README.md

Code-Lang 🚀

Code-Lang is a modern, interpreted programming language written in Go. It began as an implementation following the excellent book "Writing An Interpreter In Go" by Thorsten Ball, and has since evolved with additional features and custom extensions.

Important

Status: Code-Lang is a passion project and is currently under active development. While the core language is functional, it is not production-ready. If you intend to use this in a production environment, significant work, security audits, and optimizations are required.

🚀 Note: This project is actively evolving and will soon be moved to the Walon-Foundation!

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✨ Features

• Rich Type System:
  • Integers and Floats
  • Strings and Characters
  • Booleans
  • Arrays (e.g., [1, 2, 3])
  • Hashes/Dictionaries (e.g., {"name": "Code-Lang"})
  • Structs: Custom data structures with default values and member access.
• First-Class Functions: Function literals, closures, and higher-order functions.
• Control Flow:
  • if-elseif-else expressions (everything is an expression!).
  • while loops for simple iteration.
  • for loops for structured iteration.
  • break and continue inside loops.
• Static Analysis:
  • Symbol Table: Tracks variable scopes, identifier resolution, and constant enforcement.
  • Pre-execution Checks: Catches undefined variables and illegal reassignments before running code.
• Support for Comments: Single-line (#) and multi-line (/* */).
• Standard Operators:
  • Arithmetic: +, -, *, /, % (Modulo)
  • Advanced: ** (Power), // (Floor Division)
  • Comparison: ==, !=, <, >, <=, >=
  • Logical: && (AND), || (OR) — with short-circuit evaluation — and ! (Negation)
  • Compound Assignment: +=, -=, *=, /=, %=, **=, //=
• Built-in Functions: print, printf, typeof, len, push, and more.
• Module System: Import other .cl files or built-in modules using import "module".
• Member Access: Dot notation (obj.prop) for Hashes, Modules, Structs, and Servers.
• Networking: Built-in http client (GET, POST, etc.) and net.server for creating web servers.
• JSON Support: Built-in json.parse() and json.stringify().
• Standard Library: Go-backed modules for math, strings, time, hash, os, json, and net.
• REPL: Interactive shell with persistent history and precise line/column error tracking.
• File Execution: Run scripts with the .cl extension.
• Bytecode VM (WIP): A compiler + VM backend now powers the REPL and file execution.
  • Supports arithmetic, %, **, //, comparisons (==, !=, >, <, >=, <=) with float support.
  • Supports assignment and updates: =, +=, -=, *=, /=, %=, **=, //=, ++, --.
  • Current limitation: VM uses a global-only store (locals/scopes are still WIP in the VM).
• Language Server Protocol (LSP): Built-in Language Server providing IDE-like features:
  • Auto-completion, Hover previews, and live Diagnostics.
  • Go to Definition / Declaration / Implementation.
  • Find References, Rename variables, and Document Symbols.
  • Quickfix Code Actions (e.g., fixing undefined variables).

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🚀 Getting Started

Prerequisites

• Go (version 1.21 or higher recommended)

Installation

Option 1: Using go install (Recommended)

You can install the code-lang binary directly to your $GOPATH/bin:

go install github.com/walonCode/code-lang@latest

Option 2: Pre-built Binaries

Head over to the Releases section to download path-ready binaries for Windows, macOS, and Linux.

Option 3: From Source

Clone and build manually:

git clone https://github.com/walonCode/code-lang.git
cd code-lang
go build -o code-lang main.go

Running the REPL

Start the interactive shell by running:

go run main.go

Running a Script

You can execute a Code-Lang script by passing the filename as an argument:

go run main.go hello.cl

Running the Language Server (LSP)

The project now includes an LSP server executable that provides robust IDE features for Code-Lang! You can build the Language Server using the provided build script:

# Build the LSP using the script
./build_lsp

# Run the LSP (operates over stdin / stdout for editors like VS Code)
./lsp

Visual Studio Code Extension

A dedicated VS Code extension is currently in the works to provide syntax highlighting and deep integration with the Code-Lang Language Server! You can find the repository and follow its development here:

