Here's a racket version of a websocket cat. Sadly, racket doesn't produce a single distributable executable like OCaml or golang, so we have to make do with a turd-like tarball.

Makefile

all: clean
	@raco exe wsc.rkt
	@raco distribute wscat wsc

clean:
	@rm -rf wsc wscat

wsc.rkt

#lang racket
(require net/rfc6455)
(require net/url)
(require racket/cmdline)
(require json)
(require terminal-color)

(define ws-url
  (command-line #:args (url) url))
(define conn (ws-connect(string->url ws-url)))
(define (print-json text) (printf "~a\n " text))
(let loop ()
  (define msg (ws-recv conn))
  (print-json msg)
  (unless (eof-object? msg) (loop))
  (loop))

; (define json #<<JSON
;   {"host":"akai.skunkwerks.at",
;   "service":"uptime/uptime",
;   "state":null,
;   "description":null,
;   "metric":3096,
;   "tags":["collectd"],
;   "time":"2015-02-16T11:20:01.000Z",
;   "ttl":20,
;   "ds_index":"0",
;   "ds_name":"value",
;   "ds_type":"gauge",
;   "type":"uptime",
;   "plugin":"uptime"}
;   JSON
;   )
; (define (print-json text)
;   ((define json (string->jsexpr text))))