- Glasgow-haskell-users

Type families difference between 7.0.4 and 7.2.1
by Luite Stegeman 16 Aug '11

16 Aug '11

hi, I've been trying to debug a problem with some code that causes name conflicts with GHC 7.2.1, but not with 7.0.4. The problem appears to be that in some cases, GHC 7.2.1 creates a top-level data family, that was not there with 7.0.4. Here's a small example: -- C.hs {-# LANGUAGE TypeFamilies #-} module C where class C1 a where data F a :: * -- B.hs {-# LANGUAGE TypeFamilies #-} module B where import qualified C data B1 a = B1 a instance C.C1 (B1 a) where data C.F (B1 a) = B2 a data family D a -- ghci 7.0.4 > ghci B *B> :browse data B1 a = B1 a data instance B.R:FB1 (B1 a) = B2 a data family D a -- ghci 7.2.1 > ghci B *B> :browse data B1 a = B1 a data instance B.R:FB1 (B1 a) = B2 a data family D a data family F a I'm not sure what's going on, why there's a difference and whether this actually is the problem (and not just a difference in the :browse function). In the original code in which I ran into the problem, there's a similar top-level data family that wasn't there with GHC 7.0.4. The original issue is here: https://github.com/yesodweb/persistent/issues/17 , specifically there's a data family Field, that appears to cause conflicts with another Field type in Yesod. Unfortunately it's difficult to install the packages due to dependencies that have not yet been updated for 7.2.1, and the problem is further obscured by being buried inside template-haskell generated code. luite

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RE: Superclass defaults
by Simon Peyton-Jones 15 Aug '11

15 Aug '11

| > If someone felt able to act as moderator for the discussion, willing | > to summarise conclusions, open questions, and so on, on the wiki | > page, that would be enormously helpful. | | I'm up for that role, if that's appropriate. I'll take you up on that, thank you! I've added some "SLPJ note" notes to http://hackage.haskell.org/trac/ghc/wiki/DefaultSuperclassInstances which could perhaps do with clarifying. Simon PS: to avoid spam, maybe now we have advertised this thread, we should restrict it to ghc-users? The *current* library question about mappend etc can stay on libraries.

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HEAD does not build on OS X using 7.2.1 as bootstrap compiler
by Johan Tibell 14 Aug '11

14 Aug '11

Here's the error I get: compiler/nativeGen/PprBase.hs:26:8: Could not find module `Data.Array.Unsafe' Perhaps you meant Data.Array.Base (from array-0.3.0.3) Data.Array.Unboxed (from array-0.3.0.3) Use -v to see a list of the files searched for. This is from a clean tree.

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INLINE pragma changes in 7.2.1
by Antoine Latter 13 Aug '11

13 Aug '11

Hi GHC, Did the behavior of the INLINE prgama change in version 7.2.1? I didn't see anything in the release notes. Previously (7.0.3) I could attach an inline pragma to a class member like so: class MyClass a with foo :: a -> Int {-# INLINE foo #-} Now I get the error message: "The INLINE pragma for default method `foo' lacks an accompanying binding" Is this change on purpose? Thanks, Antoine

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foldP elemP
by Luca Ciciriello 10 Aug '11

10 Aug '11

I all. I've just installed GHC 7.2.1 In my code I import GHC.PArr but this new compiler doesn't find any more "foldP" and "elemP". Wich module I've to import in order to use "foldP" and "elemP". Thanks in advance for any answer. Luca

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hsc2hs and #include
by Evan Laforge 10 Aug '11

10 Aug '11

So when I upgrade from 6.10 to 6.12 a LONG time ago, there was a bug where hsc2hs would emit INCLUDE pragmas and ghc didn't like that. So I hacked around it with an extra grep -v step in the Makefile. I always meant to go fix it for real in hsc2hs and finally I came back to that TODO item. I took a look at the hsc2hs source, and discovered it's surrounding the INCLUDE line with #elif __GLASGOW_HASKELL__ < 610 However, that macro is never defined for me, so it always emits the bogus INCLUDE line. I can't find anywhere that defines that macro, but there is a lot of "__GLASGOW_HASKELL && ...". So I modified utils/hsc2hs/C.hs from ... "#elif __GLASGOW_HASKELL__ < 610\n"++ " printf (\"{-# INCLUDE %s #-}\\n\", \""++ showCString s++"\");\n"++ "#endif\n" to "#elif __GLASGOW_HASKELL__ && __GLASGOW_HASKELL__ < 610\n"++ " printf (\"{-# INCLUDE %s #-}\\n\", \""++ showCString s++"\");\n"++ "#endif\n" And my problem is solved. Is this the correct solution? Where is that macro defined? I don't know how to mail patches with git, but anyway it's trivial so I don't think it's needed :)

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Build failure of syb-with-class with ghc-7.2.1
by Bas van Dijk 09 Aug '11

