- Haskell-Cafe - Haskell.org

Re: [Haskell-cafe] ANNOUNCE: test-framework-golden-1.1
by Roman Cheplyaka 05 Oct '12

05 Oct '12

* Tim Docker <tim(a)dockerz.net> [2012-10-05 12:19:40+1000] > Hi Roman, > > This sounds like a great idea. As you suggest, I've put this kind of > thing together in scripts many times, without a consistent framework. > > I haven't tried it yet, but have one question. When you call a > function like > > goldenVsString > > I assume one generally provides a relative path. what is the file > path relative to? How does one arrange a package of haskell code and > associated golden files, and reference the golden files from within > the haskell so that the tree works from any location? The paths are naturally relative to the working directory of the test executable. In my projects, I typically have ./test.hs ./tests/case1.golden ./tests/case2.golden ./tests/case3.golden And so test.hs refers to test cases by relative paths like "tests/case1.golden". Of course, that'll only work if you run test.hs from its directory, but it is the case most of the time anyway. Also, since paths are relative to the directory containing the project.cabal file, "cabal test" works, too. If, for some reason, you want to be able to run tests from any location, you could provide the path to golden paths e.g. via an environment variable. Roman > On 05/10/12 07:55, Roman Cheplyaka wrote: > >I am glad to announce the first public release of test-framework-golden — a > >golden testing library. > > > >Hackage: http://hackage.haskell.org/package/test-framework-golden > >GitHub: https://github.com/feuerbach/test-framework-golden > > > >Golden tests are similar to unit tests (as implemented in HUnit), but the idea > >is to store the expected result in files (called «golden» files). > > > >I was introduced to the idea of golden testing by Bohdan Vlasyuk at ZuriHac in > >2010. Since then I've discovered that this is a nice approach and it is already > >used in variety of projects (e.g. ghc, haddock). > > > >Surprisingly, not much is written about golden testing, and I've been unable to > >find any golden testing libraries for Haskell or any other programming language. > >Every project has its own ad-hoc implementation in Haskell/Python/Shell/etc. > > > >The closest match on the market is Simon Michael's shelltestrunner. But to use > >it you have to expose the tested functionality via command line, which may be > >inconvenient. > > > >So this is my attempt at a general golden testing library. > > > >It consists of two modules. > >Test.Golden has a simple interface that helps you get started very quickly. > >Test.Golden.Advanced provides a very generic testing function that you can use > >to implement the testing system you dream about. > > > >The library is integrated with test-framework, so you can use golden tests in > >addition to SmallCheck/QuickCheck/HUnit tests. > > > >In future there's a plan to support some golden test management capabilities. > > > >Roman > > > >_______________________________________________ > >Haskell-Cafe mailing list > >Haskell-Cafe(a)haskell.org > >http://www.haskell.org/mailman/listinfo/haskell-cafe >

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Which advanced Haskell topics interest you
by Manuel M T Chakravarty 05 Oct '12

05 Oct '12

Most existing Haskell books and similar teaching material is aimed at programmers who are new to Haskell. This survey is to assess the community interest in teaching material covering advanced topics beyond the commonly taught introductory material. https://docs.google.com/spreadsheet/viewform?formkey=dE1QZFNRLTFMdkllYWIyR2… Manuel

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Re: [Haskell-cafe] Creating Repa arrays from unboxed vectors
by Janek S. 05 Oct '12

05 Oct '12

Thanks! > This makes it look like you've got two versions of vector installed, This is true, I have vector-0.9.1 and vector-0.10, but > with Repa built against the version that _isn't_ 0.9.1. this, I think, is not exactly correct: [root@GLaDOS : /dane/download] ghc-pkg field repa depends depends: QuickCheck-2.4.2-41cb2884cc20cd78948de62849bd9667 base-4.5.0.0-6db966b4cf8c1a91188e66d354ba065e bytestring-0.9.2.1-18f26186028d7c0e92e78edc9071d376 ghc-prim-0.2.0.0-c2ff696e5b8ec4d4b2bc2e42085fe471 template-haskell-2.7.0.0-133c0fdb189e05de22bd926d39f99fe3 vector-0.9.1-04dd5c58c224b03a4dc90091cf93a01d So Repa is build againts 0.9.1. Everything works when I do "ghc-pkg hide vector-0.10.0". Is there a way to tell GHCi which version of library it should load? I tried -XPackageImports but it doesn't allow to specify version of a package, only its name (or I don't know how to specify version). Jan

