rauhl
Joined 8 years ago
Joined 8 years ago
https://gigamonkeys.com/book/beyond-exception-handling-condi... is a nice introduction; https://news.ycombinator.com/item?id=24867548 points to a great book about it. I believe that Smalltalk ended up using a similar system, too.
> It would need to be the case that code that doesn’t want to handle errors (like Max’s simple website) doesn’t have any error handling code, but it’s easy to add, and common patterns (e.g. “retry this inner operation N times, maybe with back off and jitter, and then fail this outer operation, either exiting the program or leaving unaffected parts running”) are easy to express
Lisp’s condition system can handle that! Here’s a dumb function which signals a continuable error when i ≤ 3:
(defun foo ()
(loop for i from 0
do (if (> i 3)
(return (format nil "good i: ~d" i))
(cerror "Keep going." "~d is too low" i))))
If one runs (foo) by hand then i starts at 0 and FOO signals an error; the debugger will include the option to continue, then i is 1 and FOO signals another error and one may choose to continue. That’s good for interactive use, but kind of a pain in a program. Fortunately, there are ways to retry, and to even ignore errors completely.If one wishes to retry up to six times, one can bind a handler which invokes the CONTINUE restart:
(let ((j 0))
(handler-bind ((error #'(lambda (c)
(declare (ignore c))
;; only retry six times
(unless (> (incf j) 6)
(invoke-restart 'continue)))))
(foo)))
If one wants to ignore errors, then (ignore-errors (foo)) will run and handle the error by returning two values: NIL and the first error.I just have my terminal emulator spin up tmux when it starts, and I start my terminal emulator from my desktop, so it always runs in a clean environment.
That conflicts with the standard Emacs binding to move to the beginning of the current line. Many years ago, I switched to C-z instead, on the theory that it is really easy to type C-z C-z when I really want to suspend whatever is currently running.
Pity that (AFAICT) terminals have no concept of Super and Hyper (USB doesn’t know about Hyper, either, but at least X11 does).
Oddly enough, I was recently thinking of using RFC 822 messages with CommonMark bodies and MIME attachments as a way to store blog entries on disk, so I was considering this exact problem earlier this week (small world!). RFC 2046 specifies multipart messages, RFC 2392 specifies URI schemes for linking from the body of the message to other parts; and RFC 7763 specifies the text/markdown MIME type. There’s already a ton of tooling out there which deals with MIME, so one needn’t reinvent the wheel.
Maybe it was this paper: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10619792/
The authors’ statement that ‘unlike hallucinations, confabulations are not perceived experiences but instead mistaken reconstructions of information which are influenced by existing knowledge, experiences, expectations, and context’ is pretty compelling.
OTOH, I do think that now that it has shown the way, there is room for both improvement and replacement.
https://rauhl.com/