generic_function_typing.9q8w6e.ts

interface AuthenticationService {
  authenticate<I, O> (body: I): Promise<O>
}

class BasicAuthenticationService implements AuthenticationService {
  async authenticate<I, O> (body: I): Promise<O> {
    const r = { content: "authenticated" }
    return r as O
  }
}

interface IAuthenticateInput {
  code: string
}

interface IAuthenticateOutput {
  content: string
}

async function main () {
  const r = await new BasicAuthenticationService().
    authenticate<IAuthenticateInput, IAuthenticateOutput>({ code: "123456" })
  console.log(r)
}

main()