Alternative implementation of codequest-eu/codequest_pipes :-)

piglet.rb

class Trough < Array
  alias_method :|, :push

  def call(context)
    reduce(context) do |ctx, pig|
      pig.new(ctx).call
      ctx
    end
  end
end

class Pig
  def initialize(context)
    @context = context
  end

  def self.|(other)
    Trough.new.push(self).push(other)
  end

  private

  attr_reader :context
end

def Closure(&block)
  Class.new(Pig) { define_method(:call, &block) }
end

run.rb

require './piglet.rb'

class Chrum < Pig
  def call
    puts 'chrum chrum'
    context[:chrumed] = true
  end
end

class Oink < Pig
  def call
    puts 'oink oink'
    context[:oinked] = true
  end
end

TROUGH = Chrum |
         Oink  |
         Closure {
           puts 'snort snort'
           context[:snorted] = true
         }

input_context = {}
puts input_context.inspect
output_context = TROUGH.call(input_context)
puts output_context.inspect

You're missing pre- and postconditions!

that's true and intentional, not worth wasting more time on this :) if you want to improve my pig farm, feel free to update Trough#call :)