st-programming-language

An interpreted language with a JavaScript-like syntax, written in Typescript. Features a lexer, ast, parser, and interpreter, with a repl and file runner.

Table of Contents

• Syntax and Features
  • Data Types
  • Expressions
    • Unary
    • Binary
    • Assignment
    • Member Access
      • Computed
      • Object With Identifier
      • Type Specific Built-in Properties
    • Function Call
  • Statements
    • Variable Declaration
    • Control Flow
    • Loops
      • For
      • While
    • Function Declaration
  • Comments
  • Native Functions
• Installation
• Available Scripts
• Usage
• Roadmap
• Contributing
• License
• Acknowledgements

Syntax and Features

Data Types

• Number 3, 3.14
• String "Hello, World!"
• Boolean true, false
• Null null
• Array [1, 2, 3]
• Object { key: "value" }

Expressions

Unary

• Logical !
• Negation -
• Positive +

Binary

• Multiplicative (\*, /, //, %)
• Additive (+, -)
• Relational (==, !=, <, <=, >, >=)
• Logical (&&, ||)

Assignment

x = 3

Member Access

Computed

foo[0]
foo[3 + 4]
foo["bar"]

Object With Identifier

foo.bar

Type Specific Built-in Properties

const foo = []

foo.length
foo.push(3)

Function Call

add(3, 4)

Statements

Variable Declaration

const foo = 3
let bar = "Hello, World!"

Control Flow

limited to if-else for now, parentheses are optional

if 3 > 2 {
  print("3 is greater than 2")
} else {
  print("3 is equal to 2")
}

Loops

For

for let i = 0; i < 10; i = i + 1 {
  print(i)
}

While

let i = 0

while i < 10 {
  print(i)
  i = i + 1
}

Function Declaration

Function declarations support both closures and recursion.

fn fib(n) {
  if n <= 1 {
    return n
  }

  return fib(n - 1) + fib(n - 2)
}

Comments

# this is a comment

Native Functions

print("Hello, World!")

const name = input("What is your name?")

random()
random(1, 10)

typeof(3)

Installation

bun install

Available Scripts

Command	Description	Example
bun run repl	Run the repl
bun file <file>	Run a file	bun file program.st

Usage

Example file program.st:

fn add(a, b) {
  let sum = a + b
  return sum
}

const result = add(3, 4)

const foo = {
  result: result / 3,
  add,
  isBar: 1 > 2 || 3 < 4,
}

let key = "isBar"

if foo[key] == "isBar" {
  print("foo is bar")
} else {
  print("foo is not bar")
}

print(foo.result)
print(foo.add(3, 4))

fn counter() {
  let count = 0
  fn increment() {
    count = count + 1
    return count
  }

  return increment
}

let increment = counter()

while increment() < 10 {
  print(increment())
}

Run file: bun file program.st

Roadmap

• Control Flow (elif)
• Update expression (++, --) postfix/prefix
• Better Error Messages with Line Numbers and Context
• Error Handling (try-catch, throw)

Contributing

1. Fork the Project
2. Create your Feature Branch (git checkout -b feature/AmazingFeature)
3. Commit your Changes (git commit -m 'Add some AmazingFeature')
4. Push to the Branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

License

Distributed under the MIT License. See LICENSE for more information.

Acknowledgements

• https://www.youtube.com/playlist?list=PL_2VhOvlMk4UHGqYCLWc6GO8FaPl8fQTh
• https://astexplorer.net/