This is a Haskell implementation of the same algorithm as found here http://python.nulldoc.com/draw_triangle Solely for illustrative purposes; this isn't useful for anything.

drawTriangle.hs

drawTriangle size c s =
  concat (map line [0..size-1])
  where line i = map (charAt i) [0..size*2-1] ++ "\n"
        charAt i j | size + i == j = c
                   | size - i == j = c
                   | (size - 1 == i) && (j > 0) = c
                   | otherwise = s