Ruby + Type = Rubype

require 'rubype'
class MyClass
  # Assert first arg has method #to_i, second arg and return value are instance of Numeric.
  def sum(x, y)
    x.to_i + y
  end
  typesig :sum, [:to_i, Numeric] => Numeric
end

MyClass.new.sum(:has_no_to_i, 2)
#=> Rubype::ArgumentTypeError: for MyClass#sum's 1st argument
#   Expected: respond to :to_i,
#   Actual:   :has_no_to_i
#   ...(stack trace)

This gem brings you advantage of type without changing existing code's behavior.

Good point:

• Meaningful error
• Executable documentation
• Don't need to check type of method's arguments and return.
• Type info itself is object, you can check it and even change it during run time.

Bad point:

• Checking type run every time method call... it might be overhead, but it's not big deal.
• There is no static analysis.

Feature

Super clean!!!

I know it's terrible to run your important code with such a hacked gem. But this contract is implemented by less than 80 lines source code! (It is not too little, works well enough) https://github.com/gogotanaka/Rubype/blob/develop/lib/rubype.rb#L2-L79

You can read this over easily and even you can implement by yourself !(Don't need to use this gem, just take idea)

Advantage of type

• Meaningful error
• Executable documentation
• Don't need to check type of method's arguments and return .

require 'rubype'

# ex1: Assert class of args and return
class MyClass
  def sum(x, y)
    x + y
  end
  typesig :sum, [Numeric, Numeric] => Numeric

  def wrong_sum(x, y)
    'string'
  end
  typesig :wrong_sum, [Numeric, Numeric] => Numeric
end

MyClass.new.sum(1, 2)
#=> 3

MyClass.new.sum(1, 'string')
#=> Rubype::ArgumentTypeError: for MyClass#sum's 2nd argument
#   Expected: Numeric,
#   Actual:   "string"
#   ...(stack trace)

MyClass.new.wrong_sum(1, 2)
#=> Rubype::ReturnTypeError: for MyClass#wrong_sum's return
#   Expected: Numeric,
#   Actual:   "string"
#   ...(stack trace)


# ex2: Assert object has specified method
class MyClass
  def sum(x, y)
    x.to_i + y
  end
  typesig :sum, [:to_i, Numeric] => Numeric
end

MyClass.new.sum('1', 2)
#=> 3

MyClass.new.sum(:has_no_to_i, 2)
#=> Rubype::ArgumentTypeError: for MyClass#sum's 1st argument
#   Expected: respond to :to_i,
#   Actual:   :has_no_to_i
#   ...(stack trace)


# ex3: You can use Any class, if you want
class People
  def marry(people)
    # Your Ruby code as usual
  end
  typesig :marry, [People] => Any
end

People.new.marry(People.new)
#=> no error

People.new.marry('non people')
#=> Rubype::ArgumentTypeError: for People#marry's 1st argument
#   Expected: People,
#   Actual:   "non people"
#   ...(stack trace)

Typed method can coexist with non-typed method

# It's totally OK!!
class MyClass
  def method_with_type(x, y)
    x + y
  end
  typesig :method_with_type, [Numeric, Numeric] => Numeric

  def method_without_type(x, y)
    'string'
  end
end

Duck typing

You can use Any class.

class MyClass
  def foo(any_obj)
    1
  end
  typesig :foo, [Any] => Numeric

  def sum(x, y)
    x.to_i + y
  end
  typesig :sum, [:to_i, Numeric] => Numeric
end

# It's totally OK!!
MyClass.new.foo(1)
# It's totally OK!!
MyClass.new.foo(:sym)


# It's totally OK!!
MyClass.new.sum(1, 2)
# It's totally OK!!
MyClass.new.sum('1', 2)

Check type info everywhere!

class MyClass
  def sum(x, y)
    x.to_i + y
  end
  typesig :sum, [:to_i, Numeric] => Numeric
end

MyClass.new.method(:sum).type_info
# => [:to_i, Numeric] => Numeric

MyClass.new.method(:sum).arg_types
# => [:to_i, Numeric]

MyClass.new.method(:sum).return_type
# => Numeric

Benchmarks

result of bundle exec rake benchmark

Ruby 2.2.1, Macbook Pro 2.7Ghz Intel Core i5, 8GB RAM

ruby version: 2.2.1
rubype version: 0.3.0
Calculating -------------------------------------
           Pure Ruby   101.070k i/100ms
              Rubype    63.973k i/100ms
-------------------------------------------------
           Pure Ruby      7.115M (± 6.1%) i/s -     35.476M
              Rubype      1.537M (± 2.5%) i/s -      7.677M

Comparison:
           Pure Ruby:  7114786.0 i/s
              Rubype:  1536611.5 i/s - 4.63x slower

Installation

gem install rubype or add gem 'rubype' to your Gemfile.

And require 'rubype', enjoy typed Ruby.

This gem requires Ruby 2.0.0+.

Contributing

• I really wanna make Rubype elegant source code.

• Any feature or comments are welcome.

How to develop

Now Rubype is written with 100% Ruby. In terms of performance, only core module(https://github.com/gogotanaka/Rubype/blob/develop/lib/rubype.rb#L4-L80) will be translate to C.

Only two API will be translate to C, it means you don't need to know what C dose!

1. Fork it ( https://github.com/gogotanaka/Rubype/fork )

2. Create your feature branch (git checkout -b my-new-feature)

   $ bundle install --path vendor/bundle

3. Commit your changes (git commit -am 'Add some feature')

4. Run tests

   $ bundle exec rake test

   ......

5. Run benchmerk(optional)

   $ bundle exec rake bm

   ......

6. Push to the branch (git push origin my-new-feature)

7. Create a new Pull Request to develop branch

Credits

@chancancode and This article first brought this to my attention. I've stolen some idea from them.

License

MIT license (© 2015 Kazuki Tanaka)