Readonly<T> not working

TypeScript Version: 3.3.0-dev.20181208

Search Terms:

Readonly

Code

const a: Readonly<number[]> = [1,2,3]
a[1] = 4

Expected behavior:

Should not let me write.

Actual behavior:

It does.

Playground Link:

Related Issues:

Wesley Wigham (@weswigham)

Wesley Wigham (@weswigham) based on your labels, I suppose this is something that never worked the way I was expecting above?

Ah, I didn't know about ReadonlyArray, that works well:

const a: ReadonlyArray<number[]> = [1,2,3]
a[1] = 4

It should be ReadonlyArray<number> btw :)

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