July 2017 - Haskell-Cafe

Shout out for Chinese(?) speakers of Haskell
by Anthony Clayden 30 Jul '17

30 Jul '17

Is there a Chinese language(s) equivalent to StackOverflow or reddit or haskell-cafe? I'm asking because someone keeps posting to Trac with beginner/intermediate level questions. They're posting code that doesn't work/doesn't compile, and expecting Trac support to 'fix' it. Clearly they do not speak good English, because they're not explaining what they want the code to do (despite several requests). There have been some comments via Google translate, which isn't well versed in Haskell terminology (no surprise). Their first few tickets had narrative in Chinese characters. Looks like traditional script, so they're maybe a Cantonese speaker; or in Taiwan(?) Thank you AntC

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Re: [Haskell-cafe] [ANNOUNCE] GHC 8.2.1 available
by Wolfgang Jeltsch 30 Jul '17

30 Jul '17

Am Samstag, den 22.07.2017, 23:03 -0400 schrieb Ben Gamari: > In addition, there are a number of new features, > > * A new, more type-safe type reflection mechanism > > * The long-awaited Backpack module system > > * Deriving strategies to disambiguate between GHC's various instance > deriving mechanisms > > * Unboxed sum types, for efficient unpacked representation of sum > data types > > * Compact regions, allowing better control over garbage collection > in the presence of large heaps containing many long-lived objects. > > * Colorful messages and caret diagnostics for more legible errors > > A more thorough list of the changes in this release can be found in > the release notes, > > https://haskell.org/ghc/docs/8.2.1/docs/html/users_guide/8.2.1-notes.html It seems that the release notes mention the new type reflection mechanism und colorful messages only in the “Highlights” section, not in the “Full details” section, and that they do not mention the Backpack module system and unboxed sums at all. All the best, Wolfgang

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Damn you hmatrix
by Yotam Ohad 29 Jul '17

29 Jul '17

Hi cafe, I have a very annoying problem with hmatrix. I have a project which depends on it. I can use `stack build` with no errors but when I try to load it to GHCi(`stack ghci`) I get the following error: sh-4.3$ stack ghci [0mApple-0.1.0.0: configure (lib) [0m [0mConfiguring Apple-0.1.0.0... [0m [0mApple-0.1.0.0: initial-build-steps (lib) [0m [0mConfiguring GHCi with the following packages: Apple [0m GHCi, version 8.0.2: http://www.haskell.org/ghc/ :? for help ghc.EXE: addDLL: libblas.dll (Win32 error 126): The specified module could not be found. ghc.EXE: Could not load `libblas.dll'. Reason: addDLL: could not load DLL ghc.EXE: addDLL: liblapack.dll (Win32 error 126): The specified module could not be found. ghc.EXE: Could not load `liblapack.dll'. Reason: addDLL: could not load DLL ghc.EXE: C:\Users\Yotam\Apple\.stack-work\install\ebd7be2b\lib\x86_64-windows-ghc-8.0.2\hmatrix-0.18.0.0-IA7RzrKn1o84vo5PLhGcwQ\HShmatrix-0.18.0.0-IA7RzrKn1o84vo5PLhGcwQ.o: unknown symbol `dgesvd_' ghc.EXE: unable to load package `hmatrix-0.18.0.0' This is really bizarre, and could not find something online to help me fix this. I'm using stack 1.5.0 with ghc 8.0.2 On a side note, I've seen some discussions about why the C libraries can't be added automatically but did not understand most of it, if someone can explain it would be highly appreciated. Yotam

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GHCi and custom preprocessors
by aditya siram 28 Jul '17

28 Jul '17

Hi all, I have a custom file format and custom preprocessor in my project that converts it to Haskell. GHCi is unable to detect when changes are made to the custom file, it only sees that the Haskell file hasn't changed and doesn't reload anything. Is this even supported in GHCi? Thanks! -deech

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How to execute a function loaded via GHCI.ObjLink?
by Saurabh Nanda 28 Jul '17

