I have updated the APIs to incorporate all the feedback. Thank you all. Let me know if I miss any.
Summary: 1. Change to use wildcard walk(Function<? super Stream<StackFrame>, ? extends T> function) 2. Removed the walk method taking IntUnaryOperator batchSizeMapper argument 3. Add the new static factory method to create StackWalker and keep the constructors private 4. StackFrame::getFileName and StackFrame::getLineNumber return Optional<String>, OptionaIInt respectively as they are optional. 4. maxDepth is not really needed as the user can use Stream::limit. So taken out. 5. Add StackWalker::create(Set<Option> options, int estimateDepth) to take an estimate depth to give a hint the estimated number of frames to traverse by this walker. The implementation may use it to tune the buffer size. Javadoc http://cr.openjdk.java.net/~mchung/jdk9/jep259/api/java/lang/StackWalker.html FYI. I’ll post the webrevs in a new code review thread. Mandy
