From cbce8eb293321aef12d153abce31cc3c6ab14f95 Mon Sep 17 00:00:00 2001
From: Dale Mellor <mcron-lsfnyl@rdmp.org>
Date: Thu, 10 Sep 2020 05:48:26 +0100
Subject: Incorporate and use command-line-processor proposed for Guile core

Since the elimination of the C wrapping around mcron and all the
executable scripts, a weakness in Guile's (ice-9 getopt-long) module
means that the command 'mcron -s crontab.scm' does not currently
work.  A replacement for the getopt-long module, as well as a
higher-level 'command-line-processor' facility, have been pushed to
the Guile upstream developers and are awaiting approval and
incorporation.  In the meantime, those modules are temporarily
incorporated here into the mcron package, and the code is modified
to use those local versions.

 * Makefile.am: install two new Guile modules
 * src/{cron,crontab,mcron}.in: use local command-line-processor module
 * src/mcron/command-line-processor.scm: new module
 * src/mcron/getopt-long.scm: new module
 * tests/schedule{,-2}.sh: clarify tests of -s, --schedule options
---
 src/cron.in                          |   3 +-
 src/crontab.in                       |   2 +-
 src/mcron.in                         |   2 +-
 src/mcron/command-line-processor.scm | 653 +++++++++++++++++++++++++++++++++++
 src/mcron/getopt-long.scm            | 552 +++++++++++++++++++++++++++++
 5 files changed, 1208 insertions(+), 4 deletions(-)
 create mode 100644 src/mcron/command-line-processor.scm
 create mode 100644 src/mcron/getopt-long.scm

(limited to 'src')

diff --git a/src/cron.in b/src/cron.in
index b260a5e..4fb65c8 100644
--- a/src/cron.in
+++ b/src/cron.in
@@ -28,7 +28,7 @@
 
 (use-modules  (mcron scripts cron)
               (mcron utils)
-              (ice-9 command-line-processor))
+              (mcron command-line-processor))
 
 (process-command-line  (command-line)
    application "cron"
@@ -49,5 +49,4 @@
    copyright "2003 - 2022  Free Software Foundation, Inc."
    license     GPLv3)
 
-
 (catch-mcron-error (main --schedule --noetc))
diff --git a/src/crontab.in b/src/crontab.in
index f203a98..fb624a3 100644
--- a/src/crontab.in
+++ b/src/crontab.in
@@ -27,7 +27,7 @@
   (set! %load-compiled-path (cons "%modbuilddir%" %load-compiled-path)))
 
 (use-modules (mcron scripts crontab)
-             (ice-9 command-line-processor))
+             (mcron command-line-processor))
 
 (process-command-line  (command-line)
    application "crontab"
diff --git a/src/mcron.in b/src/mcron.in
index a7707e0..ac4aace 100644
--- a/src/mcron.in
+++ b/src/mcron.in
@@ -28,7 +28,7 @@
 
 (use-modules  (mcron scripts mcron)
               (mcron utils)
-              (ice-9 command-line-processor))
+              (mcron command-line-processor))
 
 (process-command-line  (command-line)
        application   "mcron"
diff --git a/src/mcron/command-line-processor.scm b/src/mcron/command-line-processor.scm
new file mode 100644
index 0000000..5b5491b
--- /dev/null
+++ b/src/mcron/command-line-processor.scm
@@ -0,0 +1,653 @@
+;;;;                                                            -*- scheme -*-
+;;;; command-line-processor.scm --- command-line options processing
+;;;;
+;;;; Copyright (C) 1998, 2001, 2006, 2009, 2011, 2020
+;;;;                                            Free Software Foundation, Inc.
+;;;;
+;;;; This library is free software; you can redistribute it and/or
+;;;; modify it under the terms of the GNU Lesser General Public
+;;;; License as published by the Free Software Foundation; either
+;;;; version 3 of the License, or (at your option) any later version.
+;;;; 
+;;;; This library is distributed in the hope that it will be useful,
+;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;;; Lesser General Public License for more details.
+;;;; 
+;;;; You should have received a copy of the GNU Lesser General Public
+;;;; License along with this library; if not, write to the Free Software
+;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+;;;; 02110-1301 USA
+
+;;; Author: Dale Mellor   May, 2020
+
+;;; Commentary:
+
+;;; Where the Guile (ice-9 getopt-long) module, modelled after the GNU C
+;;; libraryʼs ‘getopt_long’ function, allows an application to construct
+;;; a grammar prescribing the decomposition of the command-line options,
+;;; this module, inspired by the C libraryʼs ‘argp’ parser, gives the
+;;; application a higher-level paradigm in which the command-line
+;;; processing is specified declaratively.  This includes enough of the
+;;; application meta-data and some fragmentary help strings for the
+;;; completely automatic generation of responses to GNU-standard
+;;; ‘--help’, ‘--version’ and ‘--usage’ options, thus alleviating the
+;;; need of the application itself to deal with these things.
+;;;
+;;; The module has three specific aims.
+;;;
+;;;    1) Provide higher-level declarative interface, easier to use.
+;;;
+;;;    2) Automatically respond to --help, --version and --usage
+;;;       options.
+;;;
+;;;    3) Allow amalgamation of specifications, so that an application
+;;;       can mix in requirements from modules into its own option
+;;;       specification--THIS IS NOT CURRENTLY IMPLEMENTED.
