View Source Atom (Elixir v1.14.1)
Atoms are constants whose values are their own name.
They are often useful to enumerate over distinct values, such as:
iex> :apple
:apple
iex> :orange
:orange
iex> :watermelon
:watermelon
Atoms are equal if their names are equal.
iex> :apple == :apple
true
iex> :apple == :orange
false
Often they are used to express the state of an operation, by using
values such as :ok
and :error
.
The booleans true
and false
are also atoms:
iex> true == :true
true
iex> is_atom(false)
true
iex> is_boolean(:false)
true
Elixir allows you to skip the leading :
for the atoms false
, true
,
and nil
.
Atoms must be composed of Unicode characters such as letters, numbers,
underscore, and @
. If the keyword has a character that does not
belong to the category above, such as spaces, you can wrap it in
quotes:
iex> :"this is an atom with spaces"
:"this is an atom with spaces"