28 Jul '17

Hi, I'm playing around with https://www.stackage.org/haddock/lts-9.0/ghci-8.0.2/GHCi-ObjLink.html to see if I can come up with some sort of hot-loading/plugin system in Haskell. I've managed to load a shared object (compiled from a Haskell source via -rdynamic) with the following code: {-# LANGUAGE OverloadedStrings #-} {-# LANGUAGE MagicHash, UnboxedTuples #-} module Main where import GHC.Exts ( addrToAny# ) import GHC.Ptr ( Ptr(..) ) import System.Info ( os, arch ) import Encoding import GHCi.ObjLink import Debug.Trace main :: IO () main = do traceM "before initObjLinker" initObjLinker traceM "before loadObj" loadObj "/Users/saurabhnanda/projects/test-plugins/test-plugins/app/PluginMarkup.o" traceM "after loadObj" -- NOTE: I've hardcoded the symbol name that I obtained from running `symbols PluginMarkup.o` sym <- lookupSymbol "PluginMarkup_foliage_info" traceM "after lookupsymbol" traceM (show sym) I'm getting the following output, which mean that I'm probably getting the Ptr to the function. before initObjLinker before loadObj after loadObj after lookupsymbol Just 0x0000000104be49a8 Question is, how do I run the function in the same Haskell environment/runtime? The underlying function is actually `foliage :: UtcTime -> Html` The code is available at https://github.com/vacationlabs/hint-test/blob/dll/app/Main.hs and the DLL is available at https://github.com/vacationlabs/hint-test/blob/dll/app/PluginMarkup.o -- Saurabh.

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[ANN] saltine 0.0.1.0 released - Users urged to upgrade
by Max Amanshauser 27 Jul '17

27 Jul '17

Saltine is a Haskell binding to libsodium. === Thomas DuBuisson of Galois Inc. found a serious issue in saltine that can lead to data corruption. Security implications cannot be ruled out. All users are advised to upgrade to saltine 0.0.0.6 or above, which are not affected. Saltine requires libsodium 1.0.11 or higher. === Saltine 0.0.1.0 also features: * Support for detached signatures (contributed by Thomas DuBuisson) -- Cheers, Max.

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Re: [Haskell-cafe] Static analysis engineering at Facebook (Clang/OCaml)
by Don Stewart 27 Jul '17

27 Jul '17

Link moved, apply here: https://www.facebook.com/careers/jobs/a0I1200000LT8aAEAT On Thu, Jul 27, 2017 at 12:39 PM, Shannon Sequeira < shannonsequeira(a)gmail.com> wrote: > Hi Don, the job link appears to be broken. > > Best, > Shannon Sequeira > > On 26 July 2017 at 13:11, Don Stewart <dons00(a)gmail.com> wrote: > >> The Infer static analysis team at Facebook is hiring. We have a >> functional programming engineering role in London to work on the open >> source Clang/C++ frontend to Infer. >> >> Infer is a static analysis suite for C++, Java and Objective C used by >> thousands of engineers at Facebook and elsewhere to find bugs. >> >> The role is a "compiler" role - working on the Clang AST to OCaml, and >> intermediate phases of Infer to improve our C++ analysis capabilities. Good >> FP engineering skills (e.g. Haskell or OCaml) are desirable. >> >> You should have a working knowledge of C++ semantics, language or >> compiler design or experience in a range of C++ projects. >> >> Infer: >> >> http://fbinfer.com/ >> >> Apply via: >> >> https://www.facebook.com/careers/jobs/a0I1200000LT8aA >> >> _______________________________________________ >> 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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GHC Platform-independent object files
by Hugo Pacheco 27 Jul '17

27 Jul '17

Hi cafe, I am wondering if there is any easy way to distribute a Haskell module/library in a platform-independent manner without revealing the source code, that can be seamlessly linked with GHC? I am thinking about some sort of GHC object files or any intermediate representation such as C,LLVM or Haskell Core. My use case would be to release a small utility module as part of a student assignment without revealing its source code to students. Thanks, hugo -- www.di.uminho.pt/~hpacheco

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custom package for Verbosity, info, warn etc. in console programs
by Henning Thielemann 27 Jul '17

27 Jul '17

I have several command-line tools that support a verbosity flag. The Cabal library provides an appropriate data type and related reporting functions: https://hackage.haskell.org/package/Cabal-2.0.0.2/docs/Distribution-Verbosi… https://hackage.haskell.org/package/Cabal-2.0.0.2/docs/Distribution-Simple-… However, Cabal moves pretty fast (frequent version increments) and I do not need all the distribution stuff. Is there a package that provides only the Verbosity and reporting functionality?

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Static analysis engineering at Facebook (Clang/OCaml)
by Don Stewart 26 Jul '17

26 Jul '17

The Infer static analysis team at Facebook is hiring. We have a functional programming engineering role in London to work on the open source Clang/C++ frontend to Infer. Infer is a static analysis suite for C++, Java and Objective C used by thousands of engineers at Facebook and elsewhere to find bugs. The role is a "compiler" role - working on the Clang AST to OCaml, and intermediate phases of Infer to improve our C++ analysis capabilities. Good FP engineering skills (e.g. Haskell or OCaml) are desirable. You should have a working knowledge of C++ semantics, language or compiler design or experience in a range of C++ projects. Infer: http://fbinfer.com/ Apply via: https://www.facebook.com/careers/jobs/a0I1200000LT8aA

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