- Haskell-Cafe - Haskell.org

free monad versus operational for blackjack game
by Michael Litchard 23 Jan '17

23 Jan '17

I'm studying the code for a blackjack game: See marked answer. http://codereview.stackexchange.com/questions/46809/blackjack-in-haskell It uses the operational package, and mentions one could write equivalent code using a free monad. But my question is, for this use case is there any benefit for using a free monad?

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Possible to use Cabal-1.18 with ghc-6.12.3?
by Simon Peter Nicholls 23 Jan '17

23 Jan '17

Can I improve my setup, so that Cabal-1.18 will work better with ghc-6.12.3? I have an old project that I’m updating, which is currently compilable with 6.12.3. I’ve managed to get Cabal-1.18.1.7 and cabal-install-1.18.0.1 to build it, which gives me some handy extra tooling, but only if I pre-install all the project dependencies before updating Cabal. If I try to use a sandbox instead, the build will fail at the point where template-haskell is used: > Loading package utf8-string-0.3.7 ... <command line>: can't load .so/.DLL for: HSutf8-string-0.3.7 (libHSutf8-string-0.3.7.so: cannot open shared object file: No such file or directory) That’s a dependency in my sandbox, but this also fails if it’s installed to the default `~/.cabal`. I see a similar error if I try `runhaskell Setup.hs` instead of cabal: > Setup.hs: <command line>: can't load .so/.DLL for: HSCabal-1.18.1.7 (libHSCabal-1.18.1.7.so: cannot open shared object file: No such file or directory) So I figure Cabal-1.18 and my default 6.12.3 are not co-operating as well as they could. If I use —enable-shared in my dependency builds, I still get this error, and I also see it if I try to build statically. The template-haskell “Loading” steps always seems to fail by not finding a shared library, as if it’s stepping outside of Cabal (and my!) control. I note that installation locations are different in Cabal-1.18 (vs 1.16), but figure the GHC registration process takes care of something like `.cabal/lib/x86_64-linux-ghc-6.12.3/utf8-string-0.3.7/libHSutf8-string-0.3.7-ghc6.12.3.so`. A pre-installed parsec dependency looks like `ghc-6.12.3/lib/parsec-3.1.1/ghc-6.12.3/libHSparsec-3.1.1-ghc6.12.3.so`. Neither has the name format reported by the error. Is there something in my Cabal or my GHC setup that I can change, to get these working together? A clean fix would be great, but a bodge is fine, since this transition work is isolated in a docker container. Thanks.

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Soliciting feedback on my lens json parsing tutorial (please don't share yet!)
by Cody Goodman 23 Jan '17

23 Jan '17

Hi All, I wrote a lens json parsing tutorial here: https://github.com/codygman/concise-json-parsing-in-haskell I'd appreciate any feedback. My approach tries to use a prior understanding of Python into understanding lens enough to do something useful. Perhaps I can include links to tutorials that cover more of the theoretical foundations as well. Any criticism and/or ideas is welcome! Thanks, Cody Goodman

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Announce: Haskell Platform 8.0.2
by Gershom B 21 Jan '17

