Improve keyword arguments over CapTP

This serializes keyword arguments with a special `kw-arg` syrup record
and also handles parsing them out in order to pass to `keyword-apply`.

goblins/ocapn/captp.rkt

@@ -82,8 +82,7 @@
    method
    ;; Either arguments to the method or to the procedure, depending
    ;; on whether method exists
-   args
-   kw-args)
+   args)
   marshall::op:deliver-only unmarshall::op:deliver-only)
 
 ;; Queue a delivery of verb(args..) to recip, binding answer/rdr to the outcome.
@@ -91,7 +90,6 @@
   (to-desc
    method
    args
-   kw-args
    answer-pos
    resolve-me-desc)  ; a resolver, probably an import (though it could be a handoff)
   marshall::op:deliver unmarshall::op:deliver)
@@ -621,6 +619,8 @@
           ($ coordinator 'make-handoff-base-cert obj)])]
       [(? void?)
        (record* 'void)]
+      [(? keyword?)
+       (record* 'kw-arg (string->symbol (keyword->string obj)))]
       ;; TODO: Supply more machine-crossing exception types here
       [(? exn:fail?)
        (record* 'exn:fail:mystery)]
@@ -650,6 +650,8 @@
        (make-mystery-fail)]
       [(record 'void '())
        (void)]
+      [(record 'kw-arg (list keyword))
+       (string->keyword (symbol->string keyword))]
       ;; unserialize user-defined records
       [(record 'user-record (list record-tag record-args))
        (record record-tag record-args)]
@@ -719,6 +721,17 @@
     (send-to-remote (op:abort reason))
     (tear-it-down))
 
+  (define (find-and-collect-keyword-args raw-args)
+    (for/fold ([args '()]
+               [kw-args '()]
+               [kw-vals '()]
+               [next-kw-val? #f]
+               #:result (values (reverse args) (reverse kw-args) (reverse kw-vals)))
+              ([arg raw-args])
+      (cond [next-kw-val? (values args kw-args (cons arg kw-vals) #f)]
+            [(keyword? arg) (values args (cons arg kw-args) kw-vals #t)]
+            [else (values (cons arg args) kw-args kw-vals #f)])))
+
   ;; !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
   ;; TODO TODO TODO: EACH of these needs to call (handle-spare-imports!)
   ;; at the end of its behavior!  Probably the best thing to do is to
@@ -742,35 +755,29 @@
       ;; TODO: Handle case where the target doesn't exist?
       ;;   Or maybe just generally handle unmarshalling errors :P
       [(op:deliver-only to-desc method
-                        args-marshalled
-                        kw-args-marshalled)
+                        args-marshalled)
        (define args
          (incoming-post-unmarshall! args-marshalled))
-       (define kw-args
-         (incoming-post-unmarshall! kw-args-marshalled))
+
        (define target (unmarshall-to-desc to-desc))
-       (define-values (kws kw-vals)
-         (kws-hasheq->kws-lists kw-args))
-       (keyword-apply <-np kws kw-vals
-                      target args)
+       (apply <-np target args)
        (void)]
       [(op:deliver to-desc method
                    args-marshalled
-                   kw-args-marshalled
                    ;; answer-pos is either an integer (promise pipelining)
                    ;; or #f (no pipelining)
                    (and (or (? integer?) #f)
                         answer-pos)
                    resolve-me-desc)
-       (define args
+       (define raw-args
          (incoming-post-unmarshall! args-marshalled))
-       (define kw-args
-         (incoming-post-unmarshall! kw-args-marshalled))
+
+       (define-values (args kw-args kw-vals)
+         (find-and-collect-keyword-args raw-args))
+
        (define target (unmarshall-to-desc to-desc))
-       (define-values (kws kw-vals)
-         (kws-hasheq->kws-lists kw-args))
        (define sent-promise
-         (keyword-apply <- kws kw-vals target args))
+         (keyword-apply <- kw-args kw-vals target args))
        ;; We're either resolving the to the answer promise we create
        ;; or we're resolving to the actual object described by resolve-me-desc
        ;;
@@ -843,15 +850,11 @@
                            #f ;; TODO: support methods
                            ;; TODO: correctly marshall everything here
                            (outgoing-pre-marshall! args)
-                           (outgoing-pre-marshall!
-                            (kws-lists->kws-hasheq kws kw-vals))
                            answer-pos
                            (marshall-local-refr! resolve-me))
                (op:deliver-only (marshall-to to)
                                 #f ;; TODO: support methods
-                                (outgoing-pre-marshall! args)
-                                (outgoing-pre-marshall!
-                                 (kws-lists->kws-hasheq kws kw-vals)))))
+                                (outgoing-pre-marshall! args))))
          (send-to-remote deliver-msg)]
         [(cmd-send-listen (? remote-refr? to-refr) (? local-refr? listener-refr)
                           (? boolean? wants-partial?))
@@ -942,7 +945,7 @@
   ;; TODO TODO TODO: We need to make use of this and also check the
   ;;   session listed on the receive certificate to prevent a replay
   ;;   attack
-  (define remote-handoff-count 0)
+  (define remote-handoff-coont 0)
 
   (define handoff-pubkey (pk-key->public-only-key handoff-privkey))