The Pascal Programming Language

Published on 10 April 2018 (Updated: 23 October 2023)
The Pascal Programming Language

Welcome to the Pascal page! Here, you'll find a description of the language as well as a list of sample programs in that language.

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Description

According to Wikipedia, Pascal is an imperative and procedural language which first appeared in 1970. Pascal's creator, Niklaus Wirth, designed the language with compiler and runtime efficiency in mind. In addition, Wirth drew much of the inspiration for Pascal from the ALGOL family of languages.

That said, Pascal isn't simply an ALGOL clone. In fact, Pascal includes many additions to ALGOL such as mechanisms for defining custom datatypes. Likewise, the language includes several additional features like enumerations, subranges, and records.

As an added bonus, Pascal is a strongly typed language. This forces the user to explicitly write conversions between types, so errors can be caught at compile time. Unfortunately, I've read that Pascal has a loophole in the type system. I just haven't found any articles describing it. If you know, let me know in the comments.

Before we get into Hello World, I want to look a bit deeper at sets because I find them interesting. In Pascal, we can define a set as follows:

var
  Set1 : set of 5..20;
  Set2 : set of 'f'..'m';

With Pascal being such an old language, I find it interesting how intuitive the set syntax is. In fact, I can't think of many industrial languages that have such a nice syntax for setting up lists or sets. In fact, here's how you would generate a list of numbers in a few languages:

// Java 8+
int[] range = IntStream.rangeClosed(5, 20).toArray();

# Python 3
list(range(5, 20))

// JavaScript
var list = [];
for (var i = 5; i <= 20; i++) {
  list.push(i);
}

// C#
int[] values = Enumerable.Range(5, 15).ToArray();

That Pascal set syntax is great. In fact, it even allows us to do fun things like check values in some range:

if i in [5..20] then

At any rate, I think we've played around enough

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