Weather update server in Racket

#lang racket
#|
# Weather update server
# Binds PUB socket to tcp://*:5556
# Publishes random weather updates
|#
(require net/zmq)

(define ctxt (context 1))
(define sock (socket ctxt 'PUB))
(socket-bind! sock "tcp://*:5556")

(let loop ()
(define zipcode (random 100000))
(define temp (- (random 215) 80))
(define humidity (+ (random 50) 10))

(socket-send! sock (string->bytes/utf-8 (format "~a ~a ~a" zipcode temp humidity)))

(loop))

(context-close! ctxt)