May 2016 - Haskell-Cafe

ANN: stack-1.1.0
by Emanuel Borsboom 04 May '16

04 May '16

See haskellstack.org for installation and upgrade instructions. Release notes: - Added Ubuntu 16.04 LTS (xenial) Apt repo. - No longer uploading new versions to Fedora 21 repo. Behavior changes: - Snapshot packages are no longer built with executable profiling. See #1179 <https://github.com/commercialhaskell/stack/issues/1179>. - stack init now ignores symlinks when searching for cabal files. It also now ignores any directory that begins with . (as well as dist dirs) - before it would only ignore .git, .stack-work, and dist. - The stack executable is no longer built with -rtsopts. Before, when -rtsopts was enabled, stack would process +RTS options even when intended for some other program, such as when used with stack exec -- prog +RTS. See #2022 <https://github.com/commercialhaskell/stack/issues/2022>. - The stack path --ghc-paths option is deprecated and renamed to --programs. --compiler is added, which points directly at the compiler used in the current project. --compiler-bin points to the compiler’s bin dir. - For consistency with the $STACK_ROOT environment variable, the stack path --global-stack-root flag and the global-stack-root field in the output of stack path are being deprecated and replaced with the stack-root flag and output field. Additionally, the stack root can now be specified via the --stack-root command-line flag. See #1148 <https://github.com/commercialhaskell/stack/issues/1148>. - stack sig GPG-related sub-commands were removed (folded into upload and sdist) - GPG signing of packages while uploading to Hackage is now the default. Use upload --no-signature if you would rather not contribute your package signature. If you don’t yet have a GPG keyset, read this blog post on GPG keys <https://fpcomplete.com/blog/2016/04/stack-security-gnupg-keys> We can add a stack.yaml config setting to disable signing if some people desire it. We hope that people will sign. Later we will be adding GPG signature verification options. - stack build pkg-1.2.3 will now build even if the snapshot has a different package version - it is treated as an extra-dep. stack build local-pkg-1.2.3 is an error even if the version number matches the local package #2028 <https://github.com/commercialhaskell/stack/issues/2028>. - Having a nix: section no longer implies enabling nix build. This allows the user to globally configure whether nix is used (unless the project overrides the default explicitly). See #1924 <https://github.com/commercialhaskell/stack/issues/1924>. - Remove deprecated valid-wanted field. - Docker: mount home directory in container #1949 <https://github.com/commercialhaskell/stack/issues/1949>. - Deprecate --local-bin-path instead --local-bin. - stack image: allow absolute source paths for add. Other enhancements: - stack haddock --open [PACKAGE] opens the local haddocks in the browser. - Fix too much rebuilding when enabling/disabling profiling flags. - stack build pkg-1.0 will now build pkg-1.0 even if the snapshot specifies a different version (it introduces a temporary extra-dep) - Experimental support for --split-objs added #1284 <https://github.com/commercialhaskell/stack/issues/1284>. - git packages with submodules are supported by passing the --recursive flag to git clone. - When using hpack <https://github.com/sol/hpack>, only regenerate cabal files when hpack files change. - hpack files can now be used in templates - stack ghci now runs ghci as a separate process #1306 <https://github.com/commercialhaskell/stack/issues/1306> - Retry when downloading snapshots and package indices - Many build options are configurable now in stack.yaml: build: library-profiling: true executable-profiling: true haddock: true haddock-deps: true copy-bins: true prefetch: true force-dirty: true keep-going: true test: true test-arguments: rerun-tests: true additional-args: ['-fprof'] coverage: true no-run-tests: true bench: true benchmark-opts: benchmark-arguments: -O2 no-run-benchmarks: true reconfigure: true cabal-verbose: true - A number of URLs are now configurable, useful