opentofu/website/docs/language/functions/concat.html.md

---
layout: "language"
page_title: "concat - Functions - Configuration Language"
sidebar_current: "docs-funcs-collection-concat"
description: |-
  The concat function combines two or more lists into a single list.
---

# `concat` Function

`concat` takes two or more lists and combines them into a single list.

## Examples

```
> concat(["a", ""], ["b", "c"])
[
  "a",
  "",
  "b",
  "c",
]
```
lang/funcs: add acc tests for functions (#21112) * lang/funcs: testing of functions through the lang package API The function-specific unit tests do not cover the HCL conversion that happens when the functions are called in a terraform configuration. For e.g., HCL converts sets to lists before passing it to the function. This means that we could not test passing a set in the function _unit_ tests. This adds a higher-level acceptance test, plus a check that every (pure) function has a test. * website/docs: update function documentation 2019-04-29 12:11:28 -05:00			`---`
website: Adopt a ton of pages into the "language" layout As of this commit, that layout doesn't exist yet, but I'm isolating the one-line changes to their own commit to try and keep your eyes from glazing over. 2020-08-14 20:51:06 -05:00			`layout: "language"`
lang/funcs: add acc tests for functions (#21112) * lang/funcs: testing of functions through the lang package API The function-specific unit tests do not cover the HCL conversion that happens when the functions are called in a terraform configuration. For e.g., HCL converts sets to lists before passing it to the function. This means that we could not test passing a set in the function _unit_ tests. This adds a higher-level acceptance test, plus a check that every (pure) function has a test. * website/docs: update function documentation 2019-04-29 12:11:28 -05:00			`page_title: "concat - Functions - Configuration Language"`
			`sidebar_current: "docs-funcs-collection-concat"`
			`description: \|-`
			`The concat function combines two or more lists into a single list.`
			`---`

			# `concat` Function

			`concat` takes two or more lists and combines them into a single list.

			`## Examples`

			```
			`> concat(["a", ""], ["b", "c"])`
			`[`
			`"a",`
			`"",`
			`"b",`
			`"c",`
			`]`
			```