プログラミングパラダイムとは正確には何ですか?

愚か者なら誰でも、コンピューターが理解できるコードを書くことができます。優れたプログラマーは、人間が理解できるコードを記述します。

―マーティン・ファウラー

プログラミングするとき、複雑さは常に敵です。多くの可動部分と相互依存するコンポーネントを含む非常に複雑なプログラムは、最初は印象的です。ただし、実際の問題を単純または洗練されたソリューションに変換するには、より深い理解が必要です。

アプリケーションを開発したり、単純な問題を解決したりするとき、「もっと時間があれば、もっと単純なプログラムを書いていただろう」とよく言います。その理由は、より複雑なプログラムを作成したためです。複雑さが少ないほど、デバッグと理解が容易になります。プログラムが複雑になるほど、作業が難しくなります。

複雑さの管理は、プログラマーの主な関心事です。では、プログラマーはどのように複雑さに対処するのでしょうか?プログラムの複雑さを軽減したり、プログラムをより管理しやすくしたりする一般的なアプローチはたくさんあります。主なアプローチの1つは、プログラミングパラダイムです。プログラミングパラダイムに飛び込みましょう!

プログラミングパラダイムの紹介

プログラミングパラダイムという用語は、プログラミングのスタイルを指します。特定の言語を指すのではなく、プログラミング方法を指します。

よく知られているプログラミング言語はたくさんありますが、それらはすべて、実装時に何らかの戦略に従う必要があります。そして、その戦略はパラダイムです。

プログラミングパラダイムの種類

命令型プログラミングパラダイム

「命令」という言葉は、「私が命令する」を意味するラテン語の「インペロ」に由来します。

それは私たちが「皇帝」を得るのと同じ言葉であり、それは非常に適切です。あなたは皇帝です。あなたはコンピュータに少しの命令を与え、それは一度に一つずつそれを行い、報告します。

パラダイムはいくつかのステートメントで構成され、それらすべての実行後、結果が保存されます。それは、コンピュータにステップバイステップで何をすべきかを伝えるための指示のリストを書くことです。

命令型プログラミングパラダイムでは、ステップの順序が重要です。これは、特定のステップが、ステップの実行時の変数の現在の値に応じて異なる結果をもたらすためです。

説明のために、命令型パラダイムアプローチの最初の10個の自然数の合計を見つけましょう。

Cの例:

#include  int main() { int sum = 0; sum += 1; sum += 2; sum += 3; sum += 4; sum += 5; sum += 6; sum += 7; sum += 8; sum += 9; sum += 10; printf("The sum is: %d\n", sum); //prints-> The sum is 55 return 0; }

上記の例では、1行ずつ何をするかをコンピューターに指示しています。最後に、値を保存して印刷します。

1.1手続き型プログラミングパラダイム

手続き型プログラミング(これも必須です)を使用すると、これらの命令を手続きに分割できます

注:プロシージャは機能ではありません。それらの違いは、関数は値を返し、プロシージャは返さないことです。より具体的には、関数は最小限の副作用を持つように設計されており、同じ入力が与えられたときに常に同じ出力を生成します。一方、プロシージャには戻り値はありません。それらの主な目的は、特定のタスクを実行し、望ましい副作用を引き起こすことです。

手順の良い例は、よく知られているforループです。forループの主な目的は副作用を引き起こすことであり、値を返しません。

説明のために、手続き型パラダイムアプローチの最初の10個の自然数の合計を見つけましょう。

Cの例:

#include  int main() { int sum = 0; int i =0; for(i=1;i The sum is 55 return 0; }

上記の例では、単純なforループを使用して、最初の10個の自然数の合計を見つけました。

手続き型プログラミングパラダイムをサポートする言語は次のとおりです。

  • C
  • C ++
  • Java
  • ColdFusion
  • パスカル

多くの場合、手続き型プログラミングは次の場合に最適です。

  • 操作間の依存関係を含む複雑な操作があり、さまざまなアプリケーションの状態(「SQLの読み込み」、「SQLの読み込み」、「ネットワークオンライン」、「オーディオハードウェアなし」など)を明確に表示する必要がある場合。これは通常、アプリケーションの起動とシャットダウンに適しています(Holligan、2016年)。
  • プログラムは非常にユニークで、いくつかの要素が共有されました(Holligan、2016年)。
  • プログラムは静的であり、時間の経過とともに大きく変化することは期待されていません(Holligan、2016年)。
  • 今後、プロジェクトに追加される機能はないか、ごくわずかであると予想されます(Holligan、2016年)。

手続き型プログラミングのパラダイムを学ぶことを検討する必要があるのはなぜですか?

