- Haskell-Cafe - Haskell.org

Re: [Haskell-cafe] WebAssembly illustrated
by Takenobu Tani 30 Nov '18

30 Nov '18

Hi Sven, Thank you for teaching me. > Also, are you slides free to use? Could you please share the source? Of course you can use it freely :) I also commit the source. (But it is PowerPoint.) Cheers, Takenobu On Fri, Nov 30, 2018 at 9:10 PM Sven Sauleau <sven(a)sauleau.com> wrote: > Hi, > > Interesting document, thanks for sharing! > > I opened a clarification issue: [1]. > > Also, are you slides free to use? Could you please share the source? > [1]: https://github.com/takenobu-hs/WebAssembly-illustrated/issues/1 > > Thanks! > Sven > > On 30/11/2018 12:45, Takenobu Tani wrote: > > Hi cafe, > > I share this even in this place. > > WebAssembly illustrated > https://takenobu-hs.github.io/downloads/WebAssembly_illustrated.pdf > > > P.S. > Haskell has backends such as asterius [1] and dhc [2]. > > [1]: https://github.com/tweag/asterius > [2]: https://github.com/dfinity/dhc > > Cheers, > Takenobu > > > > _______________________________________________ > Haskell-Cafe mailing list > To (un)subscribe, modify options or view archives go to:http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe > Only members subscribed via the mailman list are allowed to post. > > >

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WebAssembly illustrated
by Takenobu Tani 30 Nov '18

30 Nov '18

Hi cafe, I share this even in this place. WebAssembly illustrated https://takenobu-hs.github.io/downloads/WebAssembly_illustrated.pdf P.S. Haskell has backends such as asterius [1] and dhc [2]. [1]: https://github.com/tweag/asterius [2]: https://github.com/dfinity/dhc Cheers, Takenobu

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GHC 8.6.2 zombie processes?
by Viktor Dukhovni 30 Nov '18

30 Nov '18

It seems that GHC 8.6.2 does not reap defunct child processes in a timely manner when compiling many modules (e.g. "base" when stack is building a new sandbox). This is especially visible when using LLVM 6.0 whose optimizer is particularly CPU-intensive (read mind-numbingly slow) on my X86_84 FreeBSD system: The process: $ ps -wwwwwww -o pid,etime,args -p 98525 PID ELAPSED COMMAND 98525 55:47 /home/viktor/.local/lib/ghc-8.6.2.20181122/bin/ghc -B/home/viktor/.local/lib/ghc-8.6.2.20181122 --make -fbuilding-cabal-package -O -static -dynamic-too -dynosuf dyn_o -dynhisuf dyn_hi -outputdir .stack-work/dist/x86_64-freebsd/Cabal-2.4.0.1/build -odir .stack-work/dist/x86_64-freebsd/Cabal-2.4.0.1/build -hidir .stack-work/dist/x86_64-freebsd/Cabal-2.4.0.1/build -stubdir .stack-work/dist/x86_64-freebsd/Cabal-2.4.0.1/build -i -i.stack-work/dist/x86_64-freebsd/Cabal-2.4.0.1/build -i. -i.stack-work/dist/x86_64-freebsd/Cabal-2.4.0.1/build/autogen -i.stack-work/dist/x86_64-freebsd/Cabal-2.4.0.1/build/global-autogen -I.stack-work/dist/x86_64-freebsd/Cabal-2.4.0.1/build/autogen -I.stack-work/dist/x86_64-freebsd/Cabal-2.4.0.1/build/global-autogen -I.stack-work/dist/x86_64-freebsd/Cabal-2.4.0.1/build -I/usr/local/Cellar/postgresql/10.0/include -I/usr/local/include -I/usr/local/opt/icu4c/include -optP-include -optP.stack-work/dist/x86_64-freebsd/Cabal-2.4.0.1/build/autogen/cabal_macros.h -this-unit-id Cabal-2.4.1.0-IaB5GUEm19R82R9cEdbB1D -hide-all-packages -Wmissing-home-modules -no-user-package-db -package-db /usr/home/viktor/.stack/snapshots/x86_64-freebsd/nightly-2018-11-28/8.6.2.20181122/pkgdb -package-db .stack-work/dist/x86_64-freebsd/Cabal-2.4.0.1/package.conf.inplace -package-id array-0.5.3.0 -package-id base-4.12.0.0 -package-id binary-0.8.6.0 -package-id bytestring-0.10.8.2 -package-id containers-0.6.0.1 -package-id deepseq-1.4.4.0 -package-id directory-1.3.3.0 -package-id filepath-1.4.2.1 -package-id mtl-2.2.2 -package-id parsec-3.1.13.0 -package-id pretty-1.1.3.6 -package-id process-1.6.3.0 -package-id text-1.2.3.1 -package-id time-1.8.0.2 -package-id transformers-0.5.5.0 -package-id unix-2.7.2.2 -XHaskell2010 Distribution.Backpack Distribution.Backpack.Configure Distribution.Backpack.ComponentsGraph Distribution.Backpack.ConfiguredComponent Distribution.Backpack.DescribeUnitId Distribution.Backpack.FullUnitId Distribution.Backpack.LinkedComponent Distribution.Backpack.ModSubst Distribution.Backpack.ModuleShape generated multiple hundreds of "zombies": $ ps $(pgrep -P 98525) | egrep -c defunct 460 I guess the build taking an hour is far more an issue than a few hundred zombies, but this message is about the zombies. Is this a feature or a bug? -- Viktor.

