Re: [xsl] An issue with XPath 2.0 sequences (Was Re: RE: Muenchian method, and keys 'n stuff)

[Joerg Pietschmann <joerg dot pietschmann at zkb dot ch>]

Dimitre Novatchev <dnovatchev@yahoo.com> wrote:
> Several people already expressed their curiosity about what was the
> reason to forbid a sequence to have an element-sequence.

Well, i can see people getting uneasy about sequences containing
empty sequences. In particular there may be conflicting expectations
how to interpret a sequence containing an empty sequence in various 
boolean contexts. In my LISP days i've seen quite a few people
hunting bugs ultimately caused by the difference between NIL
and '(NIL). There may be also problems in how to handle empty
sequences in unions and other functionality: should the result
of (())|(()) be (()) or (()()) or even ()? Should sum((1 () 2))
result in 3 or NaN?

Having said that, i still think it would be much cleaner to
allow sequences containing sequences, even if it breaks some
existing style sheets.

Regards
J.Pietschmann

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