I Built My Own Programming Language Engine From Scratch (Meet Eger!)

Hey fellow devs! 👋

For the past few weeks, I’ve been obsessed with how programming language parsers and runtime environments work under the hood. Instead of just reading about it, I decided to build my own interpreter engine from scratch.

Meet Eger (v0.1.0-Alpha) — an experimental, structured programming language engine written entirely in Python.

🚀 What makes Eger unique?

Eger isn't just a standard script runner; it enforces strict architectural boundaries:

1. Explicit Phase Segmentation: Programs must execute in sequential layout phases (Header Specification ➡️ Library Import Declarations ➡️ Executable Body Code).
2. Strict Layout Safety Constraints: The compiler automatically flags an error if more than 3 continuous space characters are found, promoting uniform typography.
3. Dual Execution Modes: It features a live, interactive testing REPL shell interface alongside a standard standalone script runner.

🛠️ The AI-Assisted Architecture Workflow

As a creator, I mapped out the initial grammar, constraints, and structural rules. To bring it to life rapidly, I leaned into a modern prompt engineering workflow using Gemini 3.5 Flash with Extended Thinking.

Using advanced reasoning models allowed me to rapidly test alternative pattern translations, optimize token execution, and build a fully functional compiler prototype in record time.

📝 Here is what an .egr script looks like:

eger
Envelop: "script"
#call stdio
#call math

--- Sample Launch Demo ---
try:
  write("Initializing Eger Language Engine...")
  write(div(10, 2))
flag:
  write("System Flag Triggered: An error occurred safely!")               

## 📦 Check out the Repo & Let's Connect!

The project is officially open-source today under the MIT License! I'd love for you to check out the codebase, spin up the REPL, and let me know what you think. Drop a ⭐ if you find the concept interesting!

* **GitHub Repository:** https://github.com/egerlanguage/Eger
* **Project Email:** [e-mail]