NotMonads

Simple copy of dry-monads do monads, it implements only mixin for your service object and Success/Failure result object.

Installation

Install the gem and add to the application's Gemfile by executing:

$ bundle add not_monads

or add to Gemfile

gem 'not_monads'

If bundler is not being used to manage dependencies, install the gem by executing:

$ gem install not_monads

Usage

Add module to your class with prepend:

class CreateUser
    prepend NotMonads::Do[:call]

    def call(params)
      doit validate(params)
      user = doit save(params)
      Success(user)
    end

    private

    def validate(params)
      Success() || Failure(:error)
    end

    def save(params)
      Success(user) || Failure(errors)
    end
  end
end

Prepend with a module call with array of method names in square brackets. (prepend NotMonads::Do[:call, :step1, :step3]) Use method doit to verify result, just like dry-monads with yield.

Then you can access result just like in dry-monads:

For success

result = CreateUser.new.call(params)
result.success? # true
result.value! # User#123
result.value_or(42) # User#123

For failure

result = CreateUser.new.call(params)
result.success? # false
result.value! # raises NotMonads::Error
result.value_or(42) # 42
result.failure # user.errors

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 the created tag, and push the .gem file to rubygems.org.

To release from docker container make sure your host have access to key ssh-add -l and ssh -T git@github.com, if no access run ssh-add. Then you can release with bundle exec rake release.

To run specs bundle exec rspec, to run rubocop bundle exec rubocop.

License

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