August 2015 - ghc-devs

RE: vectorisation code?
by Simon Peyton Jones 12 Sep '16

12 Sep '16

Austin, (or anyone else) Manuel says: | > Would it be ok if we left it in the repo, but CPP'd it out so that | we | > didn't compile everything? (The DPH library is in the same state at | > the moment.) | > | > It might suffer bit-rot, but it’d still be there for resurrection. | | Sure, that’s ok. Could you action this? Just avoid compiling anything in 'vectorise/', using (I suppose) cpp to create a stub where necessary. Leave enough comments to explain! Simon | | I hope everything is fine in Cambridge! | Manuel | | > | -----Original Message----- | > | From: ghc-devs [mailto:ghc-devs-bounces@haskell.org] On Behalf Of | > | Manuel M T Chakravarty | > | Sent: 16 January 2015 02:58 | > | To: Richard Eisenberg | > | Cc: ghc-devs(a)haskell.org Devs | > | Subject: Re: vectorisation code? | > | | > | [Sorry, sent from the wrong account at first.] | > | | > | We currently don’t have the resources to work on DPH. I would | > | obviously prefer to leave the code in, in the hope that we will be | > | able to return to it. | > | | > | Manuel | > | | > | > Richard Eisenberg <eir(a)cis.upenn.edu>: | > | > | > | > Hi devs, | > | > | > | > There's a sizable number of modules in the `vectorise` | > | subdirectory of GHC. I'm sure these do all sorts of wonderful | > | things. But what, exactly? And, does anyone make use of these | wonderful things? | > | > | > | > A quick poking through the code shows a tiny link between the | > | vectorise code and the rest of GHC -- the function `vectorise` | > | exported from the module `Vectorise`, which is named in exactly | one | > | place from SimplCore. From what I can tell, the function will be | > | called only when `-fvectorise` is specified, and then it seems to | > | interact with a {-# VECTORISE #-} pragma. However, `{-# VECTORISE | > | #-}` doesn't appear in the manual at all, and `-fvectorise` is | > | given only a cursory explanation. It seems these work with DPH... | > | which has been disabled, no? Searching online finds several hits, | > | but nothing more recent than 2012. | > | > | > | > I hope this question doesn't offend -- it seems that | > | vectorisation probably has amazing performance gains. Yet, the | > | feature also seems unloved. In the meantime, compiling (and | > | recompiling, and | > | recompiling...) the modules takes time, as does going through | them | > | to propagate changes from elsewhere. If this feature is truly | > | orphaned, unloved, and unused at the moment, is it reasonable to | > | consider putting it on furlough? | > | > | > | > Thanks, | > | > Richard | > | > _______________________________________________ | > | > ghc-devs mailing list | > | > ghc-devs(a)haskell.org | > | > http://www.haskell.org/mailman/listinfo/ghc-devs | > | | > | _______________________________________________ | > | ghc-devs mailing list | > | ghc-devs(a)haskell.org | > | http://www.haskell.org/mailman/listinfo/ghc-devs

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arc land changes author
by Joachim Breitner 19 Dec '15

19 Dec '15

Hi, I was just about to apply a DR by David. First I ran $ arc patch D390 which put me on a feature branch. Then I reworded the commit with $ git commit --amend and then I tried to land it with $ arc land Luckily I also passed --hold... It even asked me if I want to land the commit although I am not the author: This branch has revision 'D390: Reorder GHC.List; fix performance regressions' but you are not the author. Land this revision by dfeuer? [y/N] y But it still put me in the author field: $ git show HEAD commit a387c359b99667ce55016de3816b5d9873a155db Author: Joachim Breitner <mail(a)joachim-breitner.de> Date: Wed Oct 29 08:17:05 2014 +0100 Reorder GHC.List; fix performance regressions Summary: Rearrange some oddly placed code. (and undid my commit message changes....) Did I do something wrong? Anyways, it said something along the lines of Cleaning up feature branch... (Use `git checkout -b 'arcpatch-D390' 'a3ceb0e7f44d53f728fb8bd0dfb4c97297818029'` if you want it back.) so with $ git commit --amend -C a3ceb0e7f44d53f728fb8bd0dfb4c97297818029 I was able to get the edited commit message with the right author back. Greetings, Joachim -- Joachim “nomeata” Breitner mail(a)joachim-breitner.de • http://www.joachim-breitner.de/ Jabber: nomeata(a)joachim-breitner.de • GPG-Key: 0xF0FBF51F Debian Developer: nomeata(a)debian.org