  • 簡単です。
  • プログラムフローを追跡するためのより簡単な方法。
  • 強力にモジュール化または構造化する機能があります。
  • 必要なメモリが少なくて済みます:効率的で効果的です。

1.2オブジェクト指向プログラミングパラダイム

OOPは、コードのモジュール性や、コードの観点から実際のビジネス上の問題を直接関連付けることができるなどの独自の利点があるため、最も人気のあるプログラミングパラダイムです。

オブジェクト指向プログラミングは、スパゲッティコードを書くための持続可能な方法を提供します。プログラムを一連のパッチとして追加できます。

―ポール・グレアム

オブジェクト指向プログラミングの主な特徴には、クラス、抽象化、カプセル化、継承、およびポリモーフィズムが含まれます。

クラスは、オブジェクトが作成され、そこからテンプレートまたは設計図です。

Objects are instances of classes. Objects have attributes/states and methods/behaviors. Attributes are data associated with the object while methods are actions/functions that the object can perform.

Abstraction separates the interface from implementation. Encapsulation is the process of hiding the internal implementation of an object.

Inheritance enables hierarchical relationships to be represented and refined. Polymorphism allows objects of different types to receive the same message and respond in different ways.

To illustrate, let's find the sum of first ten natural numbers in the object-oriented paradigm approach.

Example in Java:

public class Main { public static void main(String[] args) { Addition obj = new Addition(); obj.num = 10; int answer = obj.addValues(); System.out.println("The sum is = "+answer); //prints-> The sum is 55 } } class Addition { int sum =0; int num =0; int addValues(){ for(int i=1; i<=num;i++){ sum += i; } return sum; } }

We have a class Addition that has two states, sum and num which are initialized to zero. We also have a method addValues() which returns the sum of num numbers.

In the Main class, we've created an object, obj of Addition class. Then, we've initialized the num to 10 and we've called addValues() method to get the sum.

Languages that support the object-oriented paradigm:

  • Python
  • Ruby
  • Java
  • C++
  • Smalltalk

Object-oriented programming is best used when:

  • You have multiple programmers who don’t need to understand each component (Holligan, 2016).
  • There is a lot of code that could be shared and reused (Holligan, 2016).
  • The project is anticipated to change often and be added to over time (Holligan, 2016).

Why should you consider learning the object-oriented programming paradigm?

  • Reuse of code through Inheritance.
  • Flexibility through Polymorphism.
  • High security with the use of data hiding (Encapsulation) and Abstraction mechanisms.
  • Improved software development productivity: An object-oriented programmer can stitch new software objects to make completely new programs (The Saylor Foundation, n.d.).
  • Faster development: Reuse enables faster development (The Saylor Foundation, n.d.).
  • Lower cost of development: The reuse of software also lowers the cost of development. Typically, more effort is put into the object-oriented analysis and design (OOAD), which lowers the overall cost of development (The Saylor Foundation, n.d.).
  • Higher-quality software: Faster development of software and lower cost of development allows more time and resources to be used in the verification of the software. Object-oriented programming tends to result in higher-quality software (The Saylor Foundation, n.d.).

1.3 Parallel processing approach

Parallel processing is the processing of program instructions by dividing them among multiple processors.

A parallel processing system allows many processors to run a program in less time by dividing them up.

Languages that support the Parallel processing approach:

  • NESL (one of the oldest ones)
  • C
  • C++

Parallel processing approach is often the best use when:

  • You have a system that has more than one CPU or multi-core processors which are commonly found on computers today.
  • You need to solve some computational problems that take hours/days to solve even with the benefit of a more powerful microprocessor.
  • You work with real-world data that needs more dynamic simulation and modeling.

