[Haskell-beginners] Auto-increment String

[John M. Dlugosz]

On 4/18/2014 2:38 PM, Norbert Melzer wrote:
>  > "a" to "z" then "aa" to "zz" then "aaa" to "zzz" and so on! Is it to difficult or
> impossible to create a function that enumerates all possible strings?
>
> Following your theory the next "name" would be "Joho", is that a name or just random
> letters? That's why you don't have predecessor or successor functions on String.

That's how it works in Perl.

perl -e "$x='John'; ++$x; print $x; "
produces "Joho"

It would be an interesting beginner's exercise to implement that in Haskell (re: 
http://perldoc.perl.org/perlop.html#Auto-increment-and-Auto-decrement )

A foldr would be good, I suppose, but complicated by the need to return the carry state as 
well as the accumulated tail to the next iteration.