Re: List container: Insert and Delete

[Darren New <dnew@san.rr.com>]

Ted Dennison wrote:
> Not that I'm saying  that there's nothing wrong with you if you need this or
> some other esoteric function from a list from time to time. But I think all the
> tools are already there to build your "Offset" function, and it won't really be
> any slower than if one were provided for you. 

Agreed, as long as positions can be compared for equality.

Anyway, I think the general point I was trying to make was that one
*should* be able to do most anything with the list that the data in the
list supplies. If it's not even a private type, that pretty much solves
all problems. :-)

> that is the case, the general rule ought to be to leave the function out, unless
> it is something so common that just about any disinterested observer would be
> suprised to not find it in there.

Sure, as long as stuff like that *can* be done.
 
> >Saying "we're not going to implement this operation because it's
> >inefficient" doesn't sound like a good idea to me, is all.
> 
> Stated that way, I'd agree too. What I was suggesting was that stuff that can be
> built w/ the other tools easily and is not O(1) (but *is* O(1) with the other
> List type) perhaps should not be presented as a primitive. That way people are
> encouraged to use the right tool (package) for the job. Again, this was just one
> out of three positions I'd like to see discussed, as a middle ground between
> total conformity between Bounded and Unbounded and total redesign. I frankly
> could see a good case for any of the three.

Yes. My concern was that *if* the "position" type can't be compared for
equality by the user, you have to provide that in the library somehow.
*Then* it becomes a one-liner to translate to integers and back.

It's a shame it's not *really* an ADT in the mathematical sense, or we
could prove whether or not we have all the functions anyone would want,
and whether we have the most efficient implementation of them. :-)

-- 
Darren New 
San Diego, CA, USA (PST). Cryptokeys on demand.
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