Warn when using Enum instance for Float or Double
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.
It is therefore proposed that the usage of an Enum instance for Float or Double generate a compiler warning, such as "The Enum instance for Float is subject to rounding errors".
A discussion of this on the libraries list suggested that such a warning would be desired, although the discussion mostly focused on whether the libraries list is an appropriate place for this discussion.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.6.3 |
| Type | FeatureRequest |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
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