hi, i wrote a function wich works as expected but i don't understand why the output is like that.

function

datatype prop = Atom of string | Not of prop | And of prop*prop | Or of prop*prop;


(* XOR = (A And Not B) OR (Not A Or B) *)

local

fun do_xor (alpha,beta) = Or( And( alpha, Not(beta) ), Or(Not(alpha), beta))

in
fun xor (alpha,beta) = do_xor(alpha,beta);
end;

test

val result = xor(Atom "a",Atom "b");

output

val result = Or (And (Atom #,Not #),Or (Not #,Atom #)) : prop

thanks again (specially zeuxcg)