Re: WARNING pragmas in `Prelude.undefined` and `Prelude.error`

I am missing some context of this discussion, but if this is the question of whether using `undefined` and `error` can be legitimate, yes they can. If you know your invariants, you might want to write fromMaybe undefined $ lookup key map or Map.findWithDefault undefined key map knowing you put the key into the map and the lookup cannot fail. On 2019-12-22 13:15, Zemyla wrote:

The most common legitimate usage for undefined I have is strictness:

func x y | x `seq` False = undefined func x y = ...

There's nothing else that would go there, and when it's compiled, the reference to undefined disappears.

On Sun, Dec 22, 2019, 05:50 chessai . mailto:chessai1996@gmail.com> wrote:

Right, it's been discussed before IIRC, and i know I've certainly given it passing thoughts. I think this isn't worth it because of breakage. Many people use -Wall -Werror, so I see this as a no-go.

Thanka

On Sun, Dec 22, 2019, 6:45 AM Vilem Liepelt mailto:vliepelt@futurefinance.com> wrote:

Has there been any discussion about adding WARNING pragmas to `Prelude.undefined` and `Prelude.error`, as done in some custom preludes?

I suppose this hasn't been done yet to avoid breaking existing code which makes "legitimate" use of those helpers? _______________________________________________ Libraries mailing list Libraries@haskell.org mailto:Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries

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