T9497d.hs:2:8: error: [GHC-88464]
    • Found hole: _main :: IO ()
      Or perhaps ‘_main’ is mis-spelled, or not in scope
    • In an equation for ‘main’: main = _main
    • Relevant bindings include main :: IO () (bound at T9497d.hs:2:1)
      Valid hole fits include
        main :: IO () (bound at T9497d.hs:2:1)
        readLn :: forall a. Read a => IO a
          with readLn @()
          (imported from ‘Prelude’ at T9497d.hs:1:1
           (and originally defined in ‘System.IO’))
        mempty :: forall a. Monoid a => a
          with mempty @(IO ())
          (imported from ‘Prelude’ at T9497d.hs:1:1
           (and originally defined in ‘GHC.Base’))