Feature request: Parse multiple lines between parentheses without commas for macros

[jkrumbiegel]

In Chain.jl I currently offer this syntax:

@chain df begin
	function_1
	function_2(x)
end

Sometimes I think that because the purpose of the package is to reduce complexity / redundancy as much as possible, I'd like this to work:

@chain df (
	function_1
	function_2(x)
)

# or alternative syntax

@chain(
	df
	function_1
	function_2(x)
)

The problem is that multiple lines between parentheses are not allowed, this gives a syntax error due to missing commas. I don't want commas because each line is a separate expression and not an argument to a function. What does work, but what I don't want to use because it looks weird, is this for example:

@chain {
	df
	function_1
	function_2(x)
}

@chain [
	df
	function_1
	function_2(x)
]

I think it would be reasonable to parse the syntax for usage in macros, this wouldn't break existing code. I believe this is a kind of natural extension for macros, because we already break normal syntax rules for macros a little bit by parsing this as one expression:

@somemacro arg1 arg2 begin
	something_long
end even_more trailing_arguments