- Glasgow-haskell-users

Alex requirement for Setup.lhs
by Philip K.F. Hölzenspies 04 Dec '08

04 Dec '08

Dear all, Hopefully, you will excuse me for my lack of experience with Cabal. I have seen quite a few e-mails on this list that seem related to this issue, but my specific error, I did not find. Thus: Since installing 6.10.1, I can't perform Setup.(l)hs functions. The error message I get is: Setup.hs: alex is required but it could not be found. The problem is that I get this error also when I try to "runghc Setup.lhs build" alex (is the fact that "runghc Setup.lhs configure" does *not* produce this error significant?). I'm running an OpenSuSE 10.3 installation on which I can only install rpms from standard repositories. In these repositories, there is no binary distribution of alex. How do I install alex from source without requiring alex? Regards, Philip

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ghci and user private groups
by Jason Dusek 03 Dec '08

03 Dec '08

User private groups are not an abnormal configuration, but GHCi has such strict security that they are not allowed! :; ghci GHCi, version 6.10.1: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done.Loading package integer ... linking ... done.Loading package base ... linking ... done. *** WARNING: /Users/jsn/tmp is writable by someone else, IGNORING! *** WARNING: /Users/jsn/tmp/.ghci is writable by someone else, IGNORING! Prelude> :q Leaving GHCi. :; cd ../ :; ls -laR tmp/ tmp/: total 4 drwxrwx--- 2 jsn jsn 102 2008-12-02 10:19 . drwxr-x--- 49 jsn jsn 2890 2008-12-02 10:17 .. -rw-rw---- 1 jsn jsn 159 2008-12-02 10:20 .ghci I appreciate what you guys are trying to do, but I at the very least, it should be permitted to use a GHCi that is group readable/writable as long as the group name and user name are the same. It would be preferable, however, to do away with the restriction altogether. -- _jsn

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Using Data Parallel Haskell
by Manuel M T Chakravarty 02 Dec '08

02 Dec '08

As previously announced, GHC 6.10.1 includes a technology preview of Data Parallel Haskell. However, so far, there was no documentation on how to use it. That is different now: http://haskell.org/haskellwiki/GHC/Data_Parallel_Haskell Please keep in mind that this is a very preliminary version of the system with limited functionality. However, we are very interested in feedback from interested users. Happy Vectorising! Manuel

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gtk2hs and MacPorts
by Christian Maeder 01 Dec '08

01 Dec '08

Hi, recently (last Friday) I had a chance to use MacPorts to install gtk2hs. (Usually I do not have root permissions to do so.) Actually, I only wanted to install the libraries needed to run a gtk2hs application that I've created on another machine. On that other machine gtk was (painfully) installed using http://developer.imendio.com/projects/gtk-macosx/build-instructions and gtk2hs-0.9.13 was then compiled from source. sudo port install gtk2hs began at some stage to compile ghc-6.10.1 which I aborted, because I thought, gtk2hs would not work with ghc-6.10.1. ("port search ghc" on another mac lists ghc-6.8.3, though.) Therefore I tried to only install the needed libraries for the binary. (libglade2, gtk2, etc.) Finally my binary complained about a missing libgdk-quartz-2.0.0.dylib or libgtk-quartz-2.0.0.dylib and I had no idea how to get it from MacPorts. (Initially I did not even see the difference of the two library names "gtk" vs, "gdk".) I don't know if my binary is linked against too many libraries. Is this possible or is the linker smart enough to avoid this? Below is the list of libraries my binary needs. I've just found http://www.haskell.org/haskellwiki/Gtk2Hs#Mac_OS_X and the list of dependencies: glade3 libglade2 gstreamer gst-plugins-base gtksourceview cairo librsvg gtkglext firefox Which one contains "quartz"? Another problem have been the links lib{jpeg,png,tiff}.dylib. I had to remove them from my DYLD_LIBARRY_PATH in order to avoid an error in ApplicationServices: dyld: Symbol not found: __cg_jpeg_resync_to_restart Referenced from: /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/ImageIO.framework/Versions/A/ImageIO Are the libraries lib{jpeg,png,tiff}.dylib needed at all for gtk? Cheers Christian otool -L /home/maeder/gtk/inst/lib/libglade-2.0.0.dylib (compatibility version 1.0.0, current version 1.7.0) /home/maeder/gtk/inst/lib/libxml2.2.dylib (compatibility version 9.0.0, current version 9.32.0) /home/maeder/gtk/inst/lib/libgtk-quartz-2.0.0.dylib (compatibility version 1305.0.0, current version 1305.0.0) /home/maeder/gtk/inst/lib/libgdk-quartz-2.0.0.dylib (compatibility version 1305.0.0, current version 1305.0.0) /home/maeder/gtk/inst/lib/libatk-1.0.0.dylib (compatibility version 2210.0.0, current version 2210.1.0) /home/maeder/gtk/inst/lib/libgio-2.0.0.dylib (compatibility version 1704.0.0, current version 1704.0.0) /home/maeder/gtk/inst/lib/libgdk_pixbuf-2.0.0.dylib (compatibility version 1305.0.0, current version 1305.0.0) /home/maeder/gtk/inst/lib/libpangocairo-1.0.0.dylib (compatibility version 2102.0.0, current version 2102.2.0) /home/maeder/gtk/inst/lib/libpango-1.0.0.dylib (compatibility version 2102.0.0, current version 2102.2.0) /home/maeder/gtk/inst/lib/libcairo.2.dylib (compatibility version 20.0.0, current version 20.5.0) /home/maeder/gtk/inst/lib/libgmodule-2.0.0.dylib (compatibility version 1704.0.0, current version 1704.0.0) /home/maeder/gtk/inst/lib/libgthread-2.0.0.dylib (compatibility version 1704.0.0, current version 1704.0.0) /home/maeder/gtk/inst/lib/libgobject-2.0.0.dylib (compatibility version 1704.0.0, current version 1704.0.0) /home/maeder/gtk/inst/lib/libglib-2.0.0.dylib (compatibility version 1704.0.0, current version 1704.0.0) /home/maeder/gtk/inst/lib/libintl.8.dylib (compatibility version 9.0.0, current version 9.1.0) /usr/lib/libedit.2.dylib (compatibility version 2.0.0, current version 2.9.0) /usr/lib/libncurses.5.4.dylib (compatibility version 5.4.0, current version 5.4.0) /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 111.1.1) /usr/lib/libgcc_s.1.dylib (compatibility version 1.0.0, current version 1.0.0)