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What is a functional approach to linear algebra routines? I see REPA warns that one must use fusion or risk slow routines.
by KC 05 Oct '12

05 Oct '12

Apparently using STUarrays in an imperative fashion is fraught with peril (and the performance of molasses). Casey -- -- Regards, KC

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HaskellDB Convertible Exception: incompatible types
by Andras Gyomrey 04 Oct '12

04 Oct '12

Hi, I get *** Exception: Convertible: error converting source data SqlLocalTime 2012-04-27 10:22:15 of type SqlValue to type Data.Time.LocalTime.LocalTime.ZonedTime: incompatible types when i try to show a record with a field of type CalendarTime (automatically generated by Database.HaskellDB.DBDirect, Mysql database type is "timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP" I already looked forhttp:// haskell.1045720.n5.nabble.com/programmatic-DB-interface-td3120759.html. But the problem there is about a regexp (not a type). And the incompatible type problem was caused because of a concatenation. Here, as you can see, i have no idea what's going on. Can someone please help me? Andras

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Creating Repa arrays from unboxed vectors
by Janek S. 04 Oct '12

04 Oct '12

Dear list, I'm trying to create unboxed REPA array from unboxed Vector, but I keep getting this type error: ghci> :m + Data.Array.Repa ghci> :m + Data.Array.Repa.Repr.Unboxed ghci> :m + Data.Vector.Unboxed ghci> fromUnboxed Z (Data.Vector.Unboxed.singleton 1) <interactive>:5:16: Couldn't match expected type `vector-0.9.1:Data.Vector.Unboxed.Base.Vector e0' with actual type `Data.Vector.Unboxed.Vector a0' In the return type of a call of `Data.Vector.Unboxed.singleton' In the second argument of `fromUnboxed', namely `(Data.Vector.Unboxed.singleton 1)' In the expression: fromUnboxed Z (Data.Vector.Unboxed.singleton 1) I am confused, because REPA documentation lists Vector from Data.Vector.Unboxed package as its second parameter. Why am I getting this error? I have Repa 3.2 an vector 0.9.1. Janek

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Problems installing DPH
by Janek S. 04 Oct '12

04 Oct '12

Dear list, I ran into problems when installing DPH examples: [root@GLaDOS : ~] cabal --global install dph-examples Resolving dependencies... Configuring dph-examples-0.6.1.3... Building dph-examples-0.6.1.3... Preprocessing executable 'dph-spectral-smvm' for dph-examples-0.6.1.3... [1 of 3] Compiling Vectorised ( examples/spectral/SMVM/dph/Vectorised.hs, dist/build/dph-spectral-smvm/dph-spectral-smvm-tmp/Vectorised.o ) exprType TYPE ghc-prim:GHC.Types.Double{(w) tc 3u} exprType TYPE ghc-prim:GHC.Types.Double{(w) tc 3u} exprType TYPE ghc-prim:GHC.Types.Double{(w) tc 3u} exprType TYPE ghc-prim:GHC.Types.Double{(w) tc 3u} exprType TYPE ghc-prim:GHC.Types.Double{(w) tc 3u} exprType TYPE (ghc-prim:GHC.Types.Int{(w) tc 3J}, ghc-prim:GHC.Types.Double{(w) tc 3u}) opt: Bitcode stream should be a multiple of 4 bytes in length cabal: Error: some packages failed to install: dph-examples-0.6.1.3 failed during the building phase. The exception was: ExitFailure 1 Gogling the error message leads to various LLVM pages, which suggests that LLVM is the problem. I'm using Debian Squeeze with LLVM 2.6 and I'm thinking that maybe DPH needs newer version. What is the minimum required version of LLVM for DPH to work? Or is this problem caused by semthing else? Janek

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Haskell Weekly News: Issue 246
by Daniel Santa Cruz 04 Oct '12

