Programmer Passport: Elixir

Advanced Pattern Matching and Constructors

Most pattern matching uses simple deconstruction, but not all. Sometimes, Elixir code needs to make allowances for special cases. One special case is comparing elements within a function head. Let’s take a few examples.

Comparison Across Tuples

Let’s look at some special cases of pattern matching. The first is representing exact matches of primitive data within a data structure like a tuple. When you use primitive data in a function head, Elixir will try to match it exactly. An Elixir function to check and see if a point is the origin would look like this:

def origin?({0,0}), do: true
def origin?(_point), do: false

The function has two heads. The first matches the exact {0, 0} tuple, returning ...