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Platforms that GHC supports
by Simon Peyton-Jones 01 Dec '08

01 Dec '08

Friends Lots of the bug reports on the GHC bug tracker are platform-specific. We thought it'd help for us to articulate more clearly what platforms GHC supports, and what we'd like it to support. Look here: http://hackage.haskell.org/trac/ghc/wiki/Platforms What you'll notice is that we (GHC HQ) only guarantee to support a fairly narrow range of "Tier 1" platforms, albeit ones that cover a large fraction of our users. There's a much longer list of "Tier 2" platforms, that we'd love to have working, and know of no reason they can't work, but for which we need your help. We are actively looking for sponsors for Tier 2 platforms. If you think you could help, please let us know. Thanks. Simon & Simon

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GHCi debugger status
by Daniil Elovkov 01 Dec '08

01 Dec '08

Hello folks I'd like to know, how do ghc developers and users feel about the debugger? I'm using it to some extent on ghc 6.8.2 and find it useful. But I'm getting an impression that it's not too stable. I'm not filing any bug report yet, just want to know how it feels for others. I used to make it panic. I think, it was due to existential types. Now I see it mess up the list of bindings in a funny way. For example, in a previous trace session I had a variable, say, prev. It was bound during pattern matching in a function, say, prevFunc. Now I'm having another trace session, actually stepping from the very beginning. A couple of steps after the beginning, prev suddenly appears in the bindings where prevFunc absolutely has not yet been invoked. It's completely unrelated. In 'show bindings' prev has a wrong type - SomeType (it's ADT). Its real type (when in scope) is [t]. I ask 'length prev' and get 0 :) So, what is your impression of the debugger? -- Daniil Elovkov

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cross module optimization issues
by John Lato 28 Nov '08

28 Nov '08

Hello, I have a problem with a package I'm working on, and I don't have any idea how to sort out the current problem. One part of my package is in one monolithic module, without an export list, which works fine. However, when I've started to separate out certain functions into another module, and added an export list to one of the modules, which dramatically decreases performance. The memory behavior (as shown by -hT) is also quite different, with substantial memory usage by "FUN_2_0". Are there any suggestions as to how I could improve this? Thanks, John

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GADT Type Checking GHC 6.10 versus older GHC
by Jason Dagit 28 Nov '08

28 Nov '08

Hello, Here is an example where ghc 6.8.x was fine, but now 6.10 complains. \begin{code} type CommuteFunction = forall x y. (Prim :< Prim) C(x y) -> Perhaps ((Prim :< Prim) C(x y)) commute_split :: CommuteFunction commute_split (Split patches :< patch) = toPerhaps $ do (p1 :< ps) <- cs (patches :< patch) case sort_coalesceFL ps of p :>: NilFL -> return (p1 :< p) ps' -> return (p1 :< Split ps') where cs :: ((FL Prim) :< Prim) C(x y) -> Maybe ((Prim :< (FL Prim)) C(x y)) cs (NilFL :< p1) = return (p1 :< NilFL) cs (p:>:ps :< p1) = do p1' :< p' <- commutex (p :< p1) p1'' :< ps' <- cs (ps :< p1') return (p1'' :< p':>:ps') commute_split _ = Unknown \end{code} Now with ghc 6.10 we get this error: GADT pattern match with non-rigid result type `Maybe a' Solution: add a type signature In a case alternative: p :>: NilFL -> return (p1 :< p) In the expression: case sort_coalesceFL ps of { p :>: NilFL -> return (p1 :< p) ps' -> return (p1 :< Split ps') } In the second argument of `($)', namely `do (p1 :< ps) <- cs (patches :< patch) case sort_coalesceFL ps of { p :>: NilFL -> return (p1 :< p) ps' -> return (p1 :< Split ps') }' You can see more context here: http://darcs.net/src/Darcs/Patch/Prim.lhs around line 472 My understanding was that from 6.6 to 6.8, GADT type checking was refined to fill some gaps in the soundness. Did that happen again between 6.8 and 6.10 or is 6.10 being needlessly strict here? Thanks, Jason

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simple ghci debugger question
by Peter Hercek 27 Nov '08

27 Nov '08

Is there a way to redirect output of a ghci debugger command so that I can process it with a (ghci) script before it is displayed? Peter.

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How to reliably terminate a process
by Bernd Holzmüller 27 Nov '08

27 Nov '08

Hi, I am writing an application on Windows XP using ghc 6.10.1 that manages test cases (same applies to ghc 6.8.3). For each selected test case, the application runs an executable associated with the test case using System.Process.runInteractiveCommand. These processes have to be aborted in some cases, for example, when their specified termination time is up. As I realized, however, aborting these processes using terminateProcess is not reliable. Most often, the processes do not terminate correctly but have to be killed from the Windows Task Manager. In some cases, the process still produces output - in particular if I apply getProcessExitCode on the process just killed. By the way: calling and killing the process from the shell with Ctrl-C successfully kills the process. Any advice on how to reliably terminate a process on Windows? Thanks, Bernd

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