Does Ruby perform Tail Call Optimization?

Question

Functional languages lead to use of recursion to solve a lot of problems, and therefore many of them perform Tail Call Optimization (TCO). TCO causes calls to a function fro

Answer 1

This builds on Jörg's and Ernest's answers. Basically it depends on implementation.

I couldn't get Ernest's answer to work on MRI, but it is doable. I found this example that works for MRI 1.9 to 2.1. This should print a very large number. If you don't set TCO option to true, you should get the "stack too deep" error.

source = <<-SOURCE
def fact n, acc = 1
  if n.zero?
    acc
  else
    fact n - 1, acc * n
  end
end

fact 10000
SOURCE

i_seq = RubyVM::InstructionSequence.new source, nil, nil, nil,
  tailcall_optimization: true, trace_instruction: false

#puts i_seq.disasm

begin
  value = i_seq.eval

  p value
rescue SystemStackError => e
  p e
end