From: "boris_stitnicky (Boris Stitnicky)" <boris@...>
Date: 2012-11-18T11:01:08+09:00
Subject: [ruby-core:49502] [ruby-trunk - Feature #5478] import Set into core, add syntax


Issue #5478 has been updated by boris_stitnicky (Boris Stitnicky).


I am for having Set in the core, with Set[ a, b, c ] and Set.new as basic constructors. I am against mingling it with existing collection classes. I think that the most frequent usec for Set would be order-independent comparison (instad of eg. "array1.sort == array2.sort"). I find { a, b, c } syntax tempting, otherwise I agree on this issue with headius (response #6).
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Feature #5478: import Set into core, add syntax
https://bugs.ruby-lang.org/issues/5478#change-33034

Author: rkh (Konstantin Haase)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: Next Major


=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



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