- Haskell-Cafe - Haskell.org

cabal test and tests that overlap in covarage
by Anatoly Yakovenko 25 Mar '15

25 Mar '15

is this a cabal error or hpc error? i see this when running 'cabal test' with tests that overlap in coverage 5 of 5 test suites (5 of 5 test cases) passed. hpc: found 2 instances of RBM.List in ["./.hpc","./dist/hpc/vanilla/mix/proto","./dist/hpc/vanilla/mix/perf-repa-RBM","./dist/hpc/vanilla/mix/test-repa-RBM","./dist/hpc/vanilla/mix/perf-list-RBM","./dist/hpc/vanilla/mix/test-list-RBM","./dist/hpc/vanilla/mix/rbm-0.0"] Thanks, Anatoly

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hpc - ignore some expressions
by Ozgur Akgun 25 Mar '15

25 Mar '15

Hi, I am generating code coverage reports using hpc, it works great. The reports would be much more helpful if I could somehow tell hpc to treat certain expressions as "covered" though. As an example, let's think of "impossible" cases of a function. f x | check x = result x | otherwise = error "impossible" I know there are techniques to get rid of (or minimise the number of) the impossible cases. I also can see how this information can be relevant, i.e. seeing whether `check` always holds or not in the report. However, at least for one version of the report, I want the error call like the above example to be treated as covered. Or maybe a different colour could be used to annotate "ignored"? Did anyone need/want anything like this? Is it possible? My guess is that this is somewhat possible using manually generated .tix files and merging them with the .tix file that is generated in the usual way. However this feels too adhoc, fragile and seems to be too much effort to reach a simple goal. Best, Ozgur

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GSOC 2015 proposal feedback
by Nikita Kartashov 24 Mar '15

24 Mar '15

Hello, everyone! As someone on #haskell-gsoc IRC suggested, I would like to post my proposal. Please, if you have time, read it and send me your thoughts. Thanks! Here is the link: https://gist.github.com/nkartashov/e46fd146b1df2d79aaf3 With regards, Nikita Kartashov

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GSoC Proposal: Concurrent Bag.
by Alex Semin 24 Mar '15

24 Mar '15

Hello everyone! I have written a proposal for this GSoC. It is mostly related to this ticket: https://ghc.haskell.org/trac/summer-of-code/ticket/1608 Here is link to the proposal: https://gist.github.com/Alllex/009d9842f97963aa9955 I will be glad to get any feedback and comments. Regards, Alex Semin

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Getting Haskeline to quit early
by G Philip 24 Mar '15

