In the beginning of this book, we saw that an algorithm is a sequence of steps to achieve a result. This way of solving a problem by following a sequence of instructions is called imperative programming. Each statement in the program can be thought of as an imperative sentence asking the computer to do something. However, this is not the only way of looking at it. Functional programming sees an algorithm as a composition of components rather than as a sequence of steps. A problem to solve is seen as a composition of smaller-sized problems. Instead of using a loop, we combine smaller versions of the same problem. Functional programming uses recursion as a basic component. A recursion is nothing but solving the same problem for a smaller size and then composing the result with something else to get the solution for the given size of the problem. This has a far-reaching implication in how easy it is to read and understand a program. This makes it very...