Type compatibility

[DanTsk]

Is there any way to check that two types are compatible? For example, when object literal compatible with interface definition in function argument.

[DanTsk]

Like this.

interface Named {
    name: string;
}

class Person {
    name: string;
}

let p: Named;
// OK, because of structural typing
p = new Person();

Is there any function/util to check that Person and Named types are compatible?

[dsherret]

See #357. Basically no because the compiler API does not expose that yet.

[ChristianIvicevic]

Just chiming in to the question since I was curious. @DanTsk What is your actual intention with that compatibility check? Types in TS are transparent by default and Microsoft unfortunately hasn't implemented a dedicated opaque keyword. If you want to prevent this semantically wrong assignment in code, so even before writing a static analyzer, you can use a helper such as this:

type Opaque<T> = T & { readonly __opaque: unique symbol };