draft_composition_utilities.rb

# Copyright 2018 Stanko K.R. <me@stanko.io>
#
# Permission is hereby granted, free of charge, to any 
# person obtaining a copy of this software and associated 
# documentation files (the "Software"), to deal in the 
# Software without restriction, including without limitation 
# the rights to use, copy, modify, merge, publish, distribute, 
# sublicense, and/or sell copies of the Software, and to permit 
# persons to whom the Software is furnished to do so, subject 
# to the following conditions:
#
# The above copyright notice and this permission notice shall 
# be included in all copies or substantial portions of the 
# Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES 
# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT 
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, 
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
# DEALINGS IN THE SOFTWARE.

# This module returns the method of a given class,
# module or object
#
# ```ruby
# require 'json'
# M[JSON].parse # => #<Method: JSON.parse>
# ```
# I would prefere if I could name `M` `&`
# instead and get the following syntax
# `&[JSON].parse`, but this isn't possible
# as far as I'm aware
module M
  class MethodExtractor
    def initialize(parent)
      @parent = parent
    end
    
    protected
    
    attr_reader :parent
    
    private
    
    def method_missing(method_name)
      parent.method(method_name)
    end
  end
  
  def self.[](parent)
    MethodExtractor.new(parent)
  end
end

# This module exposes a top-level `map` method thet's
# easy to compose with other functions.
#
# ```ruby
  # t = 
#   Enum.map { |x| x + 2 } \
#   >> Enum.map { |x| x * 2 }
# t.call([1, 2, 3]) # => [6, 8, 10]
# ```
module Enum
  def self.map(&block)
    -> enum { enum.map(&block) }
  end
end