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?

[noordahx]

Hi @LPTK , I am having trouble with function parameter type parsing (seems all of the parameter types are '()' by default)

[noordahx]

NewParser.scala "?" parser -> line

[LPTK]

That code does not make much sense to me. You may have mismerged the conflicts. The code is computing (argName, argOpt) by consuming an identifier, ?, and : tokens. And then it redundantly checks optionality with isOptional – the logic is all messed up. I'm guessing the () might come from consuming the type tokens and then parsing an empty expression (which produces undefined, aka ()), or it could be the later logic to make things optional that's broken. It might be better to start the parsing change from scratch.