IElib

Typescript bindings for Infinity Engine BAF.

Type branding

Numeric IDS types (e.g. SpellID, Align, ClassID, Slots) use branded types via IE<number, "..."> for nominal type safety. This prevents accidentally passing one kind of ID where another is expected. Custom numeric values can be created with a cast:

const mySpell = 42 as SpellID;

String resource reference types (ResRef, SplRef, ItmRef) are intentionally not branded. Resrefs are almost always raw string literals, and branding would require a cast on every usage (e.g. "SWORD01" as ItmRef). Unlike numeric IDS types, there is no finite set of valid resrefs to provide as pre-typed constants.

Engine action functions return a branded Action type, which allows ActionOverride to enforce that its argument is an actual action call rather than an arbitrary expression.

Named re-exports

Barrel index.ts files use explicit named re-exports (export { X } from './module' / export type { X } from './module') instead of export *. esbuild cannot statically enumerate exports from externalized .d.ts modules behind export * and falls back to runtime __reExport helpers, which break downstream transpilers. Named re-exports let esbuild resolve each binding at build time.

IDS type naming

Some IDS types use a *ID suffix (ClassID, GenderID, KitID, etc.) while others use bare names (Align, EA, State, etc.). The suffix exists to avoid name clashes with same-named trigger/action functions (e.g. Class() trigger vs ClassID type). Types without a same-named function use the bare name.