+;;;
+;;; There is just one function which needs to be called to get all of
+;;; this functionality: it is ‘process-command-line’, and has the side
+;;; effect that new variable bindings appear in the current module
+;;; corresponding to all the options.  For example, if a declared option
+;;; is ‘--do-this’, then a variable called, literally, ‘--do-this’ will
+;;; be injected in the current namespace and will have the value
+;;; provided on the command-line, or simply #t or #f to indicate whether
+;;; or not that option was present on the command line.
+;;;
+;;; Alternatively, it is possible to create and compose the
+;;; specification in separate steps, and then call the above method with
+;;; the results.  The functions ‘command-line-specification’ and
+;;; ‘merge-command-line-specifications’ are provided to this end.
+
+;;; (process-command-line  COMMAND-LINE  SPECIFICATION)
+;;; Process the COMMAND-LINE according to the application SPECIFICATION.
+;;;
+;;; COMMAND-LINE is a list of strings, such as that returned from the
+;;; core ‘command-line’ function.
+;;;
+;;; SPECIFICATION is a form holding a space-separated mix of selection
+;;; words followed by their respective declarations.  The selection
+;;; words are ‘application’, ‘author’, ‘bug-address’, ‘copyright’,
+;;; ‘help-preamble’, ‘help-postamble’, ‘license’, ‘option’, ‘usage’ and
+;;; ‘version’, and can appear in any order.
+;;;
+;;;    ‘application’ should be followed by a string: the name of the
+;;;           application with possibly the package name in
+;;;           parentheses afterwards
+;;;    ‘author’ should be followed by a string giving the name of one of
+;;;           the packageʼs authors.  This selection word can be
+;;;           repeated as many times as necessary to provide the names
+;;;           of all authors.
+;;;    ‘bug-address’ should be followed by a string giving the URL of a
+;;;           contact-point for sending bug reports, such as an
+;;;           e-mail address or web address of bug-tracking system
+;;;           interface
+;;;    ‘copyright’ should be followed by a string containing a list of
+;;;           years and an entity to whom the copyright is assigned.
+;;;           This may be repeated to list other assignees
+;;;    ‘help-preamble’ should be followed by a number of strings which
+;;;           make up a short paragraph of text displayed before
+;;;           a full list of the available program options
+;;;    ‘help-postamble’, like the preamble, is followed by strings which
+;;;           make up a paragraph of text, shown after the list
+;;;           of options
+;;;    ‘license’ can be followed by one of the words ‘GPLv3’ [this is
+;;;           currently the only standard choice implemented], or else
+;;;           a string which briefly gives out the terms of the license
+;;;    ‘option’ is followed by an option declaration, described below
+;;;    ‘usage’ is followed by a string describing the usage of the
+;;;           application on one line
+;;;    ‘version’ is followed by a string providing the current version
+;;;           number of this program
+;;;
+;;; The ‘option’ declaration is followed by another form bracketed by
+;;; parentheses and holding a space-separated mix of declarations (order
+;;; irrelevant).
+;;;
+;;;    A word beginning with two hyphens, an optional exclamation point,
+;;;    alpha-numeric characters, an optional equals sign, and an
+;;;    optional further word.  There must be exactly one of these, and
+;;;    they determine the long name of the option.  An exclamation point
+;;;    indicates that the option MUST appear on the command line, an
+;;;    equals indicates that the option MUST have a value unless it is
+;;;    followed in the specification by a value, in which case the value
+;;;    on the command-line is optional and the one in the specification
+;;;    will be taken as the default when not given on the command line.
+;;;
+;;;    A word comprised of one hyphen and one letter or number.  There
+;;;    can be exactly zero or one of these, and it declares that the
+;;;    option has this short form available on the command-line.  As a
+;;;    very special exception: if you want to use ‘-i’ as an option, it
+;;;    must be specified with the identifier ‘short-i’ (a naked /-i/ is
+;;;    read as a complex number); ditto ‘short-I’ for ‘-I’.
+;;;
+;;;    A number of strings which are catenated together to provide a
+;;;    short, succinct description of the option.  These strings should
+;;;    be approximately half the width of a page, i.e. about 40
+;;;    characters.
+;;;
+;;;    A function which will be used as a predicate to decide if a value
+;;;    is allowable for this option.  There should be zero or one of
+;;;    these.
+;;;
+;;; For the precise presentation of options on the command-line, the
+;;; reader should refer to the description of the ‘getopt-long’ module,
+;;; which underlies the present one.
+;;;
+;;; At this point a short example is in order.  The main entry point for
+;;; the GNU Mcron program has as its first clause
+;;;
+;;; (process-command-line  (command-line)
+;;;       application   "mcron"
+;;;       version       "1.4"
+;;;       usage         "[OPTIONS]... [FILES]..."
+;;;       help-preamble
+;;;  "Run an mcron process according to the specifications in the FILE... "
+;;;  "(`-' for standard input), or use all the files in ~/.config/cron "
+;;;  "(or the deprecated ~/.cron) with .guile or .vixie extensions.\n"
+;;;  "Note that --daemon and --schedule are mutually exclusive."
+;;;       option  (--daemon  -d
+;;;                      "run as a daemon process")
+;;;       option  (--stdin=guile  short-i  (λ (in) (or (string=? in "guile")
+;;;                                                    (string=? in "vixie")))
+;;;                      "format of data passed as standard input or file "
+;;;                      "arguments, 'guile' or 'vixie' (default guile)")
+;;;       option  (--schedule=8  -s  string->number
+;;;                      "display the next N (or 8) jobs that will be run")
+;;;       help-postamble
+;;;  "Mandatory or optional arguments to long options are also mandatory or "
+;;;  "optional for any corresponding short options."
