December 2009 - Glasgow-haskell-users

Formal semantics for Core?
by Matthijs Kooijman 10 Dec '09

10 Dec '09

Hi All, I was wondering if there are any formal semantics defined for GHC's core language? I'm working with some core to core rewriting passes for which I'd like to verify the soundness, but that would require some formal definition of the Core semantics of sorts... Gr. Matthijs

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Fwd: FFI and ghci
by Patrick LeBoutillier 07 Dec '09

07 Dec '09

Hi, I sent this question to haskell-cafe, realizing later that perhaps this list is a better place for it. Patrick ---------- Forwarded message ---------- From: Patrick LeBoutillier <patrick.leboutillier(a)gmail.com> Date: Fri, Dec 4, 2009 at 2:09 PM Subject: FFI and ghci To: Haskell Cafe <haskell-cafe(a)haskell.org> Hi all, I have a small FFI-based library that I like to test like this: $ ghci -I../c -L../c/.libs -lmlp t.hs 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. Loading object (dynamic) mlp ... done final link ... done [1 of 9] Compiling MLP ( MLP.hs, interpreted ) [2 of 9] Compiling MLP.Error ( MLP/Error.hs, interpreted ) [3 of 9] Compiling MLP.Context ( MLP/Context.hs, interpreted ) [4 of 9] Compiling MLP.Runtime ( MLP/Runtime.hs, interpreted ) [5 of 9] Compiling MLP.Object ( MLP/Object.hs, interpreted ) [6 of 9] Compiling MLP.Type ( MLP/Type.hs, interpreted ) [7 of 9] Compiling MLP.Value ( MLP/Value.hs, interpreted ) [8 of 9] Compiling MLP.Language ( MLP/Language.hs, interpreted ) [9 of 9] Compiling Main ( t.hs, interpreted ) Ok, modules loaded: MLP, MLP.Object, Main, MLP.Runtime, MLP.Context, MLP.Error, MLP.Value, MLP.Type, MLP.Language. *Main> main Note: Inside libmlp.so, another shared object is loaded using dlopen(). When running this test program I get some sporadic segmentation faults, which seem to always occur at entrypoint to the shared object that is loaded with dlopen(). But when I compile it with ghc, i.e. $ ghc --make -I../c -L../c/.libs -lmlp t.hs I can't reproduce crash. Can anyone see why this could be happening? It's quite possible that there is really a bug in the C code, but if someone knows about a bug or something in ghci that can cause this behaviour I can stop looking... Thanks a lot, Patrick -- ===================== Patrick LeBoutillier Rosemère, Québec, Canada

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GHC on Win x64
by Zachary Turner 07 Dec '09

07 Dec '09

I've been out of the loop for quite some time. Has there been any progress on the ability to build a native x64 version of GHC for windows? the supported platforms page on the web does not even list this as a Tier 1, 2, or 3 platform and last time I tried this (quite a while ago, admittedly) I could not get it to work. Thanks, Zach

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GHC Bug or User Error?
by Zachary Turner 07 Dec '09

07 Dec '09

GHCi, version 6.10.4: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer ... linking ... done. Loading package base ... linking ... done. Prelude> let f x = x*x Prelude> let g x y = x+y Prelude> let q x y = (f . g) x y Prelude> :t q q :: (Num (a -> a), Num a) => a -> a -> a I'm somewhat of a beginner so the error could definitely be my own, but it seems to me like the third line should be rejected by GHCi. As for the 4th line, the type of q seems nonsensical to me. I can't figure out any possible valid meaning of 'Num (a -> a) '. Can anyone shed some light on this? Zach

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GHC 6.12.1 release note suggestion
by Robin Green 02 Dec '09

02 Dec '09

Could I suggest that the following short text be included in the GHC 6.12.1 final release notes, in some form? -- cut here -- Updating third-party packages ----------------------------- A number of packages will need modifying to build on GHC 6.12.1 (in some cases, just modifying the dependencies in the .cabal file will suffice). If you fix someone else's open source Haskell library or application so that it builds or works correctly on GHC 6.12.1, please help the Haskell community by: (a) publishing your changes as a patch or a repository, and adding a link to them on this wiki page: http://haskell.org/haskellwiki/Patches_and_forks_for_GHC_6.12 (You can email updates for that page to Robin Green <greenrd(a)greenrd.org> if you don't want to create a wiki account.) (b) notifying the package's current maintainer/author (this information may be found on the package's Hackage page, if it has one), specifying where your changes may be found. (c) removing your changes from the wiki page if/when they get included upstream This will help to avoid duplicating our efforts. -- cut here -- -- Robin

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A few small points about GHCi command documentation in section 2.7
by Yitzchak Gale 01 Dec '09

01 Dec '09

Please add to the documentation for :set prompt: If you enclose \i{prompt} in quotes, you can use Haskell syntax for String literals. Actually, :set prompt is nearly useless without quotes, because GHCi strips off trailing spaces from commands. We should either add a space at the end of a prompt entered without quotes, or just require quotes. Or at least change the help text to be: :set prompt \"<prompt>\" set the prompt used in GHCi\n so that people will know the right thing to do. Perhaps add a few more words of explanation to the docs in section 2.7 once we decide which of these to do. The :run command is not documented in section 2.7 - the only mention of it is buried within the documentation for the :main command. It is also not mentioned in helpText. Thanks, Yitz

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