Re: [Haskell-cafe] operating on nested monads

G'day Marco. Quoting Marco Righele :

How can I achieve the same effect (if it is ever possible)? I feel like it should be something almost trivial, but I really can't get it.

One approach is to use a monad which works like Maybe, but as a monad transformer over IO. You might want to try NegateT, which does pretty much precisely this: http://cvs.sourceforge.net/viewcvs.py/hfl/hfl/mtl/Negate.hs?rev=1.2 Cheers, Andrew Bromage