Frtime unhappy with contracts?

General
1

In testing for the 9.3 release, I happened to run this program in the frtime language level:

(require math/number-theory)

seconds

(build-list (modulo seconds 10) identity)

(+ seconds 1)

(prime? seconds)

I was surprised to see a failure:

prime?: contract violation
  expected: exact-integer?
  given: #(struct:signal 1785874065 (#<weak-box> #<weak-box> #<weak-box>) #false #<procedure:...frtime/lang-ext.rkt:467:23> 1 #<continuation-mark-set> #<parameterization> ())
  in: the 1st argument of
      (-> exact-integer? any)
  contract from: 
      <pkgs>/math-lib/math/private/number-theory/number-theory.rkt
  blaming: top-level
   (assuming the contract is correct)
  at: <pkgs>/math-lib/math/private/number-theory/number-theory.rkt:192:8

Is this just a fact of life with frtime? I'm surprised I haven't seen this error before.

2

Is this just a fact of life with frtime?

I believe so. The frtime language provides lifted versions of many primitives.
So for example even? works out of the box.

To lift prime? you need:

(require (lifted math/number-theory prime?))

seconds
(prime? seconds)
3

Thank you! I had imagined that a lifting rewriting happened for all applications, my mistake.