for firewalls. See #1794 <https://github.com/commercialhaskell/stack/issues/1884>. - Suggest causes when executables are missing. - Allow --omit-packages even without --solver. - Improve the generated stack.yaml. - Improve ghci results after :load Main module collision with main file path. - Only load the hackage index if necessary #1883 <https://github.com/commercialhaskell/stack/issues/1883>, #1892 <https://github.com/commercialhaskell/stack/issues/1892>. - init: allow local packages to be deps of deps #1965 <https://github.com/commercialhaskell/stack/issues/1965>. - Always use full fingerprints from GPG #1952 <https://github.com/commercialhaskell/stack/issues/1952>. - Default to using gpg2 and fall back to gpg #1976 <https://github.com/commercialhaskell/stack/issues/1976>. - Add a flag for —verbosity silent. - Add haddock --open flag #1396 <https://github.com/commercialhaskell/stack/issues/1396>. Bug fixes: - Package tarballs would fail to unpack. #1884 <https://github.com/commercialhaskell/stack/issues/1884>. - Fixed errant warnings about missing modules, after deleted and removed from cabal file #921 <https://github.com/commercialhaskell/stack/issues/921> #1805 <https://github.com/commercialhaskell/stack/issues/1805>. - Now considers a package to dirty when the hpack file is changed #1819 <https://github.com/commercialhaskell/stack/issues/1819>. - Nix: cancelling a stack build now exits properly rather than dropping into a nix-shell #1778 <https://github.com/commercialhaskell/stack/issues/1778>. - allow-newer: true now causes --exact-configuration to be passed to Cabal. See #1579 <https://github.com/commercialhaskell/stack/issues/1579> . - stack solver no longer fails with InvalidRelFile for relative package paths including ... See #1954 <https://github.com/commercialhaskell/stack/issues/1954>. - Ignore emacs lock files when finding .cabal #1897 <https://github.com/commercialhaskell/stack/issues/1897>. - Use lenient UTF-8 decode for build output #1945 <https://github.com/commercialhaskell/stack/issues/1945>. - Clear index cache whenever index updated #1962 <https://github.com/commercialhaskell/stack/issues/1962>. - Fix: Building a container image drops a .stack-work dir in the current working (sub)directory #1975 <https://github.com/commercialhaskell/stack/issues/1975>. - Fix: Rebuilding when disabling profiling #2023 <https://github.com/commercialhaskell/stack/issues/2023>. ------------------------------ Thanks to all our contributors for this release: - Beerend Lauwers @beerendlauwers <https://github.com/beerendlauwers> - Chris Done @chrisdone <https://github.com/chrisdone> - Christian Hoener zu Siederdissen - @CthulhuDen <Https://Github.Com/CthulhuDen> - Emanuel Borsboom @borsboom <https://github.com/borsboom> - Erik Stevenson @narrative <https://github.com/narrative> - @fmap <https://github.com/fmap> - Greg @myfreeweb <https://github.com/myfreeweb> - Harendra Kumar @harendra-kumar <https://github.com/harendra-kumar> - Luigy Leon @luigy <https://github.com/luigy> - @malteneuss <https://github.com/malteneuss> - Mark Karpov @mrkkrp <https://github.com/mrkkrp> - Martin Dehnel-Wild @mpdehnel <https://github.com/mpdehnel> - Mathieu Boespflug @mboes <https://github.com/mboes> - Michael Sloan @mgsloan <https://github.com/mgsloan> - Michael Snoyman @snoyberg <https://github.com/snoyberg> - Noon van der Silk @silky <https://github.com/silky> - Oleg Grenrus @phadej <https://github.com/phadej> - Paul Rouse @paul-rouse <https://github.com/paul-rouse> - Rob Rix @robrix <https://github.com/robrix> - Simon Hengel @sol <https://github.com/sol> - Simon Jakobi @sjakobi <https://github.com/sjakobi> - Taylor Fausak @tfausak <https://github.com/tfausak> - @tejon <https://github.com/tejon> - Tim Dysinger @dysinger <https://github.com/dysinger> - Tobias Kortkamp @t6 <https://github.com/t6> - Tristan Webb @drwebb <https://github.com/drwebb> - Yuji Yamamoto @igrep <https://github.com/igrep> - Yuriy Syrovetskiy @cblp <https://github.com/cblp> - Yves Parès (Ywen) @YPares <Https://Github.Com/YPares> And thanks as always to the 150+ contributors to past releases!

