Why JavaScript?

• JavaScript is the most popular language in the world.
• It is possible to do a lot of functional programming in JavaScript.
• Functional JavaScript is a growing trend but there aren't many good resources for learning it.
• JavaScript is often people's first language so it needs simple explanations more that other languages.

What's with the =>?

The examples often use ES2015 (A recent version of JavaScript) to make the examples more concise. => is a terse way to define an anonymous function.

const add1 = a => a + 1;

// is equivalent to

function add1(a) {
  return a + 1;
}