Retire the gross hack of upper-case symbols standing for variables.

presence/conversation.rkt

@@ -26,6 +26,9 @@
 	 topic-subscriber
 	 co-role
 	 co-topic
+
+	 ;; Reexported from unify.rkt for convenience
+	 wild
 	 )
 
 (struct arrived (who) #:prefab) ;; someone arrived
@@ -122,7 +125,7 @@
       the-disconnected-evt)
 
     (define/public (assert!-evt name)
-      (define cname (upper-case-symbols->canonical name))
+      (define cname (canonicalize name))
       (choice-evt the-disconnected-evt
 		  (wrap-evt (channel-put-evt out-ch (arrived cname))
 			    (lambda (v)
@@ -132,7 +135,7 @@
       (sync (assert!-evt name)))
 
     (define/public (retract!-evt name [why #f])
-      (define cname (upper-case-symbols->canonical name))
+      (define cname (canonicalize name))
       (choice-evt the-disconnected-evt
 		  (wrap-evt (channel-put-evt out-ch (departed cname why))
 			    (lambda (v)
@@ -145,7 +148,7 @@
       (sync (retract!-evt name)))
 
     (define/public (say-evt who what)
-      (define cname (upper-case-symbols->canonical (freshen who))) ;; TODO freshening is a bit weird
+      (define cname (canonicalize who))
       (choice-evt the-disconnected-evt
 		  (channel-put-evt out-ch (says cname what))))
 

presence/test-conversation.rkt

@@ -14,20 +14,18 @@
 (standard-thread
  (lambda ()
    (define handle (join-room r))
-   (send handle assert! (topic-subscriber 'Any #:virtual? #t))
-   (send handle assert! (topic-publisher 'Any #:virtual? #t))
+   (send handle assert! (topic-subscriber (wild) #:virtual? #t))
+   (send handle assert! (topic-publisher (wild) #:virtual? #t))
    (let loop ()
      (define m (send handle listen))
      ;;(write `(robot heard ,m)) (newline)
      (match m
-       [(arrived who)
-	(write `(robot hears arrival ,who))
-	(newline)]
+       ;;[(arrived who) (write `(robot hears arrival ,who)) (newline)]
        [(says _ "die")
 	(error 'robot "Following orders!")]
        [(says (topic 'publisher _ _) _)
-	(send handle say (topic-subscriber 'Any) `(robot hears ,m))]
-       [else (void)])
+	(send handle say (topic-subscriber (wild)) `(robot hears ,m))]
+       [_ (void)])
      (loop))))
 
 (define (interaction i o)
@@ -39,8 +37,8 @@
 	     (newline o)
 	     (flush-output o))
       (let ((handle (join-room r)))
-	(define talk-topic (topic-publisher (list name 'Sink 'speech)))
-	(define listen-topic (topic-subscriber (list 'Speaker name 'speech)))
+	(define talk-topic   (topic-publisher  (list  name (wild) 'speech)))
+	(define listen-topic (topic-subscriber (list (wild) name  'speech)))
 	(send handle assert! talk-topic)
 	(send handle assert! listen-topic)
 	(let loop ()

presence/unify.rkt

@@ -6,6 +6,7 @@
 
 (provide (struct-out variable)
 	 (struct-out canonical-variable)
+	 wild
 	 variables-in
 	 unify
 	 unify/env
@@ -39,6 +40,11 @@
 	  (display "?!" port)
 	  (write (canonical-variable-index v) port)))
 
+;; -> Variable
+;; Create a fresh (and hence unconstrained) variable.
+(define (wild [base-name '_])
+  (variable (gensym base-name)))
+
 ;; Any -> Set<Variable>
 (define (variables-in x)
   (let walk ((x x) (acc (set)))