not necessarily ... there could be  contradictory sets of methods! :) 

like the minimal sets for Field type class,  the xor would be for defining '/' in terms of reciprocal and times or vice versa (/ vs recip) and likewise (negate vs minus) etc etc

On Wed, Oct 27, 2021 at 6:38 AM Henning Thielemann <lemming@henning-thielemann.de> wrote:

On Mon, 25 Oct 2021, Carter Schonwald wrote:

> i agree with Tom and Hecate,more strongly: 
>  https://github.com/ghc/ghc/blob/98aa29d3fe447cce3407e6864b015892244bb475/libraries/ghc-prim/GHC/Classes.hs#L142-L150 
> the current definition DOES NOT require defining both. 
>
> as it currently stands, you only need to define one of '==' XOR  '/='
>
> this actually suggests an interesting and DIFFERENT ecosystem improvement, (ignoring IEEE non-signalling NANs),
> namely we add support for XOR to minimal pragma syntax and issue a warning 
>
> perhaps something like adding (XOR "reason String" clauseExpr1 clauseexpr2) ?

The problem of implementing two methods in a contradictory way arises for
any OR in MINIMAL pragma, right?

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