Twotrack

Implements the Railway Oriented Programming pattern (https://fsharpforfunandprofit.com/rop/)

Installation

Add this line to your application's Gemfile:

gem 'twotrack'

And then execute:

$ bundle

Or install it yourself as:

$ gem install twotrack

Usage

Assumptions:

• The "left" and "right" operations need to respond to call. That means you can pass an object that has a call method, a Proc or a lambda. Ruby doesn't allow passing two blocks unfortunately, so for now there's no ability to pass blocks.
• The pipeline starts from the "left" track.
• If the previous operation returned an object that responds to switch? and if it responds with true then the tracks will switch to the "right" operation.
• There is no way to switch from the "right" track to the "left" track.
• The data returned from the previous operation is passed to the next operation's call handler through a block.

See examples/basic.rb for a quick rundown of various capabilities.

Railway Oriented Error Handling:

• "success" means that data should be passed on to the next function (aka "left")
• "failure" means to bypass all intermediate functions and go straight to the end (aka "right")

TODO: example from the talk https://fsharpforfunandprofit.com/rop/

• Validate
• CanonicalizeEmail
• UpdateDb
• SendEmail

It doesn't have to be just about "success" and "failure" (although that's the most common use case)

You can for example implement FizzBuzz with a railway design, with the "left" track being the operations you want to pass the input through, and the "right" track the output (in this case, printing Fizz Buzz FizzBuzz or the number)

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/twotrack.