21 Jan '17

On behalf of the Haskell Platform team, I'm happy to announce the release of Haskell Platform 8.0.2 Now available at https://www.haskell.org/platform/ This includes GHC 8.0.2, cabal-install 1.24.0.2, and stack 1.3.2, all with many bugfixes and improvements since the last platform release. This platform release we've cleaned up the webpage a bit, and renamed the "minimal" distribution to the "core" distribution to highlight that it is the recommended approach (and simplified the accompanying text). A number of improvements have been made to the windows installer -- notably the /S option for silent install is now in fully working order, and we have the flags /STACK and /D (for stack and platform-ghc install paths). The installer expects no quoting of paths, even with spaces within the paths, like so: HaskellPlatform-8.0.2-full-x86_64-setup.exe /S /STACK=c:\My install path for stack\local\bin /D=c:\program files\Haskell\Platform\8.0.2 There is also an updated version of msys2 included, which includes pacman, et al. to ease the installation of libraries with more complex foreign dependencies. Changes to Contents: * As a result of transitive dependencies of platform packages, the integer-logarithms and call-stack packages have been added to the full platform. A full list of contents is available at https://www.haskell.org/platform/contents.html Thanks to all the contributors to this release, thanks to all the package and tool maintainers and authors, and a big thanks to the GHC team for all their hard work. A list of new GHC changes is available at: https://ghc.haskell.org/trac/ghc/blog/ghc-8.0.2-released A list of cabal changes is available at: https://hackage.haskell.org/package/cabal-install-1.24.0.2/changelog The new cabal documentation page is at: https://cabal.readthedocs.io/en/latest/ A list of stack changes is at: https://docs.haskellstack.org/en/stable/ChangeLog/ Happy Haskell Hacking all, Gershom (Note -- one feature we have not implemented yet for the platform but would like to is a generic linux installer that allows one to set a custom location and does not require root. Anyone who would like to volunteer to help with this, please get in touch!)

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Call for Participation: BOB 2017 (February 24, Berlin)
by Stefan Wehr 21 Jan '17

21 Jan '17

Reminder: early registration ends this Monday! ================================================================ BOB 2017 Conference "What happens if we simply use what's best?" February 24, 2017 Berlin http://bobkonf.de/2017/ Program: http://bobkonf.de/2017/program.html Registration: http://bobkonf.de/2017/registration.html ================================================================ BOB is the conference for developers, architects and decision-makers to explore technologies beyond the mainstream in software development, and to find the best tools available to software developers today. Our goal is for all participants of BOB to return home with new insights that enable them to improve their own software development experiences. The program features 14 talks and 8 tutorials on current topics: http://bobkonf.de/2017/program.html The subject range of talks includes functional programming, advanced front-end development, and sophisticated uses of types. The tutorials feature introductions to Haskell, Swift, PureScript, React, QuickCheck, Agda, CRDTs and Servant. John Hughes will give the keynote talk. Registration is open online: http://bobkonf.de/2017/registration.html NOTE: The early-bird rates expire on January 23, 2017! BOB cooperates with the :clojured conference on the following day. There is a registration discount available for participants of both events. http://www.clojured.de/

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Re: [Haskell-cafe] Haskell with C++: removing runtime dependencies on Windows 10.
by David Banas 20 Jan '17

20 Jan '17

Hi Deech, Not sure this is helpful, as I haven’t tested it on Windows 10, but here are the gcc/ghc compile/link options I use for a project that has a similar need: CC = gcc CFLAGS += -I/usr/lib/ghc-7.4.2/include/ -g -fPIC HC = ghc HC_OPTS = -cpp -O3 $(EXTRA_HC_OPTS) EXTRA_HC_OPTS = -package parsec -dynamic -fPIC -rtsopts HC_LOPTS = -shared -dynamic -package parsec -lHSrts -lm -lffi -lrt -db

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Strange encoding issue with Text and Servant
by Jan von Löwenstein 20 Jan '17

20 Jan '17

Hi, I have got a two places with a `QueryParam "q" Text` and call it with a Text that contains a `=` literal. In one place the `=` is correctly encoded as %3D, in the other I see a `!D(MISSING)`. This has to happen somewhere in Servant or the lower layers. Both Texts print out nicely with an `=` sign if I just print them to stdout. Google does not find `!D(MISSING)` anywhere. Any idea what could possibly be the problem here? Best Jan

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monad prompt example missing
by Michael Litchard 20 Jan '17

20 Jan '17

There's an example from the Monad.Prompt documentation https://hackage.haskell.org/package/MonadPrompt-1.0.0.5/docs/Control-Monad-… That is a dead link. http://paste.lisp.org/display/53766 Does anyone have a copy of this example, and of course any other ones you may know of.

