this is incredible...

I haven't used it but eslint-plugin-functional might work for this. Let me know if you try it.

TypeScript has something similar, but it's not the default. In other words, if you want an array to be readonly, you have to manually annotate that.

Does Flow have a way to make readonly the default?

Makes sense. I'd love this to be built in but I understand why they haven't landed that.

Oh, interesting. Is there any documentation for how this works?

Love to see all these patterns codified in one place. I had hoped to be able to make these the default—so you didn't need to do these patterns—but I'll stick with these for now. Thanks for sending!

I enjoy how much I hate it...

your username is....so good.... this is a great honor