--prop_angleToUnitVector_0   = let (x,y) = angleToUnitVector   0 in allClose x 1.0    && allClose y 0.0
--prop_angleToUnitVector_90  = let (x,y) = angleToUnitVector  90 in allClose x 0.0    && allClose y 1.0
--prop_angleToUnitVector_180 = let (x,y) = angleToUnitVector 180 in allClose x (-1.0) && allClose y  0.0
--prop_angleToUnitVector_270 = let (x,y) = angleToUnitVector 270 in allClose x 0.0    && allClose y (-1.0)

-- `main` is here so that this module can be run from GHCi on its own.  It is
-- not needed for automatic spec discovery.
main :: IO ()
main = hspec spec
main :: IO ()
main = hspec spec
main = hspec spec