Why doesn't typescript enforce readonly keyword and prevent us from passing a read only property into non readonly one, that's defy the point 

```
let foo: {
    readonly bar: number;
} = {
        bar: 123
    };

function iMutateFoo(foo: { bar: number }) {
    foo.bar = 456;
}

iMutateFoo(foo); // The foo argument is aliased by the foo parameter
console.log(foo.bar); // 456!```

```