I don't think it would be that hard to add DEPRECATE for instances. A bit fiddly, and what should the syntax be.. but not really hard. I can offer advice if someone wants to undertake it. It's a cost/benefit question: how often will it be used? Simon | -----Original Message----- | From: libraries-bounces@haskell.org [mailto:libraries- | bounces@haskell.org] On Behalf Of Henning Thielemann | Sent: 16 June 2013 10:12 | To: harry | Cc: libraries@haskell.org | Subject: Re: Proposal: Warn when using Enum instance of Float or Double | | | On Sun, 16 Jun 2013, harry wrote: | | > The Enum instances for Float and Double have dubious semantics which | cause | > endless confusion, e.g. | > http://stackoverflow.com/questions/13203471/the-math-behind-1- | 0999999999999999-in-haskell, | > http://stackoverflow.com/questions/9810002/floating-point-list- | generator, | > http://stackoverflow.com/questions/7290438/haskell-ranges-and-floats, | > http://stackoverflow.com/questions/10328435/how-to-solve-floating- | point-number-getting-wrong-in-list-haskell, | > and many more. | > | > I would therefore like to propose that the usage of an Enum instance | of | > Float or Double generate a compiler warning, such as "The Enum | instance of | > Float is subject to rounding errors". Deadline: 2 weeks. | | I would also like to see these instances be removed or deprecated. | Unfortunately, GHC currently does not allow to DEPRECATE an instance. | With | this feature one might also tag intentionally omitted instances, like | Num | instance for (or 'of' :-) functions: | http://hackage.haskell.org/trac/ghc/ticket/7775 | | _______________________________________________ | Libraries mailing list | Libraries@haskell.org | http://www.haskell.org/mailman/listinfo/libraries