ISSUE: sequences need more explanation

Summary: Please add verbiage to the spec clarifying important points
          about sequences.

It is clear that a lot of thought and effort went into creating a
model for sequences that is usable and yet supports its XML legacy.

In particular:

    1. An item is IDENTICAL to a sequence of length 1 containing that
       item.

       That is, 1 is the same as (1).

    2. There are no nested sequences.

       That is, (1, (2, 3), ()) is the same as (1, 2, 3)

    3. The empty sequence is often used as a nil/null value.

These points (and especially the first two) are vital to understanding
and using XQuery.

However, it took me a long time to understand these points, as they
are not clearly and explicitly stated, and this sequence model is
different from most other languages (it has similarities to APL,
perhaps).

I'd propose adding some verbiage to the spec calling out these points
explicitly.  This would ideally be done in the section that defines
sequences, singleton sequences, etc.

Thank you for your time.

       -Shawn.


--
Shawn Vincent, svincent@exalt.com
Exalt Inc.

Received on Monday, 14 January 2002 10:36:33 UTC