# Questions on quoting **URL:** \ **Category:** Questions & Answers\ **Tags:** quote, unquote\ **Created:** [November 14, 2022, 9:08pm UTC](https://racket.discourse.group/t/questions-on-quoting/1472 "2022-11-14T21:08:45Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![sschwarzer](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/sschwarzer/32/1940_2.png) [@sschwarzer](https://racket.discourse.group/u/sschwarzer)\ **Post date:** [November 14, 2022, 9:08pm UTC](https://racket.discourse.group/t/questions-on-quoting/1472/1 "2022-11-14T21:08:45Z")
Disclaimer: The following questions are _not_ relevant for any code I'm working on, but I'm curious about any answers, since I'm _still_ wondering about these questions despite telling me repeatedly they're not important. 😄 - I can use `quote` or `'` to "nest" quoting as often as I want to, as in - I occasionally read the statement that quoting a literal gives the literal itself. Looking at Can anyone shed some light on these two issues? ---
**Author:** ![benknoble](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/benknoble/32/16_2.png) [@benknoble](https://racket.discourse.group/u/benknoble)\ **Post date:** [November 14, 2022, 9:31pm UTC](https://racket.discourse.group/t/questions-on-quoting/1472/2 "2022-11-14T21:31:15Z")
1. I think `eval` is precisely the opposite of `quote`: `quote` _prevents_ evaluation. The natural counterpart is to force evaluation using `eval` (though note considerations of `current-namespace`/the namespace argument to `eval` when in a module vs a REPL). 2. `(quote (quote 1))` evaluates to the list `(quote 1)`: ```scheme > (equal? ''1 (list 'quote 1)) #t ``` Recall that `quote` is a special form, and as such has its own evaluation rules. Special forms are evaluated outside-in, so in `(quote_a (quote_b 1))` (marked for clarity; assume both are actually `quote`) the `quote_a` controls evaluation of the expression `(quote_b 1)` and, by the rules of `quote`, does not evaluate it but returns it directly. ---
**Author:** ![benknoble](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/benknoble/32/16_2.png) [@benknoble](https://racket.discourse.group/u/benknoble)\ **Post date:** [November 14, 2022, 9:33pm UTC](https://racket.discourse.group/t/questions-on-quoting/1472/3 "2022-11-14T21:33:15Z")
In fact, the latter point is what makes `(eval ''a)` work (assuming appropriate namespace setup): the `''a` is given to `eval` as `(quote a)`, and evaluating that expression is of course the result `'a`. ---
**Author:** ![sorawee](https://avatars.discourse-cdn.com/v4/letter/s/ea5d25/32.png) [@sorawee](https://racket.discourse.group/u/sorawee)\ **Post date:** [November 14, 2022, 9:52pm UTC](https://racket.discourse.group/t/questions-on-quoting/1472/4 "2022-11-14T21:52:33Z")
`'` is _read/parsed_ as `(quote )`. For the rest of my comment, I will use `(quote )` explicitly to make it less confusing. `quote` is not a function. It is a form that constructs a representation of ``. It can’t be a function because if it were, `` would already be evaluated by the time “quote” consumes it, so it can’t access the underlying representation. This can partially explain why `(quote (quote 1))` doesn't necessarily need to be equal to `(quote 1)`. In Racket, some expressions have a representation that coincides with itself. Numbers, like `1`, are one of these expressions. That’s why `(quote 1)` evaluates to `1`. On the other hand, `(quote 1)` is not self-quoting. `(quote (quote 1))` needs to construct a representation of `(quote 1)`, so it constructs `(list (quote quote) 1)`. How do you remove the outer `quote` when it’s nested in more than one level? `(quote (quote ))` evaluates to `(list (quote quote) (quote ))`. As you want `(quote )`, you can simply access the second element. ```scheme > (quote (quote (hello world))) ''(hello world) > (second (quote (quote (hello world)))) '(hello world) ``` ---
