :: Branch) (a :: k) (b :: k) :: k where Product Left l r = l Product Right l r = r My goal is to have a thing like that: type family Product (v :: Branch) (a :: k1) (b :: k2) :: (Either k1 k2) where Is it possible to do such a thing? If not I can find a solution with Kind families/Kind pattern matching, but I don't think that exists, am I wrong? Thanks in advance for your help, Regards.

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How to update Cabal manually?
by Jeffrey Brown 01 Dec '14

01 Dec '14

"cabal install cabal-install" is not working for me. I am not the first to find this problem; it is mentioned here <https://www.haskell.org/haskellwiki/Cabal/Survival>: "Notice, that in some cases (OS X, especially) the new cabal-install might not be installed on top of the previous one, and the old cabal-install must be replaced manually" I don't know how to manually replace Cabal. The closest thing I could find to instructions for that were here <https://www.haskell.org/pipermail/haskell-cafe/2010-February/073526.html>, but I don't understand them. The Haskell Platform installer is what installed Cabal for me. I have not found how to undo that, nor how to install Cabal in any other fashion. Running the Haskell Platform installer again seems dangerous, potentially conflicting with its earlier work. A likely unnecessary shell transcript demonstrating the problem appears below. I am running OS X 10.9 on a MacBook Pro, of which the decision to purchase I regret more daily. Thank you. ----- When I try to update cabal, it looks like it works: jefferys-mbp:~ jbb$ cabal install cabal-install Resolving dependencies... Configuring cabal-install-1.20.0.3... Building cabal-install-1.20.0.3... Installed cabal-install-1.20.0.3 Updating documentation index /Users/jbb/Library/Haskell/share/doc/index.html But the version number exhibits no change: jefferys-mbp:~ jbb$ cabal --version cabal-install version 1.18.0.5 using version 1.18.1.4 of the Cabal library

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Typeclass Show Question
by Yasuaki Kudo 01 Dec '14

01 Dec '14

Hi, When I launch GHCI with the option -XGADTs and load the following program, f = \x y -> (1, x,y) data S a b where S :: (Num a, Num b) => a -> b -> S a b I encounter this dialog: *Main> S 1 1 <interactive>:3:1: No instance for (Show (S a0 b0)) arising from a use of `print' Possible fix: add an instance declaration for (Show (S a0 b0)) In a stmt of an interactive GHCi command: print it I tried to follow the recommendation but still could not figure out how. For example, after adding: instance Show (S a b) where show (S x y) = show(x) I still get: conmath.hs:10:24: Could not deduce (Show a) arising from a use of `show' from the context (Num a, Num b) bound by a pattern with constructor S :: forall a b. (Num a, Num b) => a -> b -> S a b, in an equation for `show' at conmath.hs:10:15-19 Possible fix: add (Show a) to the context of the data constructor `S' or the instance declaration In the expression: show (x) In an equation for `show': show (S x y) = show (x) In the instance declaration for `Show (S a b)' Failed, modules loaded: none. What should I do to show S 1 1 ? Regards, Yasu

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Hosting a static site with Yesod
by Yifan Yu 30 Nov '14

30 Nov '14

Hi all, I'm experimenting with Yesod and I've created a simple scaffolding site with yesod. I've downloaded a bootstrap template site and wish to simply host this site with yesod. The template site has an index.html and a bunch of css and js files. This seemly simple task has baffled me. By my understanding, the site should be placed under the 'static' directory, I tried to use sendFile to send the index.html file in getHomeR, but only the content of the that file is displayed, without the css and js. Should I do this with a Subsite? Thank you

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multiple declarations error in Haskell - should it be relaxed?
by Andrew Butterfield 30 Nov '14

30 Nov '14

Condsider the following Haskell program (fragment): f 0 = “zero” g 0 = “NULL” f n = “non-zero” g n = “PRESENT” This will result in two “Multiple Declaration” errors. There is a good motivation for this - disallowing such an interleaving of declarations makes it easy for the compiler to capture a common typo, namely errors of the following form - here an attempt to define a single function called myFun. myFun 0 = “zero” myfun 1 = “one” myFun n = “too big!” However I have use-cases where it would be nice to interleave as per the first example above - with markedly different function names. It invokes a large case analysis, where I have other auxiliary functions associated with each case, but which I’d like to (1) have at the top-level for testability (2) keep textually local to the case with which they are associated. I don’t think there is a language extension to disable the multiple declaration check - but would such a feature we possible. I’d see it as one which still performs the check, but issues a warning rather than an error - particularly if it notices that the interleaved names are very similar. Is this a reasonable suggestion, or are there other reasons for not doing this that I’ve missed? Maybe there is a better way to satisfy (1) and (2) above? Regards, Andrew -------------------------------------------------------------------- Andrew Butterfield Tel: +353-1-896-2517 Fax: +353-1-677-2204 Lero@TCD, Head of Foundations & Methods Research Group School of Computer Science and Statistics, Room G.39, O'Reilly Institute, Trinity College, University of Dublin http://www.scss.tcd.ie/Andrew.Butterfield/ --------------------------------------------------------------------

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[Announce] Music Suite v1.8
by Hans Höglund 30 Nov '14

30 Nov '14

I am happy to announce the release of Music Suite version 1.8. This release in short: Cleaner API for dealing with Voices, Notes and time structures in general. New equal-temperament pitch representation. Improved handling of diatonic vs. chromatic transposition in the Common pitch representation. Better support for clef and staff line positions. Better support for handling instrument ambitus etc. See full notes at https://github.com/music-suite/music-docs/blob/master/releases/Notes.md#18 The Music Suite is a language for description, analysis, composition and manipulation of music embedded in Haskell. For more information see http://music-suite.github.io or my talk at FARM2014 http://functional-art.org/2014/. Regards, Hans Hoeglund - https://twitter.com/hanshogl https://soundcloud.com/hanshoglund http://github.com/hanshoglund

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Getting Haskell in the top 20
by Henk-Jan van Tuyl 30 Nov '14

30 Nov '14

L.S., In the Tiobe Index[0], F# jumped from position 43 in June to 13 in July and is since than in the top twenty. What happened in July and how can we get Haskell in the top 20? Regards, Henk-Jan van Tuyl [0] http://www.tiobe.com/index.php/content/paperinfo/tpci/index.html -- Folding@home What if you could share your unused computer power to help find a cure? In just 5 minutes you can join the world's biggest networked computer and get us closer sooner. Watch the video. http://folding.stanford.edu/ http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html Haskell programming --

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looking for ongoing Haskell projects ..
by Vasili I. Galchin 30 Nov '14

30 Nov '14

Hi Fellow Haskellers, I was just reading at http://www.haskell.org. I am looking for a list of currently active Haskell projects needing help .. :-) Vasili

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