sequential order of evaluation

[Morris Katz <mkatz@sesame.stanford.edu>]

   Date: Mon, 7 Aug 89 17:01:45 PDT
   From: will@cs.uoregon.edu

   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.

I find the above opaque and would like to suggest the following alternative
which uses the concept os SERIALIZABILITY as established in the database
literature. 

Note: Although the precise order of evaluation is unspecified, the evaluation
of the expressions must be "serializable".  An evaluation ordering is said to
be serializable if its effects are indistinguishable from those of some
sequential evaluation of the expressions.  Interleaved evaluation of several
expresions is ONLY valid if the effects of interleaving are serializable (i.e.
undetectable). 
 
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Morry Katz
katz@polya.stanford.edu
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