- Glasgow-haskell-users

Re: ANNOUNCE: GHC 7.10.1 Release Candidate 2
by Herbert Valerio Riedel 07 Feb '15

07 Feb '15

Hi Mark, On 2015-01-28 at 04:31:29 +0100, Mark Lentczner wrote: > I've just built a bindist under 10.10, but just normal not expressly llvm. > I'll test this in a bit then post it -- but might be sometime tomorrow > before it is up. How's progress on this btw? Are you also working on a GHC 7.8.4 OSX bindist by any chance? Cheers, hvr

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Restricted Template Haskell
by Greg Weber 03 Feb '15

03 Feb '15

Hello GHC friends! I am starting up a proposal for variants of Template Haskell that restrict what operations are available. The goal is to make TH easier for users to reason about and to allow for an easier compilation story. Here is the proposal page: https://ghc.haskell.org/trac/ghc/wiki/TemplateHaskell/Restricted Right now the proposal does not have any details and the goal is to write out a clear specification. If this sounds interesting to you, let me know or leave some feedback on the wiki. Thanks, Greg Weber

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stream fusion, concatMap, exisential seed unboxing
by Christian Höner zu Siederdissen 02 Feb '15

02 Feb '15

Hi everybody, I'm playing around with concatMap in stream fusion (the vector package to be exact). concatMapM :: Monad m => (a->m (Stream m b)) -> Stream m a -> Stream m b concatMapM f (Stream ...) = ... I can get my concatMap to behave nicely and erase all Stream and Step constructors but due to the existential nature of the Stream seeds, they are re-boxed for the inner stream (which is kind-of annoying given that the seed is immediately unboxed again ;-). seq doesn't help here. Otherwise, fusion happens for streams and vectors, so that is ok. But boxing kills performance, criterion says. Do we have s.th. in place that could help here? Currently I could use the vector-concatMap which creates intermediate arrays, my version which has boxed seeds, or hermit but that is too inconvenient for non-ghc savy users. Viele Gruesse, Christian Fusing concatMapM: concatMapM f (SM.Stream ostep t _) = SM.Stream step (Left t) Unknown where step (Left t) = do r <- ostep t case r of SM.Done -> return $ SM.Done SM.Skip t' -> return $ SM.Skip (Left t') SM.Yield a t' -> do s <- f a return $ SM.Skip (Right (s,t')) step (Right (SM.Stream istep s _,t)) = do r <- istep s case r of SM.Done -> return $ SM.Skip (Left t) SM.Skip s' -> return $ SM.Skip (Right (SM.Stream istep s' Unknown,t)) SM.Yield x s' -> return $ SM.Yield x (Right (SM.Stream istep s' Unknown,t)) {-# INLINE [0] step #-} {-# INLINE [1] concatMapM #-} testConcatMapM :: Int -> Int testConcatMapM k = seq k $ U.unId . SM.foldl' (+) 0 . concatMap (\i -> SM.enumFromTo 5 k) $ SM.enumFromTo 3 k {-# NOINLINE testConcatMapM #-} CORE: testConcatMapM testConcatMapM = \ k_aCA -> let! { I# ipv_s1xv ~ _ <- k_aCA } in ### inner loop letrec { $s$wfoldlM'_loop_s29q $s$wfoldlM'_loop_s29q = \ sc_s29i sc1_s29j sc2_s29k -> ### unboxing let! { I# x_a1LA ~ _ <- sc1_s29j } in case tagToEnum# (<=# x_a1LA ipv_s1xv) of _ { False -> $s$wfoldlM'_loop1_s29c sc_s29i sc2_s29k; True -> $s$wfoldlM'_loop_s29q ### reboxing (+# sc_s29i x_a1LA) (I# (+# x_a1LA 1)) sc2_s29k }; ### outer loop $s$wfoldlM'_loop1_s29c $s$wfoldlM'_loop1_s29c = \ sc_s29a sc1_s29b -> case tagToEnum# (<=# sc1_s29b ipv_s1xv) of _ { False -> sc_s29a; True -> case tagToEnum# (<=# 5 ipv_s1xv) of _ { False -> $s$wfoldlM'_loop1_s29c sc_s29a (+# sc1_s29b 1); ### boxed seed (I# 6) True -> $s$wfoldlM'_loop_s29q (+# sc_s29a 5) (I# 6) (+# sc1_s29b 1) } }; } in let! { __DEFAULT ~ ww_s20G <- $s$wfoldlM'_loop1_s29c 0 3 } in I# ww_s20G

