blah.rb

# Make sure to do detection so it will gracefully downgrade like:
# begin
require 'psych'

Psych.add_domain_type(nil, 'code') { |_,hash|
  p hash['ruby']
}
# rescue
#   do 1.8 stuff
# end

Psych.load DATA.read

__END__
---
lambda: !code
  ruby:    'proc { "world" }'
  perl:    'sub { "world" }'
  js:      'function() { return "world" }'
  php:     'return "world";'
  python:  'lambda: "world"'
  clojure: '(fn [] "world")'