added command-line demo

collects/stepper/command-line-debugger-example.rkt

@@ -0,0 +1,94 @@
+#lang racket
+
+;; this file shows how you might build a command-line debugger. It doesn't provide much in
+;; the way of convenience functions....
+
+(provide (contract-out [run-program (-> path-string? void?)]
+                       [continue (-> void?)]
+                       [this-step (or/c false? step?)]
+                       [srcloc (-> any)])
+         (struct-out step)
+         )
+
+(require "external-interface.rkt"
+         "private/marks.rkt")
+
+(struct step (context-thunks break-kind values-returned) #:prefab)
+
+;; for convenience, we just provide mutable top-level bindings for some functions. This
+;; will cause terrible problems if you try to debug two programs at once...
+(define this-step #f)
+(define debugged-program-semaphore (make-semaphore))
+;; in case you want to kill it...:
+(define debugged-program-thread #f)
+
+;; this function gets invoked on the debugged program's thread each time a step
+;; arrives.
+(define (step-receiver a b c)
+  ;; if you wanted breakpoints, you could check if this is the
+  ;; desired step before halting...
+  (set! this-step (step a b c))
+  (printf "*ding* a new step has arrived:\n~e\n" this-step)
+  (semaphore-wait debugged-program-semaphore))
+
+;; given a program path, run the debugger
+(define (run-program program-path)
+  (set!
+   debugged-program-thread
+   (thread
+    (lambda ()
+      (step-program-file program-path step-receiver)))))
+
+;; continue running the debugger:
+(define (continue)
+  (semaphore-post debugged-program-semaphore))
+
+;; show the innermost source location associated with the current-step
+(define (srcloc)
+  (match this-step
+    [#f (error 'step-srcloc "no steps yet")]
+    [(struct step ((cons first-mark _) _ _))
+     (mark-source first-mark)]
+    [other (error 'step-srcloc "no source contexts in this step")]))
+
+;; EXAMPLE:
+
+;; Put the following code in /tmp/foo.rkt:
+
+#|
+#lang racket
+
+(define (f x) (+ x 14))
+
+(f 9)
+
+Then, you might run it from the command line like this:
+
+jclements-09740:~/plt/collects/stepper clements> racket
+Welcome to Racket v5.3.4.7.
+> (require "command-line-debugger-example.rkt")
+> (run-program "/tmp/foo.rkt")
+> *ding* a new step has arrived:
+'#s(step #f expr-finished-break ((#<procedure:...ate/annotate.rkt:1061:62> #f #<procedure>)))
+(srcloc)
+step-srcloc: no source contexts in this step
+  context...:
+   /Users/clements/plt/collects/racket/private/misc.rkt:87:7
+> (continue)
+> *ding* a new step has arrived:
+'#s(step (#<procedure> #<procedure> #<procedure>) normal-break #f)
+(srcloc)
+#<syntax:5:1 f>
+> (continue)
+> *ding* a new step has arrived:
+'#s(step (#<procedure> #<procedure> #<procedure>) result-value-break (#<procedure>))
+(srcloc)
+#<syntax:5:1 f>
+> (continue)
+> *ding* a new step has arrived:
+'#s(step (#<procedure> #<procedure>) normal-break #f)
+(srcloc)
+#<syntax:5:0 (#%app f (quote 9))>
+> (exit)
+
+|#

collects/stepper/external-interface.rkt

@@ -35,11 +35,11 @@
     (parameterize ([current-namespace 
                     (namespace-anchor->namespace here-anchor)])
       (expand stx)))
-  (printf "~s\n" expanded)
+  #;(printf "~s\n" expanded)
   (define module-name
     (syntax-case expanded ()
       [(#%module name . rest) (syntax-e #'name)]))
-  (printf "~s\n" module-name)
+  #;(printf "~s\n" module-name)
   ;; unwrap the continuation-mark-set->list part:
   (define (wrapped-handler mark-set kind vals)
     (handler (cond [mark-set (extract-mark-list mark-set)]