Re: empty intervals John Cowan 31 Jul 2015 23:57 UTC

Per Bothner scripsit:

> (1) This case
> (= (interval-lower-bound I i) (interval-upper-bound I i))
> This needs to be allowed, no ifs or buts, and the specification
> needs to say so.

I agree.  That allows arrays to be empty.  Only very C-ish languages
prohibit empty arrays, and not for any very good reason (gcc allows them).

> (2) This case:
> (= (interval-dimension I) 0)
> I don't feel as strongly about, though it would be allowed in any
> implementation I control. I think there is no good reason to not
> allow it, and good reasons (consistency, generality) to allow it.

I think it should be required to be true for consistency and generality.

John Cowan
Do what you will / this Life's a Fiction
And is made up of / Contradiction.  --William Blake