Teach Yourself Scheme: 3.3 Sequencing

We used the begin special form to bunch together a group of subforms that need to be evaluated in sequence. Many Scheme forms have implicit begins. For example, let's define a 3-argument procedure that displays its three arguments, with spaces between them. A possible definition is:

(define display3
  (lambda (arg1 arg2 arg3)
    (begin
      (display arg1)
      (display " ")
      (display arg2)
      (display " ")
      (display arg3)
      (newline))))

In Scheme, lambda-bodies are implicit begins. Thus, the begin in display3's body isn't needed, although it doesn't hurt. display3, more simply, is:

(define display3
  (lambda (arg1 arg2 arg3)
    (display arg1)
    (display " ")
    (display arg2)
    (display " ")
    (display arg3)
    (newline)))

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