Steve Horne :
I only meant that there's random number handling support in the Haskell library and, and least judging by type signatures, it's pure functional code with no hint of the IO monad. Look well at those functions, please.
Within the RandomGen class you have pure members, such as next (an Int instance of what I called rgen in my previous message. It propagates the seed "g" ). The algorithmics of the random generation has no particular "monadicity" in it, as I said, the IO (or State) monad serves to hide the seed. The generator itself should not be confounded with its iterative, sequential usage. If people wanted to do in their programmes just *one* read or write, never repeated, no IO Monad would be necessary. On the other hand, for the IO, you can sequence the World instances explicitly, without any Monads in a pure functional language, this is the style used in Clean. == I am strongly convinced that ALL people who want to understand the functional IO, refs, etc. should learn both, Haskell and Clean. Il might help them to see better the relation between the programme, and its environment. ========== You say: /random numbers are in principle non-deterministic, not determined by the current state of the outside world/ Sorry, but I haven't a slightest idea what you are talking about. Dybbuks? Jerzy