Oh, I see. Sorry. I totally misunderstood the proposal. I should have read more carefully.

I think undefined and error are useful functions to have, so why adding WARNING to them? For example, you can fold an infinite structure `xs` with `foldr f undefined xs` (for some proper `f`) without needing to define or look for an alternative to `Data.Foldable.foldr`.

Am Mo., 23. Dez. 2019 um 17:33 Uhr schrieb Vilem Liepelt <vliepelt@futurefinance.com>:

> On 23 Dec 2019, at 18:10, Daniel Díaz Casanueva <dhelta.diaz@gmail.com> wrote:
>
> Some warnings are not included in -Wall (for instance -Wincomplete-uni-patterns). New warning flags can be added without breaking any code.

Agreed, Daniel, but if we added a warning/deprecation pragma to the library (which is what I had asked about), then this would get triggered by -Wdeprecations which is part of -Wall. I'm not sure adding a flag specifically for usages of `error`/`undefined` makes much sense. E.g. what if I bind those names to genuine values?