From: "matz (Yukihiro Matsumoto)" <matz@...>
Date: 2012-03-31T00:28:01+09:00
Subject: [ruby-core:43944] [ruby-trunk - Feature #6073] Proposal of extending syntax of for loop


Issue #6073 has been updated by matz (Yukihiro Matsumoto).


The current for statement does not do any map-like work.  Under such behavior, extending for statement might not have enough benefit worth adding complexity.  So, I have to reject this proposal for now.

Matz.l

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Feature #6073: Proposal of extending syntax of for loop
https://bugs.ruby-lang.org/issues/6073#change-25470

Author: shouichi (Shouichi KAMIYA)
Status: Assigned
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: 
Target version: 


Hi,

I propose to extend syntax of for loop which allows us to write multiple loop with guard easily.
This extension is inspired by Scala. Here is a example

for i in 1..4 when i % 2 == 0
    j in 5..8 when j % 4 == 0
  puts "#{i}, #{j}"
end

Above code is same as following code.

for i in 1..4
  if i % 2 == 0
    for j in 5..8
      if j % 4 == 0
        puts "#{i}, #{j}"
      end
    end
  end
end

I already implemented this syntax and attached a patch.
What do you think about this syntax guys?

Thank you,
Shouichi


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