FracNum

FracNum.hs

instance Num Fraction where
  (-) f f'                  = f + (negate f')
  (+) (Frac a b) (Frac c d) = Frac num denom
    where denom = lcm b d
          num   = a * (denom `quot` b) + c * (denom `quot` d)
  (*) (Frac a b) (Frac c d) = Frac (a*c) (b*d)
  negate (Frac a b)         = Frac (-a) b
  abs f                     = fmapF abs f
    where fmapF f (Frac a b) = Frac (f a) (f b)
  fromInteger x             = Frac x 1
  signum (Frac a b)         = if a == 0 then 0
                              else if b > 0 then
                                if a < 0 then (-1)
                                else 1
                              else if a < 0 then 1
                              else (-1)