Part II · Profiles

11 Luau for Roblox

The profile for Roblox experiences: Luau's types and Roblox's, the class tree, the built-in library, and the files it writes.

Normative · Level 2Draft 0.1

11.1 Overview

The profile with the id roblox turns graphs into Luau scripts for Roblox experiences, laid out as a Rojo project. It is the profile Roswaal was built for, and its library has 300 built-in nodes. Luau for Lune shares most of it.

11.2 Types and conversions

• Luau's own types: number, string, boolean, table, function, thread, and nil as a value.
• Roblox's datatypes, such as Vector3, CFrame and Color3: 48 of them.
• Every engine class, such as Part and Player: 625 of them.
• The one conversion: number and string, both ways, as Luau converts them.

From a Luau annotation to a pin type

From pinTypeOf in core/nodes/variables.ts.

11.3 Families of Roblox's types

On a type chip, RBXScript is left off the front of a name (RBXScriptConnection reads Connection), a written table type reads table and a function type function.

11.4 Classes and the hierarchy

The class tree, the classes' summaries and their members come from Roblox's Creator Documentation, generated into Roswaal's source by its build scripts rather than read at run time: 625 classes, 48 datatypes and 507 enums. Every class has one parent, up to Object at the root, and a class connects into any of its ancestors (§6.3).

11.5 The built-in library

Generated from core/nodes and core/nodeGlyphs.ts. Both means the node works in a Lune graph too (§12). The Roblox Types category is split by datatype, each with a colour and a glyph of its own. A node that starts or ends a flow takes the glyph entry or terminal; Function and Declare Function take function, and Return return, whatever its category.

11.6 What each node compiles to

Every built-in node's page in these docs, such as Print, shows the Luau it compiles to. How values are bound and inlined is §7.2's rule, written as Luau: a value read once is written where it is read, and one read twice in a block becomes a local.

11.7 Scripts, modules, run contexts

Rojo decides what a file becomes in Studio from its name, so the class and run context are written into the name. A module returns what its Module Exports node is given. Where each file goes in the place is the node map's (§9.5), which becomes a Rojo project file.

The file's header

--!strict
-- Generated by Roswaal. Do not edit this file directly;
-- edit Main.nodescript and recompile instead.
-- roswaal-graph: <the graph's id>
-- roswaal-source: <a hash of the graph>
-- roswaal-output: <a hash of what follows>

The first line is the graph's typecheck: --!strict, --!nonstrict, or no line for default. Then come the services the script uses, its requires, its types, its variables, its hoisted functions, its flow, and a module's return. Where the project asks and StyLua is installed, the file is formatted by StyLua.

11.8 Packs and hand-written Luau

• A pack is a .nodedef.json file, or a .nodedef.luau file that returns a table: read as data, never run.
• A pack's nodes compile with expr, call or statement templates (§10.5).
• Graphs can hold hand-written Luau in a Code Block, a step, or a Luau Expression, a value. It is written into the program as it is.

11.9 Moonwave and comment tags