T10570.hs:10:10: error:
    • Illegal instance declaration for ‘ConsByIdx2 Int a Proxy cls’
        The coverage condition fails in class ‘ConsByIdx2’
          for functional dependency: ‘x -> m’
        Reason: lhs type ‘Int’ does not determine rhs type ‘Proxy @{k}’
        Un-determined variable: k
    • In the instance declaration for ‘ConsByIdx2 Int a Proxy cls’