"Ant turd tokens", or .,; are a big pain in the neck when refactoring stuff. For instance

    case Something of
       {ok, Val} ->
          do_something();
       _Error ->
          barf()
    end,

The ; and the , are easy to forget about. Indeed, the , might be changed to a . if you eliminate the next expression, and those things can be easy to miss when fiddling with code.