Common Lisp's #. in Racket

read-eval-test.rkt

#lang racket

#reader"read-eval.rkt"
(begin 
  #.(begin (define x 30) '(void))
  '(1 2 #.x))

read-eval.rkt

#lang racket
(require (prefix-in r: racket))

(define ns (make-base-namespace))

(define (make-rt)
  (make-readtable (current-readtable)
                  #\.
                  'dispatch-macro
                  (λ (ch in . args)
                    (define expr (r:read in))
                    (define r (eval expr ns))
                    r)))

(define (read . args)
  (parameterize ([current-readtable (make-rt)])
    (apply r:read args)))

(define (read-syntax a b . args)
  (parameterize ([current-readtable (make-rt)])
    (r:read-syntax a b)))

;(read (open-input-string "(1 2 #.(+ 10 20))")) ;; produces '(1 2 30)

(provide read read-syntax make-rt)