November 2012 - Haskell-Cafe

code length in Haskell, a comparison
by Gregory Guthrie 20 Nov '12

20 Nov '12

There is some interesting data in the article at: Code Length Measured in 14 Languages http://blog.wolfram.com/2012/11/14/code-length-measured-in-14-languages/ basically comparing program lengths in various languages, and some ensuing discussion of how this relates to language expressiveness, etc. (He does all of his analysis in Mathematica, which is the goal of the article.) It is interesting to see how well Haskell showed in the data; and it would also be interesting to see how well it could replicate the analysis example which was a nice example of web data scraping! The data is the length of a series of programs written in a number of languages (data from: http://rosettacode.org/wiki/Rosetta_Code) (The columns don't map well to text only, Haskell column marked with ≡≡≡≡ (Why doesn't this list support HTML?)). See nicer version at: http://pastehtml.com/view/ciy7woohv.rtxt The average for Haskell of 1.89 means that on the average the same program in Haskell takes ~2x in the other languages. Given the correlation of size to clarity, complexity, effort, and errors, this is a good thing! :-) Code Size relative to Mathematica Larger numbers indicate that the language on top needs more code. C C++ Fortran Java CLisp Python C# JavaScript R MATLAB Clojure Pascal Haskell Ruby Average ??????????? ???? ???? ???? ???? ???? ???? ???? ???? ???? ???? ???? ???? ≡≡≡≡ ???? Mathematica 17.0 9.1 8.1 6.4 6.3 7.2 6.4 5.0 3.2 3.2 1.6 5.8 3.5 5.2 6.29 Ruby 2.7 1.8 1.9 1.3 1.1 1.1 1.5 1.0 0.7 0.9 0.4 1.4 0.7 1.27 Haskell 3.6 2.7 2.5 2.0 1.6 1.7 2.2 1.5 1.1 1.5 0.7 2.1 1.4 1.89 Pascal 2.2 1.5 1.2 0.8 0.8 0.8 1.0 0.8 0.5 0.6 0.2 0.5 0.7 0.89 Clojure 8.8 5.3 5.2 3.6 3.7 3.3 3.8 2.5 1.9 2.9 5.0 1.5 2.6 3.85 MATLAB 3.6 2.4 1.8 1.1 1.4 1.1 1.7 0.9 0.8 0.3 1.6 0.7 1.1 1.42 R 4.7 3.3 2.4 1.9 1.8 1.7 2.1 1.5 1.3 0.5 2.2 0.9 1.4 1.98 JavaScript 2.8 2.1 1.9 1.2 1.2 1.1 1.6 0.7 1.1 0.4 1.3 0.7 1.0 1.31 C# 2.0 1.4 1.3 0.9 0.8 0.8 0.6 0.5 0.6 0.3 1.0 0.5 0.7 0.87 Python 2.2 1.6 1.5 1.1 0.9 1.2 0.9 0.6 0.9 0.3 1.3 0.6 0.9 1.07 Common Lisp 2.8 1.8 1.6 1.3 1.1 1.3 0.8 0.6 0.7 0.3 1.3 0.6 0.9 1.16 Java 2.1 1.4 1.5 0.8 0.9 1.1 0.8 0.5 0.9 0.3 1.2 0.5 0.8 0.98 Fortran 1.4 1.0 0.7 0.6 0.7 0.8 0.5 0.4 0.6 0.2 0.8 0.4 0.5 0.66 C++ 1.4 1.0 0.7 0.6 0.6 0.7 0.5 0.3 0.4 0.2 0.7 0.4 0.6 0.61 C 0.7 0.7 0.5 0.4 0.5 0.5 0.4 0.2 0.3 0.1 0.5 0.3 0.4 0.41 ???????????? ???? ???? ???? ???? ???? ???? ???? ???? ???? ???? ???? ???? ≡≡≡≡ ???? Overall: 4.1 2.58 2.3 1.68 1.56 1.61 1.85 1.27 0.85 1.14 0.41 1.86 0.83 1.29 Overall Ranking: Clojure 0.41 Haskell 0.83 R 0.85 MATLAB 1.14 JavaScript 1.27 Ruby 1.36 Common Lisp 1.56 Python 1.61 C++ 1.68 C# 1.85 Pascal 1.86 Fortran 2.33 C++ 2.58 C 4.09 -------------------------------------------

6 5

ANN: NY Haskell presents Edward Kmett on Lenses, Folds, and Traversals -- Wed., December 12
by Gershom B 20 Nov '12

