How to assign part of a matched pattern to a variable?

[Qiyamah]

Hi,
Here is an example, but it would be nice to have a syntax to (ex = :{P,pattern}) to have the matched part of the expression.

@metafunction collectwheres(member1 where *{params1}) begin
  	member2, params2 = collectwheres(member1)
  	(member2, (params1..., params2...))
end
@metafunction collectwheres(other) begin
  	(other,())
end
@metafunction parse_fn(function(*{args},) where w; *{stmts} end) begin
end

for me to use collectwheres method, i need to assign the matched part of the expression by "function(*{args},) where w;" pattern. So is there a way to assign the matched part to a variable so that i can pass it to collectwheres?

Thanks

[fcard]

I think I understand, but unfortunately julia's syntax rules makes implementing the new syntax difficult. If they were more permissive, we could just do this:

@metafunction parse_fn(function expr; *{stms} end) begin
  fn, wheres = collectwheres(expr)
  #...
end

We can do this somewhat clumsily with :R.

@metafunction parse_fn(:R{:function, expr, begin *{stms} end}) begin
  fn, wheres = collectwheres(expr)
  #...
end

"Named matches" seem worth implementing anyway, even if it's not useful for this particular case.