program move_to_front;
    tests := ["broood", "bananaaa", "hiphophiphop"];
    alph := "abcdefghijklmnopqrstuvwxyz";

    loop for test in tests do
        e := encode(test, alph);
        d := decode(e, alph);
        v := if test = d then "(ok)" else "(fail)" end;
        print(test,"->",e,"->",d,v);
    end loop;

    proc encode(s, alph);
        enc := [];
        loop for c in s do
            [i, j] := mark(alph, c);
            alph := c + alph(..i-1) + alph(j+1..);
            enc with:= i-1;
        end loop;
        return enc;
    end proc;

    proc decode(ls, alph);
        s := "";
        loop for i in ls do
            c := alph(i + 1);
            s +:= c;
            alph := c + alph(..i) + alph(i+2..);
        end loop;
        return s;
    end proc;
end program;