robmiller/transproc

Transform Ruby objects in functional style

Transproc

Transproc is a small library that allows you to compose methods into a functional pipeline using left-to-right function composition. It works like |> in Elixir or >> in F#.

It's currently used as the data mapping backend in Ruby Object Mapper.

Installation

Add this line to your application's Gemfile:

gem 'transproc'

And then execute:

$ bundle

Or install it yourself as:

$ gem install transproc

Usage

require 'json'
require 'transproc/all'
require 'inflecto'

# create your own local registry for transformation functions
module Functions
  extend Transproc::Registry
end

# import necessary functions from external modules
module Functions
  # all transformations available in the imported module
  import Transproc::HashTransformations
  import Transproc::ArrayTransformations

  # only specific transformation (renamed into the desired local name)
  import :camelize, from: Inflecto, as: :camel_case
end

def t(*args)
  Functions[*args]
end

# use imported transformation
transformation = t(:camel_case)

transformation.call 'i_am_a_camel'
# => "IAmACamel"

transformation = t(:map_array, t(:symbolize_keys)
 .>> t(:rename_keys, user_name: :user))
 .>> t(:wrap, :address, [:city, :street, :zipcode])

transformation.call(
  [
    { 'user_name' => 'Jane',
      'city' => 'NYC',
      'street' => 'Street 1',
      'zipcode' => '123' }
  ]
)
# => [{:user=>"Jane", :address=>{:city=>"NYC", :street=>"Street 1", :zipcode=>"123"}}]

# define your own composable transformation easily
transformation = t(-> v { JSON.dump(v) })

transformation.call(name: 'Jane')
# => "{\"name\":\"Jane\"}"

# ...or add it to registered functions via singleton method of the registry
module Functions
  # ...

  def self.load_json(v)
    JSON.load(v)
  end
end

transformation = t(:load_json) >> t(:map_array, t(:symbolize_keys))

transformation.call('[{"name":"Jane"}]')
# => [{ :name => "Jane" }]

Credits

This project is inspired by the work of following people:

• Markus Schirp and morpher project
• Josep M. Bach and kleisli project

Contributing

1. Fork it ( https://github.com/solnic/transproc/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request