Nominal typing using flavors/flavoring

flavor.ts

//  https://spin.atomicobject.com/2018/01/15/typescript-flexible-nominal-typing/

type Flavor<K, T> = K & { __flavor?: T };

type CatalogNumber = Flavor<string, 'catalogNumber'>;
type CasNumber = Flavor<string, 'casNumber'>;

const pge2CatalogNumber: CatalogNumber = '14010';
const pge2CasNumber: CasNumber = '363-24-6';

//  Functions (with dummy implementations) requiring specific flavored types
const validateCatalogNumber: (s: CatalogNumber) => boolean = (s) => true;
const validateCasNumber: (s: CasNumber) => boolean = (s) => true;

console.log(validateCatalogNumber(pge2CatalogNumber));

//  Fails to compile, incompatible types
console.log(validateCasNumber(pge2CatalogNumber));