+;;;       bug-address "bug-mcron@gnu.org"
+;;;       copyright   "2003, 2006, 2014, 2020  Free Software Foundation, Inc."
+;;;       license     GPLv3)
+;;;
+;;; after which there are four new variable bindings in the present
+;;; namespace: --daemon, --stdin, --schedule and --! (the latter holds
+;;; all the command-line arguments that did not partake in option
+;;; processing) whose values depend on the specific command-line options
+;;; the end user furnished.
+
+;;; (command-line-specification  SPECIFICATION)
+;;; Compiles an object which encapsulates the given SPECIFICATION.
+;;;
+;;; For details of how to give a SPECIFICATION, see the description of
+;;; the full ‘process-command-line’ function above.  The return from
+;;; this method can be used in the partial version of
+;;; ‘process-command-line’ described below, and in the following
+;;; ‘merge-command-line-specifications’ function.
+
+;;; (merge-command-line-specifications SPECIFICATION_OBJECT ...)  Make a
+;;; single specification object which embodies the amalgamation of all
+;;; of the specification objects given as arguments.
+;;;
+;;; Order is important: if two option items specify the same short form
+;;; for the option (a single letter), then only the first option will
+;;; actually have that short form available at the command-line.
+;;; Similarly, if two options have exactly the same name, the second (or
+;;; later) ones will have a numerical digit appended to their name.
+
+;;; (process-command-line COMMAND-LINE SPECIFICATION-OBJECT) Perform
+;;; exactly the same function as the full ‘process-command-line’
+;;; function described above, but takes a pre-made specification object
+;;; produced using the two functions above.
+
+;;; Bugs/To do
+;;;
+;;; 1) This stuff currently only works in the top-level module.
+;;;
+;;; 2) Want to be able to amalgamate command-line specifications from
+;;; different modules.  Will need to get to the bottom of the first
+;;; issue before we can tackle this one (somehow need to put the
+;;; --option variable bindings into the right places, or at least
+;;; replicate them all in all modules which want to do some processing
+;;; of the command line).
+;;;
+;;; 3) Want more license boilerplate text; currently we only have GPLv3.
+
+;;; Code:
+
+(define-module (mcron command-line-processor)
+  #:use-module (srfi srfi-1)       ;; fold
+  #:use-module (srfi srfi-9)       ;; records
+  #:use-module (srfi srfi-9 gnu)   ;; set/get-fields
+  #:use-module (mcron getopt-long)
+  #:use-module (ice-9 regex)
+  #:export (specific option item
+            obtain-getopt-long-results
+            process-getopt-long-results
+            
+            ;; These are the real public exports.
+            process-command-line
+            command-line-specification
+            merge-command-line-specifications))
+
+
+
+(define-record-type  <<specification>>
+       (make-specification- preamble postamble copyright authors options)
+       specification?
+          (name        spec:name      spec:set-name!)
+          (version     spec:version   spec:set-version!)
+          (usage       spec:usage     spec:set-usage!)
+          (preamble    spec:preamble  spec:set-preamble!)
+          (postamble   spec:postamble spec:set-postamble!)
+          (bug-address spec:bugs      spec:set-bugs!)
+          (copyright   spec:copyright spec:set-copyright!)
+          (license     spec:license   spec:set-license!)
+          (authors     spec:authors   spec:set-authors!)
+          (options     spec:options   spec:set-all-options!))
+
+;; We initialize the fields which are supposed to be lists, but
+;; generally this procedure should *not* be considered to be producing a
+;; properly specified <<specification>> record.
+(define (make-specification) (make-specification- '() '() '() '() '()))
+
+
+
+(define-record-type  <<option>>
+       (make-option- description)
+       option?
+          (name         option:name         option:set-name!)
+          (required?    option:required?)
+          (short-letter option:short        option:set-short!)
+          (value?       option:value?)
+          (default      option:default)
+          (description  option:description  option:set-description!)
+          (predicate    option:predicate    option:set-predicate!))
+
+;; As above, this initializer does *not* return a properly defined
+;; object.
+(define (make-option) (make-option- '()))
+
+
+
+(define (has-option-short-form spec letter)
+  (not (or (not letter)
+           (eq? #f (find (λ (a) (eqv? letter (option:short a)))
+                         (spec:options spec))))))
+
+(define (has-option-name spec name)
+  (not (eq? #f (find (λ (a) (string=? (option:name a) name))
+                     (spec:options spec)))))
+
+(define (merge-command-line-specifications- A B)
+  (for-each (λ (b-option)
+               (when (has-option-short-form A (option:short b-option))
+                 (option:set-short!  b-option  #f))
+               (let ((base-name (option:name b-option)))
+                 (when (has-option-name A base-name)
+                   (let loop ((count 1))
+                        (let ((new-name (string-append base-name "-"
+                                                       (number->string count))))
+                          (if (has-option-name A new-name)
+                              (loop (1+ count))
+                              (option:set-name!  b-option  new-name))))))
+               (spec:set-all-options! A (append (spec:options A)
+                                                (list b-option))))
+            (spec:options B))
+  A)
+
+(define-syntax merge-command-line-specifications
+  (syntax-rules ()
+  "- Scheme Procedure: merge-command-line-specifications A B ...
