I was implementing automatic differentiation in haskell and was able to code the calculation part, but I wanted to extend it to show the symbols instead of just the final value. Let me explain and copy/paste the code… 3 data ADif a = ADif a a deriving (Eq) 10 instance Floating x => Floating (ADif x) where 11 pi = ADif pi 0 12 exp (ADif x x') = ADif (exp x) (x' * exp x) 13 log (ADif x x') = ADif (log x) (x' / x) 14 sqrt (ADif x x') = ADif (sqrt x) (x' / (2 * sqrt x)) 15 sin (ADif x x') = ADif (sin x) (x' * cos x) 16 cos (ADif x x') = ADif (cos x) (x' * (- sin x)) ….And so on all the functions 27 instance Num x => Num (ADif x) where 28 ADif x x' + ADif y y' = ADif (x+y) (x'+y') 29 ADif x x' * ADif y y' = ADif (x*y) (y'*x + x'*y) 30 fromInteger x = fromInteger x let myfunction x = exp (log (sin x)) *Main> myfunction (ADif 2 1) -0.4161468365471424 I verified that this is the correct solution by hand! (& well mathematica too!) Anyway now I was hoping to print the actual symbols, so I was googling around for extending “Show” typeclass for floating and Num, kinda similar pattern. Is this the right approach? Or I need to rethink the problem? Basically my aim is to do something like mathematica where if I specify D[f[x],x] then I get the answer in symbols. -Animesh