Higher-order functions (passing a function as an argument)

This lesson covers passing a function as an argument in Julia, with the aim of treating the work itself as a component.

Being able to pass one function into another is what makes it a higher-order function. Picture specifying only how the work should be done and leaving the doing to someone else. Passing a keyword argument to sort() works on much the same idea.

The sample code sorts into descending order by passing the criterion as a keyword argument, as in sort(nums, rev=true). The map you met earlier is in fact another higher-order function.

A common early stumble is the difference between positional and keyword arguments. A keyword argument passed by name, such as rev=true, is handled differently from an ordinary positional one.

In professional work, it extends to designs where the logic is swapped out depending on the situation — an important part of what makes Julia's data handling work.