At first sight, in the examples: inc1(7) pure, inc2(8) impure, what's the meaning of inc2? (some kind of increment?) Then in the definion of map there is an arg

At first sight, in the examples: inc1(7) pure, inc2(8) impure, what's the meaning of inc2? (some kind of increment?) Then in the definion of map there is an argument function f, and in the definition there is a new function g that comes from nowhere, so for me at first sight the examples are not insightful.