flatten

? ^Aflatten

------------------------------------------------------------------------
(flatten <x>)                                 [DX]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Returns all the atoms in x , linked in a single list.

Example:
? (flatten '2)
= (2)

? (flatten '(1 2 (3 (6 7)) 4))
= (1 2 3 6 7 4)



I wanted to use 'flatten' the other day, thinking that it would
yield a list of all leafes in a tree in the order of a
depth first left-to-right traversal. But it leaves out all nils,
although nils are atoms.


Here is what I think how it should work:

(de flatten2 (arg)
   (if (consp arg)
       (let (((a . b) arg))
 	(nconc (flatten2 a) (flatten2 b)) )
     (list arg) ))

? (flatten2 '(1 2 (3 (6 7)) 4))
= (1 2 3 6 7 () () 4 ())


I think either the behavior of flatten should be changed to
that of flatten2, or the help text should be clarified.

Regards,
Ralf



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