Learning Functional Programming in Go

The directions of the arrows are significant

In the last chapter, we used the following chart to solve f(x) = x + 2:

Remember when we composed f(x) = x + 2 with g(x) = x² + 1? We solved g(f(1)) = 10:

We also proved that f(g(1)) = 4, which is obviously not 10. So, we know that function composition is not commutative. The arrows go one way only.