fibonacci.neo

-- neoscript example: Fibonacci

using neos.string;
using neos.stream;

import fn to_string(x : i32) -> string;
import fn to_integer(s : string) -> i32;
import proc input(s : out string);
import proc print(s : in string);

-- functions are pure
def fn add(x, y : i32) -> i32
{
    return x + y;
}
def fn fib(x : i32) -> i32 
{
    if (x < 2) 
        return 1; 
    else
        return add(fib(x-1), fib(x-2));
}

-- procedures are impure
def proc main()
    s : string;
{
    print("Enter a positive "
            "integer: ");
    input(s);
    print("Fibonacci(" + s + ") = " + to_string(fib(to_integer(s))) + "\n");
}