Re: [Haskell-cafe] Performance problem with random numbers

On Sat, 2007-10-13 at 12:42 -0400, Brandon S. Allbery KF8NH wrote:

Your apparently simple StdGen argument is actually a sort of program state (represented by unevaluated thunks, not by a state monad; see below) which gets altered with every invocation of random. If nothing is forced until the very end, it in effect becomes an expression which produces the desired StdGen, with the uses of the previous StdGen values as "side effects" of its computation that occur when the thunk is evaluated at the end. I'm not sure I'm up to working through an example of what this looks like.

Thanks Brandon. I understand your argument but I don't know how to put it into practice, i.e. how to force the evaluation of StdGen. - Thoralf