[Haskell-beginners] Just clarifying the "pred" and "succ" functions in Haskell

[Andy Elvey]

Felipe Lessa wrote:
 
 (snip )
>
> Although we can't have a pointer to the middle of a list [a], we
> can have another data struture that behaves sort of as if we had
> that pointer: a zipper.  For example,
>
> http://hackage.haskell.org/packages/archive/ListZipper/1.1.1.0/doc/html/Data-List-Zipper.html
>
> To understand a list zipper you could think of it as something like
>
>   struct zipper {
>     list left, right;
>   }
>
> So we track our "position" by tracking what's on the left and
> what's on the right.  By using the API of the link above you
> could have something similar to what you wanted:
>
>   lpred :: Zipper a -> a
>   lpred = focus . left
>
>   lsucc :: Zipper a -> a
>   lsucc = focus . right
>
> --
> Felipe. 
>   
Hi Felipe -
Thanks very much for that!  That's very handy to know.  I think that 
I'll base my lpred and lsucc on this approach. 
Bye for now -
- Andy