main = print $
  mybmicalculator 185 75
mybmicalculator :: (RealFloat a) => a -> a -> String
mybmicalculator weightinpound heightininches
    | bmivalue <= 18.5 = "You're underweight"
    | bmivalue <= 25.0 = "You're supposedly normal"
    | bmivalue <= 30.0 = "You're overweight"
    | otherwise     = "You're obese"
    where bmivalue = weightinpound / (heightininches) ^ 2  * 703