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Re: Can a functional language be sequential?

On 2003.06.02 12:13 Guy Steele - Sun Microsystems Labs wrote:
> Let me ask a question first, the answer to which may
> shed some light: why is it specified in Bento that the
> constructions be evaluated "in sequence"?  Would it
> make a difference if the constructions were evaluated
> in some arbitrary order, or concurrently?  If so, what
> difference would it make?

The purpose of Bento is to construct text-based data objects
such as web pages.  An object can be assembled from parts,
represented as a list of constructions.  For this purpose, the
actual sequence of evaluation doesn't matter, as long as the
final results are put together in the proper order.

Order of evaluation does matter, however, when the list of
constructions contains two or more calls to code external to
Bento.  For this reason, I think it's reasonable to specify
that external calls will be performed in the order they appear
in the list of constructions.

(Strictly speaking, the external call order need not be the
same as the order of evaluation either, but it would take some
artful coding to avoid it).


Michael St. Hippolyte