Learning Functional Programming in Go

Function composition with linear and quadratic functions

Let's compose our f(x) = x² + 1 quadratic equation with our g(x) = x + 2 linear equation table. Here's one way we could compose our two functions: y = f(g(x)). We'd say y equals f-compose-g of x or y = f o g where o is our composition operator. The way it works is that we assign a value for x, then we plug that value into g, compute g(x), and then plug the result into f.

We input 1 to g and to express that as g(1). We input g(1) to f to get f(g(1)).

Let's make it work by replacing g(1) with the value that maps from 1 to g(1), which is 3:

Replacing g(1) with 3, we get the following: ...