(pr-str '(+ 1 2)) :
pr-str is not given code-as-data , because it's not a macro. pr-str is given
the result of first evaluating its arg, that is '(+ 1 2). And evaluating '(+
1 2) results in the list (+ 1 2).
So pr-str is right, your assumptions were wrong.
To achieve your goal, just use (pr-str ''(+ 1 2)).
HTH,
--
Laurent
2010/9/29 K. <kotot...@gmail.com>
> Hello,
>
> I have some questions about how to use the prn functions.
>
> From the documentation of the prn function:
> "[...] By default, pr and prn print in a way that objects can be read
> by the reader [...]"
>
> In this case, why does the prn-str function does not quote sequences?
>
> For instance (pr-str '(+ 1 2)) returns "(+ 1 2)", which can not be
> read back since (eval (read-string (pr-str '(+ 1 2)))) returns 3!
>
> There is the *print-dup* function but it does not produce a string
> readable by an (advanced) user:
>
> (binding [*print-dup* true]
> (pr-str '(+ 1 2)))
>
> returns "^#=(clojure.lang.PersistentArrayMap/create {:line 1}) (+ 1
> 2)"
>
> where I just would like to display to the user "'(+ 1 2)"
>
>
> So how can one print and read back quoted s-expressions so that a user
> can modify them?
>
> I have implemented a pr-str-data function:
> (defn- pr-str-data [data]
> (if (seq? data)
> (str "'" (pr-str data))
> (pr-str data)))
>
> but there should be a better way.
>
> Thanks in advance for your help.
>
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