Declarative programming is one of the very much in trend paradigms to build the structure of a program, where the logic of computation is expressed without going into the details of the control flow. It is totally the opposite of the imperative and procedural styles of programming which emphasize implementing the algorithms. Functional programming supports the declarative style of programming and simplifies writing the programs which support parallel programming.
The declarative paradigm doesn't state how to solve a problem. However, it just states what the problem is. In declarative programming, a very important thing is to set some rules to match. Depending on the rules, the program continues its execution. When the rule matches, the operation executes, which is opposite to procedural programming, where an order of execution is followed. It doesn...