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ANN: monad-ste-0.1.0.0
by Carter Schonwald 04 May '16

04 May '16

hello All, I took the time this evening to clean up some work that came out of a larger project and have made a corresponding release to hackage monad-ste is sibling to ST that provides efficient abortive errors using GHC's exception machinery as well as handy machinery like being a PrimMonad and PrimBase instance! (and take heed, you cannot catch ) hackage: https://hackage.haskell.org/package/monad-ste-0.1.0.0 github: https://github.com/cartazio/monad-ste also thanks Brian Schroeder, Joel Burget and Duncan Coutts for providing invaluable feedback, debugging and the like for this library enjoy! -Carter

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Call for Papers: OCL and Textual Modeling Tools and Textual Model Transformations (OCL 2016) - Submit Your Paper Until July 17, 2016
by Achim D. Brucker 04 May '16

04 May '16

(Apologies for duplicates) CALL FOR PAPERS 16th International Workshop on OCL and Textual Modeling Co-located with ACM/IEEE 19th International Conference on Model Driven Engineering Languages and Systems (MODELS 2016) October 2-4, 2016, Saint-Malo, France (TBC) http://oclworkshop.github.io Modeling started out with UML and its precursors as a graphical notation. Such visual representations enable direct intuitive capturing of reality, but some of their features are difficult to formalize and lack the level of precision required to create complete and unambiguous specifications. Limitations of the graphical notations encouraged the development of text-based modeling languages that either integrate with or replace graphical notations for modeling. Typical examples of such languages are OCL, textual MOF, Epsilon, and Alloy. Textual modeling languages have their roots in formal language paradigms like logic, programming and databases. The goal of this workshop is to create a forum where researchers and practitioners interested in building models using OCL or other kinds of textual languages can directly interact, report advances, share results, identify tools for language development, and discuss appropriate standards. In particular, the workshop will encourage discussions for achieving synergy from different modeling language concepts and modeling language use. The close interaction will enable researchers and practitioners to identify common interests and options for potential cooperation. Topics of interest include (but are not limited to) =================================================== - Mappings between textual modeling languages and other languages or formalisms - Algorithms, evaluation strategies and optimizations in the context of textual modeling languages for -- validation, verification, and testing, -- model transformation and code generation, -- meta-modeling and DSLs, and -- query and constraint specifications - Alternative graphical/textual notations for textual modeling languages - Evolution, transformation and simplification of textual modeling expressions - Libraries, templates and patterns for textual modeling languages - Tools that support textual modeling languages (e.g., verification of OCL formulae, runtime monitoring of invariants) - Complexity results for textual modeling languages - Quality models and benchmarks for comparing and evaluating textual modeling tools and algorithms - Successful applications of textual modeling languages - Case studies on industrial applications of textual modeling languages - Experience reports -- usage of textual modeling languages and tools in complex domains, -- usability of textual modeling languages and tools for end-users - Empirical studies about the benefits and drawbacks of textual modeling languages - Innovative textual modeling tools - Comparison, evaluation and integration of modeling languages - Correlation between modeling languages and modeling tasks This year, we particularly encourage submissions describing tools that support - in a very broad sense - textual modeling languages (if you have implemented OCL.js to run OCL in a web browser, this is the right workshop to present your work) as well as textual model transformations. Venue ===== The workshop will be organized as a part of MODELS 2016 Conference in Saint-Malo, France. It continues the series of OCL workshops held at UML/MODELS conferences: York (2000), Toronto (2001), San Francisco (2003), Lisbon (2004), Montego Bay (2005), Genova (2006), Nashville (2007), Toulouse (2008), Denver (2009), Oslo (2010), Zurich (2011, at the TOOLs conference), 2012 in Innsbruck, 2013 in Miami, 2014 in Valencia, Spain, and 2015 in Ottawa, Canada. Similar to its predecessors, the workshop addresses both people from academia and industry. The aim is to provide a forum for addressing integration of OCL and other textual modeling languages, as well as tools for textual modeling, and for disseminating good practice and discussing the new requirements for textual modeling. Workshop Format =============== The workshop will include short (about 15 min) presentations, parallel sessions of working groups, and sum-up discussions. Submissions =========== Two types of papers will be considered: * short contributions (between 6 and 8 pages) describing new ideas, innovative tools or position papers. * full papers (between 12 and 16 pages) in LNCS format. Submissions should be uploaded to EasyChair (https://easychair.org/conferences/?conf=ocl16) The program committee will review the submissions (minimum 2 reviews per paper, usually 3 reviews) and select papers according to their relevance and interest for discussions that will take place at the workshop. Accepted papers will be published online in a post-conference edition of CEUR (http://www.ceur-ws.org) Important Dates =============== Submission of papers: July 17, 2016 Notification: August 14, 2016 Workshop date: October 2-4, 2016 Organizers ========== Achim D. Brucker, The University of Sheffield, UK Jordi Cabot, ICREA - Open University of Catalonia, Spain Adolfo Sánchez-Barbudo Herrera, University of York, UK Programme Committee (TBC) ========================= Thomas Baar, University of Applied Sciences Berlin, Germany Mira Balaban, Ben-Gurion University of the Negev, Israel Tricia Balfe, Nomos Software, Ireland Domenico Bianculli, University of Luxembourg Dan Chiorean, Babes-Bolyai University, Romania Robert Clariso, Universitat Oberta de Catalunya, Spain Tony Clark, Middlesex University, UK Manuel Clavel, IMDEA Software Institute, Spain Birgit Demuth, Technische Universitat Dresden, Germany Marina Egea, Indra Sistemas S.A., Spain Geri Georg, Colorado State University, USA Martin Gogolla, University of Bremen, Germany Shahar Maoz, Tel Aviv University, Israel Istvan Rath, Budapest University of Technology and Economics, Hungary Bernhard Rumpe, RWTH Aachen, Germany Massimo Tisi, Mines de Nantes, France Frederic Tuong, Univ. Paris-Sud - IRT SystemX - LRI, France Edward Willink, Willink Transformations Ltd., UK Burkhart Wolff, Univ. Paris-Sud - LRI, France Steffen Zschaler, King's College, UK -- Dr. Achim D. Brucker | Senior Lecturer | University of Sheffield https://www.brucker.ch/