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What could be the possible reason of linking errors on "_info" and "_closure"?
by Magicloud Magiclouds 02 Feb '15

02 Feb '15

Hi, I am making a cabal project including a library and a executable using the library. Building the library is fine. But when linking src/main, I got "undefined reference to someFunction1_info" and "someFunction1_closure". -- 竹密岂妨流水过山高哪阻野云飞 And for G+, please use magiclouds#gmail.com.

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ANN: deepseq-bounded 0.5 -> 0.6
by Andrew Seniuk 25 Jan '15

25 Jan '15

This may affect depending code. Please consult the distro changelog for specific information about how your code might be affected, or better yet, refer to http://www.fremissant.net/deepseq-bounded/transition-5-6-7.html and http://www.fremissant.net/deepseq-bounded/grammar.html This is a transitional version of deepseq-bounded, with stability of the grammar expected in early March for version 0.7. This also causes major version bumps to the seqaid and leaky packages. To update everything, issue cabal update cabal install --reinstall --force-reinstalls seqaid which reinstalls the latest deepseq-bounded in passing. And also if you were to run "seqaid demo" it will use the updated version of leaky, so everything's up to date. The homepage for these projects starts at http://www.fremissant.net/deepseq-bounded-seqaid-leaky.html Kind Regards, Andrew

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Unable to build 7.10.1 RC1 on Jessie
by harry 25 Jan '15

25 Jan '15

I'm trying to build 7.10.1 RC on Debian Jessie. I get an error: configure: error: in `/ghc-7.10.0.20141222/libffi/build/x86_64-unknown-linux-gnu': configure: error: C++ preprocessor "/lib/cpp" fails sanity check config.log shows: configure: failed program was: | /* confdefs.h */ | #define PACKAGE_NAME "libffi" | #define PACKAGE_TARNAME "libffi" | #define PACKAGE_VERSION "3.1" | #define PACKAGE_STRING "libffi 3.1" | #define PACKAGE_BUGREPORT "http://github.com/atgreen/libffi/issues" | #define PACKAGE_URL "" | #define PACKAGE "libffi" | #define VERSION "3.1" | #define STDC_HEADERS 1 | #define HAVE_SYS_TYPES_H 1 | #define HAVE_SYS_STAT_H 1 | #define HAVE_STDLIB_H 1 | #define HAVE_STRING_H 1 | #define HAVE_MEMORY_H 1 | #define HAVE_STRINGS_H 1 | #define HAVE_INTTYPES_H 1 | #define HAVE_STDINT_H 1 | #define HAVE_UNISTD_H 1 | #define HAVE_DLFCN_H 1 | #define LT_OBJDIR ".libs/" | /* end confdefs.h. */ | #ifdef __STDC__ | # include <limits.h> | #else | # include <assert.h> | #endif | Syntax error configure:12860: error: in `/ghc-7.10.0.20141222/libffi/build/x86_64-unknown-linux-gnu': configure:12862: error: C++ preprocessor "/lib/cpp" fails sanity check This can be reproduced by running the following commands in the debian:jessie docker image: apt-get update apt-get install ncurses-dev curl gcc ghc make libgmp-dev xz-utils curl http://downloads.haskell.org/~ghc/7.10.1-rc1/ghc-7.10.0.20141222-src.tar.xz | tar xJ cd ghc-* ./configure make Any suggestions for someone who knows nothing about c or cpp? -- View this message in context: http://haskell.1045720.n5.nabble.com/Unable-to-build-7-10-1-RC1-on-Jessie-t… Sent from the Haskell - Glasgow-haskell-users mailing list archive at Nabble.com.

