[Haskell-cafe] Inverting a Monad

Felipe Lessa felipe.lessa at gmail.com
Wed Feb 6 06:45:02 EST 2008

On Feb 6, 2008 9:39 AM, Miguel Mitrofanov <miguelimo38 at yandex.ru> wrote:
> > How can I define this for an arbitrary Monad m?
> Such as Identity?

An arbirtrary monad can't be inverted, however there's Error and
ErrorT that provide throwing and catching abilities. I guess your
parser is a monad transformer, so *maybe* the solution is to require
MonadError from the inner monad.



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