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inconsistency in backquote spec?
- To: firstname.lastname@example.org
- Subject: inconsistency in backquote spec?
- From: Michael Greenwald <Greenwald@STONY-BROOK.SCRC.Symbolics.COM>
- Date: Mon, 28 Nov 88 20:44 EST
(setq d '(a . b))
'`(,@d) => `(a . b) or `(a)?
If you read CLtL, pg 350. it says that it's equivalent to
`(,@d . nil)
(append [,@d] 'nil)
(append d 'nil)
which suggests the correct value is `(a).
If you look at most implementations, and at the examples on pg 351, then
you'd think it should be `(a . b)
However, the example at the bottom of page 350 suggest alternate
"legitimate interpretations" continued on the top of pg 351. All of
them except the first, consider (APPEND .... D NIL) to be equivalent to
(APPEND ... D), which isn't true if D can be a dotted list.
I tried Ibuki, Franz, Lucid, and Genera.
In all of them evaluating '`(,@'(a . b)) => `(a . b).
In Ibuki and Lucid '`(,@'(a . b) ,@nil) => '([bq-]append '(a . b) nil)
while in Genera and Franz '`(,@'(a . b) ,@nil) => `(a . b)
Are dotted lists not allowed as values of D? Is the spec on pg 350
correct, and the examples on pg. 351 incorrect?
I tend to believe the latter. In which case, all of the readers I tried
are incorrect. I'm not going to change the Genera reader, though, until
I hear from this list, in case my brain is just wedged. Can someone
either deconfuse or support me?