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template haskell vs. -prof
by Evan Laforge 24 Jan '15

24 Jan '15

I ran into trouble compiling template haskell with -prof, and came across the ghc manual "7.9.4. Using Template Haskell with Profiling". Unfortunately I can't use its advice directly since I put profiling and non-profiling .o files into different directories. But in principle it seems it should work, I just have to get ghc to load TH from the debug build directory, which is built with -dynamic, while continuing to load from the profile build directory. But are there flags to get it to do that? I'm using "-osuf .hs.o -ibuild/profile/obj". If I put ":build/debug/obj" on the -i line, it still seems to find the profiling one. The ghc manual advice probably gets around it by using different -osufs... I guess TH somehow ignores -osuf? Except when I compile the debug version with osuf, if finds them fine, so I don't really know how it works. Is there a way I can directly tell TH where to look? It seems awkward to rely on all these implicit and seemingly undocumented heuristics. And, this is somewhat beside the point, but shouldn't TH theoretically be able to load directly from .hs and compile to bytecode like ghci can do if it doesn't find the .o file? And, even more beside the point, the only reason I'm messing with TH is for a really simple (one line) multi-line string literal quasiquote. Surely I'm not the only person who would enjoy a -XMultiLineStringLiteral extension? The alternative seems to be a program to add or strip all of the "\n\"s, and when I want to edit, copy out, strip, edit, paste back in, add back. At that point maybe it's easier to just get used to all the \s... but then indentation is all a bit off due to the leading \.

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Fwd: UNPACK Existential datatype
by Nicholas Clarke 23 Jan '15

23 Jan '15

I'd like to be able to use the UNPACK pragma on an existentially quantified datatype. So as in the below example: {-# LANGUAGE ExistentialQuantification #-} data Foo = forall a. Show a => Foo !a instance Show Foo where show (Foo a) = "Foo! " ++ show a data Bar = Bar {-# UNPACK #-} !Foo deriving (Show) main :: IO () main = do let foo = Foo "Hello" bar = Bar foo print bar I would expect the `Foo` constructor to be unpacked into Bar, as if I had written: data Bar = forall a. Show a => Bar !a However, instead I get the 'Ignoring unusable UNPACK pragma on the first argument of ‘Bar’' warning. Is there a reason this shouldn't work, or a workaround to get it to do so? Cheers, Nick

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How to remove a cabal package from the local system?
by Volker Wysk 23 Jan '15

23 Jan '15

Hi! I have installed/registered a new version of a package with cabal by accident. How can I remove it again? There is something in ~/.cabal/packages/hackage.haskell.org, but the defective version isn't included. bye V.W.

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ANN: git-monitor
by John Wiegley 22 Jan '15

22 Jan '15

git-monitor auto-commits all changes to a Git working tree, within a special branch named "refs/snapshots/refs/heads/<branch>". It has no impact on the Git repository otherwise, and will not effect your real branches. It has the following features: - It is designed to be extremely resource efficient, both in CPU cost and memory. I wanted something I could run several instances of on my laptop, without paying much of a battery cost. This efficiency is achieved by using gitlib with the libgit2 backend. The current state of the working tree is maintained as a Git object in memory, and is updated in place before being written back out to disk. Thus, the amount of computation done remains minimal, as we do not need to rebuild the Git tree at each iteration (as "git-commit" would do). - Whenever git-monitor is exited and restarted, the previous snapshot "branch" is discarded. These are only intended to be viable during and between runs. - By having such a branch, you can easily browse through the diffs of your changes throughout the day. By default, every action taken is printed to the console where git-monitor is run, but it can also be run in silent mode, for example if you choose to background it for the rest of the day. http://hackage.haskell.org/package/git-monitor https://github.com/jwiegley/git-monitor Please report issues to the GitHub page. I have been using git-monitor on a regular basis for more than a year now, so I felt it finally deserved an announcement here. Thank you, John Wiegley (johnw on IRC/freenode)

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