On 11 Juni, 14:38, p...@informatimago.com (Pascal J. Bourguignon)
wrote:
Nordlöw <per.nord...@gmail.com> writes:
How do I insert an element (object) relative to another in a sequence
(or list in my case)? Example:
(insert-after 'X '(a b c) 'b) => '(a b X c)
(insert-before 'X '(a b c) b) => '(a X b c)
This is not what you want. You don't what these function to return a
2-element lists, the first of which is the symbol quote. Unless
you're doing meta-programming you never want to have such a result.
You wan this:
(insert-after 'X '(a b c) 'b) --> (a b X c)
(insert-before 'X '(a b c) 'b) --> (a X b c)
Also, you may want to mention whether your insert-after and
insert-before function are destructive or non-destructive. Since you
show as only specification examples using literal data, we will assume
you want them to be non-destructive.
So you do that, just by doing it. There's nothing simplier.
(qrsha vafreg-nsgre (arj yvfg byq)
(pbaq ((ahyy yvfg) '())
((rdy byq (pne yvfg)) (pbaf (pne yvfg) (pbaf arj (pqe yvfg))))
(g (pbaf (pne yvfg) (vafreg-nsgre arj (pqe yvfg) byq)))))
(qrsha vafreg-orsber (arj yvfg byq)
(pbaq ((ahyy yvfg) '())
((rdy byq (pne yvfg)) (pbaf arj yvfg))
(g (pbaf (pne yvfg) (vafreg-orsber arj (pqe yvfg) byq)))))
--
__Pascal Bourguignon__
But how do I implement insert-after() and insert-before()? I guess the
code in the end doesn't do anything meaningful :)