The GoLF Language

This is a stack-based, multi-pass compiler written in C++ for a programming language called GoLF. This was created as part of a term project for a course at the University of Calgary (CPSC 411) taught by John Aycock. If you are reading this and he is still teaching the course, enroll in it. Right now. Seriously.

Features

You can read through the whole specification here. Otherwise, here are some short snippets of what you can do in GoLF:

• GoLF has built-in functions:

  • printb(b bool): To print a boolean to the console,
  • printc(c int): To print a character to the console,
  • printb(i int): To print a number to the console,
  • printb(s string): To print a string to the console,
  • getchar(): To receive user input,
  • len(s string): To get the length of a string,
  • halt(): To halts the execution of the program,

• GoLF has support for arithmetic operators: +, -, /, *, %

• GoLF has support for comparison operators: ==, <, <=, >=, >

• GoLF has support for binary operators: &&, ||

• GoLF has support for unary operators: !, -

• GoLF supports the break statement in loops

Building

In order to build and compile, you need to install Make plus the toolchain of your choice, e.g. g++ or clang. After you setup Make with your toolchain of choice, clone the repository and build the project as follows:

git clone https://github.com/joeyvanlierop/golf.git
cd golf/
make

Hello World

To run a "hello world" program, create a file named hello-world.golf on your computer, and place the following inside it:

func main() {
    prints("Hello, world!\n")
}

Then, in a terminal window, navigate to the unzipped folder and run:

$ golf hello-world.golf

The Classic Fibonacci Number Calculator:

func main() {
    var i int
    i = 0

    // Anything larger than 47 overflows a 32-bit int...
    for i <= 47 {
        prints("fib(")
        printi(i)
        prints(") = ")
        printi(fib(i))
        prints("\n")
        i = i + 1
    }
}

func fib(n int) int {
    if n == 0 { return 0 }
    if n == 1 { return 1 }
    return fib(n-1) + fib(n-2)
}

Lifecycle of a GoLF Program

GoLF programs get executed in four separate steps: lexing, parsing, semantic analysis, and code generation.

• Lexing: The process of breaking down the source code into a stream of tokens, which represent the smallest units of meaning in the programming language.

• Parsing: The process of analyzing the sequence of tokens to construct an abstract syntax tree, which represents the structure of the program according to the rules of the programming language's grammar.

• Semantic Analysis: Performs a series of checks on the abstract syntax tree to ensure that it conforms to the rules of the programming language, such as type checking, scoping, and name resolution.

• Code Generation: Transforms the abstract syntax tree into executable code, generating machine instructions or bytecode for a virtual machine.