https://stackoverflow.com/questions/25215713/bow-tie-shape-function

0 bowtie

1                1
22              22
333            333
4444          4444
55555        55555
666666      666666
7777777    7777777
88888888  88888888
999999999999999999
999999999999999999
88888888  88888888
7777777    7777777
666666      666666
55555        55555
4444          4444
333            333
22              22
1                1

1 bowtie-quick-and-dirty.py

def bowtie(n):
    return '\n'.join(map(lambda i: (' '*2*(n-i)).join([str(i)*i]*2),
                         range(0, n+1) + list(reversed(range(n+1)))))

2 Bowtie.hs

bowtie :: Int -> [Char]
bowtie n = intercalate "\n" $ mirror2 quadrant
  where

    quadrant :: [[Char]]
    quadrant = [ (digits i) ++ (spaces $ n-i) | i <- [1..n] ]
      where
        digits i = replicate i $ intToDigit i
        spaces i = replicate i ' '

    mirror2 :: [[Char]] -> [[Char]]
    mirror2 = mirror . (map mirror)
      where mirror xs = xs ++ (reverse xs)

3 bowtie-quads.py

def bowtie(n):

    quadrant = [str(i)*i + " "*(n-i) for i in range(1, n+1)]

    def mirror2(xs):
        mirror = lambda xs: list(xs) + list(reversed(xs))
        return mirror([''.join(mirror(x)) for x in xs])

    return '\n'.join(mirror2(quadrant))