Haskell Version

gistfile1.hs

module Diamond where (diamond)

import Data.List

diamond :: Int -> String
diamond h = concat . intersperse "\n" $ diamondTop ++ diamondBottom
    where rows n        = map row [((n - x) `div` 2, x) | x <- [1..n], odd x]
          diamondTop    = rows h
          diamondBottom = drop 1 . reverse $ diamondTop 

times:: Int -> String -> String
times n = concat . take n . repeat 

row :: (Int, Int) -> String
row (s, n) = times s " " ++ times n "*"