[Haskell] Fixpoint combinator without recursion

[Felipe Almeida Lessa]

On 4/5/07, Albert Y. C. Lai <trebla at vex.net> wrote:
> Dan Weston wrote:
> > What is it called if it's both?
>
> Then we say "the argument occurs in both positive and negative
> positions" or "the argument occurs in both covariant and contravariant
> positions". There doesn't seem to be a shorter name. I want to note that
> this kind of thing drives OOP crazy.

I know that types like

> data T = T (T -> T)

are inhabitated by things other than bottom (like id or \_ ->
undefined), but can it be useful for *anything*?


Cheers,

-- 
Felipe.