don't crash on errors in evaluate

anna.scm

@@ -3,7 +3,9 @@
 
 (use-modules (ice-9 rdelim)
              (ice-9 textual-ports)
-             (ice-9 format))
+             (ice-9 format)
+             (ice-9 control)
+             (rnrs exceptions))
 
 (define +channels+ '("#tildetown" "#bots"))
 
@@ -67,13 +69,18 @@
               (format stream "JOIN ~a\r\n" chn))
             +channels+))
 
-
 (define (send-message stream chn msg)
   (format stream "PRIVMSG ~a :~a\r\n" chn msg))
 
 (define (send-action stream chn action)
   (format stream "PRIVMSG ~a :\x01ACTION ~a\x01\r\n" chn action))
 
+(define (evaluate str)
+  (guard (ex
+          (else (begin (display "error encountered!\n")
+                       'error)))
+    (eval (read (open-input-string str)) (interaction-environment))))
+
 (define (main-loop stream)
   (let* ((inl (read-line stream))
          (data (string-tokenize inl))
@@ -88,8 +95,7 @@
       (send-message stream chn "Hello! I respond to !rollcall, !anna, and !eval <s-expr>."))
      ((equal? ":!eval" (slist-ref data 3))
       (let* ((expr (string-concatenate (intersperse " " (cdr (member ":!eval" data))))))
-        (send-message stream chn (eval (read (open-input-string expr))
-                                             (interaction-environment)))))
+        (send-message stream chn (evaluate expr))))
      ((and (= 7 (length data))
            (equal? (list-tail data 4) '("ACTION" "shoots" "anna")))
       (send-action stream chn "dies")