Parallel list (Chicken Scheme)

parallel-list.scm

(import (chicken process) (chicken file posix))

(define-syntax parallel-list
  (syntax-rules ()
    ((_ arg1 arg2)
     (receive (pipefd0 pipefd1) (create-pipe)
              (let ((pid (process-fork)))
                   (if (eq? pid 0)
                       (begin (write arg1 (open-output-file* pipefd1))
                              (exit 0)) ;child is done
                       (let* ((res1 arg2) ;get to work before waiting for child to return result (else there is no point)
                              (res2 (read (open-input-file* pipefd0))))
                             (list res1 res2))))))
    ((_ arg1 arg2 argi ...)
     (let ((chain (parallel-list arg1 (parallel-list arg2 argi ...))))
          (append (car chain) (cdr chain))))))

;example:
(define (test x) (list 2 x (+ 2 x)))
(display (parallel-list (test 42) (test 3) (test 1)))
(newline)