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Run time module definition file location information?
by David Banas 25 Nov '15

25 Nov '15

Hi all, How can I get a running Haskell program to tell me where it’s looking, in order to satisfy “import …” statements? Thanks, -db

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Comparison between fields of each record
by Jeon-Young Kang 24 Nov '15

24 Nov '15

Dear All. I'd like to compare fields of each record. here is my record. data Person = Person {name:: String, age:: Int } deriving(Show) data Relations = Friend | Older | Younger class Comparison a where compare:: a -> a -> Relations instance Comparison Person where compare Person a b Person a b | b1 == b2 = Friend | b1 > b2 = Older | b1 < b2 = Younger How can I fit it? Sincerely, Jeon-Young Kang

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ANN: haskell-tor 0.1
by Adam Wick 24 Nov '15

24 Nov '15

Howdy - Galois is pleased to announce an initial release of haskell-tor. Haskell-tor is intended to be a full-featured, drop-in implementation of the Tor onion routing protocol. This release provides full support for resolving names and building connections via anonymized channels, as well as (less tested) support for running relay and exit nodes. There are still many tasks left to do, however, if you're interested in learning about and working on a Tor implementation, including support for hidden services, proper flow control, directory support, etc. So if you're interested, jump in! We welcome your patches. You can find haskell-tor on: GitHub: https://github.com/GaloisInc/haskell-tor Hackage: https://hackage.haskell.org/package/haskell-tor Haskell-tor is HaLVM-ready. - Adam

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darcs 2.10.2 release
by Guillaume Hoffmann 23 Nov '15

23 Nov '15

The darcs team is pleased to announce the release of darcs 2.10.2 ! # Downloading # The easiest way to install darcs 2.10.2 from source is by first installing the Haskell Platform (http://www.haskell.org/platform) If you have installed the Haskell Platform or cabal-install, you can install this release by doing: $ cabal update $ cabal install darcs-2.10.2 Alternatively, you can download the tarball from http://darcs.net/releases/darcs-2.10.2.tar.gz and build it by hand as explained in the README file. The 2.10 branch is also available as a darcs repository from http://darcs.net/releases/branch-2.10 # What's new in 2.10.2 (since 2.10.1) # * optimize patch apply code memory use * make patch selection lazier in presence of matchers * switch patches retrieval order when using packs * switch from dataenc (deprecated) to sandi * finish updating help strings with new command names * clean contrib scripts * disable mmap on Windows * enhance darcs send message * fix quickcheck suite * shorter README with quickstart instructions * fixed the following bugs: * 2457: fix darcs-test command line options * 2463: building darcs on powerpc * 2444: added default interactivity parameter to isInteractive # Feedback # If you have an issue with darcs 2.10.2, you can report it on http://bugs.darcs.net/ . You can also report bugs by email to bugs(a)darcs.net, or come to #darcs on irc.freenode.net.

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Munich Haskell Meeting, 2015-11-25 @ 19:30
by Christian Neukirchen 23 Nov '15

23 Nov '15

Dear all, This week, our monthly Munich Haskell Meeting will take place again on Wednesday, November 25 at Cafe Puck at 19h30. For details see here: http://chneukirchen.github.io/haskell-munich.de/dates.html 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-nov-2015/ Everybody is welcome! cu, -- Christian Neukirchen <chneukirchen(a)gmail.com> http://chneukirchen.org

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Haskell job in Berlin
by Matthias Fischmann 23 Nov '15

23 Nov '15

Hei everybody, We are looking for people to join our Haskell team at liquid democracy e.V. in Berlin. Details: | https://liqd.net/job_haskell.html cheers, matthias

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Running GHC LLVM output through LLVM bitcode linker first
by Clinton Mead 23 Nov '15

