From: nobu@...
Date: 2018-08-25T03:23:19+00:00
Subject: [ruby-core:88641] [Ruby trunk Feature#15024] Support block in	Array#join

Issue #15024 has been updated by nobu (Nobuyoshi Nakada).


`Array#join` concatenates array elements recursively.
What do you expect as the index between different level elements?

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Feature #15024: Support block in Array#join
https://bugs.ruby-lang.org/issues/15024#change-73699

* Author: graywolf (Gray Wolf)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
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I think it could be handy to have block support in Array#join.

For example

```ruby
> puts %w{a b c d}.join { |_, _, i| i % 2 == 1 ? "\n" : ', ' }
a, b
c, d
```

not sure what arguments exactly the block should take, atm I'm thinking
of

```ruby
> %w{a b c d}.join { |before, after, i| puts "#{before}:#{after}:#{i}" }
a:b:0
b:c:1
c:d:2
```

Would appreciate some feedback before I try putting together patch for this.




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