[Haskell-cafe] Re: Non Empty List?

GüŸnther Schmidt gue.schmidt at web.de
Thu Jun 4 20:08:01 EDT 2009

Hi Tony,

that's because I wasn't sure whether or not it would be applicable here. 
As with monads, continuations, delimited continuations and quite a 
number of other high level concepts I only understand them in part even 
though I realize at the same time that understanding them fully would 
yield enormous benefits. I am aware of the power of these concepts, but 
have not gained the intuition yet.

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.


PS: please also see my reply to Tillman

Tony Morris schrieb:
> I note that you didn't address the suggestion of a zipper.
> GüŸnther Schmidt wrote:
>> Dan Weston schrieb:
>>> Unless I'm missing something in your description, why not
>>>   data Container a = Single a | Many a a [a]
>> Hi Dan,
>> the above solution would still allow to construct, for instance,
>> Many 5 42 [] :: Container Int
>> The reason why I'm trying to find the design for a data structure in
>> which this would not even be possible is to be able to avoid writing
>> additional "bookkeeping" code into the functions that operate on the
>> structure, ie. the lookups, inserts, delete etc.
>> Günther
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