Issue #5478 has been updated by George Koehler. =begin Ruby stdlib already has Set::[], a method that creates a literal set. irb(main):001:0> require 'set' => true irb(main):002:0> Set[1, 2, 3] => #<Set: {1, 2, 3}> The proposed syntax <1, 2, 3> might be impossible to parse, because it conflicts with < and > operators. Consider this example: def c(*args); args.length; end p c <1, 2, 3> 4 Current Ruby (with no set literal syntax) parses this example like so: p(c() < 1, 2, (3 > 4)) If <1, 2, 3> became a set literal, then this example would become ambiguous. No parser would know whether this code has a set literal, or calls < and > operators. =end ---------------------------------------- Feature #5478: import Set into core, add syntax http://redmine.ruby-lang.org/issues/5478 Author: Konstantin Haase Status: Open Priority: Normal Assignee: Category: Target version: 3.0 =begin A set is a central data structure. However, a lot of Ruby developers use arrays for situations where it would be more reasonable to use a set. One reason for that is that it is way easier to use Array then Set at the moment, another one is that developers are simply not aware it exists. I propose moving Set from the stdlib to core and possibly add a syntax or a method on array for creating Set literals. First class syntax suggestions: <1, 2, 3> # might be tricky to parse #[1, 2, 3] # would collide with comments $[1, 2, 3] ${1, 2, 3} Method suggestions: ~[1, 2, 3] +[1, 2, 3] Whitespace separated String Sets could look like this: %w<foo bar blah> # creates an array at the moment #w[foo bar blah] # would collide with comments $w[foo bar blah] # would collide with sending :[] to $w $w{foo bar blah} ~%w[foo bar blah] # not really shorter than using an array with strings +%w[foo bar balh] # not really shorter than using an array with strings Maybe it's ok to not have a whitespace separated syntax, I'm just brainstorming here. The issue with the method approach is that it would create an Array to send the message to first. I favor the <1, 2, 3> syntax, possibly without the ability to create a whitespace separated version. I'd be willing to work on a patch not only for MRI but also for JRuby and Rubinius if you would consider this to be useful. Although I would need help with the parser. =end -- http://redmine.ruby-lang.org