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Amazon SES email issues
by David Escobar 04 May '16

04 May '16

Hi everyone, I'm having issues with sending email through Amazon SES. I'm using the *Network.Mail.Mime.SES* package. The error I get is: *email-test-exe: SESException {seStatus = Status {statusCode = 403, statusMessage = "Forbidden"}, seCode = "SignatureDoesNotMatch", seMessage = "The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method. Consult the service documentation for details.", seRequestId = "8ceb250a-0dd3-11e6-892c-4fb1a14d4732"}* What's confusing is that I'm using the same SES settings in a Rails app as well as a small Rust console program without any issues (it works from the same machine too). The only thing I can think of is that with this Haskell package, I haven't found where to set certain things like the port number (587) and so maybe it's that? Here is a small sample app that illustrates the problem. What am I missing? Thanks. *{-# LANGUAGE OverloadedStrings #-}{-# LANGUAGE QuasiQuotes #-}* *module Main where* *import Data.Function ((&))import GHC.Genericsimport Network.HTTP.Clientimport Network.HTTP.Client.TLSimport Network.Mail.Mimeimport Network.Mail.Mime.SESimport Text.Hamlet (shamlet)import Text.Blaze.Html.Renderer.String (renderHtml)import qualified Data.ByteString.Char8 as C8import qualified Data.Text as Timport qualified Data.Text.Lazy as LTmain :: IO ()main = do manager <- newManager tlsManagerSettings let sesConfig = SES { sesFrom = C8.pack "de(a)somewhere.com <de(a)somewhere.com>", sesTo = [ C8.pack "someone.else(a)somewhereelse.com <someone.else(a)somewhereelse.com>" ], sesAccessKey = "SOMEAWSACCESSKEY", sesSecretKey = "ANEVENLONGERAWSSECRETKEY1234567890", sesRegion = usEast1 } email = Mail { mailFrom = Address (Just "David Escobar") "de(a)somewhere.com <de(a)somewhere.com>", mailTo = [ Address (Just "Someone Else") "someone.else(a)somewhereelse.com <someone.else(a)somewhereelse.com>" ], mailParts = [ [ htmlPart testEmail ] ], mailCc = [], mailBcc = [], mailHeaders = [ ("subject", "Some Test Email"), ("Content-Type", "text/html; charset=ISO-8859-1") ] } renderSendMailSES manager sesConfig emailtestEmail :: LT.TexttestEmail = let rows = [ [ "1", "2", "3" ], [ "4", "5", "6" ]] in renderHtml [shamlet| $doctype 5 <html> <body> <table style="border: 1px solid black; border-collapse: collapse; margin: 25px 0; width: 100%;"> <tr> <th style="background-color: #072a2d; color: white; font-weight: bold; border-right: 1px solid white; padding: 5px 10px; width: 33%;"> Column 1 <th style="background-color: #072a2d; color: white; font-weight: bold; border-right: 1px solid white; padding: 5px 10px; width: 33%;"> Column 2 <th style="background-color: #072a2d; color: white; font-weight: bold; border-right: 1px solid white; padding: 5px 10px; width: 33%;"> Column 3 $forall row <- rows <tr style="background-color: #f8f9ee;"> <td style="border: 1px solid black; padding: 5px 10px; text-align: left; width: 33%;"> #{T.pack $ row !! 0} <td style="border: 1px solid black; padding: 5px 10px; text-align: left; width: 33%;"> #{T.pack $ row !! 1} <td style="border: 1px solid black; padding: 5px 10px; text-align: left; width: 33%;"> #{T.pack $ row !! 2} |] & LT.pack*