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Haskell with C++: removing runtime dependencies on Windows 10.
by aditya siram 20 Jan '17

20 Jan '17

Hi, I am trying to create an executable on Windows 10 with some Haskell->C++ bindings I wrote but having trouble getting rid of some runtime DLL dependencies. I'm currently compiling and linking using the MSYS2 and GHC environment that ships with Windows Stack installer but no matter what I do I end up with the following dependencies: $ ldd <executable> ... libwinpthread-1.dll => /c/Users/user/AppData/Local/Programs/stack/x86_64-windows/ghc-8.0.1/mingw/bin/libwinpthread-1.dll (0x64940000) libstdc++-6.dll => /c/Users/user/AppData/Local/Programs/stack/x86_64-windows/ghc-8.0.1/mingw/bin/libstdc++-6.dll (0x6fc40000) libgcc_s_seh-1.dll => /c/Users/user/AppData/Local/Programs/stack/x86_64-windows/ghc-8.0.1/mingw/bin/libgcc_s_seh-1.dll (0x61440000) I have verified that the standalone versions of those libs are in available in stack install: libstdc++: ../stack/x86_64-windows/ghc-8.0.1/mingw/lib/gcc/x86_64-w64-mingw32/5.2.0/libstdc++.a ../stack/x86_64-windows/ghc-8.0.1/mingw/lib/gcc/x86_64-w64-mingw32/5.2.0/libstdc++.dll.a ../stack/x86_64-windows/ghc-8.0.1/mingw/lib/gcc/x86_64-w64-mingw32/5.2.0/libgcc.a libgcc: ../stack/x86_64-windows/ghc-8.0.1/mingw/lib/gcc/x86_64-w64-mingw32/5.2.0/libgcc_eh.a ../stack/x86_64-windows/ghc-8.0.1/mingw/lib/gcc/x86_64-w64-mingw32/5.2.0/libgcc_s.a libpthread: ../stack/x86_64-windows/ghc-8.0.1/mingw/x86_64-w64-mingw32/lib/libpthread.a ../stack/x86_64-windows/ghc-8.0.1/mingw/x86_64-w64-mingw32/lib/libpthread.dll.a I've unsuccessfully tried to link them into the executable using many combinations of `-optl-static`, `-optl-static-gcc`, and `-optl-static-stdc++` and also passing along these libraries " raw" to the linker like: `ghc-Options: -pgml g++ "-optl-Wl,--whole-archive" "-optl-Wl,-Bstatic" "-optl-Wl,-lstdc++" "-optl-Wl,-Bdynamic" "-optl-Wl,--no-whole-archive" Short of shipping these DLL with the executable (which I'd really rather not do) I'm running out of ideas so any suggestions would be appreciated. Thanks! -deech

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Haskell Weekly - 01/18/2017
by Haskell Weekly 19 Jan '17

