Util/ApproxEq.hs

   1 module Util.ApproxEq where
   2 import Data.Eq.Approximate
   3 import Data.Function (on)
   4 import TypeLevel.NaturalNumber
   5
   6 type RelApproxDouble =
   7   RelativelyApproximateValue (Digits Twelve) (Digits Eight) Double
   8 wrapRelAD :: Double -> RelApproxDouble
   9 wrapRelAD = RelativelyApproximateValue
  10 unwrapRelAD :: RelApproxDouble -> Double
  11 unwrapRelAD = unwrapRelativelyApproximateValue
  12
  13 infix 4 ~~=
  14 class RelApproxEq a where
  15   (~~=) :: a -> a -> Bool
  16
  17 instance RelApproxEq Double where
  18   (~~=) = (==) `on` wrapRelAD
  19
  20 instance RelApproxEq a => RelApproxEq (Maybe a) where
  21   Nothing ~~= Nothing  = True
  22   Just x  ~~= Just y   = x ~~= y
  23   _       ~~= _        = False
  24