On Mon, 11 Dec 2006, Jean-Philippe Bernardy wrote: > You can try Data.Set.minView. > http://www.haskell.org/ghc/docs/latest/html/libraries/base/Data-Set.html Seems to be new in GHC-6.6 over GHC-6.4. I suspect that not really monadic behaviour is needed in minView, but only the fail method, isn't it? Confusing.