> import Distribution.Simple
> import Distribution.Simple.InstallDirs
> import Distribution.Simple.LocalBuildInfo
> import Distribution.PackageDescription

> import System

After Idris is built, we need to check and install the .idr library files,
and the C support they need.

FIXME: This is probably all done the wrong way, I don't really understand
Cabal properly... This is all stolen from the Epic build system.

> buildLib args flags desc local 
>     = do exit <- system "make -C lib"
>          return ()

This is a hack. I don't know how to tell cabal that a data file needs
installing but shouldn't be in the distribution. And it won't make the
distribution if it's not there, so instead I just delete
the file after configure.

> postConfLib args flags desc local
>    = do exit <- system "make -C lib clean"
>         return ()

> addPrefix pfx var c = "export " ++ var ++ "=" ++ show pfx ++ "/" ++ c ++ ":$" ++ var

> postInstLib args flags desc local
>     = do let pfx = prefix (installDirTemplates local)
>          exit <- system $ "make -C lib install PREFIX=" ++ show pfx
>          return ()

> main = defaultMainWithHooks (simpleUserHooks { postBuild = buildLib,
>                                                postConf = postConfLib,
>                                                postInst = postInstLib })