**Author:** ![jbclements](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/jbclements/32/11_2.png) [@jbclements](https://racket.discourse.group/u/jbclements)\ **Post date:** [November 14, 2022, 10:14pm UTC](https://racket.discourse.group/t/questions-on-quoting/1472/5 "2022-11-14T22:14:33Z")
Total agreement with @sorawee . To add to it: I think the printed representation ```scheme '''a ``` ... is in many ways confusing and broken. It suggests that the symbol is somehow "triply quoted". That's basically not true; the outer quote is essentially "disabling" all of the internal quotes. I think it would be probably better to print this value as ```scheme '(quote (quote a)) ``` ... which is another way of writing the same value. More generally, I think the printer would be less confusing if it didn't "compress" quotes occurring inside of already-quoted expressions. The counter-argument, I suppose, would be for values like ```scheme '(define (f x) (cons 'a x)) ``` ... which would then be printed as ```scheme '(define (f x) (cons (quote a) x)) ``` Thoughts? ---
**Author:** ![soegaard](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/soegaard/32/19_2.png) [@soegaard](https://racket.discourse.group/u/soegaard)\ **Post date:** [November 14, 2022, 10:18pm UTC](https://racket.discourse.group/t/questions-on-quoting/1472/6 "2022-11-14T22:18:26Z")
> [@sorawee](#): > > `'` is _read/parsed_ as `(quote )`. [sschwarzer](https://racket.discourse.group/u/sschwarzer): > I wonder if there's also a way to "unquote" a quoted expression like this: Since `'` is read as `(quote )` your "unquote" function is simply `cadr`. ---
**Author:** ![jbclements](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/jbclements/32/11_2.png) [@jbclements](https://racket.discourse.group/u/jbclements)\ **Post date:** [November 15, 2022, 12:30am UTC](https://racket.discourse.group/t/questions-on-quoting/1472/7 "2022-11-15T00:30:25Z")
Right, unless you try to use it on `'a`. Then you're in syntax-land. ---
**Author:** ![soegaard](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/soegaard/32/19_2.png) [@soegaard](https://racket.discourse.group/u/soegaard)\ **Post date:** [November 15, 2022, 1:01am UTC](https://racket.discourse.group/t/questions-on-quoting/1472/8 "2022-11-15T01:01:03Z")
You are right - I didn’t think this through. Only syntax transfers get the the reader result directly. ---
**Author:** ![jbclements](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/jbclements/32/11_2.png) [@jbclements](https://racket.discourse.group/u/jbclements)\ **Post date:** [November 15, 2022, 1:29am UTC](https://racket.discourse.group/t/questions-on-quoting/1472/9 "2022-11-15T01:29:47Z")
Here's a "dequote". @sschwarzer , is this what you're looking for? ```scheme #lang racket (define-syntax dequote (syntax-rules (#%quote) [(_ (_ datum)) datum])) (define a 1234) (dequote '''a) ;; yields ''a (dequote ''a) ;; yields 'a (dequote 'a) ;; yields 1234 ``` ---
**Author:** ![joskoot](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/joskoot/32/1964_2.png) [@joskoot](https://racket.discourse.group/u/joskoot)\ **Post date:** [November 15, 2022, 5:51am UTC](https://racket.discourse.group/t/questions-on-quoting/1472/10 "2022-11-15T05:51:48Z")
A similar problem arises when redefining quasiquote, unquote and unquote-splicing in a quoted let-form: ```scheme (define expr (quote (let ((quasiquote 1) (unquote 2) (unquote-splicing 3)) (+ quasiquote unquote unquote-splicing)))) (eval expr (make-base-namespace)) Ă  6 ok expr Ă  prints: (let (`1 ,2 ,@3) (+ quasiquote . ,unquote-splicing)), unreadable. ``` The outer regular quote does not inhibit reader abbreviation for quasiquote and acompanions. ![DC369554041A4649A528B20B10730B39.png](https://global.discourse-cdn.com/free1/uploads/racket/original/1X/2ad4c25f471d2cfc2782215e9bb5a535b2545175.png) ---
