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# How Do Functions Work In Elixir?

In Elixir, functions are defined using the `def` keyword followed by the function name and parameters. Functions can have multiple clauses, which allows for pattern matching based on different inputs. When calling a function, Elixir will try each clause sequentially until it finds a match.

Functions can also be defined anonymously using the `fn` keyword, which is commonly used in higher-order functions and passing functions as arguments to other functions. The `do` keyword can be used to define a multi-line anonymous function.

Elixir also supports recursion, where a function calls itself within its own definition. Recursion is commonly used in Elixir instead of traditional loop constructs like `for` or `while`.

Functions in Elixir are first-class citizens, meaning they can be passed around as arguments, assigned to variables, and returned from other functions. This makes Elixir a functional programming language, where functions play a central role in the program's logic.

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## How to compose functions in elixir?

In Elixir, functions can be composed using the `|>` operator which is known as the pipe operator. This operator allows us to pass the result of one expression as an argument to the next expression.

Here's an example to illustrate function composition in Elixir:

 ```1 2 3 4 5 6 7 8 9 ``` ```# Define two functions double = fn x -> x * 2 end square = fn x -> x * x end # Compose the functions result = 2 |> double |> square IO.puts result # Output: 16 ```

In the above example, the `double` function is applied first to the value `2` and then the `square` function is applied to the result of the `double` function. The final result is `16`.

You can compose multiple functions in this way to create complex operations. Keep in mind that the functions should be compatible in terms of their input and output types for successful function composition in Elixir.

## How to call a function in elixir?

To call a function in Elixir, you simply need to write the function name followed by parentheses ().

For example, if you have a function named `add` that takes two arguments and returns their sum, you would call it like this:

 ```1 ``` ```result = add(2, 3) ```

If the function is defined in a module, you will need to prefix the function name with the module name. For example, if the `add` function is defined in a module named `Math`, you would call it like this:

 ```1 ``` ```result = Math.add(2, 3) ```

You can also use anonymous functions in Elixir by using the `fn` keyword. For example:

 ```1 2 ``` ```add = fn a, b -> a + b end result = add.(2, 3) ```

In this case, the `add` function is an anonymous function that takes two arguments and returns their sum. The `.` after `add` is the Elixir syntax for calling an anonymous function.

## What is function arity in elixir?

In Elixir, function arity refers to the number of arguments that a function can accept. Each function in Elixir has a fixed arity, meaning that it can only accept a specific number of arguments. This is different from languages like JavaScript or Ruby, where functions can accept a variable number of arguments.

For example, a function with an arity of 2 can accept exactly 2 arguments, and if called with either too few or too many arguments, it will result in a compilation error.

It is important to be aware of the arity of functions when calling them in Elixir, as providing the wrong number of arguments can lead to unexpected results or errors.

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