Welcome to JECH Lang

A programming language created with love, as a tribute to the next generation — and an invitation to anyone who wants to learn how languages are born, grow and become real.

📘 Introduction

I bet you already know how to program. Maybe you’ve built cool things in Python, JavaScript, or even C. But... have you ever wondered how those languages actually work under the hood?

How does a command like print("Hello") turn into instructions your machine can understand?

JECH was created for exactly that curiosity — and for you. A language made by a programmer, for programmers. A step-by-step, simple, and accessible journey from raw code to running output, even if you’ve never touched compilers, interpreters, or low-level programming before.

The JECH Lang project was created to demonstrate, step by step, how a programming language can be built from scratch — in a simple, clear, and didactic way. It’s designed for programming enthusiasts who want to dive into the fascinating world of language design, using C as a foundation, much like Python is built on CPython.

🎯 Purpose

JECH is a programming language created with the goal of teaching, exploring, and celebrating the process of building a language from the ground up.

It is designed to be simple, readable, and modular — enabling anyone, even with minimal experience in low-level programming, to follow its development and understand how a full interpreter works, from the lexer to the virtual machine.

JECH does not aim to compete with existing languages. Instead, it serves as a learning platform, a documented journey, and a source of inspiration for developers curious about compilers, language design, and the inner workings of interpreters.

📖 History

JECH was born from a personal desire to learn how a programming language is built — from the most fundamental concepts to a working interpreter.

But this project is not just for me.

JECH was also created to serve as a teaching resource — a transparent, well-documented, and step-by-step guide to how programming languages work internally. I wanted to share this learning experience with other developers who, like me, are curious about what happens under the hood.

💡 Why the name “JECH”?

The name "JECH" is a tribute to my two sons: Jonathan Edwards and Charles Haddon. It combines the initials of their names as a symbolic gesture — representing not only the technical creation of a language, but also a legacy of love, curiosity, and inspiration.

🧠 Commands & Language Features

✅ say(...)

Prints a value to the terminal.

Currently supported types:

• ✅ String → say("Hello, JECH!");
• ✅ Boolean → say(true);, say(false);
• ✅ Integer → say(42);
• ✅ Float → say(3.14);
• ✅ Variables → keep x = "Hi!"; say(x);

---

✅ keep — Variable Declaration

Declares a variable that can be reused throughout the program.

keep name = "JECH";
say(name);

---

✅ when — Conditional Structures

Executes a block of code only if the condition is true.

keep show = true;

when (show) {
    say("Hello!");
}

📎 Error Handling Architecture (Preview)

Errors in JECH are modularized and categorized for clarity:

• errors/error.h → main error reporting function
• errors/parser_error.c → custom messages like "Missing semicolon after keep"
• errors/lexer_error.c → syntax issues like "Unterminated string"

This structure helps maintain clean separation between:

• Logic (e.g., keep.c)
• Presentation of messages (e.g., parser_error.c)

Example usage:

if (t[i + 4].type != TOKEN_SEMICOLON) {
    report_missing_semicolon(&t[i + 4]);
    return NULL;
}

⚙️ Architecture Pipeline

JECH now implements a fully modular interpreter pipeline, inspired by CPython:

Source Code
   ↓
Tokenizer (lexer)
   ↓
Parser
   ↓
AST Tree (ast.c)
   ↓
Bytecode Compiler
   ↓
Virtual Machine (VM)
   ↓
💾 Execution!

Each stage is fully modular and documented:

📂 Explore the documentation:

• Architecture Overview
• Tokenizer Design
• Parser Tree
• Ast
• Bytecode & VM

🌐 JECH

📘 Available Languages:

• 🇺🇸 English (en)
• 🇧🇷 Português (pt-BR)
• 🇪🇸 Español (es-ES)

🤝 Contributors

Thanks goes to these wonderful people (🔥):

João Lucas Creator and Maintainer

⚠️ License

Create Go App CLI is free and open-source software licensed under the Apache 2.0 License. Official logo was created by [Vic Shóstak][author] and distributed under Creative Commons license (CC BY-SA 4.0 International).