Re: [Haskell-cafe] least fixed points above something

On Fri, Mar 20, 2009 at 1:01 AM, Dan Doel wrote:

However, to answer Luke's wonder, I don't think fixAbove always finds fixed points, even when its preconditions are met. Consider:

 f []     = []  f (x:xs) = x:x:xs

 twos = 2:twos

How about

fixAbove f x = x `lub` fixAbove f (f x)

Probably doesn't work (or give good performance) with the current implementation of "lub" :) But if "lub" did work properly, it should give the correct answer for fixAbove f (2:undefined). -- ryan