<html> <head> <style></style> </head> <body class='hmmessage'><div dir='ltr'> 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].   <div>> From: sk@cs.brown.edu > Date: Sun, 18 Sep 2011 11:15:41 -0400 > Subject: Re: [racket] Quoted expressions in #lang racket > To: racketnoob@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 </div> </div></body> </html>