Re: Remove Enum from Float and Double
Johan Tibell johan.tibell@... writes: If we truly believe that the instance is dangerous for users (and not merely for people who don't understand floating point arithmetic on computers), then we should add a deprecation pragma to the instance and discourage its use. But what would the deprecation message encourage instead, for users to write an explicit loop that tests against some lower/upper bound? It would have the same problem as enumFromTo. I think the issue here is really that floating point math on computers is hard to think about. The issue is that these instances encourage problematic code. People who know what they're doing can write whatever they want, but we shouldn't be handing out unstable explosives on street corners :-) ___ Haskell-prime mailing list Haskell-prime@haskell.org http://www.haskell.org/mailman/listinfo/haskell-prime
Re: Remove Enum from Float and Double
Tillmann Rendel rendel@... writes: In general, I would be against removing features just because they are confusing for beginners. I don't think that's a good design principle for a language that is primarily targeted at professional programmers and computer scientists. They're confusing to beginners because they don't have consistent or sensible semantics. That should bother the professional programmers and computer scientists too! ___ Haskell-prime mailing list Haskell-prime@haskell.org http://www.haskell.org/mailman/listinfo/haskell-prime
Remove Enum from Float and Double
There have been several discussions over the years regarding Enum instances for Float and Double. The conclusion each time appears to have been that there are no instances which are both sane and practical. I would like to propose that these instances be removed from Haskell 2014. This may be covered by the various alternative prelude and number class proposals, but they are much more ambitious and less likely to make it into the standard in the short term. ___ Haskell-prime mailing list Haskell-prime@haskell.org http://www.haskell.org/mailman/listinfo/haskell-prime
Re: Remove Enum from Float and Double
Johan Tibell johan.tibell@... writes: I don't see much gain. It will break previously working code and the workaround to the breakage will likely be manually reimplementing enumFromTo in each instance. I forgot the main point of my post :-) The primary motivation for removing these instances is that they cause endless confusion for beginners, e.g. http://stackoverflow.com/questions/13203471/the-math-behind-1-0999-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. On the other hand, how much working code is there correctly using there instances? ___ Haskell-prime mailing list Haskell-prime@haskell.org http://www.haskell.org/mailman/listinfo/haskell-prime
