Dynamic list values

[pjot]

Hi,

I have the following code:

Code: Select all

(set 'a 0)
(set 'b '(0 1 2 3 4 a))

Is there a way to update the 'a' in this list dynamically? Meaning:

b
(0 1 2 3 4 0)

So, during initialization of 'b, the list will have assigned the value of 'a, instead of the symbol 'a itself.

Can this be done without tricks like (push) or (nth-set)? A similar thing is possible with an array, but is it possible with lists also?

Peter

[Lutz]

You could use expand:

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(set 'L '(1 a 3 4 b 6))
(expand L '((a 2) (b 5))
L => (1 2 3 4 5 6)

; or if 'a' and 'b' are already set previously:

(expand L 'a 'b)

The first method is nice because it treats 'a' and 'b' as local variables similar to 'let'

Lutz

[pjot]

Thanks, exactly what I was looking for!!

Peter