Re: List container: Insert and Delete

[Ted Dennison<dennison@telepath.com>]

In article <3BF3F4E9.7E32361B@brighton.ac.uk>, John English says...
>Missing from Ted's Strawman: Clear(L) = delete everything in the list,

I think that's far more important in your version than it is in the Strawman
because you use a limited type. With a limited type, the only way for someone to
reuse a list variable on a new list is to delete everything out of the old one.
With a non-limited list, you can just build your new list and assign it in.

It could still be added, of course. It just isn't vital like it was for yours.

>Cut(A,B) = remove everything between iterators A and B and return as
>a list (or raise List_Error if A and B refer to separate lists), and
>Copy(A,B) = copy a sublist. The use of Cut and Copy together with "&"
>and Insert(Iterator,List) would deal with all the sublist operations
>and operations on pairs of lists.

What do you have to do a lot that requires this? They can both be built with the
provided iterators without loosing much processing power.

>Problems encountered: students don't like Delete(Pred(Last(L))),
>they always write Delete(Last(L)) and then get a List_Error.

I'd think the "Pop" operations would be the more standard (and popular) way of
removing items off of one of the ends of the list than going though the effort
of using the active iterator routines.

---
T.E.D.    homepage   - http://www.telepath.com/dennison/Ted/TED.html

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