👉 Walon-Foundation/vscode_code-lang

---

📖 Language Syntax at a Glance

Variables & Functions

let age = 25;
let name = "Developer";
let isLearning = true;

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

const PI = 3.14159;
# PI = 3.14; # Error: cannot reassign to const

print(add(10, 15)); # Output: 25

Arrays and Hashes

let fibonacci = [0, 1, 1, 2, 3, 5, 8];
print(fibonacci[3]); # 2

let person = {"name": "Alice", "age": 30};
print(person.name); # Alice

Structs

struct User {
    name: "Guest",
    role: "User",
}

let u = User { name: "Walon", role: "Admin" };
let guest = User {}; # Uses default values

print(u.name);     # Walon
print(guest.name); # Guest

Conditionals

let x = 10;
let result = if (x > 10) {
    "Greater"
} elseif (x == 10) {
    "Equal"
} else {
    "Smaller"
};

Logical Operators (&& / ||)

&& and || use short-circuit evaluation — the right side is only evaluated when necessary.

let a = true;
let b = false;

print(a && b);  # false
print(a || b);  # true
print(!a);      # false

# Short-circuit: the right side is never evaluated when
# the result is already known from the left side.
let x = false && someUndefinedFn(); # safe — right side skipped
let y = true  || someUndefinedFn(); # safe — right side skipped

# Combine with comparisons
let age = 20;
let hasId = true;
if (age >= 18 && hasId) {
    print("Access granted");
};

Loops

# While loop
let i = 0;
while (i < 5) {
    print(i);
    i += 1;
};

# For loop with break and continue
for (let j = 0; j < 10; j += 1) {
    if (j == 2) { continue; };
    if (j == 6) { break; };
    print(j);
};

Standard Library Examples

Networking & JSON

import "http";
import "json";

let res = http.get("https://jsonplaceholder.typicode.com/todos/1");
let data = json.parse(res.body);
print(data.title);

Math & Time

import "math";
import "time";

let radius = 10;
let area = math.PI * math.pow(radius, 2);
print("Area:", math.round(area));

let start = time.now();
time.sleep(100);
print("Elapsed (ms):", time.since(start));

Strings & Hashes

import "strings";
import "hash";

let s = "  hello world  ";
print(strings.trim(strings.to_upper(s))); # HELLO WORLD

let user = {"name": "walon", "age": 25};
if (hash.has_key(user, "name")) {
    print("User keys:", hash.keys(user));
};

OS & Environment

import "os";

print("Platform:", os.platform);
print("API Key:", os.get_env("API_KEY"));
os.exit(0);

Miscellaneous

# Single-line comment
/* 
   Multi-line comment 
*/

# Formatted print
let name = "Alice";
printf("Hello, %s!\n", name);

# Type checking
print(typeof(10));   # INTEGER
print(typeof("hi")); # STRING
print(typeof([]));   # ARRAY

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🗺 Roadmap

Feature	Status
Better Error Reporting (line & column tracking)	✅ Done
Comments (single & multi-line)	✅ Done
while and for loops with break/continue	✅ Done
Logical Operators && / `
Standard Library (math, strings, time, hash, os, json, net)	✅ Done
Import System (.cl files)	✅ Done
Member Access (dot notation)	✅ Done
Compound Assignment (+=, -=, etc.)	✅ Done
Structs (define custom types & create instances)	✅ Done
Constants (const)	✅ Done
Static Analysis (Symbol Table & Scope Awareness)	✅ Done
Web Server (request/response handling)	🚧 WIP
Struct Methods	🔜 Planned
fs module (file system access)	🔜 Planned
REPL Multi-line Support	🔜 Planned
VSCode Extension (syntax highlighting)	🚧 WIP
LSP (Language Server Protocol)	🚧 WIP

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📜 License

This project is licensed under the MIT License. See the LICENSE file for details.

🙏 Acknowledgments

• Thorsten Ball for the foundational guide Writing An Interpreter In Go.
• The Go community for providing an incredible ecosystem for language development.