On Tue, Jun 5, 2012 at 9:51 AM, Warren Harris
On Jun 5, 2012, at 9:38 AM, Johan Tibell wrote:
You want to perform your test as
d1 - d2 < epsilon
What's the best way to do this though, since aeson's Value type already provides instance Eq? I guess I can write my own suite of equality comparisons, but these aeson values are the leaves of an extensive grammar and it seems a shame to mimic everything that Eq does (without the benefits of deriving) just to compare doubles differently.
I don't think applying == to something that contains floating point values at the leaves makes much sense. You want some approxEq function that uses approximate equality on floating point value or you want to equality function that ignores the floating point values. Probably not the answer you like, but I don't know how to define Eq in a robust way for types that include floating point values. -- Johan