why.rb

time_range = Time.now .. Time.now
number_range = 1.0 .. 10.0

p time_range.cover? Time.now
p number_range.cover? 5.0

begin
  time_range.to_a
rescue
  puts "time_range is unenumerable"
end

begin
  number_range.to_a
rescue
  puts "number_range is unenumerable"
end

p number_range.include? 5.0

begin
  p time_range.include? Time.now
rescue
  puts "time_range can't use #include?"
end

p number_range === 5.0

begin
  p time_range === Time.now
rescue
  puts "time_range can't use case equality"
end

$ ruby why.rb
false
true
time_range is unenumerable
number_range is unenumerable
true
time_range can't use #include?
true
time_range can't use case equality