README.md

Gold - The Programming Language (Experimental & Research Purpose)

Hello, Gold is currently under development and not intended for production use. It's primarily for learning and experimentation purposes.

Language Overview:

• Compiled language with a virtual machine
• Object-oriented tendencies (work in progress)
• Type safety with null protection
• Recent strong focus on catching errors at compile time to minimize runtime issues

With this repo, you can compile your code in Gold, run it in a VM and even use a REPL.

Inspiration:

Gold draws from Monkey, the language featured in Thorsten Ball's books "Writing An Interpreter In Go" and "Writing A Compiler In Go". While initially following its guidelines, Gold has evolved into a distinct language.

More Information:

A basic wiki is available below to guide you through Gold's core concepts. A more comprehensive wiki will be created when the language matures and resources permit.

Feature

Basics:

• Standard arithmetic operators (+, -, /, *, ==, !=, >, <, <=, >=, !)
• Prefix and postfix increment/decrement (++, --)
• Primitive types: int, float, bool, string, array, dictionary
• Type-based error checking during compilation
• Automatic type conversions (e.g., int + float) when possible
• Array and dictionary behavior similar to Python (can hold any type as keys or values)

Here are some examples:

let x = 0
while (x++ < 10) {
  print(x) // print all numbers from 1 to 10
}

[[1, 1, 1]][0][0] // will produce 1

There are also some built-in functions with obvious behavior :

• print
• len
• push
• first
• last

Typed Variables:

The incorporation of typed properties and null safety is a pivotal aspect of the language, and I invested considerable effort in refining it during the development process. Here's how it works :

• Explicit type declaration using keywords like mint, lint, mstr, lstr, mflt, lflt, marr, larr, mdct, ldct, any, may, and let.
• m or l prefix indicates whether the value can be null (may) or must be non-null (let).
• Use let or may without types to let the compiler infer the type.

The most important part of it comes with functions.

Typed function

The functions work like variables with small nuance. You will declare them the same way you declare a variable but the type is actually the type returned by the function. This is particularly useful for high-order functions or closures.

** This will work

lint x = 0
mint f = fn(mint a) {
  if (5 > 2) {
    return a
  }
}
f(x)

** This will fail

lint x = 0
mint f = fn(mstr a) {
  if (5 > 2) {
    return a
  }
}
f(x)

Everything Is an Expression (Work in Progress):

if and while statements can potentially return values like functions (experimental feature).

Known Issues:

len function: The compiler accepts any type, but the VM will catch errors. ++x--: Unsupported (and unnecessary, who wants to do that ?).

Usage

Given that this language is built on Go, you can easily initiate the REPL by running go run main.go. To compile a file named test.gold, use the command go run main.go compile test. This will generate a file called test.cold, which you can execute with go run main.go run test. Alternatively, you can simplify the language installation using go install (ensure that you add GOPATH to your PATH).