Subject: Re: newbie Q: opposite of quote
From: (Rob Warnock)
Date: Wed, 25 Oct 2006 23:22:21 -0500
Newsgroups: comp.lang.lisp
Message-ID: <>
Alan Crowe  <> wrote:
| writes:
| > Is it fair to say that eval is the opposite of quote?
| > Is there another function considered the opposite of quote?
| Type 2<RET>
| The lisp interpreter looks at 2 and evaluates it. It
| recognises it as a number, and applies the rule that numbers
| evaluatie to themselves, so the answer is 2.
| Type: (+ 2 2)<RET>
| The computer sees the opening parenthesis and realises it is
| being given a list. When it reaches the closing parenthesis
| it is able to work out that it has seen a list of three items.
| The first is the + sign, so it knows to add together the values
| of the remaining items on the list. So it evaluates them, the
| number 2 having the value 2 as before. Answer: 4

CLHS " Form Evaluation" is sometimes useful at this point:
    Forms fall into three categories: symbols, conses, and
    self-evaluating objects. The following sections explain these
    categories. Symbols as Forms Conses as Forms Self-Evaluating Objects


Rob Warnock			<>
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