Re: Proposal: add 'equating' function to Data.List

I didn't mean to preëmpt the whole discussion thread -- I'd rather let that play out, but I just wanted to express where my personal opinion lies on this matter. Data.Eq does sound like the right place for it, if we do go to put it in. -Edward

On Jul 19, 2014, at 8:50 AM, Alexander Berntsen wrote:

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256

...

On 19/07/14 14:44, Edward Kmett wrote: I'm ever so slightly +1 on this proposal.

Why? Because it gets reinvented every 4 months, and by just adding it we can stop having this discussion.

I hereby proposed there exists a "co-Fairbairn threshold", the point at which the traffic caused by fighting against adding a commonly reinvented simple composition outweighs the pedagogical gain of pushing people to understand the simpler parts. OK, you have me convinced. You should put these thresholds of yours on the GHC Wiki or something. ;-)

...

That said, I'd prefer it live alongside comparing, and not get pushed redundantly around to other modules. I suggest: equating :: Eq a => (b -> a) -> b -> b -> Bool equating p x y = (p x) == (p y)

in Data.Eq, exposing it with

module Data.Eq ( Eq(..), ) where

If this sounds good I can write a patch for it, test it & upload it to phab to have it built & reviewed by austin and you. :-) - -- Alexander alexander@plaimi.net https://secure.plaimi.net/~alexander -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/

iF4EAREIAAYFAlPKaZ8ACgkQRtClrXBQc7WqgwEAgmlzkK+/JdsGDZ2OabyNPE8W y2zffqFTvus/GYO1S00BAKC3ncHM5R01sgrZfE8BhstzNNQ3JnTF5CoReBUedc4R =u6pc -----END PGP SIGNATURE----- _______________________________________________ Libraries mailing list Libraries@haskell.org http://www.haskell.org/mailman/listinfo/libraries