What is a "sequence"?

[Lars Brinkhoff]

Stefan Monnier wrote:
>> I think there are only a few functions that wants a sequence but not a
>> record: elt, copy-sequence, concat, reverse, and sort.  In the context
>> of structure operations, the most likely function would be copy-sequence.
> 
> BTW, why not make copy-sequence and elt work on records?  After all,
> they are "sequences" (of fixed length and of heterogeneous values, but
> still).

Sure.  I did consider copy-sequence, but then you added copy-record.  I
don't see a great need for elt, but it wouldn't hurt.  Maybe it would be
good for backward compatibility.

In a similar vein, there are also some restrictions on what you can to
to byte-code objects.  You can do aref and concat and even mapcar, but
not aset, and there's no function to make a copy.  I guess a similar
argument could be made that they're "sequences".