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Undefined evaluation order
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Date: -- (:)
From: Ken Wakita <wakita@i...>
Subject: Re: Undefined evaluation order

Thanks for your correction.  I looked up in versions of "n'th revised
reports on algorithmic language Scheme" and found the following at a
section "Procedure calls":

  Note: Although the order of evaluation is otherwise unspecified, the
        effect of any concurrent evaluation of the operator and
        operand expressions is constrained to be consistent with some
        sequential order of evaluation. The order of evaluation may be
        chosen differently for each procedure call.

        (http://swissnet.ai.mit.edu/~jaffer/r5rs_6.html#SEC28)

This note first appeared in R4RS.  However, in R3RS it is rather
unclear in that "the same evaluation rules" may allow nondeterministic
evaluations:

  Note: In contrast to other dialects of Lisp, the order of evaluation
        is unspecified, and the operator expression and the operand
        expressions are always evaluated with the same evaluation
        rules.

        (http://swissnet.ai.mit.edu/~jaffer/r3rs_6.html#SEC25)

Ken Wakita