🧩 Molang Compiler — MOCO

The Molang Compiler (MOCO) allows you to create modular .molang files and compiles them into JSON that is valid for Bedrock.

Change Log

• Function parameters: now supports default values (e.g., beans = 3)
• Safe parameter substitution: only replaces standalone identifiers (will not alter t.biome.id when the parameter is biome)
• Nested function calls: functions are capable of invoking other functions; the inliner operates until a stable state is reached
• Fixed: no mandatory trailing ; at the conclusion of each compiled statement
• Minor parser enhancements for strings/commas within argument/default lists

⚡️ Installation & Command

npm i -g moco-mcbe
# or
npm i -D moco-mcbe

Initialize once:

moco init

Run:

moco run

📁 Setup

Establish a molang directory in your BP/RP and include .molang files. It is advisable to map .molang to C syntax highlighting.

✏️ Exports & Example

#export feature_rules/test_rule(minecraft:feature_rules/distribution/iterations);

This command writes the compiled statements to the specified JSON path.

🧠 Functions (New)

MOCO accommodates simple functions that you can declare once and inline wherever they are invoked.

Declaration

function name(paramA, paramB, paramC = defaultExpr) {
    // body;
}

• Parameters: multiple, optional defaults using =.
• Defaults can reference previous parameters: c = a + b.
• The body consists of plain statements separated by ;.

Calls

name(argA, argB);     // standard call
name(1);              // missing parameters utilize defaults
name();               // all parameters may derive from defaults

Nested Calls

Functions have the ability to invoke other functions. The compiler continuously inlines until no changes occur (with an internal safety limit to prevent infinite recursion).

✅ Worked Examples

1) Basic + Defaults

#export target/target(minecraft:json/target_component);

function super(multiplier = 5){
    v.my_var = v.my_var * multiplier;
}

function test(my_var, multiplier, divider = 3)