[Haskell-cafe] Uses of `fix' combinator

[Khudyakov Alexey]

Hello,

While browsing documentation I've found following function 

> -- | @'fix' f@ is the least fixed point of the function @f@,
> -- i.e. the least defined @x@ such that @f x = x at .
> fix :: (a -> a) -> a
> fix f = let x = f x in x

I have two questions. How could this function be used? I'm unable to imagine 
any. Naive approach lead to nothing (no surprise):

Prelude Data.Function> fix (^^2)
<interactive>: out of memory (requested 2097152 bytes)


Second question what does word `least' mean?`a' isn't an Ord instance. 

--
  Khudyakov Alexey