Why should you consider learning the parallel processing approach?

  • Speeds up performance.
  • Often used in Artificial Intelligence. Learn more here: Artificial Intelligence and Parallel Processing by Seyed H. Roosta.
  • It makes it easy to solve problems since this approach seems to be like a divide and conquer method.

Here are some useful resources to learn more about parallel processing:

  1. Parallel Programming in C by Paul Gribble
  2. Introduction to Parallel Programming with MPI and OpenMP by Charles Augustine
  3. INTRODUCTION TO PARALLEL PROGRAMMING WITH MPI AND OPENMP by Benedikt Steinbusch

2. Declarative programming paradigm

Declarative programming is a style of building programs that expresses the logic of a computation without talking about its control flow.

Declarative programming is a programming paradigm in which the programmer defines what needs to be accomplished by the program without defining how it needs to be implemented. In other words, the approach focuses on what needs to be achieved instead of instructing how to achieve it.

Imagine the president during the state of the union declaring their intentions for what they want to happen. On the other hand, imperative programming would be like a manager of a McDonald's franchise. They are very imperative and as a result, this makes everything important. They, therefore, tell everyone how to do everything down to the simplest of actions.

So the main differences are that imperative tells you how to do something and declarative tells you what to do.

2.1 Logic programming paradigm

The logic programming paradigm takes a declarative approach to problem-solving. It's based on formal logic.

The logic programming paradigm isn't made up of instructions - rather it's made up of facts and clauses. It uses everything it knows and tries to come up with the world where all of those facts and clauses are true.

For instance, Socrates is a man, all men are mortal, and therefore Socrates is mortal.

The following is a simple Prolog program which explains the above instance:

 man(Socrates). mortal(X) :- man(X). 

The first line can be read, "Socrates is a man.'' It is a base clause, which represents a simple fact.

The second line can be read, "X is mortal if X is a man;'' in other words, "All men are mortal.'' This is a clause, or rule, for determining when its input X is "mortal.'' (The symbol ":-'', sometimes called a turnstile, is pronounced "if''.) We can test the program by asking the question:

 ?- mortal(Socrates). 

that is, "Is Socrates mortal?'' (The "?-'' is the computer's prompt for a question). Prolog will respond "yes''. Another question we may ask is:

?- mortal(X).

That is, "Who (X) is mortal?'' Prolog will respond "X = Socrates''.

To give you an idea, John is Bill's and Lisa's father. Mary is Bill's and Lisa's mother. Now, if someone asks a question like "who is the father of Bill and Lisa?" or "who is the mother of Bill and Lisa?" we can teach the computer to answer these questions using logic programming.

Example in Prolog:

/*We're defining family tree facts*/ father(John, Bill). father(John, Lisa). mother(Mary, Bill). mother(Mary, Lisa). /*We'll ask questions to Prolog*/ ?- mother(X, Bill). X = Mary 

Example explained:

father(John, Bill).

The above code defines that John is Bill's father.

We're asking Prolog what value of X makes this statement true? X should be Mary to make the statement true. It'll respond X = Mary

?- mother(X, Bill). X = Mary 

Languages that support the logic programming paradigm:

  • Prolog
  • Absys
  • ALF (algebraic logic functional programming language)
  • Alice
  • Ciao

Logic programming paradigm is often the best use when:

  • If you're planning to work on projects like theorem proving, expert systems, term rewriting, type systems and automated planning.

Why should you consider learning the logic programming paradigm?

  • Easy to implement the code.
  • Debugging is easy.
  • Since it's structured using true/false statements, we can develop the programs quickly using logic programming.
  • As it's based on thinking, expression and implementation, it can be applied in non-computational programs too.
  • It supports special forms of knowledge such as meta-level or higher-order knowledge as it can be altered.

2.2 Functional programming paradigm

The functional programming paradigm has been in the limelight for a while now because of JavaScript, a functional programming language that has gained more popularity recently.

The functional programming paradigm has its roots in mathematics and it is language independent. The key principle of this paradigm is the execution of a series of mathematical functions.

You compose your program of short functions. All code is within a function. All variables are scoped to the function.

