How to Build Your Own Programming Language — Introduction
Building your own programming language can be an exciting and challenging project for any programmer. It requires a deep understanding of programming concepts, language design, and implementation. In this article, we will provide an overview of the steps involved in building a programming language, along with some examples.
Step 1: Define the language’s purpose and target audience
Before diving into the technical details of building a programming language, it’s essential to have a clear understanding of the language’s purpose and target audience. This will guide the design decisions and help ensure that the language is fit for its intended use.
For example, if the language is designed for data analysis, it may need to have built-in functions for statistical analysis, while if it is intended for web development, it may need to have features for working with databases and APIs.
Step 2: Design the language’s syntax and grammar
The next step is to design the language’s syntax and grammar. The syntax is the set of rules for how code is written in the language, while the grammar defines the structure of the language’s expressions and statements.
One popular approach to designing a language’s syntax and grammar is to use a formal grammar, such as Backus-Naur Form (BNF). BNF is a notation that describes the grammar of a language using production rules. These production rules define how expressions and statements are formed from symbols, keywords, and operators.
For example, the following BNF rule defines the syntax for a simple arithmetic expression in a programming language:
expression ::= term | expression ( '+' | '-' ) term
term ::= factor | term ( '*' | '/' ) factor
factor ::= '(' expression ')' | number | variable
number ::= [0-9]+
variable ::= [a-zA-Z_][a-zA-Z0-9_]*This BNF rule defines an arithmetic expression as a series of terms separated by either addition or subtraction operators. A term is a series of factors separated by multiplication or division operators. A factor can be a nested expression, a number, or a variable.
Step 3: Implement the language’s lexer and parser
Once the syntax and grammar have been defined, the next step is to implement the language’s lexer and parser. The lexer reads the source code and converts it into a stream of tokens, which are the language’s basic building blocks, such as keywords, operators, and literals.
The parser then takes this stream of tokens and uses the grammar to build an abstract syntax tree (AST) representing the structure of the code. The AST is a hierarchical representation of the code, where each node represents an expression or statement in the language.
For example, given the following code:
a = 5 + 3 * (2 - 1)The lexer would generate the following stream of tokens:
identifier(a) assignment(=) number(5) plus(+) number(3) times(*) lparen(() number(2) minus(-) number(1) rparen()) EOFThe parser would then use the grammar to build an AST that looks like this:
=
├─ a
└─ +
├─ 5
└─ *
├─ 3
└─ -
├─ 2
└─ 1Step 4: Implement the language’s semantics
Once the AST has been constructed, the next step is to implement the language’s semantics. This involves defining how the language’s expressions and statements are evaluated.
For example, in the arithmetic expression above, the semantics of the addition and multiplication operators are well-defined, but the semantics of the assignment operator depend on the programming language’s scoping rules and type system.
Step 5: Implement the language
Once the lexer, parser, and semantics have been implemented, the final step is to build the language’s interpreter or compiler. An interpreter reads the source code and directly executes it, while a compiler translates the source code into machine code that can be executed by the computer.
When implementing the interpreter or compiler, it’s important to consider the trade-offs between performance and flexibility. Interpreters are generally slower than compilers, but they offer greater flexibility since they can evaluate code at runtime. Compilers, on the other hand, are faster but offer less flexibility since they require a separate compilation step.
Step 6: Develop a standard library and tools
After implementing the language, the next step is to develop a standard library and tools. A standard library provides a set of built-in functions and classes that programmers can use in their code, while tools such as compilers, debuggers, and editors can make it easier for developers to write, test, and debug code in the language.
For example, the Python programming language comes with a rich standard library that includes modules for working with files, databases, and networking, as well as tools like the IDLE editor and the pdb debugger.
Step 7: Test and refine the language
Finally, it’s important to test and refine the language. This involves writing and running test cases to ensure that the language behaves as expected and is free from bugs and errors.
It’s also important to gather feedback from users and the programming community and use that feedback to make improvements and refinements to the language over time. This may involve adding new features, improving performance, or making changes to the language’s syntax or semantics based on user feedback.
Examples of programming languages built from scratch
- Python Python is a high-level, general-purpose programming language that was first released in 1991. It was designed by Guido van Rossum, who named it after the British comedy group Monty Python.
Python’s syntax and grammar are based on a mix of C and ABC, a language developed at CWI in the Netherlands. The language’s design is heavily influenced by its focus on readability and simplicity, which has made it a popular choice for beginners and experienced developers alike.
Python is interpreted, which means that it is executed directly by the computer without needing to be compiled first. The Python interpreter reads the source code and converts it into bytecode, which is then executed by the computer.
2. Ruby Ruby is a dynamic, object-oriented programming language that was first released in 1995. It was designed by Yukihiro Matsumoto, who sought to create a language that was more object-oriented than Perl and more powerful than Python.
Ruby’s syntax is influenced by Perl and Smalltalk, while its semantics are heavily influenced by Lisp. The language’s design is focused on simplicity and elegance, and it includes many features that make it easy to write expressive, concise code.
Ruby is interpreted, which means that it is executed directly by the computer without needing to be compiled first. The Ruby interpreter reads the source code and converts it into an abstract syntax tree, which is then executed by the computer.
3. Go Go is a statically-typed, compiled programming language that was first released in 2009. It was designed by a team at Google, led by Robert Griesemer, Rob Pike, and Ken Thompson.
Go’s syntax is similar to that of C, but it includes many features that make it easier to write concurrent and networked programs. The language’s design is focused on simplicity and efficiency, and it includes features like garbage collection and built-in concurrency support.
Go is compiled, which means that it is translated into machine code before being executed by the computer. The Go compiler generates efficient, statically-linked binaries that can be easily deployed to any platform.
Conclusion
Building a programming language is a complex task that requires a deep understanding of programming concepts and language design. However, with the right tools and approach, it can be a rewarding and educational experience. By following the steps outlined in this article, you can build your own programming language from scratch, with examples of popular programming languages to inspire your design choices.