24 Mar '15

(I posted this to Stack Overflow [1], but no luck there so far.) Hi all, I am trying to use Haskeline [2] to write a program which asks the user a sequence of questions, each one optionally with a default value in [brackets], and reads in their responses. I want the user to be able to 1. Press Enter to submit the [default] value; 2. Type in a string, edit it if needed, and then press Enter to submit this value; 3. Press Ctrl-C to reset all values to the defaults and start over; and, 4. Press Ctrl-D or enter "quit" to quit, in which case all the values which they submitted are lost. I have been able to get points 1-3 working, but I cannot get point 4 to work: pressing Ctrl-D (or entering "quit") just brings up the next prompt instead of making the program quit the questioning. Looking at my program (please see below) I understand why this happens, but I am not able to figure out how to fix this so that Ctrl-D (or "quit") actually makes the questioning stop. How do I fix the program to make this happen? I did see this question [2] over at Stack Overflow which seems to ask something similar, but I could not get much from there; I am not even sure that they are asking the same question as I am. As a secondary question: my current program has quite a few `case` statements which switch on `Maybe` values. In particular, I currently check for `Nothing` two or three levels deep so that I can correctly return a `Nothing` when the user presses Ctrl-D. I have a feeling that this could be simplified using (something like) the monadic `>>=` operator, but I am unable to figure out how to do this in this case. Is my hunch right? Is there a way to do away with all this pattern matching which looks for `Nothing`? Also: please tell me anything else which could improve my code below. I am quite new to this, so it is very likely that I am missing many obvious things here. Thanks in advance! Regards, Philip ---------------- The program --------------- My program asks the user about the composition of a fruit basket. The information associated with a fruit basket consists of the name of the owner of the fruit basket and the names of the different kinds of fruit in the basket. To be able to ask for the latter, I first ask for the _number_ of different kind of fruit in the basket, and then ask for the name of each kind. We start with a default fruit basket whose information is then modified based on what the user tells us. module Main where import System.Console.Haskeline type PersonName = String type FruitName = String data FruitBasket = FruitBasket { ownerName :: PersonName, fruitCount :: Int, fruitNames :: [FruitName] } deriving Show defaultBasket = FruitBasket "Mary" 2 ["Apple", "Peach"] main :: IO () main = do basket <- getBasketData defaultBasket putStrLn $ "Got: " ++ show(basket) -- Prompt the user for information about a fruit basket, and -- return a FruitBasket instance containing this information. The -- first argument is an instance of FruitBasket from which we get -- the default values for the various prompts. The return value -- has a Maybe type because the user may abort the questioning, in -- which case we get nothing from them. getBasketData :: FruitBasket -> IO (Maybe FruitBasket) getBasketData basket = runInputT defaultSettings $ withInterrupt $ getData basket where getData :: FruitBasket -> InputT IO (Maybe FruitBasket) getData initialBasket = handleInterrupt f $ do outputStrLn banner input <- getInputLine $ "Who owns this basket? [" ++ defaultOwner ++ "] : " basket <- case input of Nothing -> return Nothing -- User pressed Ctrl-D with the input being empty Just "" -> return (Just initialBasket) -- User pressed Enter with the input being empty Just "quit" -> return Nothing -- User typed in "quit" and pressed Enter Just newOwner -> return (Just initialBasket{ownerName = newOwner}) input <- getInputLine $ "Number of kinds of fruit in the basket? [" ++ show defaultCount ++ "] : " basket' <- case input of Nothing -> return Nothing Just "" -> return basket Just "quit" -> return Nothing Just count -> return $ updateFruitCount basket (read count) where updateFruitCount Nothing _ = Nothing updateFruitCount (Just realBasket) newCount = Just $ realBasket{fruitCount = newCount} let defaultFruitNames = pruneOrPadNames basket' newNames <- getFruitNames defaultFruitNames 1 case newNames of Nothing -> return (Just defaultBasket) Just newSetOfNames -> return $ updateFruitNames basket' newSetOfNames where updateFruitNames Nothing _ = Nothing updateFruitNames (Just realBasket) realNewNames = Just $ realBasket{fruitNames = realNewNames} where f = (outputStrLn "Press Ctrl-D or enter \"quit\" to quit." >> getData initialBasket) defaultOwner = ownerName initialBasket defaultCount = fruitCount initialBasket banner :: String banner = "Please enter details of the fruit basket below. At each prompt you can do one of the following:\n\ \\t (a) Press Enter to submit the [default] value;\n\ \\t (b) Type in a string, edit it if needed, and then press Enter to submit this value;\n\ \\t (c) Press Ctrl-C to reset all values to the defaults and start over;\n\ \\t (d) Press Ctrl-D or enter \"quit\" to quit; all the values you submitted will be lost." pruneOrPadNames :: Maybe FruitBasket -> Maybe [String] pruneOrPadNames Nothing = Nothing pruneOrPadNames (Just basket) = Just $ pruneOrPad (fruitNames basket) (fruitCount basket) -- When requiredLength is not larger than (length inputList), -- (pruneOrPad inputList requiredLength) is the prefix of -- inputList of length requiredLength. Otherwise, it is inputList -- padded with as many empty strings as required to make the total -- length equal to requiredLength. pruneOrPad :: [String] -> Int -> [String] pruneOrPad inputList requiredLength | requiredLength <= inputLength = take requiredLength inputList | otherwise = inputList ++ (replicate difference "") where inputLength = length inputList difference = requiredLength - inputLength getFruitNames Nothing _ = return Nothing getFruitNames (Just []) _ = return $ Just [""] getFruitNames (Just (name:names)) count = do input <- getInputLine $ "Name of fruit " ++ (show count) ++ " [" ++ name ++ "] : " newNames <- case input of Nothing -> return Nothing Just "" -> do -- Keep the default name for this fruit ... newNames' <- getFruitNames (Just names) (count + 1) case newNames' of Nothing -> return Nothing -- ... unless the user chose to quit -- while entering a name Just [""] -> return $ Just [name] -- At this point names = [] so it is -- already time to stop asking for -- more names. Just furtherNames -> return $ Just (name : furtherNames) Just "quit" -> return Nothing Just name' -> do newNames' <- getFruitNames (Just names) (count + 1) case newNames' of Nothing -> return Nothing Just [""] -> return $ Just [name'] Just furtherNames -> return $ Just (name' : furtherNames) return newNames References ------------- [1] http://stackoverflow.com/questions/29189428/getting-haskeline-to-quit-early [2]: https://hackage.haskell.org/package/haskeline-0.7.1.3/docs/System-Console-H… [3]: http://stackoverflow.com/questions/4771199/haskell-best-practise-early-term…

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ANN: Magic Cookies! Android board game in Haskell
by Ivan Perez 23 Mar '15

