Peter G. Hancock wrote:
Jeff Newbern wrote (on Tue, 12 Aug 2003 at 17:20): ? > The functions exported from the IO module do not > perform I/O themselves. They return I/O actions, which describe an I/O > operation to be performed. The I/O actions are combined within the IO > monad (in a purely functional manner) to create more complex I/O > actions, resulting in the final I/O action that is the main value of the > program. The result of the Haskell compiler is an executable function > incorporating the main I/O action. Executing the program "applies" this > ultimate I/O action to the outside world to produce a new state of the > world.
That seems to me the wrong thing to say. There is no application. Whether or not the word is put in quotes, it is something involving a function and an argument. An IO action is not a function.
So then, in your view, what *is* an IO action? One conceptual model is that an IO action with type (IO a) denotes a function of type World -> (World,a). Given that model, "applying" an IO action to the external world seems like a perfectly reasonable account of executing such an action. -antony -- Antony Courtney Grad. Student, Dept. of Computer Science, Yale University antony@apocalypse.org http://www.apocalypse.org/pub/u/antony