Use `TypeError` instances instead of current yaya-unsafe instances

[sellout]

Right now, using instances from yaya-unsafe is very dangerous. They’re imported transitively, so once you include them, they’re available everywhere downstream.

Instead, all the instance from that package should be part of yaya proper as negative instances (using TypeError¹). Then, yaya-unsafe should define newtype Unsafe and wrap all its existing instances in that newtype. Then, users can access them by wrapping the fixed-point in Unsafe without worrying about inflicting them on users further downstream.

Footnotes

1. The error message should recommend yaya-unsafe’s Unsafe wrapper as a last resort after considering if you really need that operation. ↩