Hi Maciej
It's taken me a while to answer this question because I wanted to see what debugger support for lambdas is currently like. It hasn't been good in the past – blog posts like
this have complained about the problem you mention, of losing the context (local variables in the enclosing method). Actually I don't think the problem was ever that serious, since you could always drop back to the stack frame for the enclosing method, but it was inconvenient. Now, though, the underlying JDK bug that caused that problem is fixed (as of 8u60b25 – last month, I think), and according to
this thread the symptoms have gone from Netbeans and Intellij Idea. I haven't checked this myself, I'm afraid.
The problems of debugging stream code are something else – but you didn't ask about them
Regards
Maurice