T22483.hs:1:1: warning: [GHC-38417] [-Wmissing-signatures (in -Wall)]
    Top-level binding with no type signature: main :: IO ()

T22483.hs:4:3: warning: [GHC-62161] [-Wincomplete-uni-patterns (in -Wall)]
    Pattern match(es) are non-exhaustive
    In a pattern binding:
        Patterns of type ‘Maybe ()’ not matched: Nothing