Dan Weston westondan at imageworks.com
Mon Jun 4 14:33:49 EDT 2007

```I would think a simple cyclic list should work without any copying at all:

rotateList myList n = take m . drop n \$ x
where x = myList ++ x
m = length myList

Just keep dropping elements to rotate.

A possible alternative is to use a more tailored data structure with a

Dan

kevin birch wrote:
> Hello all,
>
> I have an implementation question that I hope someone can help out
> with.  Say I have a fixed-size list: [1, 2, 3, 4, 5] that I want to
> treat as circular in a function in order to rotate one of the elements n
> positions.  So rotating the second element 2 positions would result in:
> [1, 3, 4, 2, 5], or rotating the fourth element 2 positions would result
> in: [1, 2, 4, 3, 5].  There are two cases: if the element can be moved
> w/o rotating and where the element must be inserted into the list at the
> front.  Is there an idomatic way to handle both of these cases in a
> function?
>
> Thanks,
> kevin
>
>
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