introduction.md

Atoms

Elixir's atom type represents a fixed constant. An atom's value is simply its own name. This gives us a type-safe way to interact with data. Atoms can be defined as follows:

# All atoms are preceded with a ':' then follow with alphanumeric snake-cased characters
variable = :an_atom

Atoms are internally represented by an integer in a lookup table, which are set automatically. It is not possible to change this internal value.

Cond

Often, we want to write code that can branch based on a condition. While there are many ways to do this in Elixir, one of the simplest ways is using a cond/1 function as a control flow structure.

At its simplest, a cond structure follows the first path that evaluates to true with one or more branches:

cond do
  sometimes -> :this_might_be_the_way
  true -> :this_is_the_default_way
end

If no path evaluates to true, an error is raised by the runtime.