20 Nov '12

The first NY Haskell Users Group meetup was a great success -- with roughly sixty attendees and conversations that stretched far too late for a weekday night. Video and slides are available for both the Practical Data Processing and Cloud Haskell talks: Video: http://vimeo.com/53906049 Slides on Practical Data Processing: http://gbaz.github.com/slides/PracticalData-11-2012.pdf Slides on Cloud Haskell: http://gbaz.github.com/slides/cloud-11-2012.html Source for Cloud Haskell: https://github.com/gbaz/slides/blob/gh-pages/cloud-11-2012.lhs We expect our next meetup will be equally exciting, at a bare minimum. We're actively seeking cool talks and presentations. If you're not a New York local, but may be passing through or are in the tri-state area or thereabouts, and would like to present some code or research with even tangentially real-world implications to an informed and appreciated audience, please do get in touch :-) Also, there will be a NY tech holiday party on December 11th, which we are organizing along with other NY technology and PL groups. Details are available at the on the meetup site: http://www.meetup.com/NY-Haskell/. Finally, at some point, we will probably cease to spam -cafe with announcements of all our events, so even if you can't make it to the next few ones, registering at the meetup site is the best way to stay on top of what we will have planned. - - - - Lenses, Folds, and Traversals presented by Edward Kmett Wednesday, December 12, 2012 7:00 PM To 9:00 PM Pivotal Labs, 841 Broadway New York, NY (8th Floor) RSVP: http://www.meetup.com/NY-Haskell/ Edward Kmett will introduce his lens library, which provides a highly composable toolbox for accessing and modifying multiple parts of data structures. >From simple beginnings, starting with building blocks such as fmap and (.), we will build up combinators suitable for working with a wide array of data structures. These generalize the notions you already know how to use into a form that is easier to compose, and simultaneously allow them to be used for monomorphic containers such as Data.Text. All without compromising on your ability to reason about them using laws! Once we've built up some foundations, we'll do a bit of a deep dive, exploring consequences of this design. We will discuss the efficient generic programming programming framework exported by lens, and type-safe Traversal-based zippers. Familiarity with the Applicative and Traversable classes from the Haskell base libraries will be helpful (links provided below), but a basic understanding of the concepts will be introduced we go along. Attendees should expect to be gobsmacked with a newfound appreciation for the power of a little (or a lot of) abstraction. Useful (but not mandatory) references: The lens library and documentation: http://hackage.haskell.org/package/lens A previous, more introductory talk on how to use the lenses Edward Kmett wrote for the scalaz in the Scala programming language: https://www.youtube.com/watch?v=efv0SQNde5Q The original Applicative paper: http://www.soi.city.ac.uk/~ross/papers/Applicative.pdf Lots of information on Traversable: http://www.cs.ox.ac.uk/jeremy.gibbons/publications/iterator.pdf A write-up of this talk, as presented at the Bay Area Haskell Users Group: http://google-opensource.blogspot.com/2012/10/lenses-folds-and-traversals-h…

1 0

Re: [Haskell-cafe] Cabal failures...
by Gregory Guthrie 20 Nov '12

20 Nov '12

Thanks to all for the comparisons between apt & cabal. Your reply basically explains why it is broken, and gives a rationale (cost and trouble to do it), but no prognosis for repair. My interest is in using Haskell for teaching, and so far the package system failures often present problems that I can't solve for all but the simplest examples, so I couldn't much pass this onto students! My libraries may have gotten corrupted, so when I get time I will try to reset and clean out everything and start over, but that will of course break a lot of things and take a lot of time for some re-installs, most particularly things depending on underlying C libraries. Any hints for a simple way to do this are welcome. I look forward to the outcomes from the current cabal discussions. It was also interesting to note a comment that most developers don't have access to a Windows machine for testing. With Windows at >90% of the computing market (Linux = 1.6%), this seems like a problem which might limit growth of Haskell usage. Just an observation. :-) Thanks for your article on the topic of Cabal - interesting! ---------------------------------------------- Date: Tue, 20 Nov 2012 01:03:20 -0500 From: "Albert Y. C. Lai" <trebla(a)vex.net> Subject: Re: [Haskell-cafe] Cabal failures... At least I paid my 3 hours to explain some cabal stuff at http://www.vex.net/~trebla/haskell/sicp.xhtml ----------------------------------------------

3 2

Re: [Haskell-cafe] code length in Haskell, a comparison
by Gregory Guthrie 20 Nov '12

20 Nov '12

They also have other comparisons at the referenced site, including for different sizes of programs, and for counting characters or tokens instead of lines over each of these program example groups. The data source does include APL & REBOL (& 483 different languages!), so one could run this analysis with most any languages you liked. Analysis from: http://blog.wolfram.com/2012/11/14/code-length-measured-in-14-languages/ Data from: http://rosettacode.org/wiki/Rosetta_Code ---------------------------------------------------------------- Re: [Haskell-cafe] code length in Haskell, a comparison > I find myself wondering where Rebol would stand in this. Or APL. Greets, Ertugrul -------------------------------------------

