ts-tagged
v1.0.0
Published
Base generic type for weak nominal typing in Typescript
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ts-tagged
Defines the Tagged<T, N>
generic type letting you created tagged types with base type T
and name N
.
Two variables of a tagged type can only be assigned to each other if they have the same base type and name.
This implements a weak form of nominal typing suitable for types shared across multiple packages.
Installation
npm install -S ts-tagged
Example
import { Tagged } from "ts-tagged";
type Email = Tagged<string, "Email">;
type DisplayName = Tagged<string, "DisplayName">;
const email: Email = "[email protected]";
const displayName: DisplayName = "Foo Bar";
function sendEmail(recipient: Email) {
// ...
}
sendEmail(email); // OK
sendEmail(displayName); // Compilation error: the names don't match
sendEmail("[email protected]"); // OK: Unnamed, but the base type matches
sendEmail(42); // Compilation error: The base type does not match