steveklabnik/frappuccino

---

steveklabnik/frappuccino.json

{
  "createdAt": "2013-04-22T14:53:51Z",
  "defaultBranch": "master",
  "description": "Functional Reactive Programming in Ruby.",
  "fullName": "steveklabnik/frappuccino",
  "homepage": "https://github.com/steveklabnik/frappuccino",
  "language": "Ruby",
  "name": "frappuccino",
  "pushedAt": "2016-02-09T21:52:19Z",
  "stargazersCount": 354,
  "topics": [],
  "updatedAt": "2025-08-26T03:22:18Z",
  "url": "https://github.com/steveklabnik/frappuccino"
}

Frappuccino

Functional Reactive Programming for Ruby.

Installation

Add this line to your application’s Gemfile:

gem 'frappuccino'

And then execute:

$ bundle

Or install it yourself as:

$ git clone https://github.com/steveklabnik/frappuccino
$ cd frappuccino
$ bundle
$ rake install

Usage

Basically, this:

require 'frappuccino'

class Button
  def push
    emit(:pushed) # emit sends a value into the stream
  end
end

button = Button.new
stream = Frappuccino::Stream.new(button)

counter = stream
            .map {|event| event == :pushed ? 1 : 0 } # convert events to ints
            .inject(0) {|sum, n| sum + n } # add them up

counter.now # => 0

button.push
button.push
button.push

counter.now # => 3

button.push

counter.now # => 4

You can also map via a hash, if you prefer:

.map(:pushed => 1, :default => 0)

You can also register callbacks to a Stream. These will be executed for each event that occurs in the Stream:

stream.on_value do |event|
  puts "I got a #{event}!"
end

You can combine two streams together:

merged_stream = stream_one.merge(stream_two)

# or

merged_stream = Frappuccino::Stream.merge(one_stream , other_stream)

# or

merged_stream = Frappuccino::Stream.new(button_one, button_two)

You can select events from a stream, too:

stream = Frappuccino::Stream.new(button, something_else)
filtered_stream = stream.select{|event| event == :pushed }

filtered_stream.on_value do |event|
  # event will only ever be :pushed
end

Contributing

1. Fork it
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 new Pull Request