I apologize for the naivety of this question, but whenever I see libraries/discussions of enhanced mechanisms for exceptions/conditions/errors/restarts/etc in Clojure I wonder if they could provide a couple of features that I dearly miss from Common Lisp, and this contribution makes me wonder the same thing. I looked briefly through the guide (nice diagrams!) but couldn't quite tell if it could do what I miss from Common Lisp in Clojure, and therefore whether I should take the time to study it in more detail.
What do I miss from Common Lisp condition handling? When you hit an error in Common Lisp you get a REPL (sometimes called a "break loop") that lives in the context where the error occurred. The most useful thing to me is that you can examine the state of the system there (through normal REPL interactions) and look at the values of local variables all up and down the stack. In addition, you can change the values of variables and restart the computation, and the restart mechanisms can be customized based on the type of error/condition... which is very cool and occasionally useful, but for me personally the big win is in just being able to really examine the state at the point of the error (including running little pieces of code to help to examine the state, etc.). Note that this happens in Common Lisp wherever an error occurs, and the programmer doesn't have to mark or wrap expressions in any special way to get this functionality. Which is crucial, because many of the situations in which this is useful are ones when you hit an error that you had no idea existed, and you certainly didn't know in advance where errors would occur. Another Common Lisp feature that's very handy in this context is the ability to trigger an interrupt manually from the keyboard and end up in the same kind of break loop. Your program seems to be hung and you have no idea what it's doing? Interrupt it and look at the stack and the local variables. Everything looks okay but it's just taking a long time? Restart and you're back in action, continuing from where the interrupt occurred. If it doesn't look okay then examine the state to try to figure out what went wrong, abort the computation, fix the problem and re-run from the beginning. My sense has been that this kind of functionality doesn't exist in any Clojure environment, maybe due to something about how the JVM works (about which I don't know very much, which may be very clear to all of you :-). But when I see fancy new conditional restart mechanisms etc. then I get a glimmer of hope that maybe I'm wrong about this. So, can any existing libraries/systems in the Clojure ecosystem provide this functionality? Is it conceivable that any would in the future? Thanks, -Lee On Sep 25, 2013, at 3:14 AM, zcaudate wrote: > I've done a pretty comprehensive guide on conditional restart systems in > clojure with diagrams to show why it is much more flexible over try/catch > mechanism > > Project: > https://github.com/zcaudate/ribol > > Generated Documentation: > http://z.caudate.me/ribol/ > -- -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
