FailDueToGivenOverlapping.hs:27:9:
    Overlapping instances for E [t0] arising from a use of ‘eop’
    Matching givens (or their superclasses):
      E [Int]
        bound by the type signature for: bar :: E [Int] => () -> ()
        at FailDueToGivenOverlapping.hs:26:8-26
    Matching instances:
      instance E [a] -- Defined at FailDueToGivenOverlapping.hs:21:10
    (The choice depends on the instantiation of ‘t0’)
    In the expression: eop [undefined]
    In an equation for ‘bar’: bar _ = eop [undefined]