[Haskell-beginners] Simple laplace solver

[Edward Z. Yang]

On Sat, 28 Mar 2009, Francesco Bochicchio wrote:
> There was a thread on this ML which was about an implementation of average which
> avoids
> traversing the list twice, one for 'sum' and one for 'length'. You could use it,
> if you care for
> performance and your list is long enough to matter

The list is four elements long, so I don't particularly care. Although,
I wonder why there isn't a built-in average function.

Cheers,
Edward