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jutememo/swap07.hs

Created April 25, 2011 04:18
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swap07.hs
swap 0 j (x:xs) = idxAt (j-1) xs : set x (j-1) xs
where
idxAt 0 (x:_) = x
idxAt j (_:xs) = idxAt (j-1) xs
set x 0 (_:ys) = x:ys
set x j (y:ys) = y:set x (j-1) ys
swap i j (x:xs) = x : swap (i-1) (j-1) xs
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