RFC: `with ... yield` replacement

Crystal Contrib
54

Reviewed the list of ideas in this thread again. If we go with using keyword for this I was thinking that we can’t use in , but it looks like it’s not used now?

So maybe we can in fact replace

App.routes do |c|
  c.get :foo 
  c.post :bar 
end

With

App.routes in
  get :foo 
  post :bar 
end

It’s shorter, but to me it looks similar to this @jhass idea

with App.routes do 
  get :foo 
  post :bar 
end