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Re: [plt-scheme] Symbol
From: pocm@rnl.ist.utl.pt (Paulo J. Matos)
Date: 18 May 2002 20:38:28 +0100
Hi all,
Playing around with symbol names I was surprised with:
> '{3, 2}
(3 ,2)
Why?
This is specific to PLT Scheme, not something that will work that way
in all Schemes. It is related to the following other examples:
> {+ 3 4}
7
> (equal? ',2 (list 'unquote 2))
#t
> (equal? '{3, 2}
(list 3
(list 'unquote 2)))
#t
In other words:
(1) PLT Scheme is choosing to read {} as the same as (), .
(2) The comma is a special character, akin to the quote mark, in that
it causes whatever is after it to be wrapped in an unquote form.
-max