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Is there some way to hack the type system without recompiling GHC?
by ducis 29 Nov '18

29 Nov '18

We know that the type system is now a second language where you spec formal requirements and let the compiler solve it, kinda like logic programming. But sometimes I knew something is correct or at least willing to take the risk of runtime errors, but the typechecker is not (yet) able to figure it out. In this case is it possible to somehow insert (regular haskell) code into the typechecker and force the compiler to think some values are of some types, rather than waiting for or inventing some formally correct solution, which may be fundamentally very difficult?

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Tidal (musical pattern library) refactor - feedback appreciated
by Alex McLean 28 Nov '18

28 Nov '18

https://slab.org/tidal-1-0-0-refactor/ -- blog: http://slab.org/

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XText vs DSL in Haskell in mission critical software
by Puck 28 Nov '18

28 Nov '18

Hello all, how can I convince my bosses to use existing functional languages for specifying the future embedded softwares from the company instead of using Xtext or other things that firm under the name "model driven development". The softwares are mission critical. A local cooperation is already building an research institute with the goal of "model driven development". Why they do not use plain Haskell, LiquidHaskell and Coq? Neither can I imagine, that Haskell or Coq is so hard to learn, neither can I imagine that they want the developers to dive through handwritten Java extensions for their tool, that can only be analyzed with Java-tools and cannot be proven. Is XText, for example, really so good? Is a Haskell-DSL as a counterpart, not very much fewer dependent on other things, and very much easier to maintain? Thanks for suggestions and arguments Puck

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Re: [Haskell-cafe] XText vs DSL in Haskell in mission critical software
by Johannes Waldmann 28 Nov '18

28 Nov '18

> how can I convince my bosses to use existing functional languages You don't. Instead you have a coffee and read about bosses and software at dilbert.com and hackernews. While the browser refreshes the page, you write a compiler from xtext (or whatever the current buzzword is) to Haskell and back. - J.W.

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haddock (on hackage/stackage) missing references to external libraries
by Johannes Waldmann 28 Nov '18

28 Nov '18

Dear Cafe, it seems that haddock (as used on hackage) does not link to identifiers from other packages (neither in HTML nor in hyperlinked source). This hurts, especially if a project has several packages that are meant to be used together, but are split for others reasons (modularity, maintenance). Example: This index has an entry for "bpf", with a non-linked module name Csound.Base: https://hackage.haskell.org/package/csound-expression-5.3.2/docs/doc-index-… The reason is (I think) that "bpf" is defined elsewhere, but re-exported, and "elsewhere" is in a different package. It is very hard to find the name of this package! (in this case, csound-expression-opcodes) Of course, in no way is this a complaint about Anton's csound-* project. I use it in teaching, and I wonder how could we make documentation more accessible - without extra manual work. Now, :doc of ghc-8.6 works, and :info helps somewhat: :info bpf ... -- Defined in ‘Csound.Typed.Opcode.SignalGenerators’ but it still does not show the name of the package. But at least we know the name of the module to look for. - J.W.

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how to cabal-install so that :doc works?
by Johannes Waldmann 28 Nov '18

28 Nov '18

Dear Cafe - what do I have to put in my global .cabal/config in order to make ghci's new :doc command https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/ghci.html#g… work after "cabal install <foo>"? I thought "documentation: True" should do it but I am invariably getting this: GHCi, version 8.6.2: http://www.haskell.org/ghc/ :? for help Prelude> import Ersatz Prelude Ersatz> :doc solveWith ghc: Can't find any documentation for Ersatz.Solver. This is probably because the module was compiled without '-haddock', but it's also possible that the module contains no documentation. I do have the .cabal/share/doc/x86_64-linux-ghc-8.6.2/ersatz-0.4.4/html directory. The :doc command seems to work for the libraries that come with ghc (documentation in /opt/ghc/ghc-8.6.2/share/doc/ghc-8.6.2/html/ ) - J.W.

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Munich Haskell Meeting, 2018-11-28 @ 19:30
by Leah Neukirchen 27 Nov '18

27 Nov '18

Dear all, This week, our monthly Munich Haskell Meeting will take place again on Wednesday, November 28 at Cafe Puck at 19h30. For details see here: http://muenchen.haskell.bayern/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-2018/ Everybody is welcome! cu, -- Leah Neukirchen <leah(a)vuxu.org> http://leah.zone

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