🎮 GMLC

📘 Overview

The first full public release of GMLC, a runtime compiler and interpreter that lets GameMaker projects load, compile, and execute real GML code at runtime, enabling mod support, live scripting, and scratchpad experimentation directly inside GameMaker.

⚙️ Core Features

• Runtime Compilation: Parse and evaluate GML source strings during gameplay.
• Sandboxed Execution: Tiered capability profiles (pure, safe, moderate, unsafe) for secure script isolation.
• Hook System: Functions defined in a compile can be referenced back in native runtime (main(), create(), step(), etc.).
• Environment Support: Correct handling of self, other, global, and static scopes.
• Constructor & Function Parity: Full support for static, constructor, and method semantics.
• AST-Driven Architecture: Real GML syntax parsing with tokenization and abstract syntax trees.
• Error Diagnostics: Structured compile/runtime error messages with caret and line reporting.
• Namespace Management: Mods and scratchpad sessions can run in isolated namespaces with safe reloads.

🧩 Setup & Installation

GMLC depends on SNAP by Juju Adams, which must be installed first.

Requirements

• SNAP (required): https://github.com/JujuAdams/SNAP

Installation Steps

1. Download and import SNAP into your project (via its .yymps or preferred install method).
2. Download the latest GMLC .yymps package from the repository or itch.io page.
3. In the GameMaker IDE, select Tools > Import Local Package.
4. Choose the GMLC .yymps file and confirm import.
5. The GMLC scripts will appear under your project’s resource tree and are immediately ready to use.

No special initialization is required after import.

🚀 Quickstart

GMLC allows you to compile and execute GML source code strings at runtime. Here’s the most minimal example possible:

var env = new GMLC_Env();
var program = env.compile("return 42;");
var result = program();        // Executes the compiled code
show_debug_message(result);    // Prints: 42

A compiled program behaves similarly to a native gm script. It’s callable, but can also contain other callable functions.

For example, fetching a specific function such as main, step, or draw from a compiled program:

var env = new GMLC_Env();
var program = env.compile(@'
function foo() {
    return "bar";
}
');

var _foo = env.get("foo");
show_debug_message(_foo());    // Prints: bar

If the user declares a constant named global or uses GameMaker’s built-in global, functions can also be accessed directly via global.foo.

Note: GMLC can be updated to recognize newer GML functions than those bundled with its release by supplying a newer GmlSpec.xml file from your local GameMaker runtime cache:

C:\ProgramData\GameMakerStudio2\Cache\runtimes\runtime-<runtime.version>

⚠️ Note on execute_string()

GMLC also includes a legacy style helper named execute_string(_code). It compiles and runs a code string immediately without caching or environment reuse. This makes it significantly slower than using a GMLC_Env, but it can be convenient for quick, throwaway tests or debugging.

Example:

execute_string(@'show_debug_message("quick test");');

Use this only for temporary experimentation; for any real runtime scripting, always prefer creating an environment and compiling once.

🧠 Additional Notes

That’s all you need for a first run, but you may want to:

• Read about sandbox profiles GMLC_EXPOSURE enum if you plan to expose runtime functions safely.
• Use hooks if you want your compiled code to integrate into native events (create, step, draw, etc.).
• Special thanks to Juju Adams for use SNAP's XML parser until a stand alone design is finished.
• Special thanks to TabularElf for the many talks about his GMLSpeak, and improvements and design changes. Much of our work is shared between the projects.

❓ FAQ

Q: Can I use GMLC outside of GameMaker?
No; GMLC runs entirely inside the GameMaker runtime and is intended for in engine use.

Q: Is this compatible with both LTS and Monthly builds?
Yes.* GMLC targets standard GML syntax and should work in both, however I can not ensure that every feature will work as testing the entire runtime on multiple versions is an insermountable task, if you have issues please submit a bug report or feature request.

Q: Why is execute_string() so slow?
It does not reuse or cache the compiler environment, it recompiles the string every call.
Use GMLC_Env for anything persistent.

Q: Can I give my modders access to built-in GameMaker functions?
Yes. Use the sandbox capability system (pure, safe, moderate, unsafe) to control what functions are exposed.

Q: Can I expose my own functions?
Yes. Yes please see the variety of expose_* in GMLC_Env.

🔀 Alternatives

catspeak-lang - Catsaii: An extremely robust modding toolset with long term support.

gmlspeak - TabularElf: An extension to catspeak-lang, which allows for gml like code to be parsed for use inside catspeak

TXR - YellowAfterLife: A lightweight and simple expression parser.

SNAP - JujuAdams: SNAP contains a module for parsing and executing simple GML.

RunGML - sdelaughter: A lisp structured GML executer, very unique!

gml.gml - kenan238: A newer lightweight, single script GML interpreter.

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inspiration from neerikiffu: https://discord.com/channels/724320164371497020/724320751624257646/1178721426983882915