**Author:** ![spdegabrielle](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/spdegabrielle/32/95_2.png) [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Post date:** [November 15, 2022, 10:42am UTC](https://racket.discourse.group/t/questions-on-quoting/1472/11 "2022-11-15T10:42:45Z")
not unrelated: [99 ways to say '(I love you) in Racket](https://matt.might.net/articles/i-love-you-in-racket/) also - for laughs; [https://twitter.com/BotRacket](https://twitter.com/BotRacket) ![image](https://global.discourse-cdn.com/free1/uploads/racket/original/1X/9f0a5f8ca9a3f8b265a14b8c576d5f569b300b36.png) source: [https://cheapbotsdonequick.com/source/BotRacket](https://cheapbotsdonequick.com/source/BotRacket) s. ---
**Author:** ![sschwarzer](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/sschwarzer/32/1940_2.png) [@sschwarzer](https://racket.discourse.group/u/sschwarzer)\ **Post date:** [November 15, 2022, 4:57pm UTC](https://racket.discourse.group/t/questions-on-quoting/1472/12 "2022-11-15T16:57:58Z")
Thanks a lot for all your replies! 🙂 It's much clearer now. @sorawee I knew that `quote` was a form, not a function, but due to the printing confusion that @jbclements mentioned, I somehow thought that `quote`, applied to an inner `quote` would handle the inner `quote` in some special way and I couldn't understand how exactly. Now I understand that the inner `quote` is just treated like any other "word" and becomes a symbol (i.e. `'quote` = `(quote quote)`). Having both representations, `'foo` and `(quote foo)` can make things more difficult to follow, but I do understand that `'foo` is more practical in a lot of cases. (I also use things like `'foo` and `'(1 2 3)` all the time.) @sorawee, along these lines, I think it was a good idea to explain everything in terms of `quote` instead of also using `'`. 👍 > [@jbclements](#): > > I think the printed representation > > ```scheme > '''a > > ``` > > ... is in many ways confusing and broken. It suggests that the symbol is somehow "triply quoted". Indeed, I guess that was the source of my confusion. > [@jbclements](#): > > Here's a "dequote". @sschwarzer , is this what you're looking for? Yes. ---
**Author:** ![greghendershott](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/greghendershott/32/98_2.png) [@greghendershott](https://racket.discourse.group/u/greghendershott)\ **Post date:** [November 16, 2022, 4:28pm UTC](https://racket.discourse.group/t/questions-on-quoting/1472/13 "2022-11-16T16:28:56Z")
In my early days with Racket, I managed to stumble into a situation like: ```scheme #lang racket/base (define quote "To be, or not to be.") ;; many other lines of code to make this more obscure 'foo ``` which leads to an error message that... didn't exactly clear things up for me: ```scheme ; /var/tmp/quote.rkt:7:1: foo: unbound identifier ; in: foo ``` Like anything initially imported by the `#lang` (whether function or syntax) `quote` can be redefined. Add on the `'` reader shorthand, and you can get enough layers to make a fine confusion. * * * I seem to recall an even more mysterious situation where I redefined something that caused input to the REPL to hang? Alas I can't remember now, exactly; it's probably somewhere on the old mailing list archives. ---
**Author:** ![sorawee](https://avatars.discourse-cdn.com/v4/letter/s/ea5d25/32.png) [@sorawee](https://racket.discourse.group/u/sorawee)\ **Post date:** [November 17, 2022, 2:18am UTC](https://racket.discourse.group/t/questions-on-quoting/1472/14 "2022-11-17T02:18:39Z")
I think there’s a slight typo in @jbclements’s program. `(dequote (1 2))` probably should not expand to `2`. Here’s a corrected version: ```scheme (define-syntax dequote (syntax-rules (quote) [(_ (quote datum)) datum])) ``` ---
**Author:** ![jbclements](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/jbclements/32/11_2.png) [@jbclements](https://racket.discourse.group/u/jbclements)\ **Post date:** [November 17, 2022, 6:25am UTC](https://racket.discourse.group/t/questions-on-quoting/1472/15 "2022-11-17T06:25:22Z")
Yeah, you're right, I got lazy, I couldn't be bothered to figure out what identifier would be left there. Should probably have realized that it's "quote", though :). Ooh, but what if you stack your dequotes? Okay, actually I have work to do....