grammar: optional parens for function calls & definition

[Tuxified]

currently the grammar doesn't allow for function calls & definitions without parens, like: String.split "1, 2", ","

[addcninblue]

I believe that currently implementing this is impossible, since the grammar allows for invalid conflicting configurations, such as "1" "1", which it parses into (source_file (string) (string)). We might be able to require a new line after every statement (which would give us valid Elixir), and the above problem is probably solved by changing the const args to optionalParens.

[Tuxified]

Yes, I think this might be the hardest issue on the list of todos. Semicolons and newlines are valid expression terminators, however some expression span multiple lines, so I don't think it can be solved by "only" changing the const args to optionalParens. But feel free to prove me wrong, I'm not an expert when it comes to building parsers :smile:

[addcninblue]

I've thought about this a lot more, and I cautiously think this might be impossible in the general case.

Consider the case of simply

func

.

We have no idea whether this is a 0-arity function call or a lookup to the variable func. Even the interpreter wouldn't know if it was a variable or a function, as I'm sure we've all seen undefined function func/0 when we misspelled a variable name before!

Perhaps the way to "solve" this problem is to be opinionated -- perhaps we reject all 0-arity functions and only accept 1+ ones. I believe that solving this might give us a cleaner way represent certain things, such as , :do notation, since those are all simply arguments to a macro.