v.map(&:to_s)

rubyonrails-talk
1

How &: works? if it is a method, and where is it defined? It is rails addition to ruby obviously.

2

Eric Archangel wrote:

How &: works? if it is a method, and where is it defined? It is rails addition to ruby obviously.

http://caboo.se/doc/classes/Symbol.html#M003931

Symbol#to_proc

This is tricky thing to document. It exploits a ruby syntax quirk where prepending a & to a method argument calls "to_proc" on that object in an attempt to make it eligible to be a block.

  v.map(&:to_s)

Is the same as:

  v.map { |i| i.to_s }