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Re: sequential order of evaluation
- To: email@example.com
- Subject: Re: sequential order of evaluation
- From: Paul Hudak <firstname.lastname@example.org>
- Date: Tue, 8 Aug 89 09:56:16 EDT
- Cc: rrrs-authors
- In-Reply-To: email@example.com, Mon, 7 Aug 89 17:01:45 PDT
The choice is explicit in the rather informal formal semantics, which says
the expressions must be evaluated sequentially in some permuted order.
To be more precise, the informal formal semantics says that whatever
permuted order is chosen must be used for ALL expressions. That bothers
me much more than having it prohibit interleaving.
How do the authors feel about adding the following note to section 4.1.3?
Note: Although the precise order of evaluation is unspecified, the
expressions must be evaluated without interleaving. Interleaving is
not allowed because Scheme provides no facilities for serializing
concurrent side effects.
Completely prohibiting interleaving seems too strong.
To kill two birds with one stone, I think the note should read something like:
(1) The unspecified order-of-evaluation may be chosen differently for
(2) An implementation is only required to guarantee a result that is
consistent with SOME sequential order-of-evaluation (and thus
interleaving is not necessarily prohibited).