remove (display)

[8sync.git] / eightsync / agenda.scm

diff --git a/eightsync/agenda.scm b/eightsync/agenda.scm
index 15220d7494f0f5ec107d778e0a43754d2853a761..ba075361339f469d9047c1df0eefc3d9f36963a2 100644 (file)
--- a/eightsync/agenda.scm
+++ b/eightsync/agenda.scm
@@ -444,8 +444,9 @@ Will produce (0 . 0) instead of a negative number, if needed."
   "Run BODY asynchronously at a prompt, passing args to make-future.
 
 Runs things asynchronously (8synchronously?)"
-  (abort-to-prompt (current-agenda-prompt)
-                   async-request))
+  (propagate-%async-exceptions
+   (abort-to-prompt (current-agenda-prompt)
+                    async-request)))
 
 ;; Async port request and run-request meta-requests
 (define (make-async-request proc)
@@ -466,16 +467,55 @@ return the wrong thing via (%8sync) and trip themselves up."
               "Invalid request passed back via an (%8sync) procedure."
               async-request))))
 
+(define-record-type <wrapped-exception>
+  (make-wrapped-exception key args stack)
+  wrapped-exception?
+  (key wrapped-exception-key)
+  (args wrapped-exception-args)
+  (stack wrapped-exception-stack))
+
+(define-syntax-rule (propagate-%async-exceptions body)
+  (let ((body-result body))
+    (if (wrapped-exception? body-result)
+        (throw '%8sync-caught-error
+               (wrapped-exception-key body-result)
+               (wrapped-exception-args body-result)
+               (wrapped-exception-stack body-result))
+        body-result)))
+
 (define-syntax-rule (%run body ...)
   (%run-at body ... #f))
 
 (define-syntax-rule (%run-at body ... when)
+  ;; Send an asynchronous request to apply a continuation to the
+  ;; following function, then handle that as a request to the agenda
   (make-async-request
    (lambda (kont)
+     ;; We're making a run request
      (make-run-request
+      ;; Wrapping the following execution to run...
       (wrap
+       ;; Once we get the result from the inner part, we'll resume
+       ;; this continuation, but first
+       ;; @@: Is this running immediately, or queueing the result
+       ;;   after evaluation for the next agenda tick?  It looks
+       ;;   like evaluating immediately.  Is that what we want?
        (kont
-        (begin body ...)))
+        ;; Any unhandled errors are caught
+        (let ((exception-stack #f))
+          (catch #t
+            ;; Run the actual code the user requested
+            (lambda ()
+              body ...)
+            ;; If something bad happened and we didn't catch it,
+            ;; we'll wrap it up in such a way that the continuation
+            ;; can address it
+            ;; @@: For this stack to work doesn't it have to be
+            (lambda (key . args)
+              (make-wrapped-exception key args
+                                      exception-stack))
+            (lambda _
+              (set! exception-stack (make-stack #t 1 0)))))))
       when))))
 
 (define-syntax-rule (%run-delay body ... delay-time)