# [plt-scheme] Help with #0 and #0# notation in the REPL

They are a form of definition and use that you can use in quoted
constants. In this case, it means that the cdr of that pair is the
same as the pair itself. The "#0=" is in introduction of the name and
"#0#" is the use of the name. In general the "0" can be natural
number.
hth,
Robby
On Jan 28, 2008 7:26 PM, Grant Rettke <grettke at acm.org> wrote:
>* In the rep if you do
*>*
*>* (define a (cons 'a null))
*>* (set-cdr! a a)
*>* a
*>* > #0=(a . #0#)
*>*
*>* The writer shows you an improper list notation, but what is the #0 and #0#?
*>*
*>* Neither show up in the help desk.
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