Suppose I do something similar with the GHC API (6.12.3, linux, x86, 32 bit). The attachment g.hs is my program to get a value from the package (called watermelon-0.1), print it, wait for me to press return, (at this point I modify the source code of the package, rebuild, reinstall), then loop back to get a value from the package again... how should I refresh so I get the new value?
Or I am supposed to forget this and just bump the version number of the package?
I attach my program g.hs and the package tarball for watermelon-0.1.
import Control.Monad(forever,liftM)
import GHC
import Unsafe.Coerce(unsafeCoerce)
import GHC.Paths(libdir)
import DynFlags(defaultDynFlags)
import Linker(getHValue,initDynLinker,linkPackages,showLinkerState)
import Module(mainPackageId,stringToPackageId)
import Name(nameOccName)
import OccName(isValOcc,occNameString)
import MonadUtils(liftIO)
main = forever $ do
e <- ghcheader (unsafepkgget "watermelon-0.1" "W" "wm")
print (e :: Int)
getLine
ghcheader :: Ghc a -> IO a
ghcheader body = runGhc (Just libdir) $ do
f0 <- getSessionDynFlags
let f = dfmod f0
defaultCleanupHandler f $ do
todo <- setSessionDynFlags f
f1 <- getSessionDynFlags
liftIO (initDynLinker f1)
body
where dfmod f = f{ghcLink=LinkInMemory}
unsafepkgget :: (GhcMonad m) => String -> String -> String -> m a
unsafepkgget spkg smod sval = unsafeget (pkgmod spkg smod) sval
pkgmod :: String -> String -> Module
pkgmod spkg smod = mkModule (stringToPackageId spkg) (mkModuleName smod)
unsafeget :: (GhcMonad m) => Module -> String -> m a
unsafeget m v = do
mi <- getModuleInfo m
case mi of
Nothing -> error ("unsafeget fails at " ++ mns)
Just i -> do
case filter (match v) (modInfoExports i) of
[n] -> do h <- getSession
liftIO $ do
val <- unsafeCoerce `liftM` getHValue h n
-- showLinkerState
return val
_ -> error ("unsafegetval cannot find value " ++ v ++
" in module " ++ mns)
where mns = moduleNameString (moduleName m)
match s n = let o = nameOccName n in isValOcc o && s == occNameString o
watermelon-0.1.tar.gz
Description: GNU Zip compressed data
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