Schema Reference

File-Level Declarations

Top-level declarations in an IDL file:

• option - Configure compiler behavior.
• scope - Namespace grouping.
• struct - Define data structures.
• enum - Define enums (unit or tagged).
• set - Define packed boolean-flag sets.
• event - Define network messages.
• function - Define request/response RPCs.

Comments

Line comments are supported:

// This is a comment
-- This is also a comment

Option Syntax

option Validate = Full;
option DecodeStruct = Table;

Option values may be strings, identifiers/keywords, or numbers.

Scopes

Scopes namespace messages and can nest arbitrarily.

scope Gameplay {
  scope Vehicles {
    event Spawned { Data: u16 }
  }
}

Generated path: Net.Gameplay.Vehicles.Spawned

Scope Rules

• IDs are assigned by declaration order.
• IDs are global per category (Reliable, Unreliable, Function), not per scope.

Name Resolution

Root API Table

Generated APIs start at Net.

Net.Gameplay.Vehicles.Spawned

Global Type Names

Struct/enum/set names must be unique across the full schema (not just within one scope).

Possible errors include E_DUP_STRUCT, E_DUP_ENUM, E_DUP_SET, and E_DUP_DECL.

Structs

Two field styles are supported.

struct Car {
  id: u16,
  name: string<64>,
}

struct Car {
  u16 id;
  string<64> name;
}

Layout Rules

• Fields are serialized in declaration order.
• Reordering fields changes wire format.

Enums

enum Team {
  Red,
  Blue,
}

Emitted as Luau string-literal unions.

Sets

set Flags {
  A,
  B,
  C
}

Emitted as { A: boolean, B: boolean, C: boolean } and encoded as packed bits.

Tagged Enums

enum Command {
  Move { x: u16, y: u16 },
  Stop,
}

Default tag field is Type.

enum Command = "kind-type" {
  Move { x: u16, y: u16 },
  Stop,
}

Custom tag fields can be identifiers or quoted strings.

Events

Block Syntax

event Position {
  From: Client,
  Type: Reliable,
  Call: ManySync,
  Data: (u16, f32, f32),
}

Key	Values	Default	Description
From	Client, Server, Both	Both	Who sends this event.
Type	Reliable, Unreliable	Reliable	Delivery channel.
Call	SingleSync, ManySync, SingleAsync, ManyAsync, Polling	ManySync	Receive-side handler model.
Data	Type or Tuple	-	Event payload.

Call behavior in current generator:

• SingleSync / SingleAsync: single active On handler.
• ManySync / ManyAsync: multiple active On handlers.
• Polling: no On; generated API exposes Iter().

Unknown Keys

Unknown block keys trigger E_EVENT_KEY.

Legacy Syntax

event reliable Position(u16 id, f32 x, f32 y);
event unreliable Ping(u16 seq);

Functions

Block Syntax

function GetState {
  Yield: SingleSync,
  Data: (u16),
  Return: (bool, string<32>),
}

Key	Values	Default	Description
Yield	SingleSync	SingleSync	Function mode (only SingleSync is currently valid).
Data	Type or Tuple	-	Request args.
Return	Type or Tuple	-	Response args.

Legacy Syntax

function GetState(u16 id) -> (bool active, string<32> mode);

Syntax Rules

• Struct fields and list items may use , or ;.
• Trailing separators are allowed.
• Reordering event/function declarations changes message IDs and can break wire compatibility.