Hierarchical Flu/Cough Model

(define flu-dist
  (repeat 
   1000
   (lambda ()
     (rejection-query
      
      ;; model
      (define flu-probability (uniform 0 1))
      (define flu (mem (lambda (person) (flip flu-probability))))
      (define cough
        (mem 
         (lambda (person)
           (if (flu person)
               (flip .85)
               (flip .1)))))
      
      ;; query
      (flu 'jim)
      
      ;; condition
      (and (cough 'bob) 
           (flu 'mary)
           (flu 'jane))))))

(hist flu-dist)