Optional Arguments

[noordahx]

Draft PR:

• Resolved merge conflicts of original PR
• Tests failed at OptionalArgs.mls

  fun f1(a: Int, b: Int) = a + b
  //│ ╔══[ERROR] Type mismatch in operator application:
  //│ ║  l.17:    fun f1(a: Int, b: Int) = a + b
  //│ ║                                    ^^^^^
  //│ ╟── type `()` is not an instance of type `Int`
  //│ ║  l.17:    fun f1(a: Int, b: Int) = a + b
  //│ ║                     ^^^
  //│ ╟── but it flows into reference with expected type `Int`
  //│ ║  l.17:    fun f1(a: Int, b: Int) = a + b
  //│ ╙──                                  ^
  //│ TEST CASE FAILURE: There was an unexpected type error
  //│ fun f1: (a: Int | (), b: Int | ()) -> (Int | error)

[LPTK]

Hi @noordahx, thanks for the PR draft. Do you need some assistance in moving it forward?