Partial application that works on all Ruby implementations

partial_application.rb

class Object
  def _(name, *partial_args)
    Proc.new do |*new_args|
      send name, *partial_args.map {|arg| arg == :_ ? new_args.shift : arg}
    end
  end
end

# Practical examples:
[1,2,3].each &_(:puts, :_)
#=> 1\n2\n3\n

[:send, :puts].select &'foo'._(:respond_to?, :_, false)
#=> [:send]

partial_application2.rb

class Object
  def _(name, *partial_args)
    identifier = "a"
    spreads = []
    partials = []
    params = partial_args.map do |arg|
      if arg == :_
        partials << identifier
        spreads << "_"
      else
        spreads << identifier
      end
      (result, identifier = identifier, identifier.succ)[0]
    end
    
    eval <<-PROC
      #{spreads.join(',')} = partial_args
      Proc.new do |#{partials.join(',')}|
        #{name}(#{params.join(',')})
      end
    PROC
  end
end