generic-context.ts

interface Injectable<TContext, Tokens extends (keyof TContext)[], R> {
    new(...args: CorrespondingTypes<TContext, Tokens>): R;
    inject: Tokens;
}
type CorrespondingTypes<TContext, Tokens extends (keyof TContext)[]> = {
    [Token in keyof Tokens]: Tokens[Token] extends keyof TContext ? TContext[Tokens[Token]] : never;
}
class Injector<TContext> {
    inject<Tokens extends (keyof TContext)[]>(injectable: Injectable<TContext, Tokens, R>): R {
        /* out of scope */
    }
}