Hands-On Design Patterns and Best Practices with Julia

Understanding first-class functions

Functions are said to be first-class when they can be assigned to variables or struct fields, passed into functions, returned from a function, and so on. They are treated as first-class citizens just like regular data types. We will now take a look at how functions can be passed around like regular data values.

Let's design a new function that can propel a spaceship to leap in a random direction for a random distance. You may recall from the beginning of this chapter that we have already defined four move functions—move_up!, move_down!, move_left!, and move_right!. Here's our strategy:

1. Create a random_move function that returns one of the possible move functions. This provides the basis for choosing a ...