Psych::Stream is a streaming YAML emitter. It will not buffer your YAML, but send it straight to an IO.
Here is an example use:
stream = Psych::Stream.new($stdout) stream.start stream.push({:foo => 'bar'}) stream.finish
YAML will be immediately emitted to $stdout with no buffering.
Psych::Streaming#start will take a block and ensure that Psych::Visitors::YAMLTree#finish is called, so you can do this form:
stream = Psych::Stream.new($stdout) stream.start do |em| em.push(:foo => 'bar') end