functional programming - "Monad transformers more powerful than effects" - Examples? -

the paper "programming , reasoning algebraic effects , dependent types" edwin c. brady on effects in idris contains (unreferenced) claim that:

although [effects , monad transformers] not equivalent in power — monads , monad transformers can express more concepts — many common effectful computations captured.

what examples there can modelled monad transformers not effects?

continuations can modelled monads, using cps, not algebraic effects cannot modelled using lawvere theories. see martin hyland , john power, 2007, the category theoretic understanding of universal algebra: lawvere theories , monads (pdf), entcs 172:437-458.