Make static contracts for channels.

original commit: 333a93000ab2593950e123cda67345a6e4e28f66

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

@@ -306,11 +306,8 @@
          (parameter/sc (t->sc in) (t->sc out))]
         [(Hashtable: k v)
          (hash/sc (t->sc k) (t->sc v))]
-        ;; TODO add channel static contracts
-        #;
         [(Channel: t)
-         (set-chaperone!)
-         #`(channel/c #,(t->c/both t))]
+         (channel/sc (t->sc t))]
         [else
          (fail)]))))
 

pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/static-contracts/combinators/structural.rkt

@@ -126,4 +126,5 @@
   ((box/sc (#:invariant)) box/c #:chaperone)
   ((parameter/sc (#:contravariant) (#:covariant)) parameter/c #:chaperone)
   ((sequence/sc . (#:covariant)) sequence/c #:impersonator)
+  ((channel/sc . (#:invariant)) channel/c #:chaperone)
   ((continuation-mark-key/sc (#:invariant)) continuation-mark-key/c #:chaperone))