Declarative vs Imperative Programming
Using multiple approaches to develop a program often ends up building programming paradigms. By paradigm, we mean the classification of programming languages based on their style and format. Simply it can mean syntax, code structure, and grammar. Some languages have a single paradigm while others might have multiple paradigms. Identifying the list of rules to define the paradigm is tough.
A developer has to decide the type of programming language before writing his/her first line of code. Developers are spoilt for choices as there are several languages available to choose. But we can classify all of them into two buckets - declarative and imperative programming.
Do you know as a programmer you would have used both types of paradigms without even being familiar with these terms. Remember this - if we use both imperative and declarative syntax, then the programming language you are using is most probably a multi-paradigm language. However, one must know the differences between declarative and imperative programming to identify the differences between functional, procedural, and OOP styles.
Table of Contents
- What is declarative programming?
- What are the advantages of declarative programming?
- What are the disadvantages of declarative programming?
- What is imperative programming?
- What are the advantages of imperative programming?
- What are the disadvantages of imperative programming?
- Differences between declarative and imperative programming
- Final thoughts
What is declarative programming?
We can call a programming paradigm declarative programming if it can express computation logic without describing the control flow. Languages that fall under the declarative paradigm are functional, logical, and domain-specific languages. The main focus of the declarative code is to build the software logic without its flow description. Several programming languages use this paradigm to eliminate the side effects of programming. It focuses on describing the accomplishment of the program in the problem domain rather than describing the approach.Some well-known examples of Declarative programming are XML, HTML, SQL, CSS, Prolog, Lisp, and XQuery.
For example, suppose we have a button and we want to change the color of it. Here is a program to do this in React.
What are the advantages of declarative programming?
Improved Code Quality
The structure of Declarative Programming is precise & short. The declarative paradigm of coding can also massively reduce code complexity. Hence, the quality of the code is better & efficient.
The declarative paradigm gives programmers the flexibility to implement unknown methods during the programming time.
We can easily optimize the code using declarative programming as an algorithm that controls the implementation.
Programmers can independently maintain their codes without developing an application.
Using the declarative paradigm, programmers can get the opportunity to construct code that they can use for different purposes in the future.
What are the disadvantages of declarative programming?
Difficult to understand
Sometimes, declarative programming becomes very difficult to understand for beginners.
Unknown theoretical model
Generally, declarative paradigm depends on abstract theoretical models for programmers.
It is tough to personalize codes as per requirement in declarative programming as it depends on the implementation of an algorithm. Declarative programming has a complex syntax. Thus, it is considerably hard to modify the programs.
Declarative programming tools are more complex to operate. Sometimes a simple problem has to be solved using a feature that doesn’t exist in the tool.
Some declarative programs require you to be more specific to carry out complicated algorithms and functions.
What is imperative programming?
Imperative programming uses some statements which can change the state of the program. An imperative program has multiple commands for a system to execute. It always focuses on the operational procedure of a program. In this, programmers use typical code styles including mutable states and loops.
Programmers have to follow step by step instructions to write an imperative program. Here the instructions are not detailed, but someone needs to mention the steps for finishing the program.
Object-Oriented Programming(OOP), Procedural Programming, parallel processing approach falls under imperative programming. Some well-known languages that use the Imperative paradigm are C, C#, C++, Java, and PHP.
Here is the same example done using imperative programming -
What are the advantages of imperative programming?
Programmers can easily adopt the structure of imperative programming. A beginner can easily learn and read imperative programming codes.
Beginners can easily understand the step-by-step solution process and implement the conceptual solution models in their programs.
Developers can easily consider and use the features of a precise application to execute their programs.
Developers can reason a source code easily by determining what a single-core processor can do with it.
Imperative programming is being taught in schools, colleges, and workplaces by authority. Programmers and developers have a high degree of familiarity with it.
What are the disadvantages of imperative programming?
The codes which are written using the Imperative paradigm are very extensive and wide. Thus it creates confusion.
Errors in Editing
There is a risk of editing errors when codes are being modified by the programmer.
Limitations on extensions and upgrades
It is very difficult to provide upgrades and add extensions in Imperative programming. Thus it is tough to optimize the codes.
Limitation in Application Development
Imperative Programming is system-oriented programming. Thus it can block the overall application development during maintenance.
Vulnerable to Data Race
As imperative programs contain mutable variables and are always vulnerable to data races.
Differences between declarative and imperative programming
Generally Declarative languages like SQL, XQuery are widely used to manage the database. For example, Microsoft uses SQL in its SQL Servers, Open Database Connectivity, and Active X data objects. The majority of companies use SQL to manage their database effectively and efficiently. Declarative programming on the other hand is being used to design and develop web-pages by companies. Languages like CSS, HTML makes the process easier.
As imperative programs are easy to learn, it is widely used in school and colleges to teach students different aspects of programming. We can observe the implementation of the imperative paradigm in college-level coding competitions and application development. Since imperative programming is an old programming paradigm, it has been historically used to write & develop system and application software.
For example, Microsoft has used C to write Windows. In 1972, the code of Unix Os was written in C from the assembly. Oracle has also upgraded its code from assembly to C in 1983. Adobe Inc. has used C++ to develop Image Ready, Illustrator, and Premiere Pro.
There aren’t many differences between the declarative and imperative paradigms. It might not be easy in the initial days to choose the right paradigm for your programming needs. But with growing experience, you can easily choose the perfect paradigm based on the situation.