immutability - SML-Functional Programming -

i want write code in sml mimics of c++ like

i=i+1; 

or

i++ 

in short want count how many times loop(recursion) running when if statement true. elucidating further. problematic code looks this:

val = 0; fun <function_name>() =     if <condition>    (i+1;          <recursive_expression>)   else expression 

but problem here answer 1 no matter how many times recursion performed due immutability in sml/nj.

any ideas helpful!

since didn't post whole code, created simple 1 here:

fun evens(int_list: int list) =     let fun evens_helper(int_list: int list, times: int) =     if null int_list     times         else if null (tl int_list)              if (hd int_list) mod 2 = 0         1         else 0     else if (hd int_list) mod 2 = 0     1 + evens_helper(tl int_list, times + 1)     else evens_helper(tl int_list, times)     in evens_helper(int_list, 0)     end 

to need, simplest thing create helper function inside function, exact same thing original function, take 1 argument more (your counter). if counter should activated, call recursive call counter +1. if dont want activated, call recursive function using same counter value.

if don't yet, post whole code, can see it.