For a given integer return a result of dividing 8 by that number with handling 0.

eight_divide_by.rb

Contract Num, Func[Num => Any], Proc => Any
def eight_divide_by(number, success_action, failure_action)
  case number
    # ...
    when 4 then success_action[2]
    when 2 then success_action[4]
    when 1 then success_action[8]
    when 0 then failure_action.call
  end
end

success_action = lambda { |value| "Got #{value}" }
failure_action = lambda { "You probably wanted to divide by 0, didn't you?" }

eight_divide_by(1, success_action, failure_action) # => Got 8
eight_divide_by(0, success_action, failure_action) # => You probably wanted to divide by 0, didn't you?