I want to learn how to use FFI with Win32, so I'm looking through the GHC source code. I encountered the function

terminateProcess :: ProcessHandle -> IO ()
terminateProcess ph = do
withProcessHandle_ ph $ \p_ ->
    case p_ of
      ClosedHandle _ -> return p_
      OpenHandle h -> do
    throwErrnoIfMinus1_ "terminateProcess" $ c_terminateProcess h
    return p_

which uses withProcessHandle_. What does it do?

Thanks

-John