23 Mar '15

Dear Café This is a just a quick announcement: we have just released Magic Cookies, an Android board game written in Haskell. It is now available on Google Play [1]. The game uses the Functional Reactive Programming library Yampa and SDL2 for multimedia. If you like the game, please share the link on facebook/twitter/etc and let all of your friends know. We have gone through dozens of iterations during beta testing, but we cannot guarantee that the game works 100% perfectly on all devices. If you find a bug, or anything else you don't like, please do not rate low. Instead, open an issue [2] or send us an email (support(a)keera.co.uk) Suggestions are also welcome. We will continue working to make the game lighter, faster, and more fun. See [3] for more details, and to sign up as a beta-tester for other games we are already working on. We certainly enjoyed making it, and we hope you all enjoy playing it. All the best Ivan, Fass & Jorge [1] https://play.google.com/store/apps/details?id=uk.co.keera.games.magiccookies [2] https://github.com/keera-studios/magic-cookies [3] http://keera.co.uk/blog/2015/03/19/magic-cookies-released-google-play/

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Re: [Haskell-cafe] Cabal and cabal-install minor release (1.22.2.0)
by Miëtek Bak 23 Mar '15

23 Mar '15

Thanks, Ryan. Binaries of cabal-install 1.22.2.0 are now available in Halcyon on the following platforms: - Amazon Linux 2014.09 (x86_64) - Arch Linux (x86_64) - CentOS 6 (i386 and x86_64) - CentOS 7 (x86_64) - Debian 6 (i386 and x86_64) - Debian 7 (i386 and x86_64) - Fedora 19 (i386 and x86_64) - Fedora 20 (i386 and x86_64) - Fedora 21 (x86_64) - openSUSE 13.2 (x86_64) - OS X 10.8 (x86_64) - OS X 10.9 (x86_64) - OS X 10.10 (x86_64) - Red Hat Enterprise Linux 6 (x86_64) - Red Hat Enterprise Linux 7 (x86_64) - SUSE Linux Enterprise Server 12 (x86_64) - Ubuntu 10.04 LTS (i386 and x86_64) - Ubuntu 12.04 LTS (i386 and x86_64) - Ubuntu 14.04 LTS (i386 and x86_64) - Ubuntu 14.10 (i386 and x86_64) See https://github.com/mietek/halcyon/issues/38 for details of cross-platform support. Let me know if I can help with the automation. -- Miëtek On 2015-03-21, at 21:34, Ryan Thomas <ryan(a)ryant.org> wrote: > I have released both Cabal and cabal-install 1.22.2.0 today, > cabal-install has just gone out now. > > These have been published to Hackage and are available on the download > page of haskell.org. > > As a part of this process I have also updated the release > documentation (https://github.com/haskell/cabal/wiki/Making-a-release) > to support the new sftp-only push to haskell.org. > > There are a couple of outstanding items to tie off with this release: > - The {Cabal|cabal-install}-latest symlinks on haskell.org still need > to be updated > - The Windows/OSX/Linux specific binaries need to be built and updated > on the download page; Johan I will probably need some guidance on the > process for this. > > Once I get these items tied off, my main focus will be the automation > of this release process. > > > Cheers, > > ryan > _______________________________________________ > cabal-devel mailing list > cabal-devel(a)haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/cabal-devel

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ANN: Lambdabot 5.0.1
by Bertram Felgenhauer 23 Mar '15

23 Mar '15

Dear Haskell users, I'm pleased to announce a minor release of Lambdabot. Lambdabot is an IRC bot that can also be used offline; it provides tools for querying information about and even for producing Haskell code. To install it, use the following command: cabal install lambdabot --constraint 'transformers installed' (the constraint helps cabal-install to find an install plan) * What's new - lambdabot is now smarter about locating its data files. This means that commands like @src now work out of the box, without having to copy files into ~/.lambdabot/State - lambdabot-5.0.1 uses (and requires) monad-control 1.0 * Development Development of lambdabot happens on github, where you can also find the bugtracker: https://github.com/lambdabot/lambdabot Have fun with lambdabot, Bertram

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time and TimeLocale compatibility
by Tom Ellis 22 Mar '15

22 Mar '15

Hello all, The `formatTime` function from time-1.4 uses the TimeLocale type from old-locale, whereas time-1.5 provides its own definition of the TimeLocale type. I want to provide `formatTime` with the argument `defaultTimeLocale`. 1.4 requires the version in old-locale whereas 1.5 requires the version it defines itself. Is it possible to use this function in a way that is compatible with both 1.4 and 1.5? If time-1.5 had merely reexported the old-locale version, and then (the future) time-1.6 replaced it completely this would have offered a smoother upgrade path, but as far as I can tell nothing like this was done. What are my options? Tom

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Munich Haskell Meeting, 2015-03-25 @ 19:30
by Christian Neukirchen 22 Mar '15

22 Mar '15

Dear all, Next week, our monthly Munich Haskell Meeting will take place again on Wednesday, March 25 at Cafe Puck at 19h30. For details see here: http://www.haskell-munich.de/dates If you plan to join, please add yourself to this dudle so we can reserve enough seats! It is OK to add yourself to the dudle anonymously or pseudonymously. https://dudle.inf.tu-dresden.de/haskell-munich-mar-2015/ Everybody is welcome! cu, -- Christian Neukirchen <chneukirchen(a)gmail.com> http://chneukirchen.org

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