[lomnakkus]

Assuming you're right about the guesses for those parameters, we could go a little further. Let's define

   data Directionality = Clockwise | Anticlockwise

   data AngularInterval = {
     beginAngle :: Double,
     endAngle :: Double,
     directionality :: Directionality
   }

... and then we're down to three parameters, all of different types (so no opportunity for mistakes, assuming static checking) and who knows, you might even have other uses for AngularInterval.