| --- |
| page_title: lookup - Functions - Configuration Language |
| description: The lookup function retrieves an element value from a map given its key. |
| --- |
| |
| # `lookup` Function |
| |
| `lookup` retrieves the value of a single element from a map, given its key. |
| If the given key does not exist, the given default value is returned instead. |
| |
| ``` |
| lookup(map, key, default) |
| ``` |
| |
| -> For historical reasons, the `default` parameter is actually optional. However, |
| omitting `default` is deprecated since v0.7 because that would then be |
| equivalent to the native index syntax, `map[key]`. |
| |
| ## Examples |
| |
| ``` |
| > lookup({a="ay", b="bee"}, "a", "what?") |
| ay |
| > lookup({a="ay", b="bee"}, "c", "what?") |
| what? |
| ``` |
| |
| ## Related Functions |
| |
| * [`element`](/language/functions/element) retrieves a value from a _list_ given its _index_. |
