Add `debugm' to unstable/debug

- `debugm' does not parse or print the arguments to the form,
    so it works for macros, not just function application

collects/unstable/debug.rkt

@@ -1,6 +1,6 @@
 #lang racket/base
 
-(provide debug)
+(provide debug debugm)
 
 ;; printf debugging convenience
 (define-syntax debug
@@ -20,4 +20,17 @@
                     (printf "~a result was ~a~n" 'f (car e))
                     (printf "~a results were ~a~n" 'f e))
                 (apply values e))))]
-    [(_ f . args) (debug (f . args))]))
+    [(_ f . args) (debug (f . args))]))
+
+(define-syntax debugm
+  (syntax-rules ()
+    [(_ kw . forms)
+     (begin (printf "starting ~a\n" 'kw)
+            (let ([e (with-handlers ([values (lambda (exn)
+                                                 (printf "~a raised exception ~a~n" 'kw exn)
+                                                 (raise exn))])
+                         (call-with-values (lambda () (kw . forms)) list))])
+                (if (and (pair? e) (null? (cdr e)))
+                    (printf "~a result was ~a~n" 'kw (car e))
+                    (printf "~a results were ~a~n" 'kw e))
+                (apply values e)))]))

collects/unstable/scribblings/debug.scrbl

@@ -9,7 +9,7 @@
 
 @title[#:tag "debug"]{Debugging}
 @(define the-eval (make-base-eval))
-@(the-eval '(require unstable/debug))
+@(the-eval '(require unstable/debug racket/match))
 
 @defmodule[unstable/debug]
 
@@ -23,3 +23,13 @@ Produce debugging output for the application of @racket[f], including the values
 (debug + 1 2 3)
 ]
 }
+
+@defform*[[(debugm f args ...)]]{
+Produce debugging output for the application of @racket[f], but does
+not parse or print args.  Suitable for use debugging macros.
+@examples[#:eval the-eval
+(debugm match (list 1 2 3)
+  [(list x y z) (+ x y z)])
+(debugm + 1 2 3)
+]
+}

collects/unstable/scribblings/unstable.scrbl

@@ -94,6 +94,7 @@ Keep documentation and tests up to date.
 @include-section["interval-map.scrbl"]
 @include-section["generics.scrbl"]
 @include-section["markparam.scrbl"]
+@include-section["debug.scrbl"]
 
 @;{--------}