[Haskell-cafe] GHC 6.8.2 as a library on Windows and GHCi

[gwern0 at gmail.com]

On 2008.01.09 17:07:46 +0100, Peter Verswyvelen <bf3 at telenet.be> scribbled 4.7K characters:
>    I while I ago I sent an email regarding hs-plugins not working on windows.
>
>    I now tried to directly use GHC API, but I also failed.
>
>    The following program (which might be buggy, I copy/pasted from various
>    sources)
>
>    import DynFlags
>    import GHC
>
>    main = defaultErrorHandler defaultDynFlags $ do
>      session <- newSession (Just "d:/app/ghc-6.8.2")
>      flags <- getSessionDynFlags session
>      (flags, _) <- parseDynamicFlags flags []
>      GHC.defaultCleanupHandler flags $ do
>        setSessionDynFlags session flags{ hscTarget=HscInterpreted }
>        prelude <- findModule session (mkModuleName "Prelude") Nothing
>        setContext session [] [prelude]
>        runStmt session "let n = 2 + 2" RunToCompletion -- n is bound
>        runStmt session "n"  RunToCompletion            -- 4 is printed (note
>    "it" is bound)
>
>    gives the following error when run from GHCi
>    *Main> :load "l:/test.hs"
>    [1 of 1] Compiling Main             ( l:/test.hs, interpreted )
>    Ok, modules loaded: Main.
>    *Main> main
>
>    GHCi runtime linker: fatal error: I found a duplicate definition for
>    symbol
>       _forkOS_entry
>    whilst processing object file
>       d:/app/ghc-6.8.2/lib\base-3.0.1.0/HSbase-3.0.1.0.o
>    This could be caused by:
>       * Loading two different object files which export the same symbol
>       * Specifying the same object file twice on the GHCi command line
>       * An incorrect `package.conf' entry, causing some object to be
>         loaded twice.
>    GHCi cannot safely continue in this situation.  Exiting now.  Sorry.
>
>    Process haskell finished
>
>    Is my code incorrect, or is this a (known?) bug in GHC 6.8.2 on Windows? I
>    haven't tried the Linux version yet.
>
>    NOTE: The program *does* run fine when compiling via GHC --make.
>
>    Thanks,
>    Peter

I think your installation is just buggy. I ran it here, and it compiles fine (although it doesn't run, as Linux obviously has "d:/app/ghc-6.8.2") and runs, printing "4" if I replace the string with "/usr/lib/ghc-6.8.2". Could it be that your GHCi is not the 6.8.2 one, or your path incorrect?

--
gwern
& b AHPCRC Playboy Dolch += SG530 Karimov CNCIS beef
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