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NNTP-Posting-Date: Thu, 18 Aug 2011 08:34:16 -0500
Date: Thu, 18 Aug 2011 06:34:14 -0700
From: Patricia Shanahan <pats@acm.org>
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Subject: Re: enhance an array's static type by a lower length-bound.
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On 8/18/2011 3:41 AM, Andreas Leitgeb wrote:
> Unfortunately, Roedy completely misunderstood what my post was about.
>
> It was not about lower-bounding the indices, but about lower-bounding
> the *length* - thus morphing certain runtime-ArrayIndexOutOfBoundExceptions
> into compile-time errors.  Are my postings really that hard to grasp?
> Even the examples I provided?

I think the confusion may have arisen because a lot of us are familiar
with specified index lower bounds from the languages we know that
implement them.

I don't think I've ever seen a language with dynamic array creation that
has a lower bound on the length of an array a variable can reference.
I'm not sure how it would work, or how I would use it.

Usually, if I have a non-zero lower length bound it is 1 or 2, but most
of my array handling code is designed and tested for zero length and up.
Even when there is a lower bound, I'm not sure knowing it would help
much with compile time error detection. For example, a method to
calculate the sample mean of some observations requires at least one
element, but is going to iterate over the whole array.

Patricia