Tutorial by Examples

Some languages include a list data structure. Common Lisp, and other languages in the Lisp family, make extensive use of lists (and the name Lisp is based on the idea of a LISt Processor). However, Common Lisp doesn't actually include a primitive list datatype. Instead, lists exist by convention....

A cons cell, also known as a dotted pair (because of its printed representation), is simply a pair of two objects. A cons cell is created by the function cons, and elements in the pair are extracted using the functions car and cdr. (cons "a" 4) For instance, this returns a pair whose ...

To better understand the semantics of conses and lists, a graphical representation of this kind of structures is often used. A cons cell is usually represented with two boxes in contact, that contain either two arrows that point to the car and cdr values, or directly the values. For instance, the re...