Reified Object#send

send.rb

class Send
  class << self
    def method_missing meth, *holes_or_args, &block
      do_send = -> args {
        -> receiver {
          receiver.__send__(meth, *args, &block)
        }
      }
      if holes_or_args.any? { |hoa| hoa == Hole }
        -> *args_for_holes {
          actual_args = holes_or_args.map { |hoa| hoa == Hole ? args_for_holes.shift : hoa }
          do_send[actual_args]
        }
      else
        do_send[holes_or_args]
      end
    end
  end
end

# TYMOWTDI: `data Hole = Hole` translated to Ruby
class Hole; end

class Object
  def receive
    yield self
  end
end

# This script should invoked by spec command
describe 'usage' do
  example 'simple send/receive' do
    twice_all = Send.map { |n| n * 2 }
    [1,2,3].receive(&twice_all).should == [2,4,6]
  end
end

describe 'holes' do
  it 'is left for arguments' do
    zero_pad = Send.rjust(Hole, '0')
    "foo".receive(&zero_pad[10]).should == "foo".rjust(10, '0')
  end

  it 'should be filled different arguments each time' do
    to_i = Send.to_i(Hole)
    "10".receive(&to_i[10]).should == "10".to_i(10)
    "10".receive(&to_i[16]).should == "10".to_i(16)
  end
end