The Well-Grounded Rubyist, Second Edition

8.2. Symbols and their uses

Symbols are instances of the built-in Ruby class Symbol. They have a literal constructor: the leading colon. You can always recognize a symbol literal (and distinguish it from a string, a variable name, a method name, or anything else) by this token:

:a
:book
:"Here's how to make a symbol with spaces in it."

You can also create a symbol programmatically by calling the to_sym method (also known by the synonym intern) on a string, as you saw in the last section:

>> "a".to_sym
=> :a
>> "Converting string to symbol with intern....".intern
=> :"Converting string to symbol with intern...."

Note the telltale leading colons on the evaluation results returned by irb.

You can easily convert a symbol to a string:

>> :a.to_s => ...