Generate channel contracts in TR

pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/private/type-contract.rkt

@@ -487,6 +487,9 @@
         [(Hashtable: k v)
          (when (equal? kind flat-sym) (exit (fail)))
          #`(hash/c #,(t->c k #:kind chaperone-sym) #,(t->c v) #:immutable 'dont-care)]
+        [(Channel: t)
+         (set-chaperone!)
+         #`(channel/c #,(t->c/both t))]
         [else
          (exit (fail #:reason "contract generation not supported for this type"))]))))
 

pkgs/typed-racket-pkgs/typed-racket-test/tests/typed-racket/fail/channel-contract.rkt

@@ -0,0 +1,18 @@
+#;
+(exn-pred #rx"expected: Integer.*blaming: top-level")
+#lang racket/load
+
+;; Test typed-untyped interaction with channels
+
+(module typed typed/racket
+  (: ch (Channelof (Boxof Integer)))
+  (define ch (make-channel))
+  (: putter (-> Thread))
+  (define (putter)
+    (thread (λ () (channel-put ch (box 3)))))
+  (provide putter ch))
+
+(require 'typed)
+(putter)
+(set-box! (channel-get ch) "not an integer")
+