---
title: Work with functions
description: A function type is a set of parameters that perform an operation. Learn how to work with functions in flux.
url: https://docs.influxdata.com/flux/v0/data-types/composite/function/
estimated_tokens: 339
product: Flux
version: v0
publisher: InfluxData
canonical: https://docs.influxdata.com/flux/v0/data-types/composite/function/
date: '2023-11-06T17:08:22-07:00'
lastmod: '2023-11-06T17:08:22-07:00'
---

A **function** type is a set of parameters that perform an operation.

* [Function syntax](#function-syntax)
* [Define functions](#define-functions)

## Function syntax

A Flux **function** literal contains the following:

* Zero or more parameters enclosed in parentheses (`()`)
  * Parameters are comma separated
  * Parameters must be named (no positional params)
  * Optionally assign a default value for each parameter with the `=`[assignment operator](/flux/v0/spec/operators/#assignment-operators).
    Parameters without a default value require user input and are considered **required parameters**.

* `=>` [arrow operator](/flux/v0/spec/operators/#function-operators) to pass parameters into the function body.
* Function body to define function operations and return a response.

##### Example functions

```
// Function that returns the value 1
() => 1

// Function that returns the sum of a and b
(a, b) => a + b

// Function with default values
(x=1, y=1) => x * y

// Function with a block body
(a, b, c) => {
    d = a + b
    return d / c
}
```

## Define functions

*For information about defining custom functions, see [Define custom functions](/flux/v0/define-functions/).*

#### Related

* [Define custom functions](/flux/v0/define-functions/)

[composite types](/flux/v0/tags/composite-types/)[data types](/flux/v0/tags/data-types/)