[Haskell-cafe] Re: Non Empty List?

GüŸnther Schmidt gue.schmidt at web.de
Thu Jun 4 20:25:08 EDT 2009


Hi Jeff,

it might actually be, I'll check it out after a good nights sleep. 
Apparently working on this in the wee hours only leads to self 
embarrassing requests for help.

Actually when it comes to the "underlying" data structure, Jake and 
Tillmann have already found it for me, even though I failed to realize 
that in Jakes post and only "got it" after Tillmanns post.

It's been a long night :)

Günther



Jeff Wheeler schrieb:
> On Fri, 2009-06-05 at 02:08 +0200, GüŸnther Schmidt wrote:
> 
>> As for the zipper: In some of the examples I've seen, the zipper is 
>> implemented "on top" of an underlying data structure, but not the data 
>> structure itself.
>> In my app I was actually going to pull a zipper over it, once I had the 
>> underlying structure right.
> 
> I have a package on Hackage that implements a zipper-ish non-empty list
> structure. PointedList [1] is a datatype composed of a list of items on
> the left, the current item, and a list of items on the right.
> 
> Is that close to what you're looking for?
> 
> [1]
> http://hackage.haskell.org/cgi-bin/hackage-scripts/package/pointedlist




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