(include stdio.h)

(fn sum ((a int) (b int)) int
  (return (+ a b)))

;;; A lambda captures nothing and is a bare function pointer; a closure
;;; captures and is a value carrying its own environment
(fn make-adder ((a int)) (closure ((int)) int)
  (return (closure ((b int)) int (a)
            (return (+ a b)))))

(pub fn main () int
  (var a int 10)
  (var b int 20)
  (var sum-fn (fn ((int) (int)) int) sum)

  (var sum-lambda (fn ((int) (int)) int)

       (lambda ((a int) (b int)) int
         (return (+ a b))))

  (var sum-lambda-2 (fn ((int)) int)

       (lambda ((a int)) int
         (return (+ a 20))))

  (printf "Hello from main fn!\n")
  (printf "We will now perform some function calling.\n")

  (printf "Calling fn ptr: %d\n" (sum-fn a b))
  (printf "Calling lambda: %d\n" (sum-lambda a b))
  (printf "Calling other lambda: %d\n" (sum-lambda-2 a))
  (printf "Calling lambda inplace: %d\n" ((lambda ((a int) (b int)) int
                                            (return (+ a b 100)))
                                          a b))

  (var l-1 (fn ((int)) int)
       (lambda ((a int)) int
         (var l-2 (fn ((int)) int)
              (lambda ((a int)) int
                (return (+ 60 a))))
         (return (+ 600 (l-2 a)))))
  (printf "Calling nested lambdas: %d\n" (l-1 6))

  (var add-10 (closure ((int)) int) (make-adder 10))
  (var add-20 (closure ((int)) int) (make-adder 20))
  (printf "Calling closures: %d %d\n" (add-10 24) (add-20 24))
  (return 0))