+
+Append the list of options in A with those in B, but drop any
+short-forms in B which clash with existing ones, and if a long option
+name clashes then append a number to make it unique.  All of the
+arguments will be mutilated in the process, and a new specification
+object will be returned."
+    ((_ A B) (merge-command-line-specifications- A B))
+    ((_ A B . C) (merge-command-line-specifications
+                   (merge-command-line-specifications- A B)
+                   . C))))
+
+
+
+(define  long-re   (make-regexp "^--(!)?([[:alnum:]][-_[:alnum:]]*)(=(.+)?)?$"))
+(define  short-re  (make-regexp  "^-[[:alnum:]]$"))
+
+
+(define-syntax item   ;; As in, an option item (long name, short form...).
+  (λ (x) (syntax-case x (short-i short-I)
+
+    ;; No more work to do.
+    ((_ O) #'#t)
+
+    ;; Next option is a string: take as description.
+    ((_ O desc . args)
+     (string? (syntax->datum #'desc))
+     #'(begin (option:set-description! O (append (option:description O)
+                                                 (list desc)))
+              (item O . args)))
+
+    ;; Next option is short-form.
+    ((_ O short-i . args)
+     #'(begin (option:set-short! O #\i)
+              (item O . args)))
+
+    ((_ O short-I . args)
+     #'(begin (option:set-short! O #\I)
+              (item O . args)))
+
+    ((_ O short . args)
+     (and (identifier? #'short)
+          (regexp-exec short-re (symbol->string (syntax->datum #'short))))
+     #'(begin (option:set-short! O (string-ref (symbol->string 'short) 1))
+              (item O . args)))
+
+    ;; Next option is long-form.
+    ((_ O long . args)
+     (and (identifier? #'long)
+          (regexp-exec long-re (symbol->string (syntax->datum #'long))))
+     #'(begin (let ((match (regexp-exec long-re
+                                (symbol->string (syntax->datum #'long)))))
+                (set! O
+                   (set-fields O
+                     ((option:name)       (match:substring match 2))
+                     ((option:required?)  (if (match:substring match 1) #t #f))
+                     ((option:value?)
+                                 (cond ((not (match:substring match 3)) #f)
+                                       ((match:substring match 4)  'optional)
+                                       (else #t)))
+                     ((option:default)    (match:substring match 4)))))
+              (item O . args)))
+
+    ;; Next option is a procedure: take as predicate.
+
+    ((_ O (lambda args ...) . Args)
+     #'(begin (option:set-predicate! O (lambda args ...))
+              (item O . Args)))
+
+    ((_ O pred . args)
+     (and (identifier? #'pred)
+          ;; (procedure? (primitive-eval (syntax->datum #'pred)))
+          )
+     #'(begin (option:set-predicate! O pred)
+              (item O . args))))))
+
+
+
+(define-syntax-rule  (option args ...)
+    (let ((O (make-option))) (item O args ...) O))
+
+
+
+(define-syntax  specific
+  (λ (x)  (syntax-case  x  (application  author         bug-address
+                            copyright    help-preamble  help-postamble
+                            license      option         usage
+                            version)
+     ((specific spec application A args ...)
+      (string? (syntax->datum #'A))
+            #'(begin (spec:set-name! spec A)
+                     (specific spec args ...)))
+     ((specific spec author A args ...)
+      (string? (syntax->datum #'A))
+            #'(begin (spec:set-author! spec (append (spec:authors spec)
+                                                    (list A)))
+                     (specific spec args ...)))
+     ((specific spec bug-address B args ...)
+      (string? (syntax->datum #'B))
+            #'(begin (spec:set-bugs! spec B)
+                     (specific spec args ...)))
+     ((specific spec copyright C args ...)
+      (string? (syntax->datum #'C))
+            #'(begin (spec:set-copyright! spec (append (spec:copyright spec)
+                                                       (list C)))
+                      (specific spec args ...)))
+     ((specific spec help-preamble id args ...)
+      (identifier? #'id)
+            #'(specific spec id args ...))
+     ((specific spec help-preamble quotation args ...)
+      (string? (syntax->datum #'quotation))
+            #'(begin (spec:set-preamble! spec (append (spec:preamble spec)
+                                                      (list quotation)))
+                     (specific spec help-preamble args ...)))
+     ((specific spec help-postamble id args ...)
+      (identifier? #'id)
+            #'(specific spec id args ...))
+     ((specific spec help-postamble quotation args ...)
+      (string? (syntax->datum #'quotation))
+            #'(begin (spec:set-postamble! spec (append (spec:postamble spec)
+                                                       (list quotation)))
+                     (specific spec help-postamble args ...)))
+     ((specific spec license L args ...)
+      (identifier? #'L)
+            #'(begin (spec:set-license! spec 'L)
+                     (specific spec args ...)))
+     ((specific spec license L args ...)
+      (string? (syntax->datum #'L))
+            #'(begin (spec:set-license! spec L)
+                     (specific spec args ...)))
+     ((specific spec option (args ...) Args ...)
+            #'(begin (spec:set-all-options! spec
+                                            (append (spec:options spec)
+                                                    (list (option args ...))))
+                     (specific spec Args ...)))
+     ((specific spec usage U args ...)
