From: "drbrain (Eric Hodel)" <drbrain@...7.net>
Date: 2012-12-12T01:44:17+09:00
Subject: [ruby-core:50775] [ruby-trunk - Feature #7545] Make Range act as a "lazy ordered set"


Issue #7545 has been updated by drbrain (Eric Hodel).

Target version set to Next Major

=begin
How would (({(3..1).to_a})) be implemented? The opposite uses #succ today.

Why should (({1...1})) equal (({3...3}))? I don't understand at all. This would break existing code.

In (({1...3.include?(2.5)})) is the change to Ruby syntax also part of the proposal, or a typo? (Currently NoMethodError is raised due to low precedence of (({...}). Is there something wrong with Range#cover?

What is a deglex? What is a lex?
=end

----------------------------------------
Feature #7545: Make Range act as a "lazy ordered set"
https://bugs.ruby-lang.org/issues/7545#change-34625

Author: alexeymuranov (Alexey Muranov)
Status: Open
Priority: Normal
Assignee: 
Category: core
Target version: Next Major


=begin
# Make Range act as a "lazy ordered set"

This replaces my older feature request #5534.

I propose the following new behavior of (({Range})):

  (1..3).to_a               # => [1, 2, 3]
  (3..1).to_a               # => [3, 2, 1]
  'a'..'c'.to_a             # => ['a', 'b', 'c']
  'c'..'a'.to_a             # => ['c', 'b', 'a']
  1...1 == 3...3            # => true
  1...1 == 'a'...'a'        # => true
  1...1 == Range::EMPTY_SET # => true
  1..2 == 1...3             # => false
  1...3.include?(2.5)       # => true

Also, maybe in the future the following behavior can be possible:

  r1 = Range.new('a', 'bc', :deglex)
  r1.include?('abc') # => false
  r1.to_a            # => ['a', 'b', ..., 'az', 'ba', 'bb', 'bc']
  r2 = Range.new('a', 'bc', :lex)
  r2.include?('abc') # => true
  r2.to_a            # => Error

and this:

  ((0.5)..(5.5)).to_a(Integer) # => [1, 2, 3, 4, 5]
  ((0.5)..(5.5)).each(Integer) do |i| puts i end

(i imagine this would require additions to the (({Integer})) class, so that it
know more about "real" ranges).


=end



-- 
http://bugs.ruby-lang.org/