import "StandardLibrary"

mapping relation Fib Integer Integer

rule FibRecurrence where
    @when
    Fib ?n ?a
    Fib (?n+1) ?b
    ?n < 20
    
    @where
    Fib (?n+2) (?a + 1)

rule PrintIt where
    @when
    Fib ?n ?a
    
    @to
    Execute (print "\(?n) -> \(?a)")

main = transformation OneShotForward where
    Fib 0 1
    Fib 1 1
--
21 -> 11
20 -> 11
19 -> 10
18 -> 10
17 -> 9
16 -> 9
15 -> 8
14 -> 8
13 -> 7
12 -> 7
11 -> 6
10 -> 6
9 -> 5
8 -> 5
7 -> 4
6 -> 4
5 -> 3
4 -> 3
3 -> 2
2 -> 2
1 -> 1
0 -> 1
()