T9497a-run: T9497a-run.hs:2:8: error:
    Found hole: _main :: IO ()
    Or perhaps ‘_main’ is mis-spelled, or not in scope
    In the expression: _main
    In an equation for ‘main’: main = _main
    Relevant bindings include
      main :: IO () (bound at T9497a-run.hs:2:1)
(deferred type error)