I believe he wants to use the as const feature while still type checking that the structure matches an interface. A workaround I'd use for something like that would be interface ITest { a: number; b: string; } let foo = { a: 5, b: "Hello" } as const;

possible to tell the compiler to infer the type of a tuple of literals as a tuple of literals, instead of as, say, string[], by using the as const syntax.