Functional Vs. Imperative Programming

            Imperative programming is 3^rd generation of programming language where the programmers are concerned with what is required as well as how it will achieved whereas in Functional programming language programmers are concerned with only what is required, not with how to achieve it.

Imperative programming treats both functions and data independently whereas for Functional programming data and functions are one and a same thing. Functional programming does not support side effects as there is no mutable data in functional programming as there is no variable assignment that is why functional programs are also known as stateless programs.

Functional programming supports Lazy Evaluation sometimes referred to as “Call by Need” where first the function is evaluated then the arguments whereas Imperative supports Eager evaluation i.e. evaluate the argument first then the function.

Functional programming has various features that are foreigners to Imperative such as currying, partial execution of function, side effects, pure functions, referential transparency etc.

The concept of looping is not present in Functional programming instead it uses Recursion as a substitute to looping constructs.

Functional programming also supports automatic memory management and garbage collection however some of the imperative programming language do supports but not all.

Functional programs are often shorter and easier to understand than their imperative counterparts. Since various studies have shown that the average programmer's productivity in terms of lines of code is more or less the same for any programming language, this translates also to higher productivity.