gistfile1.hrl

shuffle(Cards) when is_list(Cards) -> 
  Size = length(Cards),
  lists:foldr(fun(I, Arr) -> 
    swap(Arr, I, next_int(1, I + 1))
  end, Cards, lists:seq(1, Size)).

swap(List, I, J) -> 
  Ielement = lists:nth(I, List),
  Jelement = lists:nth(J, List),
  lists:map(fun(Index) -> 
    if Index == I -> Jelement;
       Index == J -> Ielement;
       true -> lists:nth(Index, List)
    end
  end, lists:seq(1,length(List))).
  
next_int(Lo, Hi) ->
  try
    crypto:rand_uniform(Lo, Hi)
  catch error:badarg ->
    crypto:start(),
    crypto:rand_uniform(Lo, Hi)
  end.