> For the complete documentation index, see [llms.txt](https://liavt.gitbook.io/styleguide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://liavt.gitbook.io/styleguide/style/lambdas.md).

# Lambdas

Use lambda expressions and interfaces to increase modularity in your code.

{% tabs %}
{% tab title="C++" %}
Avoid catching all by value `[=]` or by reference `[&]` when declaring a lambda function. Try to list out every variable your lambda will need, and prefer to pass by reference as opposed to by value.

When using a function pointer, always put the `&` (dereference operator) to avoid any confusion.

BAD:

```
foo(frc5431::myLambda);
```

GOOD:

```
foo(&frc5431::myLambda);
```

{% endtab %}

{% tab title="Java" %}
When defining a functional interface, use the `@FunctionalInterface` annotation:

```
@FunctionalInterface
public interface Footerface {
  public void doFoo();
}
```

{% endtab %}
{% endtabs %}