Typescript - Opaque type

opaque.ts

export type Opaque<T, K> = K & { __TYPE__: T };


// Create a new opaque type
type WaffleId = Opaque<number, "waffledId">;

// This function now handles the knowledge of what a waffleId is, change will only happen there if needed 
function makeWaffleId( number: number ): WaffleId
{
	// ...do stuff
	
	return (number as any) as WaffleId;
}


const willFail: WaffleId = 5 // Type "5" is not assignable to type "WaffleId"

const willWork: WaffleId = makeWaffleId( 5 )