The basic data types are available in Emacs Lisp. Numbers can be represented by integers or floats. Integers can have their sign representation before the digit (+1, -2). Floating point numbers can be represented using a decimal point (3.1415) or with an exponent (314.15e-2). A character (S) is represented by its integer code (83), while a string is a list of characters enclosed within double quotes (“A string’’).
A symbol is an object with a name. A keyword symbol is one that starts with a colon (:). A vector is an array and can contain different types ([1 “two’’ :three]). The Boolean values for true and false are ‘t’ and ‘nil’ respectively. A cons cell is an object with two slots. The first slot is called the CAR (Contents of the Address part of the Register number) and the second slot is called the CDR (Contents of the Decrement part of the Register number). A list is a series of linked cons cells. For example, in the list ‘(A B)’, the CAR is A and the CDR is B.