Demo of type inference of local variables through concurrently ran fibers

arcane_lvar.cr

waiter = Channel(Nil).new
var = "Hello"

spawn do
  waiter.receive
  var = 5
end

puts "var is a #{typeof(var)}"
puts "var right now is a #{var.class}"
waiter.send(nil)
puts "var right now is a #{var.class}"