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For EVAL and EVPROGN see Figure 11.

Figure N8 Treating COND Clauses and Procedure Bodies as Implicit PROGN Forms

Finally, we note that PROGN is unnecessary except as a programming convenience. Because the language is defined to be executed in applicative order (cf. {Note Normal Order Loses} in [Revised Report]), we can force the sequencing of evaluation, as well as throw away unwanted values, by using LAMBDA-expressions. We first note that

so that we need worry only about PROGN with two subforms:

(see [Imperative] and [Revised Report]).