Re: [Chicken-users] Idiomatic way to access nth element of a list

[Bahman Movaqar]

On 12/14/2014 09:18 PM, Richard wrote:

Hello Bayman,

The get to the nth element of a list one would use list-ref.
For example:

(list-ref (list 1 2 3 4) 2) -> 3

The problem with linked lists is that in order to get to the nth element
the list has to be traversed, which does bring a performance penalty.

You can use vectors instead of list if you want to access/modify
elements in constant time. If you need a vector that can dynamically
grow take a look at the dyn-vector egg:
http://wiki.call-cc.org/eggref/4/dyn-vector.


Bahman Movaqar writes:

How would a seasoned Schemer access the nth element of a list? (drop)?
Does it have any performance penalty?

Thanks Richard and Shawn for the answer. For my use case I find it acceptable to use the cleaner more comprehensive list interface (rather than vectors) at the expense of the performance penalty.

-- 
Bahman Movaqar

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