O'Reilly logo

Learning Elixir by Kenny Ballou

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

When patterns aren't enough for matching

So far, we have seen pattern matching very basically in our functions and assignment (reading binding) expressions. However, there's more that can be done when doing pattern matches, particularly when defining functions. When a simple type decomposition pattern isn't enough, we can use guards to add an extra layer to our matches.

Guards are simply boolean expressions we can add to our function definitions to make the pattern matches that we define more strict or specific.

Here are some basic examples:

iex(1)> defmodule MyMath do
...(1)> def sqrt(x) when x >= 0, do: #implement sqrt
...(1)> end

However, we are only allowed a limited set of expressions. The following is a pretty exhaustive list of the available ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required