T3613.hs:14:20:
    Couldn't match type ‘IO’ with ‘Maybe’
    Expected type: Maybe ()
      Actual type: IO ()
    In the first argument of ‘(>>)’, namely ‘bar’
    In the first argument of ‘fooThen’, namely ‘(bar >> undefined)’

T3613.hs:17:24:
    Couldn't match expected type ‘Maybe a0’ with actual type ‘IO ()’
    In a stmt of a 'do' block: bar
    In the first argument of ‘fooThen’, namely
      ‘(do { bar;
             undefined })’