Class: Lalka::Task

Inherits:
Object
  • Object
show all
Defined in:
lib/lalka.rb

Overview

TODO: Invalidate resolve and reject at the same time

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(&block) ⇒ Task

Returns a new instance of Task.



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# File 'lib/lalka.rb', line 33

def initialize(&block)
  @computation = block
end

Class Method Details

.reject(error) ⇒ Object 



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# File 'lib/lalka.rb', line 18

def reject(error)
  new do |t|
    t.reject(error)
  end
end

.resolve(value) ⇒ Object Also known as: of 



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# File 'lib/lalka.rb', line 12

def resolve(value)
  new do |t|
    t.resolve(value)
  end
end

.try(&block) ⇒ Object 



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# File 'lib/lalka.rb', line 24

def try(&block)
  new do |t|
    t.try(&block)
  end
end

Instance Method Details

#ap(other_task) ⇒ Object 



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# File 'lib/lalka.rb', line 101

def ap(other_task)
  Task.new do |t|
    mutex = Mutex.new
    completed = false
    either = M.Right([M.None(), M.None()])

    complete_task = lambda do |&block|
      mutex.synchronize do
        return if completed

        either = block.call(either)

        if either.right?
          (e_fn, e_arg) = either.value

          e_fn.bind { |fn| e_arg.fmap(fn) }.fmap do |value|
            t.resolve(value)
            completed = true
          end
        else
          error = either.value
          t.reject(error)
          completed = true
        end
      end
    end

    fork do |this|
      this.on_success do |fn|
        complete_task.call do |either|
          either.bind { |_, e_arg| M.Right([M.Some(fn), e_arg]) }
        end
      end

      this.on_error do |error|
        complete_task.call do |either|
          either.bind { M.Left(error) }
        end
      end
    end

    other_task.fork do |other|
      other.on_success do |arg|
        complete_task.call do |either|
          either.bind { |e_fn, _| M.Right([e_fn, M.Some(arg)]) }
        end
      end

      other.on_error do |error|
        complete_task.call do |either|
          either.bind { M.Left(error) }
        end
      end
    end
  end
end

#bind(*args, &block) ⇒ Object Also known as: chain, flat_map 



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# File 'lib/lalka.rb', line 75

def bind(*args, &block)
  block = function_from_arguments(*args, &block)

  Task.new do |t|
    fork do |this|
      this.on_success do |first_value|
        other_task = block.call(first_value)

        other_task.fork do |other|
          other.on_success do |second_value|
            t.resolve(second_value)
          end

          other.on_error do |error|
            t.reject(error)
          end
        end
      end

      this.on_error do |error|
        t.reject(error)
      end
    end
  end
end

#fork {|internal| ... } ⇒ Object

Yields:

  • (internal) 


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# File 'lib/lalka.rb', line 52

def fork
  internal = InternalAsync.new
  yield internal
  internal.call(&@computation)
  nil
end

#fork_wait ⇒ Object 



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# File 'lib/lalka.rb', line 37

def fork_wait
  queue = Queue.new
  internal = Internal.new(queue)

  if block_given?
    yield internal
  else
    internal.on_success { |v| v }
    internal.on_error { |e| e }
  end

  internal.call(&@computation)
  queue.pop
end

#map(*args, &block) ⇒ Object Also known as: fmap 



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# File 'lib/lalka.rb', line 59

def map(*args, &block)
  block = function_from_arguments(*args, &block)

  Task.new do |t|
    fork do |this|
      this.on_success do |value|
        t.resolve(block.call(value))
      end

      this.on_error do |error|
        t.reject(error)
      end
    end
  end
end