On Mon, Dec 05, 2016 at 01:44:53AM -0500, Bruno Franco wrote:
> Is there a function that would copy A so that no changes in any of the
> nested lists in A would change B, and vice versa?
You mean a "deep copy".
Contrary to what one might expect, it is very rarely needed. At least I never
needed it in my 35 years of Lisp. I almost never used even the single-level
'copy' function.
Instead, you would rather re-consider your data structures, and operate on them
in a non-destructive way.
Having said this, you can do e.g. a 2-level copy with
(mapcar copy List)
For an arbitrary depth you must use recursion
(recur (List)
(if (atom List)
List
(cons (recurse (car List)) (recurse (cdr List))) ) )
> Also, as a more general question, is there a name for when two variables
> are entangled like this? Where changing one changes the other?
The term is "destructive" operations. In the PicoLisp reference, all destructive
functions should be marked as that.
♪♫ Alex
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