Add catching exceptions, and lots of much needed docuemntation

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

diff --git a/eightsync/agenda.scm b/eightsync/agenda.scm
index 77bd63b5ccc0f6ec9f598a8edb2bcbfb22a8edf8..a965a2c6d3b50fff9a86567145bd5d5ac4b6ebeb 100644 (file)
--- a/eightsync/agenda.scm
+++ b/eightsync/agenda.scm
@@ -64,7 +64,6 @@
             run-it wrap wrap-apply run run-at run-delay
 
             %port-request %run %run-at %run-delay
-            8port-request 8run 8run-at 8run-delay
             
             print-error-and-continue
 
@@ -435,36 +434,12 @@ Will produce (0 . 0) instead of a negative number, if needed."
 ;;; Asynchronous escape to run things
 ;;; =================================
 
-;; The future's in futures
-;; @@: ... kinda conflicts with ice-9 futures.  Should we rename
-;;   to "futurists"? :)
-
-(define (make-future call-first on-success on-fail on-error)
-  ;; TODO: add error stuff here
-  (lambda ()
-    (let ((call-result (call-first)))
-      ;; queue up calling the 
-      (run (on-success call-result)))))
-
 (define (agenda-on-error agenda)
   (const #f))
 
 (define (agenda-on-fail agenda)
   (const #f))
 
-(define* (request-future call-first on-success
-                         #:key
-                         (agenda (%current-agenda))
-                         (on-fail (agenda-on-fail agenda))
-                         (on-error (agenda-on-error agenda))  
-                         (when #f))
-  ;; TODO: error handling
-  ;; do we need some distinction between expected, catchable errors,
-  ;; and unexpected, uncatchable ones?  Probably...?
-  (make-run-request
-   (make-future call-first on-success on-fail on-error)
-   when))
-
 (define-syntax-rule (%8sync async-request)
   "Run BODY asynchronously at a prompt, passing args to make-future.
 
@@ -491,16 +466,42 @@ 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 (%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
+        (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
+          (lambda (key . args)
+            (make-wrapped-exception key args
+                                    (make-stack #t 1 0))))))
       when))))
 
 (define-syntax-rule (%run-delay body ... delay-time)
@@ -520,12 +521,6 @@ return the wrong thing via (%8sync) and trip themselves up."
        (lambda ()
          body ...)))))
 
-;; Aliases
-(define-syntax-rule (8run args ...) (%run args ...))
-(define-syntax-rule (8run-at args ...) (%run-at args ...))
-(define-syntax-rule (8run-delay args ...) (%run-delay args ...))
-(define-syntax-rule (8port-request args ...) (%port-request args ...))
-
 
 \f
 ;;; Execution of agenda, and current agenda