Atoms

An atom is a constant whose value is its own name. Some other languages call these symbols.

Atoms can be created using a preceding colon, like :apple or :orange.

Atoms with the same name are equal:

:apple == :apple

Atoms with different names are not equal:

:apple == :orange

true, false and nil are also atoms - Elixir allows to skip the colon for them:

# 💡 Try using `is_boolean` to check if atom `:false` is a boolean.
is_atom(true)

true and :true are the same:

true == :true

Other commonly used atoms are :ok and :error. They usually denote a success or a failure of some operation. For example, IO.puts/1 always returns :ok:

IO.puts("foo")