19 Jan '17

View this email in your browser (http://us10.campaign-archive2.com/?u=49a6a2e17b12be2c5c4dcb232&id=d1f16b3bf…) ** Haskell Weekly (http://news.us10.list-manage1.com/track/click?u=49a6a2e17b12be2c5c4dcb232&i…) ------------------------------------------------------------ ** Issue 38 (http://news.us10.list-manage.com/track/click?u=49a6a2e17b12be2c5c4dcb232&id…) ------------------------------------------------------------ Welcome to Haskell Weekly! Haskell (http://news.us10.list-manage.com/track/click?u=49a6a2e17b12be2c5c4dcb232&id…) is an advanced, purely functional programming language. This is a weekly summary of what’s going on in its community. You can subscribe to the email newsletter (http://news.us10.list-manage1.com/track/click?u=49a6a2e17b12be2c5c4dcb232&i…) or the Atom feed (/haskell-weekly.atom) . Want to contribute to Haskell Weekly? Send us a message on Twitter (http://news.us10.list-manage.com/track/click?u=49a6a2e17b12be2c5c4dcb232&id…) or open an issue on GitHub (http://news.us10.list-manage1.com/track/click?u=49a6a2e17b12be2c5c4dcb232&i…) . ** News from the Haskell community ------------------------------------------------------------ * Brent Yorgey’s new programming languages course (http://news.us10.list-manage.com/track/click?u=49a6a2e17b12be2c5c4dcb232&id…) My new PL course is now finished, and all the course materials are freely available. Working through all the exercises should be a great option for anyone wishing to learn some basics of programming language design and implementation. * CLaSH 0.7 released: GHC 8 support and more (http://news.us10.list-manage.com/track/click?u=49a6a2e17b12be2c5c4dcb232&id…) Our company has been hired to do FPGA development work, and best of all, we get to use CLaSH. As a consequence, I cannot put as much time into CLaSH development as during my days as a PhD/PostDoc. However, we do now get to use CLaSH in industry! And as part of the contract there is time to find and fix bugs in CLaSH! * safe-prelude: a thought experiment (http://news.us10.list-manage.com/track/click?u=49a6a2e17b12be2c5c4dcb232&id…) This is a thought experiment in a different point in the alternative prelude design space. After my blog post on readFile, I realized I was unhappy with the polymorphic nature of readFile in classy-prelude. Adding that with Haskell Pitfalls I’ve been itching to try something else. * Selecting a platform: JavaScript vs Elm vs PureScript vs GHCJS vs Scala.js (http://news.us10.list-manage.com/track/click?u=49a6a2e17b12be2c5c4dcb232&id…) There are not many people who have worked on production applications in multiple frontend FP systems, and lived to tell the tale. So here goes, my guide to selecting a functional programming platform for the browser. * The design and use of QuickCheck (http://news.us10.list-manage.com/track/click?u=49a6a2e17b12be2c5c4dcb232&id…) The typical examples you’ll find online have deceptively simple code. The examples make it hard to learn how their succinct tests are possible, and how to customize them when things go wrong. This guide puts it all together piece by piece so you can use QuickCheck with confidence. * Monads made difficult (http://news.us10.list-manage.com/track/click?u=49a6a2e17b12be2c5c4dcb232&id…) This is a short, fast and analogy-free introduction to Haskell monads derived from a categorical perspective. This assumes you are familiar with Haskell and basic category theory. * Constraint kinds (http://news.us10.list-manage.com/track/click?u=49a6a2e17b12be2c5c4dcb232&id…) In this blog post, I will show some examples of using the ConstraintKinds GHC extension. Classes and contexts were not first-class citizens in Haskell, but the introduction of the Constraint kind has changed this and allows them to be used as parameters of types. * Expressive types, not oppressive types (http://news.us10.list-manage.com/track/click?u=49a6a2e17b12be2c5c4dcb232&id…) Uncle Bob looks at advanced type systems and sees them as more oppressive rather than more expressive. Being able to describe whether or not a function can return null is an opportunity, not a constraint. * LiquidHaskell (http://news.us10.list-manage.com/track/click?u=49a6a2e17b12be2c5c4dcb232&id…) LiquidHaskell (LH) refines Haskell’s types with logical predicates that let you enforce critical properties at compile time. ** Package of the week ------------------------------------------------------------ This week’s package of the week is dump-core (http://news.us10.list-manage.com/track/click?u=49a6a2e17b12be2c5c4dcb232&id…) , a GHC plugin for rendering Core. Send us a message on Twitter (http://news.us10.list-manage2.com/track/click?u=49a6a2e17b12be2c5c4dcb232&i…) to nominate next week’s package! ============================================================ Copyright © 2017 Haskell Weekly, All rights reserved. You are receiving this email because you opted in at our website haskellweekly.news. Our mailing address is: Haskell Weekly 13140 Coit Rd Ste 405 Dallas, TX 75240 USA Want to change how you receive these emails? You can ** update your preferences (http://news.us10.list-manage.com/profile?u=49a6a2e17b12be2c5c4dcb232&id=ffb…) or ** unsubscribe from this list (http://news.us10.list-manage.com/unsubscribe?u=49a6a2e17b12be2c5c4dcb232&id…) Email Marketing Powered by MailChimp http://www.mailchimp.com/monkey-rewards/?utm_source=freemium_newsletter&utm…

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