Convert Proc object to a block

Ruby methods like yield or instance_eval accept only block not Proc object. In order to use instance_eval in inner method, we need to convert Proc to block, the syntax is pretty simple just precede Proc object with ampersand.

def m1 &block
  m2 &block
end

def m2 
 yield
end

m1 {puts "hello"} # hello

a = Proc.new {puts "world"}

m2 &a # world

def m3 block
  instance_eval &block
end

m3 a # world