Why Build Another Programming Language?

This book will show you how to build your own programming language, but first, you should ask yourself, why would I want to do this? For a few of you, the answer will be simple: because it is so much fun. However, for the rest of us, it is a lot of work to build a programming language, and we need to be sure about it before we make that kind of effort. Do you have the patience and persistence that it takes?

This chapter points out a few good reasons to build your own programming language, as well as some circumstances in which you don’t need to build your contemplated language. After all, designing a class library for your application domain is often simpler and just as effective. However, libraries have their limitations, and sometimes, only a new language will do.

After this chapter, the rest of this book will take for granted that, having considered things carefully, you have decided to build a language. But first, we’re going to consider our initial options by covering the following main topics in this chapter:

• Motivations for writing your own programming language
• Types of programming language implementations
• Organizing a bytecode language implementation
• Languages used in the examples
• The difference between programming languages and libraries
• Applicability to other software engineering tasks
• Establishing the requirements for your language
• Case study – requirements that inspired the Unicon language

Let’s start by looking at motivations.