I am trying to write an interface for a specific function that will take in an object and perform some intended functionality. I would like to type the input to ensure it follows a specific shape.

When I go to build such an interface, I would expect my code to work, but at compile it complains, “Type ‘string’ is not assignable to type ‘”message”‘.”

interface BodyInterface {
    settings?: any;
    body?: Array<Message>;
}

interface Message {
    type: MessageTypeType;
    text: string;
}

type MessageTypeType = "message";

const inputBody = {
    body: [
        {
            type: 'message',
            text: 'hello world'
        }
    ]
}

const caller = (body: BodyInterface) => {
    console.log(body)
}

caller(inputBody)

How can I declare this interface so that the body is expected to be an Array with contents that are objects with type: 'SOME_EXPLICIT_VALUE'?