Piped Ruby

-> { "Pipe" }.| { |e| "#{e} things"  }
             .| { |e| "#{e} in Ruby!" }
             .unwrap #=> "Pipe things in Ruby!"

Piped Ruby is a tiny piece of code that aims to bring the beauty of pipe operators and data transformation to your Ruby application.

Credit to Elixir's Pipe Operator and Chainable Methods gem which were the source of inspiration for this gem :-)

Installation

Add this line to your application's Gemfile:

gem 'piped_ruby'

And then execute:

$ bundle

Or install it yourself as:

$ gem install piped_ruby

And require the gem manually:

require 'piped_ruby'

Usage

With Piped Ruby doing this:

-> { some_text.upcase }.>> { |e| MyModule.method_a(e)  }
                       .>> { |e| MyModule.method_b(e, "something") }
                       .>> { |e| MyModule.method_c(e) { |c| do_something3(c) } }
                       .unwrap

...is equivalent to this:

a = some_text.upcase
b = MyModule.method_a(a)
c = MyModule.method_b(b, "something")
d = MyModule.method_c(c) { |c| do_something3(c) }

More examples

Exporting clients from CSV file:

#...
def call
  File.foreach(file) do |line|
    -> { values_from(line) }
      .>> { |e| match_fields_for(e) }
      .>> { |e| sanitize(e) }
      .>> { |e| Save.new(attributes: sanitize(e)) }
      .>> { |save| save.call }
      .unwrap
  end
end

Fun with strings:

module Foo
  class << self
    def number; 1 end
    def answer(x); "So the answer of the life, the universe and everything is... #{x}!" end
  end
end

-> { Foo.number }.>> { |e| e + 1 }
                 .>> { |e| e * 21 }
                 .>> { |e| Foo.answer(e) }
                 .>> { |e| e + ' :-)' }
                 .unwrap #=> "So the answer of the life, the universe and everything is... 42! :-)"

Backstage

Pipe operations happen between Proc objects (blocks). After requiring the gem every Proc in your Ruby program will be capable to start a pipe operation.

operation = -> { 'Foo' }.>> { |e| "#{e}bar" }
operation.class #=> Proc
operation.unwrap #=> "Foobar"

The PipedRuby#unwrap method is the way to get the returning value from the last evaluated block:

operation = -> { 'Foo' }.>> { |e| "#{e}bar" }
operation.>> { |e| puts e } #=> Prints "Foobar" and returns a Proc object
operation.>> { |e| puts e }.unwrap #=> Prints "Foobar" and returns nil

TODO

• [ ] Write more cool examples in README;
• [ ] Introduce something similar to Elixir's Streams;
• [ ] Store Procs and be able to unwrap a returning value in different points of execution.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/piped_ruby. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.