Kotlin Programming: The Big Nerd Ranch Guide, 2nd Edition

Defining a Function That Accepts a Function

You have already seen a few ways that lambdas can customize the work of standard library functions. The count function, for example, can take in a lambda to influence what it counts. You can also pass lambdas into functions that you write yourself.

A function parameter can accept arguments of any type, including arguments that are functions. A function-type parameter is defined like a parameter of any other type: You list it in the parentheses after the function name and include the type. To see how this works, you will add a new argument to narrate that will override the narrator’s current mood to allow for one-off formatting.

Add a parameter called modifier to the narrate function in ...