ABSTRACT
A higher-order function is a function that takes a function as an input or returns a function as output. We’ve already seen one type of higher order function: closures, functions returned by another function. The complement to a closure is a functional, a function that takes a function as an input and returns a vector as output. Here’s a simple functional: it calls the function provided as input with 1000 random uniform numbers.
randomise <- function(f) f(runif(1e3))