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Re: [Haskell-cafe] Bikeshedding request for GHCi's :type
by Richard Eisenberg 03 May '16

03 May '16

I have collected feedback gleaned here, on the ticket, and on reddit and summarized here: https://ghc.haskell.org/trac/ghc/wiki/Design/GHCi/Type#Summaryoffeedbackabo… That summary includes this concrete proposal: 1. Ask for concrete suggestions about names for the new commands. 2. Use these names on my current implementation (which prints out only one specialization) 3. Post a feature request looking for more specializations. I simply don't have time to specify a design or implement an algorithm for printing out multiple specializations. Furthermore, my current implementation meets all specifications proffered for printing out multiple specializations, for all values of "multiple" that equal 1. It is easy to extend later. Separately, there is a groundswell of support for :doc, but that's beyond the scope of my work on this point. (I personally would love :doc, too.) So, what shall we name the two new commands? 1. A new command that specializes a type. (Currently with one specialization, but perhaps more examples in the future.) 2. A new command that preserves specialized type variables so that users of TypeApplications know what type parameters to pass in next. I have suggested :type-def for (1) and :type-spec for (2). I don't strongly like either. :examples and :inst have been suggested for (1). Any other ideas? Thanks! Richard On Apr 26, 2016, at 9:08 AM, Richard Eisenberg <eir(a)cis.upenn.edu> wrote: > Hi devs, > > Over the weekend, I was pondering the Haskell course I will be teaching next year and shuddered at having to teach Foldable at the same time as `length`. So I implemented feature request #10963 (https://ghc.haskell.org/trac/ghc/ticket/10963) which allows for a way for a user to request a specialization of a type. It all works wonderfully, but there is a real user-facing design issue here around the default behavior of :type and whether or not to add new :type-y like commands. I have outlined the situation here: https://ghc.haskell.org/trac/ghc/wiki/Design/GHCi/Type > > I'd love some broad input on this issue. If you've got a stake in how this all works, please skim that wiki page and comment on #10963. > > Thanks! > Richard > _______________________________________________ > ghc-devs mailing list > ghc-devs(a)haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs

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Re: [Haskell-cafe] Controlling how test data is generated in, QuickCheck 2
by Li-yao Xia 03 May '16

03 May '16

Hi Michael, > What I noticed was the answer suggested that one should write a `newtype`, > wrapping a `[Int]` and making a new `Arbitrary` instance. However, I also > noticed that the answer is from 2012, and `QuickCheck 2` has an `Args` > `datatype` that appears to be able to do what I need. So, can I create a > new `Args` to limit the range of tests, (just want the first 1000 Fibonacci > numbers), and also to limit the number of tests run? If not is the solution > from the above link the approach I would have to take? The module Test.Hspec.QuickCheck has functions to modify the number of tests to be run (modifyMaxSuccess) and the maximum size passed to the generators (modifyMaxSize) (and indeed internally they modify the Args passed to QuickCheck's driver). I believe their purpose is to modify values coming from outside the program, via the command line options --qc-max-success and --qc-max-size. You can certainly set them to constants: modifyMaxSuccess (const 1000) $ prop ... But to specify the domains of your properties from within the program, the approaches mentioned in the answer you linked to are still current. Defining a newtype wrapper with an Arbitrary instance is a somewhat heavyweight solution. Some already exist for common preconditions, for example you can use Positive instead of the first check in modfiz: modfiz :: Positive Int -> Bool modfiz (Positive int) = ... The answer also mentions forAll and standalone generators, which I find to be most straightforward to set the domain of testfib: testfib :: Property testfib = forAll (choose (1, 1000)) $ \n -> ... Li-yao

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Controlling how test data is generated in QuickCheck 2
by Michael Litchard 03 May '16

