Why is this string key in a hash converted to a symbol?

Question

Using Ruby 2.3:

In example 1, the string key \"a\" is automatically converted to a symbol, whereas with example 2, it stays a string.

Example 1

Answer 1

According to Ruby documentation:

Blockquote Symbol objects represent names and some strings inside the Ruby interpreter. They are generated using the :name and :"string" literals syntax, and by the various to_sym methods. [...]

This means that running:

$ ruby -e ruby -e "h = {key: \"value\"}; puts h"
$ ruby -e ruby -e "h = {:key => \"value\"}; puts h"
$ ruby -e ruby -e "h = {\"key\": \"value\"}; puts h"
$ ruby -e ruby -e "h = {:\"key\" => \"value\"}; puts h"
$ ruby -e ruby -e "h = {\"#{:key}\": \"value\"}; puts h"

Will produce the same result:

$ {:key=>"value"}