04 Oct '12

Welcome to issue 246 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week of September 23 to September 23, 2012. Want to contribute quotes for HWN? Until today the only way to help with those was to use @remember in the IRC channel. Now you can also use @HWNQuotes in twitter to submit quotes for the weekly newsletter. Quotes of the Week * carpi: all said ... the brain of someone of who writes compilers for haskell scares me nuts. I wouldn't want them concentrating on me, lest I catch fire. * Igloo: The major problem, as far as I can see, is how to construct the mumble'. * edwardk: i want to be able to know if the compiler is being stupid or if its just me, and without any sort of model to reason about it with, i always have to assume it could be the compiler; i already have to deal with that problem, its called 'scala' * ddarius: Now I can just point people at a readable and relevant paper instead of having to Cale it. * rwbarton: also, a generally safe answer to "was there an update to lambdabot recently" is "no" * camccann: you want a debugger? GHC has one. Except that stepping through lazy evaluation is like listening to a stream of consciousness narrative told by a 5-year-old with ADHD. Top Reddit Stories * My Haskell book is not dead! I'd love some feedback now that it's six chapters long and growing. Domain: sthaskell.com, Score: 61, Comments: 18 On Reddit: [1] http://goo.gl/AfLwS Original: [2] http://goo.gl/oB0e8 * What commercial users say they want from Haskell Domain: fpcomplete.com, Score: 46, Comments: 54 On Reddit: [3] http://goo.gl/JTtMG Original: [4] http://goo.gl/ZoHrh * Haskell rewarding moments: Orc Battle translation Domain: self.haskell, Score: 41, Comments: 22 On Reddit: [5] http://goo.gl/5xjJJ Original: [6] http://goo.gl/5xjJJ * Does Stroustroup have some FP envy? This is a pretty neat library implementation of pattern matching in C++. Domain: open-std.org, Score: 40, Comments: 44 On Reddit: [7] http://goo.gl/PH7ZU Original: [8] http://goo.gl/KuGrw * Functional TDD: a clash of cultures? Domain: facebook.com, Score: 34, Comments: 34 On Reddit: [9] http://goo.gl/9xBLo Original: [10] http://goo.gl/kOi2G * Dovetailing Domain: self.haskell, Score: 33, Comments: 21 On Reddit: [11] http://goo.gl/GdlMi Original: [12] http://goo.gl/GdlMi * Oh the fun of trying to install wxhaskell Domain: self.haskell, Score: 33, Comments: 33 On Reddit: [13] http://goo.gl/4F3Fu Original: [14] http://goo.gl/4F3Fu * Lazy v. Yield: Incremental, Linear Pretty-printing (Kiselyov, Peyton-Jones, Sabry) [pdf] Domain: cs.indiana.edu, Score: 31, Comments: 54 On Reddit: [15] http://goo.gl/PfVHl Original: [16] http://goo.gl/ub46l * Call for discussion: OverloadedLists extension Domain: gist.github.com, Score: 24, Comments: 52 On Reddit: [17] http://goo.gl/0O1G8 Original: [18] http://goo.gl/xYyTq * Real World Haskell: is there a second edition coming? Domain: self.haskell, Score: 24, Comments: 9 On Reddit: [19] http://goo.gl/rjjQb Original: [20] http://goo.gl/rjjQb * Introduction to Functional Reactive Programming [video] Domain: blog.edwardamsden.com, Score: 23, Comments: 3 On Reddit: [21] http://goo.gl/vSVKP Original: [22] http://goo.gl/IH3MF Top StackOverflow Questions * What optimizations can GHC be expected to perform reliably? votes: 27, answers: 2 Read on SO: [23] http://goo.gl/E6bH4 * A simple example showing that IO doesn't satisfy the monad laws? votes: 22, answers: 4 Read on SO: [24] http://goo.gl/YptHT * Are there any good use cases for OverlappingInstances? votes: 12, answers: 3 Read on SO: [25] http://goo.gl/FLChO * Why is ListT monad transformer considered buggy - what monad laws it breaks? votes: 11, answers: 1 Read on SO: [26] http://goo.gl/HX7Oa * How to build and use a bootstrap executable in a Cabal package votes: 10, answers: 1 Read on SO: [27] http://goo.gl/tvA03 * Continuation passing style representation of types votes: 10, answers: 1 Read on SO: [28] http://goo.gl/6R60n * GHC code generation for type class function calls votes: 10, answers: 3 Read on SO: [29] http://goo.gl/3ggvE * Why inductive datatypes forbid types like `data Bad a = C (Bad a -> a)` where the type recursion occurs in front of ->? votes: 10, answers: 2 Read on SO: [30] http://goo.gl/jtG6d * Are functions of arity-n really just an n-category due to currying? Can they be made into a 1-category? votes: 9, answers: 2 Read on SO: [31] http://goo.gl/JfJLF * Setting socket options on OSX votes: 9, answers: 0 Read on SO: [32] http://goo.gl/aybHY Until next time, Daniel Santa Cruz References 1. http://www.sthaskell.com/ 2. http://www.reddit.com/r/haskell/comments/10fx9w/my_haskell_book_is_not_dead… 3. http://fpcomplete.com/commercialuserneeds/ 4. http://www.reddit.com/r/haskell/comments/10me87/what_commercial_users_say_t… 5. http://www.reddit.com/r/haskell/comments/10c7n5/haskell_rewarding_moments_o… 6. http://www.reddit.com/r/haskell/comments/10c7n5/haskell_rewarding_moments_o… 7. http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3449.pdf 8. http://www.reddit.com/r/haskell/comments/10i859/does_stroustroup_have_some_… 9. https://www.facebook.com/notes/kent-beck/functional-tdd-a-clash-of-cultures… 10. http://www.reddit.com/r/haskell/comments/10jk06/functional_tdd_a_clash_of_c… 11. http://www.reddit.com/r/haskell/comments/10d7gx/dovetailing/ 12. http://www.reddit.com/r/haskell/comments/10d7gx/dovetailing/ 13. http://www.reddit.com/r/haskell/comments/10lyaw/oh_the_fun_of_trying_to_ins… 14. http://www.reddit.com/r/haskell/comments/10lyaw/oh_the_fun_of_trying_to_ins… 15. http://www.cs.indiana.edu/~sabry/papers/yield-pp.pdf 16. http://www.reddit.com/r/haskell/comments/10nsmw/lazy_v_yield_incremental_li… 17. https://gist.github.com/3761252 18. http://www.reddit.com/r/haskell/comments/10c8ld/call_for_discussion_overloa… 19. http://www.reddit.com/r/haskell/comments/10gcpp/real_world_haskell_is_there… 20. http://www.reddit.com/r/haskell/comments/10gcpp/real_world_haskell_is_there… 21. http://blog.edwardamsden.com/2012/09/video-introduction-to-functional.html 22. http://www.reddit.com/r/haskell/comments/10nho4/introduction_to_functional_… 23. http://stackoverflow.com/questions/12653787/what-optimizations-can-ghc-be-e… 24. http://stackoverflow.com/questions/12617664/a-simple-example-showing-that-i… 25. http://stackoverflow.com/questions/12628700/are-there-any-good-use-cases-fo… 26. http://stackoverflow.com/questions/12617916/why-is-listt-monad-transformer-… 27. http://stackoverflow.com/questions/12571205/how-to-build-and-use-a-bootstra… 28. http://stackoverflow.com/questions/12589765/continuation-passing-style-repr… 29. http://stackoverflow.com/questions/12645254/ghc-code-generation-for-type-cl… 30. http://stackoverflow.com/questions/12651146/why-inductive-datatypes-forbid-… 31. http://stackoverflow.com/questions/12571161/are-functions-of-arity-n-really… 32. http://stackoverflow.com/questions/12590202/setting-socket-options-on-osx