03 May '16

I have a problem similar to this question < http://stackoverflow.com/questions/9977734/controlling-how-test-data-is-gen…>. Below I will articulate my specifics, the code I am using, and the particular question I have. I have written a fizz-buzz program that uses a Fibonacci sequence as input. I would like to test two things. (1) Does my program emit the correct string given an Int that meets a particular condition. (2) Is my Fibonacci generator generating Fibonacci numbers? The problem I am having is similar to the link above. The range of `Int`s is too large. How do I constrain my tests to say, the first 1000 Fibonacci numbers? Here is code that I think is both adequate and minimal. Please let me know if I need to elaborate. import Data.Numbers.Primes (isPrime) import Test.Hspec (Spec,hspec,describe,it,shouldBe) import Test.Hspec.QuickCheck (prop) qcheck :: Spec qcheck = do describe "QuickCheck test fiz" $ prop "QuickCheck test" $ modfiz describe "QuickCheck test fib" $ prop "QuickCheck test fib" $ testfib modfiz int | int <= 0 = True -- code smell, should never generate number less than or equal to zero. | int == 3 = test3 | int == 5 = test5 | int `mod` 15 == 0 = testMod35 | int `mod` 3 == 0 = testMod3 | int `mod` 5 == 0 = testMod5 | isPrime int == True = testPrime | otherwise = testRest where test3 = Right "Buzz BuzzFizz" == fizzbuzz 3 test5 = Right "Fizz BuzzFizz" == fizzbuzz 5 testMod3 = Right "Buzz " == fizzbuzz int testMod5 = Right "Fizz " == fizzbuzz int testMod35 = Right "Buzz Fizz " == fizzbuzz int testPrime = Right "BuzzFizz" == fizzbuzz int testRest = Right (show int) == fizzbuzz int testfib :: Integer -> Bool testfib n = case (fibb n) of Left _ -> False Right n' -> isFib n' `fibb` takes an `Int` and finds that nth Fibonacci. So `fibb 6` would return `Right 8`. The `Left` value is not relevant to this problem. What I noticed was the answer suggested that one should write a `newtype`, wrapping a `[Int]` and making a new `Arbitrary` instance. However, I also noticed that the answer is from 2012, and `QuickCheck 2` has an `Args` `datatype` that appears to be able to do what I need. So, can I create a new `Args` to limit the range of tests, (just want the first 1000 Fibonacci numbers), and also to limit the number of tests run? If not is the solution from the above link the approach I would have to take? the entire project here <https://github.com/mlitchard/swiftfizz>

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Applications using generalized monads?
by Jan Bracker 02 May '16

02 May '16

Hello, I am currently looking into applications of generalized monads. I am aware of the following generalized monad concepts (and libraries implementing them): * Indexed/Parameterized/Hoare Monads [1] * indexed [8] * simple-sessions [9][4] * monad-param [10][3][6] * Effect Monads [2] * effect-monad [11][5] * monad-param [12][3] * Constrained Monads * rmonad [13] Question 1: Do you know of other libraries that implement generalized monad concepts? Most of the libraries I listed above are in working condition, but still outdated. Question 2: Do you know of (open source) software and applications that use these concepts/libraries to implement something? This mail is a copy of my post on Reddit [7]. I am sorry for reposting it here, but I dod not get a response on that post for almost 2 weeks now. Best, Jan [1]: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.104.3020 [2]: http://dl.acm.org/citation.cfm?doid=2578855.2535846 [3]: http://comonad.com/reader/2007/parameterized-monads-in-haskell/ [4]: http://www.ccs.neu.edu/home/tov/pubs/haskell-session-types/session08.pdf [5]: https://www.cl.cam.ac.uk/~dao29/publ/haskell14-effects.pdf [6]: http://www.researchgate.net/profile/Dominique_Devriese/publication/22128235… [7]: https://www.reddit.com/r/haskellquestions/comments/4fs80x/ [8]: http://hackage.haskell.org/package/indexed [9]: http://hackage.haskell.org/package/simple-sessions [10]: http://hackage.haskell.org/package/monad-param [11]: http://hackage.haskell.org/package/effect-monad [12]: http://hackage.haskell.org/package/monad-param [13]: http://hackage.haskell.org/package/rmonad

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cannot perform arithmetic with GHC.TypeLits?
by Baojun Wang 02 May '16

