I'm not exactly sure what you mean by preserve order, but no, Doubles would
not behave as expected in an EnumMap because fromEnum for Doubles just
truncates:
fromEnum (2.0 :: Double) == 2
fromEnum (2.5 :: Double) == 2
However I think that is more an issue with the Enum instances than with
EnumMap.
I really don't think Double should be an instance of Enum. (or if it is, it
should actually _enumerate_ the values)
It's basically just there for the list comprehension syntax.
take 5 [1.0 ..] :: [Double] == [1.0,2.0,3.0,4.0,5.0]
But I feel like that would be better handled with Num instances or
something, or with a separate typeclass.
- Job
On Mon, Aug 10, 2009 at 1:37 PM, Louis Wasserman
Pardon my asking, but are fromEnum and toEnum guaranteed to preserve order on types like Double? I'd like to see a Double-backed Patricia tree map, but are we certain that EnumMap as presented will behave properly on such types?
Louis Wasserman wasserman.louis@gmail.com
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