09 Aug '11

Hello, the HEAD of syb-with-class fails with the following error when build with ghc-7.2.1 and template-haskell-2.6: http://code.google.com/p/syb-with-class/issues/detail?id=4 Is this a bug in TH? Regards, Bas

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7.2.1-rc1 fails to build on kfreebsd-*, mips*, s390 and sparc
by Joachim Breitner 07 Aug '11

07 Aug '11

Dear GHC team, I have uploaded 7.2.1-rc1 to Debian experimental. It build fine on i386, amd64 and powerpc, but fails on the other architectures: https://buildd.debian.org/status/package.php?p=ghc&suite=experimental („last log“ gives you the full build log) The causes seem to be different. On kfreebsd, we get: ghc-stage1: panic! (the 'impossible' happened) (GHC version 7.2.0.20110728 for i386-unknown-kfreebsdgnu): Don't know if OSUnknown is elf This might be something that is easy to fix in compiler/utils/Platform.hs, but you will know better if one should add a new OS value, or reuse OSFreeBSD. On the other architectures there are complaints about static declarations following non-static declaration that I do not understand. I hope you do :-) With best regards, Joachim -- Joachim "nomeata" Breitner Debian Developer nomeata(a)debian.org | ICQ# 74513189 | GPG-Keyid: 4743206C JID: nomeata(a)joachim-breitner.de | http://people.debian.org/~nomeata

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-fllvm
by Luca Ciciriello 06 Aug '11

06 Aug '11

Hi all. I'm trying to build my Haskell code using llvm option, but using the command: ghc --make -O2 -fllvm Main.hs -o myapp I get the following warning: Warning: -fllvm is incompatible with -fPIC and -dynamic on this platform; ignoring -fllvm I'm using GHC 7.0.4 (64-bit) on MacOS Lion (10.7) with Xcode 4.1. Thanks in advance for any answer. Luca.

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GHCJS
by Victor Nazarov 05 Aug '11

05 Aug '11

Hello, I'm a maintainer and creator of GHCJS tool [1]. GHCJS currently uses GHC API to produce Javascript code from Haskell sources. There is a great interest to the project, but there have been little progress recently. I'm considering the future of it and I'd like to get some advices or suggestions from GHC maintainers. GHCJS originally was fork of GHC 6.6 with javascript generation built in. Since javascript generation is very experimental, I wasn't trying to push it into GHC mainline. Besides it was expressed several times [2] that GHC HQ doesn't want to support another backend which brings lots of interoperability problems with it. Since then GHCJS switched to GHC API. For now code generation works decently well. But I have many problems that I'd like to solve and I'm not sure if it is feasible using GHC API, == Command line interface == I'd like to reproduce GHC command line interface for GHCJS tool. For now I'm using something like this: main :: IO () main = do args <- getArgs defaultErrorHandler defaultDynFlags $ runGhc (Just GHC.Paths.libdir) $ do sdflags <- getSessionDynFlags (dflags, fileargs, _) <- parseDynamicFlags sdflags (map noLoc args) _ <- setSessionDynFlags dflags let fileargs' = map unLoc fileargs targets <- mapM (flip guessTarget Nothing) fileargs This works, but I'm not allowed to parse some custom flags used by GHCJS code and not by GHC API. ParseDynamicFlags throws UsageError if it encounters some unknown flags. What can I do to extend GHC's command line arguments' syntax with some custom arguments used by GHCJS? I can parse arguments myself and throw the rest of them to parseDynamicFlags, but GHC's flags are really complicated and I'm not aware of any argument parsing library that can be used to filter out some specified flags and return the rest GHC's flags untouched. == Foreign Function Interface == What I want is to provide FFI for Javascript, But GHC doesn't allow to extend FFI declaration syntax. I'd like to create some new FFI calling convention ("javascript") like this: foreign import javascript "alert" jsalert :: Ptr JSString -> IO () But GHC always emit parse error on "javascript" keyword. For now I'm using (abusing) ccall calling convention and simple imports works pretty well, but I would like to support exports and static/dynamic wrappers. GHC generates C-code to support them, and GHCJS should generate Javascript-code, but I have no idea how to use GHC API to generate custom (Javascript) stubs. Is it possible at all? == Packages support == It will be very handy if users can use Cabal to install and build packages with GHCJS. It should work if I replicate ghc and ghc-pkg command line interface, but remaining problem is that package index and package directories will be shared with GHC, I'd like to create ghcjs and ghcjs-pkg tools that will use their own directories and package index and will not interfere with ghc. Is it possible with GHC API? How can I do it? [1] https://github.com/sviperll/ghcjs [2] http://www.haskell.org/haskellwiki/GHC:FAQ#Why_isn.27t_GHC_available_for_.N… -- Victor Nazarov

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