Allow resetting to previous error stacks; Fixes to toplevel variable evaluation

lisp/l/toplevel.l

@@ -124,28 +124,30 @@
   (let* ((eof (cons nil nil))
 	 (command (read input nil eof))
 	 (arglist) (arg) result)
-  (cond	((eq command eof) )
+    (flet ((normal-eval (comm)
+             (setq - comm)
+             (setq result (eval comm))))
+      (cond
+	((eq command eof) )
 	((symbolp command)
 ;;	 (if *history* (add-history (input . buffer)))
 	 (cond ((fboundp command)
 		(setq arglist nil)
 		(while (not (eq (setq arg (read input nil eof)) eof))
 		    (push arg arglist))
-		(setq - (cons command (nreverse arglist)))
-		(setq result (eval -)))
-	       ((and (boundp command)
-		     (eq (read input nil eof) eof))
-		(setq - command)
-		(setq result (eval command)))
+		(if (and (null arglist) (boundp command))
+                    (normal-eval command) ;; eval symbol if bound and w/o args
+                    (normal-eval (cons command (nreverse arglist)))))
+	       ((boundp command)
+                (normal-eval command))
 	       ((find-package (string command)) (in-package (string command)))
-	       (*try-unix*
-		(setq - (list 'unix:system (input . buffer)))
-		(setq result (unix:system (input . buffer)) ) )
-	       (t (warn "?~%")) ))
+	       ((and *try-unix*
+		  ;; try normal-eval when unix command is not found (errno 127)
+		  (not (equal (normal-eval (list 'unix:system (input . buffer))) #x7f00))))
+	       (t (normal-eval command)) ))
    	(t
 ;;	 (if *history* (add-history (input . buffer)))
-	 (setq - command)
-	 (setq result (eval command)) ))
+	 (normal-eval command) )))
    result))
 
 (defun toplevel-prompt (strm)
@@ -291,8 +293,8 @@
    (format *error-output* "~C[0m~%"  #x1b)
    (let ((*replevel* (1+ *replevel*))
 	 (*reptype* "E"))
-      (catch *replevel* (reploop #'toplevel-prompt)))
-   (throw *replevel* nil))
+     (while (catch *replevel* (reploop #'toplevel-prompt))))
+   (throw *replevel* t))
 
 ;;;
 ;;; default toplevel