More TR thread & contract issues

gistfile1.rkt

#lang racket
                                     
(module a racket
  (define f (λ () (displayln ((thread-receive) 'foo))))
  (provide f))
            
(module b typed/racket 
  (require/typed (submod ".." a)
                 [f (-> Void)])
  (define t (thread f))
  (thread-send t (λ: ([x : Flonum]) (* x 5.3))))
                                                   
(require 'b)