Distributed Life

List

List is the the most important data type in Erlang, as in every (?) functional programming language. We have seen and used lists in almost every previous post. In this post, I will briefly present the “theory” of lists and then present the Erlang’s lists module and its most important functions.

Definition

A list can be recursively defined as the construct that

• either is the empty list (denoted as [] in Erlang),
• or is a cosntruct that its first element is a term (called head) and what remains if the head is removed is a list (called tail)

In Erlang a list of N elements has the [Element1, Element2, ..., ElementN] format (N is called the length of the list). So, [] is the empty list, [1], [{a}] are 1-element lists, [1, 2], [a, {b, c}] are 2-elements lists, etc. As we will see in a while, the format [Element1, Element2, ..., ElementN] is a shorthand for the [Element1 | [Element2 | ... | [ElementN | []] ... ] representation.
Read the rest of this entry »