Hombre-x/ruby-on-tails

Quasi Tail-Call optimiser for Ruby

Ruby on Tails

A quasi tail-call optimiser for Ruby

How to use it

First of all, design your tail recursive function and put the soft keyword rec to let the compiler know that it is a tail-recursive function:

def factorial(n)
  # Don't forget the rec keyword!
  def rec tailfactorial(n, acc)
    if n < 0
      return 0 - 1
    elsif n == 0
      return acc
    else
      return tailfactorial(n - 1, acc * n)
    end
  end

  return tailfactorial(n, 1) # Call the clojure

end

Then, place your code inside the program.rb located in the src/main/resources folder.

Finally, run Main.kt using gradlew or your IDE, and run the generated code in an online Ruby interpreter or in your local machine.

$ ./gradlew run

---

Examples:

These are some examples of tail-recursive functions written in Ruby that you can use:

Nth Fibonacci number:

def fibonacci(n)
  def rec tailfibonacci(n, prev, curr)
    if n == 0
      return prev
    elsif n == 1
      return curr
    else
      return tailfibonacci(n - 1, curr, prev + curr)
    end
  end

  return tailfibonacci(n, 0, 1)
end

Sum of the first n natural numbers:

def sum(n)
  def rec tailsum(n, acc)
    if n == 0
      return acc
    else
      return tailsum(n - 1, acc + n)
    end
  end

  return tailsum(n, 0)
end