-- local functions with free variables
module test015;

import Stdlib.Prelude open;

terminating
f : Nat → Nat → Nat
  | x :=
    let
      g (y : Nat) : Nat := x + y;
    in if
      | x == 0 := f 10
      | else := ite (x < 10) λ {y := g (f (sub x 1) y)} g;

g (x : Nat) (h : Nat → Nat) : Nat := x + h x;

terminating
h : Nat → Nat
  | zero := 0
  | (suc x) := g x h;

main : IO :=
  printNatLn (f 100 500)
    >>> -- 600
      printNatLn
      (f 5 0)
    >>> -- 25
      printNatLn
      (f 5 5)
    >>> -- 30
      printNatLn
      (h 10)
    >>> -- 45
      printNatLn
      (g 10 h)
    >>> -- 55
      printNatLn
      (g 3 (f 10));