pass arguments to spawn

[kostya]

would be nice if this works:

x = rand < 0.5 ? 1 : nil

spawn(args: {x}) do |x|
  p(x + 1) if x
end

p(x + 1) if x 

sleep 0.1

because right now i cant just compare with if x, i should write this, which is noise in big code:

x = rand < 0.5 ? 1 : nil

spawn do
  if y = x
    p y + 1
  end
end

if y = x
  p y + 1
end

sleep 0.1

[asterite]

I think the compiler should just be a bit smarter and notice that x doesn't change, so if x should just work

[asterite]

Closing as duplicate of #3093 (which describes the problem in a better way)