Booleans

Elixir supports true and false as booleans:

iex> true
true
iex> true == false
false

Elixir provides a bunch of predicate functions to check for a value type. For example, the is_boolean/1 function can be used to check if a value is a boolean or not:

Note: Functions in Elixir are identified by name and by number of arguments (i.e. arity). Therefore, is_boolean/1 identifies a function named is_boolean that takes 1 argument. is_boolean/2 identifies a different (nonexistent) function with the same name but different arity.

iex> is_boolean(true)
true
iex> is_boolean(1)
false

You can also use is_integer/1, is_float/1 or is_number/1 to check, respectively, if an argument is an integer, a float or either.

Note: At any moment you can type h in the shell to print information on how to use the shell. The h helper can also be used to access documentation for any function. For example, typing h is_integer/1 is going to print the documentation for the is_integer/1 function. It also works with operators and other constructs (try h ==/2).