Replace an item in a list in Common Lisp?

list lisp replace common-lisp
Paul Wicks picture Paul Wicks · Oct 4, 2008 · Viewed 33.1k times · Source

I have a list of things (I'll call it L), an index(N) and a new thing(NEW). If I want to replace the thing in L at N with NEW, what is the best way to do this? Should I get the sublist up to N and from N to the end of the list and then glue together a new list from the first part, NEW, and the last part using list? Or is there a better way to do this?

Answer

l0st3d picture l0st3d · Oct 4, 2008 
(setf (nth N L) NEW)

should do the trick.

Related questions

Check if item is in a list (Lisp)

What's a simple way to check if an item is in a list? Something like (in item list) might return true if item=1 and list=(5 9 1 2) and false if item=7

Read More
lisp filter out results from list not matching predicate

I am trying to learn lisp, using emacs dialect and I have a question. let us say list has some members, for which predicate evaluates to false. how do I create a new list without those members? something like { A …

Read More
Lisp: list vs S-expression

I'm studying Lisp now. I encountered 2 terms "list" and "S-expression". I just can't distinguish between them. Are they just synonyms in Lisp?

Read More