> rotating the fourth element 2 positions would result in: [1, 2, 4, 3, 5]
Seems odd.  Should that be [4,1,2,3,5]?

Yes, I meant to use the 5 element in my second example.  Sorry for the confusion.

> Is there an idomatic way to handle both of these cases in a function?
Generally people like to see your attempt at a solution before giving the idomatic one so that they are sure it's not a homework question.  What do you have so far?

Yeah, I only wish I had gone to a school that would be forward thinking enough to each FP.  ;-)

Here is my version:

rotate :: Array Integer Card -> Integer -> Integer -> Array Integer Card

rotate a i n

    | i <= u - n = a // [(i, a ! (i + 1)), (i + 1, a ! (i + 2)), (i + 2, a ! i)]

    | otherwise = a // zip [l..u] (h ++ [a ! i] ++ filter (not . (== (a ! i))) t)

    where (l, u) = bounds a

          (h, t) = splitAt (fromInteger ((i - u) + n)) $ elems a

This function is part of my implementation of the Solitaire encryption algorithm, so that is why I have the reference to a Card data type.  This does what I want, and seems basically idiomatic, but perhaps it could be better.

Thanks,

Kevin