Saying that (quote (1 2 3)) evaluates to (quote (1 2 3)) [instead to (1 2 3)]
is the same nonsanse to me like saying that (+ 1 2) evaluates to (+ 1 2)
[instead to 3].
> From: s...@cs.brown.edu
> Date: Sun, 18 Sep 2011 11:15:41 -0400
> Subject: Re: [racket] Quoted expressions in #lang racket
> To: racketn...@hotmail.com
> CC: users@racket-lang.org
>
> Yep, that's what he's saying.
>
> I know why you're confused. Let me see if I can help.
>
> Here's an input program:
>
> '(1 2 3)
>
> Now be careful to make the following distinction:
>
> - what it computes
> - what it prints
>
> What it computes is a list with three values. There are at least
> three different ways to PRINT this:
>
> 1. (1 2 3)
> 2. #<list>
> 3. (quote (1 2 3))
>
> The first has the disadvantage Matthias pointed out: you can't paste
> the value back in in a bigger computation. The second has the same
> disadvantage. The third has the advantage you can paste it back in.
>
> You're probably concerned that pasting it back in "makes a new list".
> Yes, it does. But if the expression '(1 2 3) were part of some bigger
> computation -- eg,
>
> (length '(1 2 3))
>
> -- then no "new list" would be created. So it's only if you try
> copying the output of one computation as the input of another that
> there might be new allocation. But look at the word I just used:
> "copy".
>
> This isn't the full answer, but I think you need to make sure you've
> got at least these steps under your belt before we go further. Do ask
> questions.
>
> Shriram
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