go =>
  ["1223334444",
   "Rosetta Code is the best site in the world!",
   "1234567890abcdefghijklmnopqrstuvwxyz",
   "Picat is fun"].map(entropy).println(),
  nl.

% probabilities of each element/character in L
entropy(L) = Entropy =>
  Len = L.length,
  Occ = new_map(), % # of occurrences
  foreach(E in L)
    Occ.put(E, Occ.get(E,0) + 1)
  end,
  Entropy = -sum([P2*log2(P2) : _C=P in Occ, P2 = P/Len]).