gistfile1.hs

solveQuadratic :: Double -> Double -> Double -> Intersections
solveQuadratic a b c = 
  case compare discr 0.0 of 
    LT -> [] 
    EQ -> [-b / (2 * a)]
    GT -> [abc (-), abc (+)]
  where discr  = b ^ 2 - 4 * a * c
        abc op = (-b `op` sqrt discr) / (2 * a)

-- vs

solveQuadratic :: Double -> Double -> Double -> [Double]
solveQuadratic a b c = 
  case compare discr 0.0 of 
    LT -> [] 
    EQ -> [-b / (2 * a)]
    GT -> [abc (-), abc (+)]
  where discr  = b ^ 2 - 4 * a * c
        sqrtdiscr = sqrt discr
        a2 = 2*a
        abc op = (-b `op` sqrtdiscr) / a2