Using GHC-as-a-library

[Mathew Mills]

check out main/SysTools.lhs.

Looks like it uses some heuristic to decide whether GHC is  
"installed" or not.  I suspect your test app is running from a  
location it considers to be part of the build-tree.

Look at initSysTools and findTopDir.


On Oct 5, 2006, at 4:43 AM, Martin Grabmueller wrote:

> Hello all,
>
> I've been playing around with GHC-as-a-library a bit now, and using
> yesterday's snapshot of GHC (ghc-6.5.20061004, compiled from source),
> I ran into the following problem:
>
> When using the Haskell program at the end of this mail, it compiles
> fine (after exposing the ghc package with ghc-pkg), but when running
> it complains:
>
> Main: Can't find package.conf as /usr/local/ghc/lib/ 
> ghc-6.5.20061004/driver/package.conf.inplace
>
> So it seems to search for a package.conf file in the build tree  
> instead
> of an installed one.  Passing in the path to the build tree  
> (commented out
> in the program) to GHC.newSession works.
>
> Has anyone else encountered this problem?  There is probably only a  
> small
> fix necessary, but I have not yet been able to figure it out by  
> myself.
>
> Thanks,
>   Martin
>
> module Main where
>
> import qualified GHC
> import DynFlags (defaultDynFlags)
> import Outputable (ppr, showSDoc, text, (<+>), ($$), empty)
> import BasicTypes
>
> import Data.List
>
> -- This should work, but compiler complains:
> --   Main: Can't find package.conf as
> --     /usr/local/ghc/lib/ghc-6.5.20061004/driver/package.conf.inplace
> my_ghc_root = "/usr/local/ghc/lib/ghc-6.5.20061004"
>
> -- This does work:
> --my_ghc_root = "/home/misc/src/ghc-6.5.20061004"
>
> main =  GHC.defaultErrorHandler defaultDynFlags $ do
>         let ghcMode = GHC.JustTypecheck
>
>         -- Create GHC session, passing GHC installation directory
>         session <- GHC.newSession ghcMode (Just my_ghc_root)
>         dflags0 <- GHC.getSessionDynFlags session
>         GHC.defaultCleanupHandler dflags0 $ do
>         GHC.setSessionDynFlags session dflags0
>         putStrLn "New session defined"
>         let testModule = (GHC.mkModuleName "Test")
>         t <- GHC.guessTarget "Test.hs" Nothing
>         GHC.setTargets session [t]
>         ok <- GHC.load session GHC.LoadAllTargets
>         if failed ok
>            then putStrLn "Loading failed!"
>            else putStrLn "Loading OK!"
>         checked <- GHC.checkModule session testModule
>         case checked of
>           Nothing -> putStrLn "Couldn't check"
>           Just (GHC.CheckedModule parsed renamed typechecked info) ->
>               do putStrLn (showSDoc (ppr parsed))
>                  putStrLn (showSDoc (ppr renamed))
>                  putStrLn (showSDoc (ppr typechecked))
>                  putStrLn (showSDoc
> 	          (case info of
> 	           Just cm | Just scope <- GHC.modInfoTopLevelScope cm ->
> 		           let
> 		               (local,global) = partition ((== testModule) .  
> GHC.moduleName . GHC.nameModule) scope
> 		           in
> 			     (text "global names: " <+> ppr global) $$
> 		           (text "local  names: " <+> ppr local)
> 	           _ -> empty))
>
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