Programming Language Paradigms

Programming Language Paradigms

• A programming language paradigm is the approach a language takes to solve problems.

What is Paradigm?

• A paradigm is a style or method of thinking to solve a problem.

What is Programming Language Paradigm?

• A programming language paradigm is how a computer language addresses problem-solving.

Types of Programming Language Paradigms

• Imperative and declarative programming are the two main paradigms.
• Imperative paradigms include procedural, object-oriented, and parallel processing.
• Declarative paradigms include logic, functional, and database.

Why So Many Paradigms?

• Using different paradigms aids in the facilitation of different styles of approach to meet the requirements of various problems.
• Some problems need mathematical models and clear flow, others just need a straightforward solution.

Which to Learn First?

• It is important to learn the paradigm of a subject before diving into the language itself.
• This enables coding that aligns with the compiler's assumed control flow, leading to optimized coding.

Imperative Paradigm

• Focuses on the "how" of solving a task through a step-by-step process.
• Programming involves instructing the computer in a specific manner to achieve a task.

Declarative Programming Paradigm

• Focuses on "what" the desired result is, rather than detailing the steps.

• Code focuses on building the logic of the software without detailing flow.

• HTML, XML, CSS, SQL, Prolog, Haskell, F#, and Lisp are languages that fall under the declarative paradigm.

• Programs often compile to efficient binary executables.

• Statements are grouped into sections using blocks for simplicity.

• C, C++, C#, and Java are imperative languages.

Procedural Programming Paradigm

• Writing instructions step-by-step to get the final result.

• A process that directly instructs a device to execute logical steps to finish a task.

• Approached in a linear, top-down manner.

• Data and procedures are treated as separate entities.

• Programs are divided into procedures/routines/functions which each contain a series of steps.

• Languages derived in third-generations.

• Contrasted with event-driven programming.

• Procedures are called/executed only in response to events.

• Events are unpredictable.

• Procedures to handle unpredictable events cannot be executed linearly.

Key Features of Procedural Programming

• Utilizes predefined functions, local and global variables, modularity, and parameter passing.

Procedural Programming Languages

• Common Business Oriented Language (COBOL)
• Formula Translation (FORTRAN)
• Algorithmic Language (ALGOL)
• Programming Language One (PL/I)
• Beginners All-purpose Symbolic Instruction Code (BASIC)
• C

Parallel Computing

• Computation where calculations or processes are executed simultaneously.
• Problem-solving using multiple processing elements at the same time.
• Problems are broken down into instructions solved concurrently by multiple resources.
• An example of parallel computing can be illustrated by a scenario where two cashiers give movie tickets to people waiting in two queues at the same time.

Why Parallel Computing?

• It is useful for real-world, dynamic simulations.
• Offers time and money savings by providing concurrency.
• Effectively manages complex, large datasets.
• Ensures effective utilization of resources and hardware.
• It is impractical to implement real-time systems using serial computing.

Limitations of Parallel Computing

• Communication and synchronization between multiple sub-tasks is difficult.
• Algorithms need proper managing that can be handled in a parallel mechanism.
• Algorithms/programs must have low coupling and high cohesion, which is difficult to achieve.
• Requires skilled and expert programmers.

Applications of Parallel Computing

• Used in databases, data mining, real-time simulations, science, engineering, advanced graphics, augmented reality, and virtual reality.

Object-Oriented Programming

• Based on objects containing data and methods.
• Aims to incorporate advantages of modularity and reusability.
• Object-instances of classes interact with each other.
• Examples of languages: C++, Java, Python, Ruby.

Important Features of Object-Oriented Programming

• Bottom-up approach in program design.
• Programs are organized around objects grouped into classes.
• Centers on data with methods for object operations.
• Enables interaction between objects through functions.
• Provides design reusability through new classes that add to existing classes

Basic Concepts of Object-Oriented Programming

• Includes classes, objects, attributes, methods, inheritance, abstraction, encapsulation, information hiding, and polymorphism.

Class

• An abstract data type and a blueprint describing the nature of something.
• A data structure may contain different fields.
• An object defined to contain procedures that act on it.
• Attributes / fields are like data.
• Operations / methods are like functions.

Object

• An individual instance of a class created at runtime.
• The state of an object consists of values assigned to its attributes.
• Behaviour is defined in the class.
• Initialized by implicitly calling its constructor.
• A member function is one of the methods an object has.

Attributes

• Data members or member variables that are encapsulated within a class or object.
• Variables are initialized using a constructor.
• Represent the state of an object

Inheritance

• Compartmentalizes code, making it reusable.
• Based on collections of attributes and behaviors from previously defined classes.
• Subclasses inherit attributes and behaviors from superclasses.
• This relationship creates a hierarchy.
• A single class can inherit from 2 classes that have members bearing the same names but different meanings.

Abstraction

• Simplifying complex reality by modeling classes appropriately to the problem.
• Object-oriented programming provides abstraction through composition and inheritance.
• A Class Car, can be viewed as a composition of engine, gearbox, and steering.
• When driving, there is no need to know how different components work internally.

Encapsulation and Information Hiding

• Bundling of data members and member functions.
• Choosing whether to expose or hide members of a class.
• Achieved by specifying which classes may use the members.
• Prevents unauthorized objects from changing the state of an object.