+      (string? (syntax->datum #'U))
+            #'(begin (spec:set-usage! spec U)
+                     (specific spec args ...)))
+     ((specific spec version V args ...)
+      (string? (syntax->datum #'V))
+            #'(begin (spec:set-version! spec V)
+                     (specific spec args ...)))
+     ((specific spec)  #'#t))))
+
+
+
+(define-syntax-rule  (command-line-specification args ...)
+;;   " - Scheme Procedure: command-line-specification ARGS ...
+
+;; Furnish an application specification object with attributes specified in
+;; ARGS followed by a number of values for the attribute.  Please refer to
+;; full documentation for a proper description of a specification object.
+
+;; The attributes are
+
+;;  application: string: the formal name of this application.  Must appear
+;;          exactly once.
+;;  author: string: the name of an author.  May appear any number of times.
+;;  bug-address: string: The URI to which bug reports should be addressed.
+;;          May appear zero or one times.
+;;  copyright: string: list of years and owning entity.  May appear any
+;;          number of times.
+;;  help-preamble: string: text to precede the list of options in a
+;;          response to the --help option.  This attribute may appear any
+;;          number of times, and each occurrence can be followed by one or
+;;          more strings which will be assembled together into paragraphs.
+;;  help-postamble: string: text to succeed the list of options in a help
+;;          message.  Same considerations apply as to ‘help-preamble’.
+;;  license: identifier or string: either the identifier ‘GPLv3’ or a
+;;          string describing the terms of the license.
+;;  option: (sub-form): the sub-form must contain one identifier composed
+;;          of two hyphens, an optional exclamation point, a token of
+;;          letters, numbers, underscore and hyphen, an optional equals
+;;          sign, and an optional word; the sub-form may have zero or one
+;;          identifiers composed of a hyphen and a single letter; any
+;;          number of strings which will be composed into a paragraph of
+;;          help for the option (these should be sized to half-line
+;;          lengths); and zero or one procedures which will be applied as a
+;;          predicate on allowable option values.  Any number of these
+;;          option attributes may appear in the specification.
+;;  usage: string: a single line of text prototyping the command line.
+;;          Zero or one of these may appear.
+;;  version: string: the version number of this application.  Zero or one
+;;          of these attributes may appear."
+
+  (let ((spec (make-specification)))
+    (specific spec args ...)
+    spec))
+
+
+
+(define (version-string spec)
+  (with-output-to-string (λ ()
+    (display (if (string? (spec:name spec))
+                 (spec:name spec)
+                 (car (command-line))))
+    (when (string? (spec:version spec))
+      (for-each display `(" " ,(spec:version spec) "\n")))
+    (unless (null? (spec:copyright spec))
+      (for-each display `("Copyright © "
+                          ,(string-join (spec:copyright spec) "\n            ")
+                          "\n")))
+    (cond ((eq? (spec:license spec) 'GPLv3)
+                (display (string-append
+                          "License GPLv3+: GNU GPL version 3 or later "
+                          "<https://gnu.org/licenses/gpl.html>.\nThis is "
+                          "free software: you are free to change and "
+                          "redistribute it.\nThere is NO WARRANTY, to the "
+                          "extent permitted by law.\n")))
+          ((string? (spec:license spec))
+                (display (spec:license spec)) (newline)))
+    (unless (null? (spec:authors spec))
+      (display (string-append "Written by "
+                        (case (length (spec:authors spec))
+                          ((1 2)  (string-join (spec:authors spec) " and "))
+                          (else
+                           (let loop ((a (cdr (spec:authors spec)))
+                                      (ret (car (spec:authors spec))))
+                                (if (null? (cdr a))
+                                    (string-append ret " and " (car a))
+                                  (loop (cdr a) (string-append ret ", "
+                                                               (car a)))))))
+                        ".\n"))))))
+
+
+
+(define (usage-string spec)
+  (string-append "Usage: " (spec:name spec) " " (spec:usage spec) "\n"))
+
+
+
+(define  (help-string spec)
+  (with-output-to-string (λ ()
+    (for-each display `(,(usage-string spec)
+                        ,(string-join (spec:preamble spec) "\n")
+                        "\n\n"))
+    (let ((max-length (fold (λ (o r) (max r (string-length (option:name o))))
+                            0
+                            (spec:options spec))))
+      (for-each (λ (o)
+              (display "  ")
+              (cond ((option:short o)
+                     (display "-") (display (option:short o))
+                     (case (option:value? o)  ((#t)        (display "N,   "))
+                                              ((optional)  (display "[N], "))
+                                              (else        (display ",    "))))
+                    (else (display "       ")))
+              (display "--")
+              (display (option:name o))
+              (case (option:value? o)  ((#t)       (display "=N  "))
+                                       ((optional) (display "[=N]"))
+                                       (else       (display "    ")))
+              (display (make-string (- max-length
+                                       (string-length (option:name o)))
+                                    #\space))
+              (display "  ")
+              (when  (option:required? o)  (display "*REQUIRED*: "))
+              (display (string-join (option:description o)
+                                    (string-append "\n"
+                                                   (make-string max-length
+                                                                #\space)
+                                                   "                   ")))
+              (newline))
+           (spec:options spec)))
+     (newline)
+     (display (string-join (spec:postamble spec) "\n"))
+     (when (spec:bugs spec)
+       (for-each display
+                 `("\nSend bug reports to " ,(spec:bugs spec) ".\n"))))))
+
+
+
+;;  Make a list out of the args, omitting any #f.
