You mean

  f'(x) = eml(x,x) + eml(1,eml(eml(1,x)),1) + eml(eml(1, exp(eml(1, 1))),-eml(1, eml(eml(1, x))),1)

and I still have to macroexpand a few

  x-y = eml(eml(1, exp(eml(1, x))), eml(y,1)) 

but I got really bored