lineSegment :: Point' Double -> Point' Double -> Curve
lineSegment (Point xa ya) (Point xb yb) = line xa ya xb yb
lineSegment :: Point' Double -> Point' Double -> Curve
lineSegment (Point xa ya) (Point xb yb) = line xa ya xb yb
lineSegment (Point xa ya) (Point xb yb) = line xa ya xb yb