tcfail083.hs:8:39:
    Constructor ‘Bar’ does not have field ‘baz’
    In the pattern: Bar {flag = f, baz = b}
    In the pattern: State {bar = Bar {flag = f, baz = b}}
    In an equation for ‘display’:
        display (State {bar = Bar {flag = f, baz = b}}) = print (f, b)