

      \ Correct way, using stack manipulation

    
: fibonacci ( fib -- return ) recursive


   dup 2 >= if
                 ( fib )

    
      dup 1- fibonnaci         ( fib fib-1 )


      swap 2 - fibonnaci       ( fib-1 fib-2 )

            +                        ( fib )

         then                        ( fib )

      ;

    
\ Incorrect way - using variable "fib", which will get
      overwritten during recursion

    
0 value fib;


: fibonnaci ( fib -- return ) recursive


   to fib                     
\ to avoid stack
      manipulation

         fib 2 < if

            fib exit

         then

         fib 1- fibonnaci           ( fib-1)

         fib 2 - fibonnaci          ( fib-1 fib-2 )

         +                          ( fib )

      ;