This isn't a specifically Haskell related question, but has any one seen any applications of Internal Set Theory (Edward Nelson's approach to non-standard analysis) to functional programming or symbolic manipulation. I'm just beginning to learn about IST, but at least superficially it's predicate standard may have computational significants---something which isn't real, but can be manipulated away later. Also, do Nelson's applications of non-standard analysis to complexity theory go down this line? Thanks.. Jeff Jeff Burdges - [EMAIL PROTECTED] - http://havoc.gtf.gatech.edu/weasel