Hello Federico, Wednesday, May 30, 2007, 12:54:35 PM, you wrote:
Control.Monad.ST And Control.Monad.State
ST monad is just reduced IO monad which like IO organizes sequential (imperative) ordr of execution but unlike IO supports only a small closed set of operations - those working with STRef and STArray State monad provides just two operations - get and put, which provides access to some "monad state". unlike ST/IO monads operations in State monad (and all other monads) can be performed in any order as typical for lazy computations. of course, there are guarantees that put operation will be performed before get that reads appropriate state you may be interested looking at http://haskell.org/haskellwiki/IO_inside although it doesn't say about ST/State monads directly (btw, there is also Lazy.ST monad but it is not used too much :) -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com