Seven language "Io" p61

fib.io

// Seven language "Io" day2 Q1
// fib

fib_recur := method(if((call sender doMessage(call message argAt(0))) == 1, 1,
              if((call sender doMessage(call message argAt(0))) == 2, 1,
              fib_recur( (call sender doMessage(call message argAt(0))) -1) +
              fib_recur( (call sender doMessage(call message argAt(0))) -2))))

(fib_recur(1) == 1 and
 fib_recur(2) == 1 and
 fib_recur(3) == 2 and
 fib_recur(4) == 3 and
 fib_recur(5) == 5 and
 fib_recur(6) == 8 and
 fib_recur(7) == 13 and
 fib_recur(8) == 21) println


fib_loop := method(
  arg := (call sender doMessage(call message argAt(0)));
  x := 1;
  //x println;
  if(arg == 1, x, 
  y := 1;
  //y println;
  if(arg == 2, y,
  for(i, 3, arg, 1, z := x; x := y; y := z + y; /*y println*/);
  y)))

(fib_loop(1) == 1 and
 fib_loop(2) == 1 and
 fib_loop(3) == 2 and
 fib_loop(4) == 3 and
 fib_loop(5) == 5 and
 fib_loop(6) == 8 and
 fib_loop(7) == 13 and
 fib_loop(8) == 21) println