+(define (compose-list . args)
+  (let loop ((ret '()) (args args))
+       (cond ((null? args) (reverse ret))
+             ((not (car args)) (loop ret (cdr args)))
+             (else (loop (cons (car args) ret) (cdr args))))))
+
+(define (make-getopt-long-input spec)
+  (map (λ (o)
+         (compose-list (string->symbol (option:name o))
+                       (and=> (option:short o) (λ (x) `(single-char ,x)))
+                       `(required? ,(option:required? o))
+                       `(value ,(if (option:default o)
+                                    'optional
+                                  (option:value? o)))
+                       (and=> (option:predicate o) (λ (x) `(predicate ,x)))))
+       (spec:options spec)))
+
+
+
+(define-syntax-rule (obtain-getopt-long-results args spec)
+  (getopt-long args (make-getopt-long-input spec)))
+
+
+
+(define  (distill-getopt-long-results  go-l  spec)
+  (cons (cons "!" (option-ref go-l '() '()))
+        (map (λ (o)
+                (let ((g (option-ref go-l
+                                     (string->symbol (option:name o))
+                                     #f)))
+                  (when g
+                    (case (string->symbol (option:name o))
+                          ((help)    (display (help-string spec))    (exit 0))
+                          ((version) (display (version-string spec)) (exit 0))
+                          ((usage)   (display (usage-string spec))   (exit 0))))
+                  (cons (option:name o)
+                        (if (and (eq? #t g)
+                                 (not (eq? #f (option:default o))))
+                            (option:default o)
+                            g))))
+             (spec:options spec))))
+
+
+
+(define  (process-getopt-long-results go-l spec)
+  (for-each (λ (option)
+               (module-define!
+                        (current-module)
+                        (string->symbol (string-append "--" (car option)))
+                        (cdr option)))
+            (distill-getopt-long-results go-l spec)))
+
+
+
+(define-syntax  process-command-line
+;;   "- Scheme Procedure: process-command-line COMMAND-LINE SPECS [...]
+
+;; Process the COMMAND-LINE according to the SPECS, extracting options and
+;; their values, dealing with --help, --version and --usage requests.  The
+;; procedure has no return values, but has the side effect of creating
+;; variable bindings in the current module corresponding to the long form
+;; of the options, plus a variable called ‘--!’ which gets a list of all
+;; the arguments on the command-line which did not participate in option
+;; processing.
+
+;; The COMMAND-LINE is a list of strings, starting with the name of the
+;; program and containing all the tokens passed to the program on the
+;; command line, such as returned from the core ‘command-line’ procedure.
+
+;; The SPECS should have been obtained with the
+;; ‘command-line-specification’ procedure, or, as a short-cut, can be
+;; supplied directly as arguments to this procedure."
+
+  (syntax-rules ()
+    ((_ command-line specs)
+         (let ((S (merge-command-line-specifications
+                   specs
+                   (command-line-specification
+                     option (-h --help    "display this help and exit")
+                     option (-V --version "output version information and exit")
+                     option (-u --usage   "show brief usage summary")))))
+           (process-getopt-long-results
+             (obtain-getopt-long-results command-line S)
+             S)))
+    ((_ command-line item ...)
+         (process-command-line
+              command-line
+              (command-line-specification item ...)))))
diff --git a/src/mcron/getopt-long.scm b/src/mcron/getopt-long.scm
new file mode 100644
index 0000000..b05c9a8
--- /dev/null
+++ b/src/mcron/getopt-long.scm
@@ -0,0 +1,552 @@
+;;;; getopt-long.scm --- long options processing           -*- scheme -*-
+;;;;
+;;;; Copyright (C) 1998, 2001, 2006, 2009, 2011, 2020
+;;;;                                            Free Software Foundation, Inc.
+;;;;
+;;;; This library is free software; you can redistribute it and/or
+;;;; modify it under the terms of the GNU Lesser General Public
+;;;; License as published by the Free Software Foundation; either
+;;;; version 3 of the License, or (at your option) any later version.
+;;;; 
+;;;; This library is distributed in the hope that it will be useful,
+;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;;; Lesser General Public License for more details.
+;;;; 
+;;;; You should have received a copy of the GNU Lesser General Public
+;;;; License along with this library; if not, write to the Free Software
+;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+;;;; 02110-1301 USA
+
+;;; Author: Russ McManus
+;;;         Rewritten by Thien-Thi Nguyen
+;;;         Rewritten by Dale Mellor 2020-04-14
+
+;;; Commentary:
+
+;;; This module implements some complex command line option parsing, in
+;;; the spirit of the GNU C library function ‘getopt_long’.  Both long
+;;; and short options are supported.
+;;;
+;;; The theory is that people should be able to constrain the set of
+;;; options they want to process using a grammar, rather than some ad
+;;; hoc procedure.  The grammar makes the option descriptions easy to
+;;; read.
+;;;
+;;; ‘getopt-long’ is a procedure for parsing command-line arguments in a
+;;; manner consistent with other GNU programs.  ‘option-ref’ is a procedure
+;;; that facilitates processing of the ‘getopt-long’ return value.
+
+;;; (getopt-long ARGS GRAMMAR)
+;;; Parse the arguments ARGS according to the argument list grammar GRAMMAR.
