Pascal: A Classic Programming Language with Lasting Impact

Turbo Pascal is one of the languages I really wanted to include in my online IDE for retro programmers, along with a personal favourite of mine, Turbo C, and the ever-popular QBasic.

But why?

Many programming languages have shaped the way we think about coding, and Pascal is one of those.

Despite being created over 50 years ago, its influence continues in both education and certain technical domains today.

Whether you're a beginner or simply interested in the history of programming, understanding Pascal offers valuable insights into the roots of modern software development.

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Why Is Pascal Important?

Pascal holds a special place in the history of programming for several reasons:

• While BASIC was incredibly successful at introducing regular folks to the world of programming, Pascal was specifically designed as a teaching language to introduce students to good programming.

• Niklaus Wirth, inventor of Pascal, helped shape many future languages, including Modula-2 and Ada. He sadly passed away January 2024.

• Although created in the 1960s, it became the standard language for teaching computer science in the 1980s, and perhaps as a consequence it was used in real-world commercial software like early computer games (e.g., Crisis Mountain, Gravity Wars), and desktop applications on the Apple Mac, such as Adobe Photoshop!

Today, although its popularity has declined, Pascal (and it's Object relatives) remains relevant, especially in educational settings and niche projects. Its clear syntax and strong structure make it a useful language for learning core programming concepts.

Getting Started with Pascal

To begin coding in Pascal:

1. Install a Modern Compiler: The Free Pascal Compiler (FPC) is a free, open-source command-line tool available for tons of operating systems that allows you to compile and run Pascal programs. Not sure why it is over 1gb though!

2. Delphi and Lazarus: While you can write Pascal code in any text editor, IDEs like Lazarus provide helpful features like syntax highlighting and easy debugging.

3. Use my Online IDE: As mentioned, I have a free online development environment built especially around the goal of giving people the tools to code in retro languages and for classic computers!

Your First Program: "Hello, World!"

Here's a simple example to get you started.

program HelloWorld;
begin
    writeln('Hello World!');
    writeln('Press any key to continue...');
    readln;
end.

• program marks the beginning of the program.

• begin and end. wrap the program's executable statements.

• WriteLn outputs text to the screen, and readLn reads input from the console.

Variables and Constants

Pascal is strongly typed, meaning each variable must have a defined type, similar to C or TypeScript. Examples include Integer, Boolean, String, and user-defined types.

• Constants: Immutable data (unchanged once set):

const Pi = 3.14159;

• Variables: Changeable data, with explicit types:

var count: Integer; name: string;

Functions vs Procedures

• Functions: Perform calculations or operations and return a value.

function IsEven(num: Integer): Boolean; 
begin 
  Result := (num mod 2 = 0); 
end;

• Procedures: Execute actions without returning a value.

procedure PrintMessage(message: string); 
begin 
  WriteLn(message); 
end;

Here's how to use these in your program:

var number: Integer; evenCheck: Boolean;
begin 
  number := 10; 
  evenCheck := IsEven(number); 
  PrintMessage('Number is even: ' + BoolToStr(evenCheck, True)); 
end.

Creating Custom Data Types

Pascal supports creating complex data structures using records, similar to structs in C:

type Person = record 
  Name: string; 
  Age: Integer; 
end;
var person1: Person; 
begin 
  person1.Name := 'Alice'; 
  person1.Age := 30; 
  WriteLn('Name: ', person1.Name, ', Age: ', person1.Age); 
end.

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Building and Executing Pascal Programs

Once your code is ready:

• Compile it using the Free Pascal Compiler (FPC).

• The compiler transforms your source code into an executable file.

• Run the compiled program on your operating system to see results.

For example:

fpc myprogram.pas ./myprogram

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Final Thoughts

Pascal remains a notable milestone in the history of programming. It demonstrates how thoughtful language design can influence education, software development, and even hardware. If you're interested in learning programming fundamentals or exploring the roots of many modern languages, getting familiar with Pascal offers a lot of fun and rewards.

Pascal's clarity and structure, along with modern tools, continue to make it a valuable language, especially for people desiring to understand core programming concepts.

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Resources for Getting Started

• Free Pascal Compiler (FPC): https://www.freepascal.org/

• Lazarus IDE: https://www.lazarus-ide.org/