Steps to shrink .reduce code for finding an average of an array of Ints

reduceForAverageExamples.swift

var scores = [83, 85, 90, 100]
// The full syntax .reduce above does the same thing as this one-liner:

let total = scores.reduce(0, {$0 + $1})

// Swift even allows us to eliminate the closure, replacing it with an operator and automatically assuming it’ll apply the current accumulating value on the left of the operator, and the next accumulating value to the right

let anotherWayToTotal = scores.reduce(0, +)

// You can even do the entire calculation in a single line, although it starts to get more difficult to read:

let average = Double(scores.reduce(0, +)) / Double(scores.count)