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Re: [Haskell-cafe] Explicitly passing an argument to an arrow
by Alfredo Di Napoli 03 Oct '12

03 Oct '12

I see. There exists an equivalent version but more generic? Just out of curiosity, I'm still pretty new to arrows, as you may have read :) Thanks, A. On 3 October 2012 15:59, Ertugrul Söylemez <es(a)ertes.de> wrote: > Alfredo Di Napoli <alfredo.dinapoli(a)gmail.com> wrote: > > > Solution was simple, after reading that functions are arrows: > > > > swapA' t = (swapFirst >>> swapSecond) (t,t) > > where > > swapFirst = first snd > > swapSecond = second fst > > No, that's not a solution, unless a = (->) is acceptable. This code is > specific to the function arrow. > > > Greets, > Ertugrul > > -- > Key-ID: E5DD8D11 "Ertugrul Soeylemez <es(a)ertes.de>" > FPrint: BD28 3E3F BE63 BADD 4157 9134 D56A 37FA E5DD 8D11 > Keysrv: hkp://subkeys.pgp.net/ >

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Explicitly passing an argument to an arrow
by Alfredo Di Napoli 03 Oct '12

03 Oct '12

Hello everyone, sorry for the dumb question but I'm wrapping my head around arrow just from this morning. Consider this toy function to swap argument of a tuple: swapA' :: (Arrow a) => a ((b,c), (b,c)) (c,b) swapA' = swapFirst >>> swapSecond where swapFirst = first $ arr snd swapSecond = second $ arr fst It works but requires to pass a tuple of tuple, namely ((b,c), (b,c)). How can I explicitly pass my tuple of tuple to swapFirst so I can simply invoke swapA' (1,2) and get the correct result? ps. I know that swap can be easily and elegantly be written as: swap = snd &&& fst but the point of the exercise was to experiment with first, second and arrow concatenation Thanks in advance, Alfredo

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