One step closer to a good pipeline operator for Ruby

I’ve previously yearned for something like Elm and Elixir’s |> operator in Ruby. Turns out, this clever bit of concision is in Ruby 2.5:

object.yield_self {|x| block } → an_object
# Yields self to the block and returns the result of the block.

class Object
  def yield_self
    yield(self)
  end
end

I would prefer then or even | to the verbosely literal yield_self, but I’ll take anything. Surprisingly, both of my options are legal method names!

class Object

  def then
    yield self
  end

  def |
    yield self
  end

end

require "pathname"

__FILE__.
 then { |s| Pathname.new(s) }.
 yield_self { |p| p.read }.
 | { |source| source.each_line }.
 select { |line| line.match /^\W*def ([\S]*)/ }.
 map { |defn| p defn }

However, | already has 20+ implementations, either of the mathematical logical-OR variety or of the shell piping variety. Given the latter, maybe there’s a chance!

Next, all we need is:

  • a syntax to curry a method by name (which is in the works!)
  • a syntax to partially apply said curry

If those two things make their way into Ruby, I can move on to my next pet feature request: a module/non-global namespace scheme ala Python, ES6, Elixir, etc. A guy can dream!

Published by Adam Keys

Telling a joke. Typing.