isort.hs

insert :: Ord a => a -> [a] -> [a]
insert x []             = [x]
insert x (y : ys)
          | x <= y      = x:y:ys
          | otherwise   = y: insert x ys
    
isort :: Ord a => [a] -> [a]
isort [] = []
isort (x:xs) = insert x $ isort xs 
     
main = do
    print $ insert 3 [1 .. 10]
    -- [1,2,3,3,4,5,6,7,8,9,10]
    print $ isort [4, 6, 9, 8, 3, 5, 1, 7, 2]
    -- [1,2,3,4,5,6,7,8,9]