T19397E2.hs:1:1: error:
    Ambiguous occurrence ‘main’
    It could refer to
       either ‘T19397S.main’,
              imported from ‘T19397S’ at T19397E2.hs:2:1-14
              (and originally defined at T19397S.hs:4:1-4)
           or ‘Main.main’, defined at T19397E2.hs:5:1