> For the complete documentation index, see [llms.txt](https://trizen.gitbook.io/sidef-lang/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://trizen.gitbook.io/sidef-lang/programming_tasks/h/higher-order_functions.md).

# Higher-order functions

```ruby
func first(f) {
  return f()
}
 
func second {
  return "second"
}
 
say first(second)               # => "second"
say first(func { "third" })     # => "third"
```