02 May '16

Hi List, When I try to build below program, the compiler complains Couldn't match type ‘n’ with ‘1 + (n - 1)’ … Why GHC (7.10.3) cannot do type level natural number arithmetic? `` n /= 1 + (n-1)`` at type level? -- | main.hs {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE KindSignatures #-} {-# LANGUAGE TypeOperators #-} {-# LANGUAGE DataKinds #-} {-# LANGUAGE OverloadedStrings #-} {-# LANGUAGE DeriveGeneric #-} module Main where import qualified Data.ByteString as B import Data.ByteString(ByteString) import Data.Serialize -- require cereal import GHC.TypeLits data Scalar :: Nat -> * -> * where Nil :: Scalar 0 a Cons :: a -> Scalar m a -> Scalar (1+m) a instance (Serialize a) => Serialize (Scalar 0 a) where get = return Nil put _ = return $ mempty instance (Serialize a) => Serialize (Scalar n a) where get = do x <- get :: Get a xs <- get :: Get (Scalar (n-1) a) return $! Cons x xs put (Cons x xs) = do put (x :: a) put xs -- /tmp/vect1/app/Main.hs:31:15: Couldn't match type ‘n’ with ‘1 + (n - 1)’ … ‘n’ is a rigid type variable bound by the instance declaration at /tmp/vect1/app/Main.hs:27:10 Expected type: Scalar n a Actual type: Scalar (1 + (n - 1)) a Relevant bindings include xs :: Scalar (n - 1) a (bound at /tmp/vect1/app/Main.hs:30:5) get :: Get (Scalar n a) (bound at /tmp/vect1/app/Main.hs:28:3) In the second argument of ‘($!)’, namely ‘Cons x xs’ In a stmt of a 'do' block: return $! Cons x xs Compilation failed. - baojun

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Hackage package upload error: Invalid package
by Kostiantyn Rybnikov 02 May '16

