checkpoint: example fix for msgpack failure

Author: bennn

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

@@ -160,10 +160,10 @@
   ((vectorof/sc (#:invariant)) vectorof #:chaperone)
   ((promise/sc (#:covariant)) promise-not-name/c #:chaperone)
   ((syntax/sc (#:covariant #:flat)) syntax/c #:flat)
-  ((hash/sc (#:invariant #:flat) (#:invariant)) hash/c #:chaperone)
-  ((mutable-hash/sc (#:invariant #:flat) (#:invariant)) mutable-hash/c #:chaperone)
-  ((immutable-hash/sc (#:covariant #:flat) (#:covariant)) immutable-hash/c #:flat)
-  ((weak-hash/sc (#:invariant #:flat) (#:invariant)) weak-hash/c #:chaperone)
+  ((hash/sc (#:invariant) (#:invariant)) tr-hash/c #:chaperone)
+  ((mutable-hash/sc (#:invariant) (#:invariant)) mutable-hash/c #:chaperone)
+  ((immutable-hash/sc (#:covariant) (#:covariant)) immutable-hash/c #:flat)
+  ((weak-hash/sc (#:invariant) (#:invariant)) weak-hash/c #:chaperone)
   ((box/sc (#:invariant)) box/c #:chaperone)
   ((parameter/sc (#:contravariant) (#:covariant)) parameter/c #:chaperone)
   ((sequence/sc . (#:covariant)) sequence/c #:impersonator)

typed-racket-lib/typed-racket/utils/hash-contract.rkt

@@ -1,8 +1,18 @@
 #lang racket/base
 
 (require racket/contract)
-(provide mutable-hash/c immutable-hash/c weak-hash/c)
+(provide tr-hash/c mutable-hash/c immutable-hash/c weak-hash/c)
 
-(define (mutable-hash/c k v) (and/c hash? (not/c hash-weak?) (hash/c k v #:immutable #f)))
-(define (immutable-hash/c k v) (hash/c k v #:immutable #t))
-(define (weak-hash/c k v) (and/c hash? hash-weak? (hash/c k v #:immutable #f)))
+(define (mutable-hash/c k v)
+  (and/c hash? (not/c hash-weak?) (tr-hash/c k v #:immutable #f)))
+
+(define (immutable-hash/c k v)
+  (tr-hash/c k v #:immutable #t))
+
+(define (weak-hash/c k v)
+  (and/c hash? hash-weak? (tr-hash/c k v #:immutable #f)))
+
+(define (tr-hash/c k v #:immutable [immutable 'dont-care])
+  (if (flat-contract? k)
+    (hash/c k v #:immutable immutable)
+    (and/c hash? hash-equal? (hash/c k v #:immutable immutable))))