1 0

Cabal failures...
by Gregory Guthrie 20 Nov '12

20 Nov '12

I follow the Cabal-messes threads with some interest, since that is the hardest area for me since starting to use Haskell. Probably 40-60% of all package install fail for some mysterious reason, with threats that trying to fix them will break more things, which generally is true. :-) I am not exert in the area, but I wonder how /why/ this is different than other package managers, like apt in Linux, I have never had any problems with it, and I would think that their dependencies are of at least similar complexities. In any case; Trying to do a cabal update" I was told to try to update "cabal-install", which I think means actually updating cabal (since I actually run installs via cabal install...), but that fails with this message below, and I don't know how to proceed. Linking C:\Users\guthrie\AppData\Local\Temp\Cabal-1.16.0.3-13880\Cabal-1.16.0.3\dist\setup\setup.exe ... Configuring Cabal-1.16.0.3... Warning: This package indirectly depends on multiple versions of the same package. This is highly likely to cause a compile failure. package process-1.1.0.1 requires base-4.5.0.0 package pretty-1.1.1.0 requires base-4.5.0.0 package old-time-1.1.0.0 requires base-4.5.0.0 package old-locale-1.0.0.4 requires base-4.5.0.0 package filepath-1.3.0.0 requires base-4.5.0.0 package directory-1.1.0.2 requires base-4.5.0.0 package deepseq-1.3.0.0 requires base-4.5.0.0 package containers-0.4.2.1 requires base-4.5.0.0 package bytestring-0.9.2.1 requires base-4.5.0.0 package array-0.4.0.0 requires base-4.5.0.0 package Win32-2.2.2.0 requires base-4.5.0.0 package filepath-1.3.0.0 requires base-4.5.1.0 package Cabal-1.16.0.3 requires base-4.5.1.0 package Cabal-1.16.0.3 requires filepath-1.3.0.0 package process-1.1.0.1 requires filepath-1.3.0.0 package directory-1.1.0.2 requires filepath-1.3.0.0 package integer-gmp-0.4.0.0 requires ghc-prim-0.2.0.0 package bytestring-0.9.2.1 requires ghc-prim-0.2.0.0 package base-4.5.0.0 requires ghc-prim-0.2.0.0 package integer-gmp-0.4.0.0 requires ghc-prim-0.2.0.0 package base-4.5.1.0 requires ghc-prim-0.2.0.0 package base-4.5.1.0 requires integer-gmp-0.4.0.0 package base-4.5.0.0 requires integer-gmp-0.4.0.0 Building Cabal-1.16.0.3... Preprocessing library Cabal-1.16.0.3... <command line>: cannot satisfy -package-id array-0.4.0.0-3cf1bc3f5cd0078adea24752c18081b9 (use -v for more information) cabal: Error: some packages failed to install: Cabal-1.16.0.3 failed during the building phase. The exception was: ExitFailure 1 cabal-install-1.16.0.2 depends on Cabal-1.16.0.3 which failed to install. -------------------------------------------

5 8

On Windows defragment (Defraggler'ize, etc) the hard drive and turn off your A/V before installing cabal-install :)
by KC 19 Nov '12

19 Nov '12

:) Casey -- -- Regards, KC

1 0

cabal errors
by Gregory Guthrie 19 Nov '12

19 Nov '12

I did a package check, and I always get a ton of these things: Warning: haddock-html: E:\Plang\Haskell Platform\lib\extralibs\doc\haskell-src-1.0.1.4\html doesn't exist or isn't a directory Which I think is just missing documentation, so I ignore them. But this time I also got this: The following packages are broken, either because they have a problem listed above, or because they depend on a broken package. HTTP-4000.2.3 haskell-platform-2012.2.0.0 ghc-pkg list shows: Cabal-1.10.1.0 Cabal-1.10.2.0 Cabal-1.14.0 Cabal-1.14.0 GLUT-2.1.2.1 GLUT-2.1.2.1 GLUT-2.1.2.1 {HTTP-4000.2.3} HTTP-4000.2.5 ... {haskell-platform-2012.2.0.0} haskell-platform-2012.4.0.0 haskell-src-1.0.1.4 haskell-src-1.0.1.4 haskell-src-1.0.1.5 haskell-src-1.0.1.5 (haskell2010-1.0.0.0) (haskell2010-1.1.0.1) (haskell2010-1.1.0.1) haskell98-1.1.0.1 (haskell98-2.0.0.1) (haskell98-2.0.0.1) Not sure what it all means, but looks somewhat goofy to me. I always just do "cabal installs", and an occasional "-force-reinstalls" when told that it is the only option, but recently when they might fail tried a "cabal-dev install" a few times, I assume that is what the "{}" entries are, but am not sure if they can all peacefully coexist. Do I need to do a reset and start over? I hope not, as it took me many hours of fiddling to install some packages like glut, wxcore, and a few others. Argh. -------------------------------------------