02 May '16

Hi! Wanted to upload the 0.8.1 version of hedis, did what I usually did, but getting an error. Running "stack -v upload ." seems to show some tls-related details. ``` ➜ hedis git:(master) stack -v upload . Version 1.0.4.3 x86_64 2016-05-01 15:29:31.034044: [debug] Checking for project config at: /Users/kb/workspace/hedis/stack.yaml @(stack_2rXRdr1j02iFXWAif5re4K:Stack.Config src/Stack/Config.hs:761:9) 2016-05-01 15:29:31.037100: [debug] Loading project config file stack.yaml @(stack_2rXRdr1j02iFXWAif5re4K:Stack.Config src/Stack/Config.hs:779:13) 2016-05-01 15:29:31.110561: [debug] Checking for project config at: /Users/kb/workspace/hedis/stack.yaml @(stack_2rXRdr1j02iFXWAif5re4K:Stack.Config src/Stack/Config.hs:761:9) 2016-05-01 15:29:31.110690: [debug] Loading project config file stack.yaml @(stack_2rXRdr1j02iFXWAif5re4K:Stack.Config src/Stack/Config.hs:779:13) 2016-05-01 15:29:31.111459: [debug] Trying to decode /Users/kb/.stack/build-plan-cache/x86_64-osx/lts-5.3.cache @(stack_2rXRdr1j02iFXWAif5re4K:Data.Binary.VersionTagged src/Data/Binary/VersionTagged.hs:55:5) 2016-05-01 15:29:31.124939: [debug] Success decoding /Users/kb/.stack/build-plan-cache/x86_64-osx/lts-5.3.cache @(stack_2rXRdr1j02iFXWAif5re4K:Data.Binary.VersionTagged src/Data/Binary/VersionTagged.hs:64:13) 2016-05-01 15:29:31.132890: [debug] Trying to decode /Users/kb/.stack/indices/Hackage/00-index.cache @(stack_2rXRdr1j02iFXWAif5re4K:Data.Binary.VersionTagged src/Data/Binary/VersionTagged.hs:55:5) 2016-05-01 15:29:31.421690: [debug] Success decoding /Users/kb/.stack/indices/Hackage/00-index.cache @(stack_2rXRdr1j02iFXWAif5re4K:Data.Binary.VersionTagged src/Data/Binary/VersionTagged.hs:64:13) 2016-05-01 15:29:31.434522: [debug] Run process: ghc --info @(stack_2rXRdr1j02iFXWAif5re4K:System.Process.Read src/System/Process/Read.hs:269:3) 2016-05-01 15:29:31.498337: [debug] Run process: ghc --numeric-version @(stack_2rXRdr1j02iFXWAif5re4K:System.Process.Read src/System/Process/Read.hs:269:3) 2016-05-01 15:29:31.543696: [debug] Run process: ghc-pkg --no-user-package-db field --simple-output Cabal version @(stack_2rXRdr1j02iFXWAif5re4K:System.Process.Read src/System/Process/Read.hs:269:3) 2016-05-01 15:29:31.576011: [debug] Run process: ghc-pkg --no-user-package-db list --global @(stack_2rXRdr1j02iFXWAif5re4K:System.Process.Read src/System/Process/Read.hs:269:3) 2016-05-01 15:29:31.625682: [info] Getting file list for /Users/kb/workspace/hedis/ @(stack_2rXRdr1j02iFXWAif5re4K:Stack.SDist src/Stack/SDist.hs:96:5) 2016-05-01 15:29:31.628599: [debug] Checking resolver: lts-5.3 @(stack_2rXRdr1j02iFXWAif5re4K:Stack.Build.Source src/Stack/Build/Source.hs:164:17) 2016-05-01 15:29:31.628777: [debug] Trying to decode /Users/kb/.stack/build-plan-cache/x86_64-osx/lts-5.3.cache @(stack_2rXRdr1j02iFXWAif5re4K:Data.Binary.VersionTagged src/Data/Binary/VersionTagged.hs:55:5) 2016-05-01 15:29:31.636259: [debug] Success decoding /Users/kb/.stack/build-plan-cache/x86_64-osx/lts-5.3.cache @(stack_2rXRdr1j02iFXWAif5re4K:Data.Binary.VersionTagged src/Data/Binary/VersionTagged.hs:64:13) 2016-05-01 15:29:31.650120: [debug] Run process: ghc-pkg --no-user-package-db list --global @(stack_2rXRdr1j02iFXWAif5re4K:System.Process.Read src/System/Process/Read.hs:269:3) 2016-05-01 15:29:31.679601: [debug] Run process: /Users/kb/.stack/setup-exe-cache/x86_64-osx/setup-Simple-Cabal-1.22.5.0-ghc-7.10.3 --builddir=.stack-work/dist/x86_64-osx/Cabal-1.22.5.0 sdist --list-sources /private/var/folders/7l/3ys9j0lx20j6z69lm6s_9r780000gn/T/stack-sdist56408/source-files-list @(stack_2rXRdr1j02iFXWAif5re4K:System.Process.Read src/System/Process/Read.hs:287:3) 2016-05-01 15:29:31.728919: [info] Building sdist tarball for /Users/kb/workspace/hedis/ @(stack_2rXRdr1j02iFXWAif5re4K:Stack.SDist src/Stack/SDist.hs:98:5) 2016-05-01 15:29:31.756558: [info] Checking package 'hedis' for common mistakes @(stack_2rXRdr1j02iFXWAif5re4K:Stack.SDist src/Stack/SDist.hs:274:5) 2016-05-01 15:29:31.758110: [warn] Package check reported the following warnings: 'ghc-options: -Wall -Werror' makes the package very easy to break with future GHC versions because new GHC versions often add new warnings. Use just 'ghc-options: -Wall' instead. 'ghc-prof-options: -auto-all' is fine during development, but not recommended in a distributed package. @(stack_2rXRdr1j02iFXWAif5re4K:Stack.SDist src/Stack/SDist.hs:285:9) Uploading hedis-0.8.1.tar.gz... TlsExceptionHostPort (HandshakeFailed (Error_Packet_unexpected "Alert [(AlertLevel_Fatal,BadRecordMac)]" " expected: change cipher")) "hackage.haskell.org" 443 ➜ hedis git:(master) stack upload . Getting file list for /Users/kb/workspace/hedis/ Building sdist tarball for /Users/kb/workspace/hedis/ Checking package 'hedis' for common mistakes Package check reported the following warnings: 'ghc-options: -Wall -Werror' makes the package very easy to break with future GHC versions because new GHC versions often add new warnings. Use just 'ghc-options: -Wall' instead. 'ghc-prof-options: -auto-all' is fine during development, but not recommended in a distributed package. Uploading hedis-0.8.1.tar.gz... unhandled status code: 400 Error: Invalid package 'ghc-options: -Wall -Werror' makes the package very easy to break with future GHC versions because new GHC versions often add new warnings. Use just 'ghc-options: -Wall' instead. Upload failed on hedis-0.8.1.tar.gz ``` Hope somebody can take a look. Thank you.

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