“The most popular functional programming language in the world is Excel ,” he says. A simple Excel worksheet might have a column with a bunch of values in it, such as A1 X 2. “That’s a pure function on A1, and A1 doesn’t change, so you’re computing values from that existing data.”

“The most popular functional programming language in the world is Excel ,” he says. A simple Excel worksheet might have a column with a bunch of values in it, such as A1 X 2. “That’s a pure function on A1, and A1 doesn’t change, so you’re computing values from that existing data.”