Attempt to implement a Pipe operator-like behavior in Crystal

cr_chainable_methods.cr

# this was copied from https://carc.in/#/r/fg2
# thanks to @waterlink from this issue thread https://github.com/crystal-lang/crystal/issues/1388
module CrChainableMethods
  module Pipe
    macro pipe(ast)
      {% uast = ast.stringify.gsub(/ >>/, ".pipe").id %}
      {% pp uast %}

      {% if uast.stringify != ast.stringify %}
        pipe {{uast}}
      {% else %}
        {% if ast.name.id == "pipe".id %}
          {% if ast.args.first.receiver.is_a?(Nop) %}
            {% pp ast.args.first %}
            {{ast.args.first.name}}({{ast.receiver}}, {{ast.args.first.args.argify}})
          {% else %}
            pipe {{ast.args.first.receiver.name}}({{ast.receiver}}, {{ast.args.first.receiver.args.argify}}).pipe {{ast.args.first.args.argify}}
          {% end %}
        {% else %}
          {{ast}}
        {% end %}
      {% end %}
    end

    macro included
      #FIXME this should be used as the last call in the chain if the previous call explicitly calls from a module such as:
      # .>> Foo.method .>> unwrap
      # Still don't know why the ast parsing works ok for just .>> method but fails for .>> Foo.method
      def self.unwrap(foo)
        foo
      end
    end
  end
end

module Foo
  include CrChainableMethods::Pipe

  def self.split_words(phrase)
    phrase.split(" ")
  end

  def self.append_message(words, message)
    words + [message]
  end

  def self.join(words)
    words.join(" - ")
  end

end

module Bar
  def self.add_something(words)
    words + ["something"]
  end
end

module Foo
  # for some reason I am unable to make the chain from outside the context of the module
  # I can't even create another module and include Foo, for example
  # this example explicitly name the Module (Foo.split_words) but it's not necessary, but if I do so
  # I need to add the #unwrap method as the last in the chain
  # I'd like to see if I can mix and match methods from different modules
  def self.workflow
    pipe "Hello World"
      .>> Foo.split_words
      .>> Foo.append_message("Bar")
      .>> Bar.add_something # mixing this in doesn't work
      .>> Foo.join
      .>> unwrap
  end
end

puts Foo.workflow