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A GHC Library
by Richard Eisenberg 08 Dec '15

08 Dec '15

Hi devs, It has struck me that we have a vast trove of documentation about GHC in the form of academic papers, but little organization to this trove. The papers are scattered across authors' websites, and sometimes it is hard to remember what a paper is titled when searching for it. I have thus started a wiki page here: https://ghc.haskell.org/trac/ghc/wiki/Library I would love for this page to be the Definitive List of GHC-related papers. The list I've included is, of course, woefully short, but it is a starting point. Please add to it! Have you written a GHC paper? If so, make sure it's included. Thanks, Richard

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question about GHC API on GHC plugin
by Mike Izbicki 22 Sep '15

22 Sep '15

I'm trying to write a GHC plugin. The purpose of the plugin is to provide Haskell bindings to Herbie. Herbie (https://github.com/uwplse/herbie) is a program that takes a mathematical statement as input, and gives you a numerically stable formula to compute it as output. The plugin is supposed to automate this process for Haskell programs. I can convert the core expressions into a format for Herbie just fine. Where I'm having trouble is converting the output from Herbie back into core. Given a string that represents a numeric operator (e.g. "log" or "+"), I can get that converted into a Name that matches the Name of the version of that operator in scope at the location. But in order to create an Expr, I need to convert the Name into a Var. All the functions that I can find for this (e.g. mkGlobalVar) also require the type of the variable. But I can't find a way to figure out the Type given a Name. How can I do this?

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utils/hp2ps/Main.c:88: possible missing break ?
by David Binderman 15 Sep '15

15 Sep '15

Hello there, [utils/hp2ps/Main.c:88] -> [utils/hp2ps/Main.c:91]: (warning) Variable 'iflag' is reassigned a value before the old one has been used. 'break;' missing? Source code is switch( *(*argv + 1) ) { case '-': iflag = -1; case '+': default: iflag = 1; } Suggest add missing break. Regards David Binderman

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Using GHC API to compile Haskell file
by Neil Mitchell 15 Sep '15

15 Sep '15

Hi, Is this the right place for GHC API queries? If not, is there anywhere better? I want to compile a Haskell module, much like `ghc --make` or `ghc -c` does. The sample code on the Haskell wiki (https://wiki.haskell.org/GHC/As_a_library#A_Simple_Example) StackOverflow (http://stackoverflow.com/a/5631338/160673) and in GHC API slides (http://sneezy.cs.nott.ac.uk/fplunch/weblog/wp-content/uploads/2008/12/ghc-a…) says: import GHC import GHC.Paths ( libdir ) import DynFlags main = defaultErrorHandler defaultFatalMessager defaultFlushOut $ do runGhc (Just libdir) $ do dflags <- getSessionDynFlags setSessionDynFlags dflags target <- guessTarget "Test.hs" Nothing setTargets [target] load LoadAllTargets However, given a `Test.hs` file with the contents `main = print 1`, I get the error: C:/Program Files (x86)/MinGHC-7.8.3/ghc-7.8.3/mingw/bin/ld.exe: cannot find -lHSbase-4.7.0.1-ghc7.8.3 C:/Program Files (x86)/MinGHC-7.8.3/ghc-7.8.3/mingw/bin/ld.exe: cannot find -lHSinteger-gmp-0.5.1.0-ghc7.8.3 C:/Program Files (x86)/MinGHC-7.8.3/ghc-7.8.3/mingw/bin/ld.exe: cannot find -lHSghc-prim-0.3.1.0-ghc7.8.3 C:/Program Files (x86)/MinGHC-7.8.3/ghc-7.8.3/mingw/bin/ld.exe: cannot find -lHSrts-ghc7.8.3 C:/Program Files (x86)/MinGHC-7.8.3/ghc-7.8.3/mingw/bin/ld.exe: cannot find -lffi-6 collect2: ld returned 1 exit status Has the recipe changed? By turning up the verbosity, I was able to compare the command line passed to the linker. The failing GHC API call contains: "-lHSbase-4.7.0.1-ghc7.8.3" "-lHSinteger-gmp-0.5.1.0-ghc7.8.3" "-lHSghc-prim-0.3.1.0-ghc7.8.3" "-lHSrts-ghc7.8.3" "-lffi-6" While the succeeding ghc --make contains: "-lHSbase-4.7.0.1" "-lHSinteger-gmp-0.5.1.0" "-lHSghc-prim-0.3.1.0" "-lHSrts" "-lCffi-6" Should I be getting DynFlags differently to influence those link variables? Thanks, Neil