+;;;
+;;; ARGS should be a list of strings.  Its first element should be the
+;;; name of the program, and subsequent elements should be the arguments
+;;; that were passed to the program on the command line.  The
+;;; ‘program-arguments’ procedure returns a list of this form.
+;;;
+;;; GRAMMAR is a list of the form:
+;;; ((OPTION (PROPERTY VALUE) ...) ...)
+;;;
+;;; Each OPTION should be a symbol.  ‘getopt-long’ will accept a
+;;; command-line option named ‘--OPTION’.
+;;; Each option can have the following (PROPERTY VALUE) pairs:
+;;;
+;;;   (single-char CHAR) --- Accept ‘-CHAR’ as a single-character
+;;;		equivalent to ‘--OPTION’.  This is how to specify traditional
+;;;		Unix-style flags.
+;;;   (required? BOOL) --- If BOOL is true, the option is required.
+;;;		getopt-long will raise an error if it is not found in ARGS.
+;;;   (value BOOL) --- If BOOL is #t, the option accepts a value; if
+;;;		it is #f, it does not; and if it is the symbol
+;;;		‘optional’, the option may appear in ARGS with or
+;;;		without a value.
+;;;   (predicate FUNC) --- If the option accepts a value (i.e. you
+;;;		specified ‘(value #t)’ or ‘(value 'optional)’ for this
+;;;		option), then getopt will apply FUNC to the value, and
+;;;		will not take the value if it returns #f.  FUNC should
+;;;		be a procedure which accepts a string and returns a
+;;;		boolean value; you may need to use quasiquotes to get it
+;;;		into GRAMMAR.
+;;;
+;;; The (PROPERTY VALUE) pairs may occur in any order, but each
+;;; property may occur only once.  By default, options do not have
+;;; single-character equivalents, are not required, and do not take
+;;; values.
+;;;
+;;; In ARGS, single-character options may be combined, in the usual
+;;; Unix fashion: ("-x" "-y") is equivalent to ("-xy").  If an option
+;;; accepts values, then it must be the last option in the
+;;; combination; the value is the next argument.  So, for example, using
+;;; the following grammar:
+;;;      ((apples    (single-char #\a))
+;;;       (blimps    (single-char #\b) (value #t))
+;;;       (catalexis (single-char #\c) (value #t)))
+;;; the following argument lists would be acceptable:
+;;;    ("-a" "-b" "bang" "-c" "couth")     ("bang" and "couth" are the values
+;;;                                         for "blimps" and "catalexis")
+;;;    ("-ab" "bang" "-c" "couth")         (same)
+;;;    ("-ac" "couth" "-b" "bang")         (same)
+;;;
+;;; If an option's value is optional, then ‘getopt-long’ decides whether
+;;; it has a value by looking at what follows it in ARGS.  If the next
+;;; element does not appear to be an option itself, and passes a
+;;; predicate if given, then that element is taken to be the option's
+;;; value.  Note that predicate functions are invaluable in this respect
+;;; for differentiating options and option values, and in the case of
+;;; options with optional values, PREDICATES REALLY SHOULD BE GIVEN.  If
+;;; an option is supposed to take a numerical value, then
+;;; ‘string->number’ can be used as the predicate; this will also allow
+;;; negative values to be used, which would ordinarily be regarded as
+;;; bad options causing the module, and the application consuming it, to
+;;; bail out with an immediate exit to the operating system.
+;;;
+;;; The value of a long option can appear as the next element in ARGS,
+;;; or it can follow the option name, separated by an ‘=’ character.
+;;; Thus, using the same grammar as above, the following argument lists
+;;; are equivalent:
+;;;   ("--apples" "Braeburn" "--blimps" "Goodyear")
+;;;   ("--apples=Braeburn" "--blimps" "Goodyear")
+;;;   ("--blimps" "Goodyear" "--apples=Braeburn")
+;;;
+;;; If the option "--" appears in ARGS, argument parsing stops there;
+;;; subsequent arguments are returned as ordinary arguments, even if
+;;; they resemble options.  So, in the argument list:
+;;;         ("--apples" "Granny Smith" "--" "--blimp" "Goodyear")
+;;; ‘getopt-long’ will recognize the ‘apples’ option as having the value
+;;; "Granny Smith", but it will not recognize the ‘blimp’ option; it
+;;; will return the strings "--blimp" and "Goodyear" as ordinary
+;;; argument strings.  The first "--" argument itself will *not* appear
+;;; in the ordinary arguments list, although the occurrence of
+;;; subsequent ones will.
+;;;
+;;; The ‘getopt-long’ function returns the parsed argument list as an
+;;; assocation list, mapping option names --- the symbols from GRAMMAR
+;;; --- onto their values, or #t if the option does not accept a value.
+;;; Unused options do not appear in the alist.
+;;;
+;;; All arguments that are not the value of any option are returned as a
+;;; list, associated with the empty list in the above returned
+;;; association.
+;;;
+;;; ‘getopt-long’ throws an exception if:
+;;; - it finds an unrecognized property in GRAMMAR
+;;; - the value of the ‘single-char’ property is not a character
+;;; - it finds an unrecognized option in ARGS
+;;; - a required option is omitted
+;;; - an option that requires an argument doesn't get one
+;;; - an option that doesn't accept an argument does get one (this can
+;;;   only happen using the long option ‘--opt=value’ syntax)
+;;; - an option predicate fails
+;;;
+;;; So, for example:
+;;;
+;;; (define grammar
+;;;   `((lockfile-dir (required? #t)
+;;;                   (value #t)
+;;;                   (single-char #\k)
+;;;                   (predicate ,file-is-directory?))
