How to detect finite/infinite lists?

[Juanma Barranquero]

On Thu, 18 Sep 2003 15:53:12 -0400, Derek Elkins <ddarius at hotpop.com> wrote:

> In Haskell 98, no.  With a slightly impure extension (observable
> sharing) sometimes but in general, no. 

Interesting.

> just use a data structure that says, "an
> infinity of x". The simplest thing I would think of is to follow the
> arithmetic operation exactly.
> 
> data SN
>   = Zero 
>   | Up 
>   | Down 
>   | SN :+: SN
>   | SN :*: SN 
>   | SN :^: SN
>   | Omega SN

:)

Thanks,

                                                           /L/e/k/t/u