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Proposal: Include GHC version target in libraries' description
by Alexander Berntsen 14 Sep '15

14 Sep '15

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 Problem: A frequent usecase for especially base is browsing the haddocks online on hackage (I do this myself sometimes). A frequent associated pain with this is remembering which base version corresponds to which GHC version (I feel this myself sometimes). Current solution: Consult the boot library version chart[0]. An additional step -- where there needn't be one -- may annoy the user. Furthermore, if they don't know about the chart then they're essentially lost; which usually leads to them consulting another user - -- and now we've wasted a little time for *two* of our users for no real good reason. I conjecture that this happens quite often. Which means our culmination of GHC-related time waste eventually adds up quite a bit, detracting from the overall experience. Proposed improvement: Add "[library]-[library version] is bundled with ghc-[GHC version]." in the description string of [library].cabal. This immediately clears up the confusion when looking at [library]'s hackage page. [0] <https://ghc.haskell.org/trac/ghc/wiki/Commentary/Libraries/VersionHisto ry> - -- Alexander alexander(a)plaimi.net https://secure.plaimi.net/~alexander -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCgAGBQJVwezFAAoJENQqWdRUGk8B8jEQAMuAYjn25VB/aG5VWr8IdPoZ OSoUu+26XdJhmbOcYzHWje7gUs8FSfqxHyflasiO22uWOHHO3kfyzwOEZX0Nqc0b WboMRuNZ5dEPGAGFqxi/DWzPoaQ9shA+EUmCl8r2Qn9W7ZximaP3b1ORO0UvvgBo YK3T0f4TCoYKOYS2Txl5gjO3FKK6STdNxcELs3p6g0+paf5crEf3hcw2WZCcsdSc 0yU3dl5iFin4ofaByDmx7tj1ACYn7MusEH4zF+jjGYb4XbIV+WCy78Nsmlqt3AF9 P++HD4DMmh+rXW9tkqAbTgxn3LAgrkB0F3vYAEfiH4xFmWlQyzANtjILN6WYDOt0 5Gnpz/Meg6aGJY0U5y/XAPxzpar7oc/HPbdjS747iOTLj4dsOHeswmw++goG8ugw j/Yq00T17/3RJlZ03OdaRyl+HrXiNCq0J48LUUJu9jY9LCjr57hKZa3fFFM++fIU UaIMllxCiOdGDaTJCCZ/HEvZBtvxaeWWEc/Zi2XrtMI4PcAS/QACxlJJsHfnb/1B mCi5fIWjzX0UPo6YeRI2MeUlasKp8fLPm8AGKHQJGx2XHNHToNFR5X75VpCWWlp3 oboVm1qN46qpwnkrxWrIvlK40fLjmiZZMb0HS4cm+4ofNFc+CQMBqQ5fZxrwAO7e CTzw91s+6tbcp43Y+lgI =rmBv -----END PGP SIGNATURE-----

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the platform has outgrown Travis-CI
by Mark Lentczner 09 Sep '15

09 Sep '15

I finally figured out what was wrong with the Travis CI build for Haskell Platform, and got it all working w/hvr's .debs of GHC (for the boot compiler)... and ran smack into this: Your test run exceeded 50 minutes. SO... I'd like to find another CI solution. Is phabricator.haskell.org an option? Can we / should we create a project there? - Mark

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ArrayArrays
by Edward Kmett 08 Sep '15

08 Sep '15

Would it be possible to add unsafe primops to add Array# and SmallArray# entries to an ArrayArray#? The fact that the ArrayArray# entries are all directly unlifted avoiding a level of indirection for the containing structure is amazing, but I can only currently use it if my leaf level data can be 100% unboxed and distributed among ByteArray#s. It'd be nice to be able to have the ability to put SmallArray# a stuff down at the leaves to hold lifted contents. I accept fully that if I name the wrong type when I go to access one of the fields it'll lie to me, but I suppose it'd do that if i tried to use one of the members that held a nested ArrayArray# as a ByteArray# anyways, so it isn't like there is a safety story preventing this. I've been hunting for ways to try to kill the indirection problems I get with Haskell and mutable structures, and I could shoehorn a number of them into ArrayArrays if this worked. Right now I'm stuck paying for 2 or 3 levels of unnecessary indirection compared to c/java and this could reduce that pain to just 1 level of unnecessary indirection. -Edward

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Re: Planning for the 7.12 release
by Harry . 01 Sep '15

01 Sep '15

What's the status of splitting up base? This has been spoken about a few times but I can't find any public activity from GHC or Libraries HQ.

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