Learn clojure in Y minutes - Types

The following is from Learn clojure in Y minutes.

The three object types used in Clojure are:

1. booleans
2. strings
3. numbers

You can use the class function to inspect objects:

> (class 1)
    java.lang.Long
    
    > (class 1.)
    java.lang.Double
    
    > (class (""))
    java.lang.String
    
    > (class false)
    java.lang.Boolean
    
    > (class nil)
    nil

To create a literal list of data:

> '(+ 1 2)
    (+ 1 2)
    
    > (quote (+ (1 2)))
    (+ 1 2)

The ' character prevents the form from being evaluated.

The opposite of ' is eval:

> (eval '(+ 1 2))
    3