[Haskell-beginners] Would you shed light on "undefined values" please?

[Brent Yorgey]

On Fri, Jun 24, 2011 at 08:13:26AM +0200, Ertugrul Soeylemez wrote:
> 
> Bottom arises, as soon as a language is total.  This is related to the
> halting problem.  Bottom is the value, which is never computed in the
> sense that it never results.  Only nontotal languages (like Agda) can
> prevent bottom values from appearing.

That is a funny use of the word "total"; I think you mean
"Turing-complete".  "Total" is usually used of languages in which it
is only possible to define total functions -- such as Agda.  Haskell
is non-total since it is possible to define non-total, i.e. partial,
functions, which are undefined for some inputs.

-Brent