Barely using Arrow array library from Racket

arrow-array.rkt

#lang racket/base

(require ffi/unsafe
         gir)

(define arrow-lib (gi-ffi "Arrow"))

(define (make-arrow-buffer buf size)
  (arrow-lib 'Buffer 'new buf size))

(define (make-arrow-double-array size buf)
  (arrow-lib 'DoubleArray 'new size (buf ':this) #f 0))

(define array-size 32)
(define bytes-size (* 8 array-size))

(define rdata (make-bytes bytes-size))

(for ([n (in-naturals 42)]
      [i (in-range array-size)])
  (real->floating-point-bytes n 8 (system-big-endian?) rdata (* i 8)))

;; memory for the buffer
(define data (malloc bytes-size 'raw))
;; copy racket bytes into a raw bit of memory
(memcpy data rdata bytes-size)

(define an-arrow-buffer
  (make-arrow-buffer data bytes-size))

(define a-double-array
  (make-arrow-double-array array-size an-arrow-buffer))

(for ([i (in-range array-size)])
  (displayln (a-double-array 'get_value i)))