23 Nov '15

Is there a way to run the LLVM code (both generated by Haskell and provided by the user) though the LLVM bitcode linker to perform intermodule optimizations (like inlining) http://llvm.org/docs/CommandGuide/llvm-link.html Here's some example code: -- Main.hs -- {-# LANGUAGE MagicHash #-} {-# LANGUAGE UnboxedTuples #-} {-# LANGUAGE GHCForeignImportPrim #-} {-# LANGUAGE ForeignFunctionInterface #-} {-# LANGUAGE UnliftedFFITypes #-} {-# LANGUAGE BangPatterns #-} import GHC.Exts(Word(W#)) import GHC.Prim(Word#) foreign import ccall llvmid :: Word# -> Word# main = do line1 <- getLine let !(W# x1) = read line1 let !r1 = llvminc x1 print (W# r1) -- funcs.ll -- define fastcc i64 @llvminc(i64 inreg %x) { %r = add i64 %x, 1 ret i64 %r } When I compile like the following: ghc -O2 -fllvm -keep-s-files Main.hs funcs.ll I get an executable that performs correctly, but when I look at the assembly output in Main.s I get the following: callq suspendThread movq %rax, %rbp movq %rbx, %rdi callq llvminc movq %rax, %rbx movq %rbp, %rdi callq resumeThread This leads me to believe that this is being done like a c call through registers, but not inlined, though I'm not sure about this. I also suspect sending the "Main.ll" and "funcs.ll" files through the LLVM bitcode linker and then sending the resulting one bitcode to the LLVM compiler would perform these intramodule optimisations. Is there anyway to get GHC to use the LLVM bitcode linker to link all the LLVM files (both user provided and resulting from GHC compilation) though the LLVM bitcode linker first before the system linker?

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[NL-FP 2016] 2nd CFP: Dutch Functional Programming Day 2016
by Atze Dijkstra 23 Nov '15

23 Nov '15

[My apologies for multiple received copies of the same message] 2nd Call for Participation: Dear all, The next Dutch Functional Programming day (NL-FP 2016) will be held on Friday, January 8, 2016 at the Utrecht University, The Netherlands. You are invited to participate and to give a presentation. At the end of the day we will have a joint dinner. On the web page http://foswiki.cs.uu.nl/foswiki/NlFpDay2016/WebHome <http://foswiki.cs.uu.nl/foswiki/NlFpDay2016/WebHome> for the day you’ll find preliminary information which will be further filled in due time. Registration is by letting me know via email (with a subject header that begins with [NL-FP 2016]) whether you want to (1) participate, (2) join dinner, (3) give a presentation (please include title + abstract), also see the webpage for additional details. If you intend to participate, please let me know as soon as possible because we like to know how many people we can expect. Hope to meet you all in Utrecht at the next FP Day! Best regards, - Atze - Atze Dijkstra, Department of Information and Computing Sciences. /|\ Utrecht University, PO Box 80089, 3508 TB Utrecht, Netherlands. / | \ Tel.: +31-30-2534118/1454 | WWW : http://www.cs.uu.nl/~atze <http://www.cs.uu.nl/~atze> . /--| \ Fax : +31-30-2513971 .... | Email: atze(a)uu.nl <mailto:atze@uu.nl> ............... / |___\

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Is there an overview of backend technologies for Haskell?
by Joachim Durchholz 23 Nov '15

23 Nov '15

Hi to all, I'm wondering how the various backend technologies are regarded. What trade-offs are involved (e.g. spineless-tagless vs. generating machine code, seems to be very, very different), what options there might be, what the choice would be if a compiler were to be written from scratch, that kind of stuff. The first two pages of a web search for "Haskell backends" returned only references to GHC's LLVM backend. Which was interesting but not an overview :-) URLs welcome. Regards, Jo

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type operators and colon in GHC
by John Leo 22 Nov '15

22 Nov '15

According to sections 7.4.3 and 7.4.4 of the latest Haskell documentation https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/data-type-e… you can define (7.4.3) an infix type constructor as long as it begins with a colon, for example data a :*: b = Foo a b and furthermore (7.4.4) you can define an infix operator without having to use a colon if you enable the TypeOperators extension: data a * b = Foo a b However if I try the former without using TypeOperators I get this compiler error in 7.10.2: Illegal declaration of a type or class operator ‘:*:’ Use TypeOperators to declare operators in type and declarations Using TypeOperators fixes this, but then * without colon also works so I don't see the point of using colon anymore. My guess is this was some some kind of historical distinction which is no longer valid and the documentation needs to be updated. Is this true, or am I missing something? John

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