keyword_argument_currying.rb

#
#               Please don't use this in any Ruby library or code.
#  This is for proof-of-concept purposes only and will break Ruby functionality
#

class Proc
  alias :greedy_curry :curry
  
  def curry
    if self.has_kwarg_parameters?
      -> **kwargs {
        if kwargs.length == kwarg_parameters.length
          self[**kwargs]
        else
          -> **more_kwargs {
            self[kwargs.merge more_kwargs]
          }
        end
      }
    else
      greedy_curry
    end
  end
  
  def kwarg_parameters
    self.parameters.select {|(p,_)| p == :keyreq || p == :key || p == :keyrest}
  end
  
  def has_kwarg_parameters?
    self.parameters.find {|(p,_)| p == :keyreq || p == :key || p == :keyrest}
  end
end

print_name = -> first:,last: {puts "#{last}, #{first}"}

print_name.curry[first: "Jim", last: "Smith"]
#=> Smith, Jim
print_name.curry[last: "Smith", first: "Jim"]
#=> Smith, Jim
print_name.curry[first: "Jim"][last: "Smith"]
#=> Smith, Jim
print_name.curry[last: "Smith"][first: "Jim"]
#=> Smith, Jim

# This version only works two calls deep, but with recursion could be made more robust.