examples/scripts/hello

   1 #! /usr/local/bin/guile -s
   2 !#
   3 ;;; Commentary:
   4
   5 ;;; This is the famous Hello-World-program, written for Guile.  It is a
   6 ;;; little bit enhanced in that it understands the command line options
   7 ;;; `--help' (-h) and `--version' (-v), which print a short usage
   8 ;;; decription or version information, respectively.
   9
  10 ;;; Author: Martin Grabmueller
  11 ;;; Date: 2001-05-29
  12
  13 ;;; Code:
  14
  15 (use-modules (ice-9 getopt-long))
  16
  17 ;; This is the grammar for the command line synopsis we expect.
  18 ;;
  19 (define command-synopsis
  20   '((version (single-char #\v) (value #f))
  21     (help    (single-char #\h) (value #f))))
  22
  23 ;; Display version information and exit.
  24 ;;
  25 (define (display-version)
  26   (display "hello 0.0.1\n"))
  27
  28 ;; Display the usage help message and exit.
  29 ;;
  30 (define (display-help)
  31   (display "Usage: hello [options...]\n")
  32   (display "  --help, -h           Show this usage information\n")
  33   (display "  --version, -v        Show version information\n"))
  34
  35 ;; Interpret options, if --help or --version was given, print out the
  36 ;; requested information and exit.  Otherwise, print the famous
  37 ;; message.
  38 ;;
  39 (define (main options)
  40   (let ((help-wanted (option-ref options 'help #f))
  41         (version-wanted (option-ref options 'version #f)))
  42     (if (or version-wanted help-wanted)
  43         (begin
  44           (if version-wanted
  45               (display-version))
  46           (if help-wanted
  47               (display-help)))
  48         (begin
  49           (display "Hello, World!") (newline)))))
  50
  51 ;; Call the main program with parsed command line options.
  52 ;;
  53 (main (getopt-long (command-line) command-synopsis))
  54
  55 ;; Local variables:
  56 ;; mode: scheme
  57 ;; End:
  58