Book Image

Build Your Own Programming Language

By : Clinton L. Jeffery
Book Image

Build Your Own Programming Language

By: Clinton L. Jeffery

Overview of this book

The need for different types of computer languages is growing rapidly and developers prefer creating domain-specific languages for solving specific application domain problems. Building your own programming language has its advantages. It can be your antidote to the ever-increasing size and complexity of software. In this book, you’ll start with implementing the frontend of a compiler for your language, including a lexical analyzer and parser. The book covers a series of traversals of syntax trees, culminating with code generation for a bytecode virtual machine. Moving ahead, you’ll learn how domain-specific language features are often best represented by operators and functions that are built into the language, rather than library functions. We’ll conclude with how to implement garbage collection, including reference counting and mark-and-sweep garbage collection. Throughout the book, Dr. Jeffery weaves in his experience of building the Unicon programming language to give better context to the concepts where relevant examples are provided in both Unicon and Java so that you can follow the code of your choice of either a very high-level language with advanced features, or a mainstream language. By the end of this book, you’ll be able to build and deploy your own domain-specific languages, capable of compiling and running programs.
Table of Contents (25 chapters)
1
Section 1: Programming Language Frontends
7
Section 2: Syntax Tree Traversals
13
Section 3: Code Generation and Runtime Systems
21
Section 4: Appendix

Chapter 7: Checking Base Types

This is the first of two chapters about type checking. In most mainstream programming languages, type checking is a key aspect of semantic analysis that must be performed before you can generate code.

This chapter will show you how to do simple type checks for the base types included in the Jzero subset of Java. A byproduct of checking the types is to add type information to the syntax tree. Knowing the types of operands in the syntax tree enables you to generate correct instructions for various operations.

This chapter covers the following main topics:

  • Type representation in the compiler
  • Assigning type information to declared variables
  • Determining the type at each syntax tree node
  • Runtime type checks and type inference – a Unicon example

It is time to learn about type checking, starting with base types. Some of you may be wondering, why do type checking at all? If your compiler does not do type checking, it has...