Today I Learned

A Hashrocket project

Ruby 2.6 introduces endless ranges `(1..)`

This syntax is basically a substitute for either (1..Float::INFINITY) or [1, 2, 3][1..-1].

One of the best use cases I’ve seen is from this April 2018 post:

case 2022
when(2030..)
  :mysterious_future
when(2020..)
  :twenties
when(2010..)
  :nowish
else
  :ancient_past
end
#=> :twenties

This reads a lot cleaner than it would with 2010...Float::INFINITY.

Another cool use is a short with_index using zip.

[1, 2, 3].zip(1..) { |a, index| puts "#{a}, #{index}"}
# 1 1
# 2 2
# 3 3

And additionally, you get a bit of safety that you didn’t get with (1..Float::INFINITY):

(1..Float::INFINITY).to_a
# endless loop
(1..).to_a
# RangeError (cannot convert endless range to an array)

Which is a much better outcome for your program!

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