Arity Of a Function

Hey, Devs!

Do you know what an arity of a function is?

In math, the arity of a function represents the number of arguments of a function.

On programming is not different, an arity is also the representation of the number of its positional params.

When we have a function:

• With No arguments, we say it has the arity 0 and can be called a Nullary function.

• With only 1 argument, we say it has the arity 1 and can be called a Unary Function.

• With 2 arguments, we say it has the arity 2 and can be called a Binary function.

• With 3 arguments, we say it has the arity 3 and can be called a Ternary function.

• With more than 3 arguments, now we can be called according to the quantity of the arguments post-fixed with ary.
  Eg.: 4-ary, 5-ary, 6-ary.

Let's code with Elixir...

defmodule Example do
  def say(), do: "Hey I am here!"
  def say(name), do: "Hey #{name}, I am here!"
  def say(first_name, last_name), do: "Hey #{first_name} #{last_name}, I am here!"
end

The arity can be represented like that: function/number of arity

Eg.: When we executed the function Example.say/0

Example.say()
--> "Hey I am here!"
# Arity: say/0
# -------------------

Eg.: When we executed the function Example.say/1

Example.say("Diego")
--> "Hey Diego, I am here!"
# Arity: say/1
# -------------------

Eg.: When we executed the function Example.say/2

Example.say("Diego", "Novais")
--> "Hey Diego Novais, I am here!"
# Arity: say/2

I hope that makes sense to you! And see you in the next content.

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