1 0

Reactive-Banana-Wx Install Trouble
by Ian 19 Nov '12

19 Nov '12

Hi Everyone, I'm currently trying to install reactive-banana-wx on OSX. Whenever I try to cabal install it though, I get this error back: [1 of 1] Compiling Main ( /var/folders/yy/k1kyw7252q1f_01xv4q5nnj40000gn/T/reactive-banana-wx-0.7.1.0-91555/reactive-banana-wx-0.7.1.0/Setup.hs, /var/folders/yy/k1kyw7252q1f_01xv4q5nnj40000gn/T/reactive-banana-wx-0.7.1.0-91555/reactive-banana-wx-0.7.1.0/dist/setup/Main.o ) /var/folders/yy/k1kyw7252q1f_01xv4q5nnj40000gn/T/reactive-banana-wx-0.7.1.0-91555/reactive-banana-wx-0.7.1.0/Setup.hs:10:22: Couldn't match expected type `Distribution.Simple.Setup.BuildFlags' with actual type `Cabal-1.16.0.3:Distribution.Simple.Setup.BuildFlags' Expected type: Args -> Distribution.Simple.Setup.BuildFlags -> Distribution.PackageDescription.PackageDescription -> Distribution.Simple.LocalBuildInfo.LocalBuildInfo -> IO () Actual type: Cabal-1.16.0.3:Distribution.Simple.UserHooks.Args -> Cabal-1.16.0.3:Distribution.Simple.Setup.BuildFlags -> Cabal-1.16.0.3:Distribution.PackageDescription.PackageDescription -> Cabal-1.16.0.3:Distribution.Simple.LocalBuildInfo.LocalBuildInfo -> IO () In the return type of a call of `appBundleBuildHook' In the `postBuild' field of a record cabal: Error: some packages failed to install: reactive-banana-wx-0.7.1.0 failed during the configure step. The exception was: ExitFailure 1 A couple of things; The version of cabal installed is: cabal-install version 0.14.0 using version 1.14.0 of the Cabal library The version of GHC that I'm using is: The Glorious Glasgow Haskell Compilation System, version 7.4.2 One other thing I should probably note is that I have cabal-macosx installed, but whenever I try to just call it by saying "cabal-macosx" it doesn't work, I have to tunnel down into the actual macosx-app to build any wx stuff. I'm not sure if I'm just using it wrong (I'm quite new to the wx stuff) or if it's a problem with the installation. Any help on these two (possibly related) problems would be fantastic. Cheers, Ian

2 1

[repa] beginner questions
by Dmitry Malikov 19 Nov '12

19 Nov '12

Playing around with repa arrays and got some questions. 1) How I can get list of indexes of array that suffice some predicate? > a1 AUnboxed (Z :. 3) (fromList [False,False,True]) it :: Array U (Z :. Int) Bool Indexes of element that satisfying specific predicate could be obtained like that: > (\a p → Data.List.map (subtract 1 . snd) $ filter (p . fst) $ zip (toList a) [1..]) a1 (== False) [0,1] Looks ugly. How REPA users used to do filtering like that without converting to list? 2) How can I apply some function `f' to each row of 2D array `a' and collect results in single value? f ∷ (Shape sh, Source r Bool) ⇒ Array r sh Bool → Bool f a = (== toList a) $ foldl1 (Prelude.zipWith (||)) $ Prelude.map toList $ foldl (\l k -> filter (\x -> x ! (Z :. k) == False) l) [b1,b2,b3,b4] $ findWhich (== False) a and ∷ [Bool] → Bool [a1,a2] :: [Array U (Z :. Int) Bool] Having all that I could find what I want like that: and $ map f [a1,a2] > True All going on ridiculous and ugly because: - 2D arrays are not 2D arrays but lists of 1D arrays b1,b2,b3,b4,a1,a2 ∷ Array U (Z :. Int) Bool b1 = fromListUnboxed (Z :. (3::Int)) [False, True, False] b2 = fromListUnboxed (Z :. (3::Int)) [False, False, False] b3 = fromListUnboxed (Z :. (3::Int)) [False, False, True] b4 = fromListUnboxed (Z :. (3::Int)) [True, False, False] a1 = fromListUnboxed (Z :. (3::Int)) [False, False, True] a2 = fromListUnboxed (Z :. (3::Int)) [True, True, True] How 2D array could be split to list of 1D arrays? - redundant usage of `toList'; all operations are list-specified. How `f' could be rewritten in REPA terms? -- Best regards, dmitry malikov !

2 2

Reaching Max Bolingbroke
by Roman Cheplyaka 18 Nov '12

18 Nov '12

For the last two months I've been trying to reach Max Bolingbroke via his hotmail address, github and linkedin, but did not succeed. Does anyone know if he's well? If someone could help by telling him that I'd like to get in touch, I'd appreciate that. Roman

2 1