Re: Proposal: add `on` to the Prelude

-1 I find `on` rather handy, but I would prefer that Prelude not claim so many identifiers, especially short ones like this. On Sun, 15 Sep 2019 at 12:18, David Feuer wrote:

I consider equating (and comparing) a bit of an anti-pattern. They're extra names to express what `on` does more generally, and barely save any characters over it

On Sat, Sep 14, 2019, 2:51 PM Erik Hesselink wrote:

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On Fri, 13 Sep 2019 at 13:54, Henning Thielemann wrote:

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On Tue, 10 Sep 2019, David Feuer wrote:

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Every time I reach for Data.Function.on, I feel like a total dolt for having to import a module to get a function whose implementation is barely longer than the import. And it's a really good function too! Can we please add it to the Prelude? on :: (b -> b -> c) -> (a -> b) -> a -> a -> c (.*.) `on` f = \x y -> f x .*. f y

Most of the time I would use this I can use the more specific 'equating' and 'comparing'.

Does 'equating' exist in base now? I've always missed having that function in the past, and defined it myself many times.

Erik

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