while<>.rkt

#lang racket/base

(require racket/cmdline)

(define-syntax-rule
  (while<> line body ...)
  (let ([process-port
         (lambda ()
           (for ([line (in-port read-line)])
             body ...))])
    (command-line #:args files
      (if (empty? files)
          (process-port)
          (for ([f files])
            (with-input-from-file f process-port))))))