In the functional programming paradigm, the functions do not modify any values outside the scope of that function and the functions themselves are not affected by any values outside their scope.

To illustrate, let's identify whether the given number is prime or not in the functional programming paradigm.

Example in JavaScript:

function isPrime(number){ for(let i=2; i<=Math.floor(Math.sqrt(number)); i++){ if(number % i == 0 ){ return false; } } return true; } isPrime(15); //returns false

In the above example, we've used Math.floor() and Math.sqrt() mathematical functions to solve our problem efficiently. We can solve this problem without using built-in JavaScript mathematical functions, but to run the code efficiently it is recommended to use built-in JS functions.

number is scoped to the function isPrime() and it will not be affected by any values outside its scope. isPrime() function always produces the same output when given the same input.

NOTE: there are no for and while loops in functional programming. Instead, functional programming languages rely on recursion for iteration (Bhadwal, 2019).

Languages that support functional programming paradigm:

  • Haskell
  • OCaml
  • Scala
  • Clojure
  • Racket
  • JavaScript

Functional programming paradigm is often best used when:

  • Working with mathematical computations.
  • Working with applications aimed at concurrency or parallelism.

Why should you consider learning the functional programming paradigm?

  • Functions can be coded quickly and easily.
  • General-purpose functions can be reusable which leads to rapid software development.
  • Unit testing is easier.
  • Debugging is easier.
  • Overall application is less complex since functions are pretty straightforward.

2.3 Database processing approach

This programming methodology is based on data and its movement. Program statements are defined by data rather than hard-coding a series of steps.

A database is an organized collection of structured information, or data, typically stored electronically in a computer system. A database is usually controlled by a database management system (DBMS) ("What is a Database", Oracle, 2019).

To process the data and querying them, databases use tables. Data can then be easily accessed, managed, modified, updated, controlled and organized.

A good database processing approach is crucial to any company or organization. This is because the database stores all the pertinent details about the company such as employee records, transaction records and salary details.

Most databases use Structured Query Language (SQL) for writing and querying data.

Here’s an example in database processing approach (SQL):

CREATE DATABASE personalDetails; CREATE TABLE Persons ( PersonID int, LastName varchar(255), FirstName varchar(255), Address varchar(255), City varchar(255) );

The PersonID column is of type int and will hold an integer. The LastName, FirstName, Address, and City columns are of type varchar and will hold characters, and the maximum length for these fields is 255 characters.

The empty Persons table will now look like this:

Database processing approach is often best used when:

  • Working with databases to structure them.
  • Accessing, modifying, updating data on the database.
  • Communicating with servers.

Why are databases important and why should you consider learning database processing approach?

  • Massive amount of data is handled by the database: Unlike spreadsheet or other tools, databases are used to store large amount of data daily.
  • Accurate: With the help of built-in functionalities in a database, we can easily validate.
  • Easy to update data: Data Manipulation Languages (DML) such as SQL are used to update data in a database easily.
  • Data integrity: With the help of built-in validity checks, we can ensure the consistency of data.

Conclusion

Programming paradigms reduce the complexity of programs. Every programmer must follow a paradigm approach when implementing their code. Each one has its advantages and disadvantages.

If you're a beginner, I would like to suggest learning object-oriented programming and functional programming first. Understand their concepts and try to apply them in your projects.

For example, if you're learning object-oriented programming, the pillars of object-oriented programming are Encapsulation, Abstraction, Inheritance and Polymorphism. Learn them by doing it. It will help you to understand their concepts on a deeper level, and your code will be less complex and more efficient and effective.

I strongly encourage you to read more related articles on programming paradigms. I hope this article helped you.

Please feel free to let me know if you have any questions.

You can contact and connect with me on Twitter @ThanoshanMV.

Thank you for reading.

Happy Coding!

References

  • Akhil Bhadwal. (2019). Functional Programming: Concepts, Advantages, Disadvantages, and Applications
  • Alena Holligan. (2016). When to use OOP over procedural coding
  • The Saylor Foundation. (n.d.). Advantages and Disadvantages of Object-Oriented Programming (OOP)
  • What is a Database | Oracle. (2019).