#
# http://stackoverflow.com/questions/824562/does-ruby-perform-tail-call-optimization
# See also:
#        http://nithinbekal.com/posts/ruby-tco/
#  and   http://blog.tdg5.com/tail-call-optimization-in-ruby-deep-dive/
#
source = <<-SOURCE
def fact n, acc = 1
  if n.zero?
    acc
  else
    fact n - 1, acc * n
  end
end

fact 100000
SOURCE

# This should print a very large number. If you don't set TCO option
# to true, you should get the "stack too deep" error.

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

# Indeed, prints "#<SystemStackError: stack level too deep>" for 2.0--2.2 for 10,000
#  For 2.3, prints the result 10,000 anyway, but for 100,000
#    also runs out of stack. Just

# Uncomment this to see bytecode:
puts i_seq.disasm

begin
  value = i_seq.eval

  p value
rescue SystemStackError => e
  p e
end