import GHC
import HscTypes (liftIO)
import GHC.Paths (libdir)
import Outputable (SDoc, showSDoc)

ppr :: SDoc -> GhcT IO ()
ppr = liftIO . putStrLn . showSDoc

main = runGhcT (Just libdir) $ do
  dlflags <- getSessionDynFlags
  setSessionDynFlags dlflags

  mod <- findModule (mkModuleName "Prelude") Nothing
  setContext [] [mod]
  exprType "length []" >>= ppr . pprParendType
  exprType "print" >>= ppr . pprParendType