Swap two elements in a list by its indices

Question

Is there any way to swap two elements in a list if the only thing I know about the elements is the position at which they occur in the list.

To be more specific, I a

Answer 1

first-order one-pass swapping

swap 1 j    l  = let (jth,ith:l') = swapHelp j l ith in jth:l'
swap j 1    l  = swap 1 j l
swap i j (h:t) = h : swap (i-1) (j-1) t

swapHelp 1 (h:t) x = (h,x:t)
swapHelp n (h:t) x = (y,h:t') where
                     (y,  t') = swapHelp (n-1) t x

• now with precondition in compliance with original question, i.e. relaxed to 1 <= i,j <= length l for swap i j l
• draws heavily on an idea by @dfeuer to reduce the problem to swapping the 1st element of a list with another from a given position