toUrlPiece and parseUrlPiece are not reversible

[roelvandijk]

x :: Double
x = 9.0e3

t :: Text
t = toUrlPiece x 
-- t == "9.0e-3"

x' :: Either Text Double
x' = parseUrlPiece t
-- x' == Right 9.000000000000001e-3

isReversible :: Bool
isReversible = Right x == x'
-- isReversible == False

The underlying issue is probably in rational :: Fractional a => Reader a not being compatible with show :: Double -> String.