simulateDotBracket.hs

-- this is very simple and also ambiguous, e.g. the open structure will be constructed multiple times

s :: Integer -> [String]
s 2 = [".."]
s 1 = ["."]
s n = (map inbrackets $ s (n-2)) ++ (map adddot $ s (n-1) ) ++ (concatMap branches (splits n))
      where
         inbrackets a = "("++a++")"
         adddot a = '.':a
         branches (a,b) = [a'++b' | a' <- s a, b' <- s b ]
         splits n = [ (k, n-k) | k <- [ 3 .. n-1 ]]