Lesson 2: Constants with let - Intro to Swift

Constants with let Store a value that never changes.

1let message = "Hi there"

2print(message)

Terminal

$ swift main.swift

Hi there

Every line, explained

let message = "Hi there": let creates a constant: a named box whose value is set once and can never change. Swift people reach for let by default: if a value never needs to change, locking it down prevents accidents. Here it creates message and locks in the text "Hi there".
print(message): print(...) shows whatever is inside its round brackets in the terminal, then moves to a new line. All lowercase, both brackets needed, and no semicolon at the end; Swift doesn't use them. No quotes around message, so Swift prints what is stored in the constant, not the word message itself.