Exercise 4.23: Alyssa P. Hacker doesn’t
understand why analyze-sequence needs to be so complicated.  All the
other analysis procedures are straightforward transformations of the
corresponding evaluation procedures (or eval clauses) in 
4.1.1.  She expected analyze-sequence to look like this:


(define (analyze-sequence exps)
  (define (execute-sequence procs env)
    (cond ((null? (cdr procs)) 
           ((car procs) env))
          (else ((car procs) env)
                (execute-sequence 
                 (cdr procs) env))))
  (let ((procs (map analyze exps)))
    (if (null? procs)
        (error "Empty sequence: 
                ANALYZE"))
    (lambda (env) 
      (execute-sequence procs env))))

Eva Lu Ator explains to Alyssa that the version in the text does more of the
work of evaluating a sequence at analysis time.  Alyssa’s sequence-execution
procedure, rather than having the calls to the individual execution procedures
built in, loops through the procedures in order to call them: In effect,
although the individual expressions in the sequence have been analyzed, the
sequence itself has not been.

Compare the two versions of analyze-sequence.  For example, consider the
common case (typical of procedure bodies) where the sequence has just one
expression.  What work will the execution procedure produced by Alyssa’s
program do?  What about the execution procedure produced by the program in the
text above?  How do the two versions compare for a sequence with two
expressions?