Polymorphism

• "Poly" means many and "morph" means forms.
• The ability of a message to be displayed in more than one form.
• For example, a man as a Father, husband, and employee
• The same person possesses different behaviors in different situations.
• One interface, multiple implementations.

Types of Declarative Paradigm

• Divided into Logic, Functional and Database paradigms

Logic Paradigm

• Program statements express facts and rules within a formal logic system.
• Divided into definitions, facts, and a declaration of aims as a request
• Deducible answers to a query are returned, built entirely from relations.

Advantages of Logical Programming

• The programming steps are minimal since the system solves the problem.
• Demonstrating the rationality of a given program is easy.

Languages using Logic Paradigm

• Datalog
• ASP
• Prolog

Functional Paradigm

• The key principle is the execution of a series of mathematical functions.
• Functions can be replaced with their values without changing the program's meaning.
• Math operations are based on inputs, avoiding temporary variables to store results between inputs.

Advantage of Funtional Paradigm

• The code is more readable and easily understandable.
• Testing and debugging is easier.
• Useful for pure function concurrency.
• Values are stored only when needed.
• Provides a protected environment with no side effects.

Disadvantage of Functional Paradigm

• Recursion can decrease performance.
• Functional programming can be less efficient than other styles.
• Requires large amounts of time and memory.
• Purely functional languages are not widely used in commercial software development.

Programming Language using Functional Paradigm

• Haskell
• JavaScript
• Scala
• Lisp
• ML
• Clojure
• Common Lisp

Database/Data Driven Programming Approach

• Database programming methodology based on data and its movement.
• Program statements are defined by data.
• Database programs are the heart of information systems, offering creation, entry, update, query, and reporting functions.

Database or Datadriven Programming Language

• AWK
• Oz
• Perl
• sed
• Lua
• Clojure

Advantages of Database Paradigm

• Requires awareness of the abstract data type.
• Functions and interfaces can be used on all objects with the same data field.
• Data of objects/entities can be grouped without consequences.

Disadvantage of Database Paradigm

• Dealing with abstract data types may lead to poor object-oriented programming.
• Modifying object structures can break functions.

Minor Paradigms

• Aspect-oriented programming
• Event-driven programming

Aspect Oriented Programming

• AOP is complementary to OOP.
• AOP modularizes code into processes, while OOP modularizes into objects.
• Provides separation of concern in code.
• Facilitates cross-cutting concerns.
• Adds behavior to code without modifying the code.

Need for AOP

• Provides cross-cutting concerns and creates cleaner, reusable code.
• The common purposes of usage can include security, transactions, and logging.
• Increases code understanding and is applied using an aspect weaver.

Basic Terminologies of AOP

• Aspects are parts of the application that cross-cut core concerns of objects.

• Join points are behaviors like exception handling or method execution of objects.

• Advice is an action taken by an aspect at a join point, either before or after its execution.

• Pointcuts determine the join points where advice should be applied.

• AOP enhances OOP.

• AOP and OOP can be utilized at the same time.

• Programs where the flow of execution is determined by events.

• Designed to detect and handle them via Event Handling Procedures

• Extension of interrupt-driven programming found in DOS, Embedded Systems

• The majority of object-oriented and visual languages support event-driven programming, such as Visual Basic, Visual C++, and Java.

• VB is specifically designed for event-driven approach and provides IDE.

• VB provides much of the code for detecting events automatically that the programmer designs interface design and other event handling code

Background of Event Driven Programming

• Before its evolution, procedural programs determined flow.

• Modern event-driven programs have no discernible control flow.

• Event loops wait for events and invoke appropriate routines.

• Code for the event loop provided by event-development environment.

• Change from procedural to event-driven is accelerated by the introduction of Graphical User Interface (GUI).

• It emerged during the introduction of Object Oriented Programming in the late 1970s.

• Software at the time had user interfaces and a set of event handling procedures to deal with queries and updates.

Working of Event Driven Programming

• Scheduler determines the event type and calls the appropriate handler.

• Centralized element of event applications.

• Event handlers deal with specific occurrences using blocks of procedural code.

• Causes a visual response and a state change of the system, that encompasses both data used and the user interface.

• Leads to the invocation of a second event handler.

• Event handlers can also discard series of events.

Event Queue

• Series of events cannot be processed at the same time.
• Events are handled by an Event Queue
• Priority scheme enables fast tracking by the scheduler.
• Queue length and processing time depend on processor speed, RAM, and simultaneously running applications.

Imperative vs Declarative Paradigm

Imperative Paradigm

• Focuses on "how" to do something, detailing exactly how to achieve the result.
• Provides more flexibility but sometimes involves complexity.

Var numbers=[1,2,3];
Var doubledNumbers= [];
for(var i=0;i<numbers.length;++i){
    doubledNumbers.push(numbers[i]*2);
}
console.log(doubledNumbers)

- -----&gt {2,4,6}

• It is a strategy involved to use a condition for initialization to create a new array.

Declarative Paradigm

• Expresses the logic of a computation without describing its control flow.
• Provides simplicity and hides complexity.

Var Numbers=[1,2,3];
Var doubleNumbers= numbers.map (function(number)){
    return number *2;

console.log(doubledNumbers)--------&gt {2,4,6}

• Map functions iterate over an array and push items into a new array before returning the computed array.
• Increases the readability and compactness of the program.