In thinlisp 1.0.1, there's a construct that can be reduced to:
> `(progn ,(let ((b '(a b c)) (d nil))
``(,@',(if d `(the ,(second d)) '(progn)) ,,(car b))))
(PROGN (LIST (QUOTE) '(IF D (LIST 'THE (SECOND D)) '(PROGN)) A))
which doesn't give the exected result in clisp-2.35.
They wanted something like:
(PROGN (LIST (QUOTE (PROGN)) A))
sbcl-0.9.0 gives it:
(PROGN (SB-IMPL::BACKQ-APPEND (QUOTE (PROGN)) (SB-IMPL::BACKQ-LIST A)))
gcl-2.6.7 gives it:
(PROGN (APPEND '(PROGN) (LIST A)))
cmucl-18e-pre2 gives it:
(PROGN `(PROGN ,A))
__Pascal Bourguignon__ http://www.informatimago.com/
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