+;;;     (verbose (required? #f)
+;;;              (single-char #\v)
+;;;              (value #f))
+;;;     (x-includes (single-char #\x))
+;;;     (rnet-server (single-char #\y)
+;;;                  (predicate ,string?))))
+;;;
+;;; (getopt-long '("my-prog" "-vk" "/tmp" "foo1" "--x-includes=/usr/include"
+;;;                "--rnet-server=lamprod" "--" "-fred" "foo2" "foo3")
+;;;                grammar)
+;;; => ((() "foo1" "-fred" "foo2" "foo3")
+;;; 	(rnet-server . "lamprod")
+;;; 	(x-includes . "/usr/include")
+;;; 	(lockfile-dir . "/tmp")
+;;; 	(verbose . #t))
+
+;;; (option-ref OPTIONS KEY DEFAULT)
+;;; Return value in alist OPTIONS using KEY, a symbol; or DEFAULT if not
+;;; found.  The return is either a string or ‘#t’, or whatever DEFAULT
+;;; is.
+;;;
+;;; For example, using the ‘getopt-long’ return value from above:
+;;;
+;;; (option-ref (getopt-long ...) 'x-includes 42) => "/usr/include"
+;;; (option-ref (getopt-long ...) 'not-a-key! 31) => 31
+
+;;; Code:
+
+(define-module (mcron getopt-long)
+  #:use-module (ice-9 control)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-9)
+  #:use-module (ice-9 match)
+  #:use-module (ice-9 regex)
+  #:use-module (ice-9 receive)
+  #:export (getopt-long option-ref))
+
+(define program-name (make-parameter "guile"))
+
+(define (fatal-error fmt . args)
+  (format (current-error-port) "~a: " (program-name))
+  (apply format (current-error-port) fmt args)
+  (newline (current-error-port))
+  (exit 1))
+
+;; name: string, required?: bool, single-char: char or #f, predicate:
+;; procedure or #f, value-policy: bool or 'optional.
+(define-record-type option-spec
+  (%make-option-spec name required? single-char predicate value-policy)
+  option-spec?
+  (name         option-spec->name)
+  (required?    option-spec->required?    set-option-spec-required?!)
+  (single-char  option-spec->single-char  set-option-spec-single-char!)
+  (predicate    option-spec->predicate    set-option-spec-predicate!)
+  (value-policy option-spec->value-policy set-option-spec-value-policy!))
+
+(define (make-option-spec name)
+  (%make-option-spec name #f #f #f #f))
+
+(define (parse-option-spec desc)
+  (let ((spec (make-option-spec (symbol->string (car desc)))))
+    (for-each (match-lambda
+                (('required? val)
+                 (set-option-spec-required?! spec val))
+                (('value val)
+                 (set-option-spec-value-policy! spec val))
+                (('single-char val)
+                 (unless (char? val)
+                   (fatal-error "‘single-char’ value must be a char!"))
+                 (set-option-spec-single-char! spec val))
+                (('predicate pred)
+                 (set-option-spec-predicate! spec pred))
+                ((prop val)
+                 (fatal-error "invalid getopt-long option property: " prop)))
+               (cdr desc))
+    spec))
+
+
+;; Extract the name of a long option given that it may or may not be
+;; surrounded by '--' and '=...'.
+(define isolate-long-name-re (make-regexp "^(--)?([^=]+)"))
+
+(define (isolate-long-name name)
+  (and=> (regexp-exec isolate-long-name-re name)
+    (λ (match) (match:substring match 2))))
+
+
+;;  Whatever the presentation of the long option, make sure it is in a
+;;  clean, normalized form (but this does NOT account for any value the
+;;  option might have).
+(define (re-present option)
+  (string-append "--" (isolate-long-name option) "="))
+
+
+;;  The /name/ can take the form of a long option entry on the command
+;;  line, with whatever decoration that entails.  Will return #f if a
+;;  spec does not exist for this named option.
+(define (find-spec-long specs name)
+  (and=> (isolate-long-name name)
+    (λ (name) (find (λ (a) (string=? (option-spec->name a) name)) specs))))
+
+
+;;  Return #f if a spec with the short /letter/ name does not exist.
+(define (find-spec-short specs letter)
+  (find (λ (a) (eqv? (option-spec->single-char a) letter)) specs))
+
+
+;;  Take, for example, /short/='-h' to '--help='.
+(define (double-up short specs)
+  (and=> (find-spec-short specs (string-ref short 1))
+    (λ (spec) (string-append "--" (option-spec->name spec) "="))))
+
+
+;;  This procedure does whatever is necessary to put the (ostensibly)
+;;  first item on the command-line into the canonical (normal) form
+;;  '--item=value'; this may mean consuming the next item of the
+;;  command-line (the first item of /rest/) to get the value.  Note that
+;;  the value may be missing, but the '=' sign will always be there in
+;;  the return.  The first item (/A/) will always be more than two
+;;  characters, and the first two characters will be "--", i.e. we are
+;;  processing a long option.
+;;
+;;  A          IN   string               The first argument on the command-line
+;;  rest       IN   list of strings      The remaining items of the command-line
+;;  specs      IN   list of option-spec  Options specification
+;;  remnant    OUT  list of strings      The unprocessed command line
+;;  processed  OUT  string               New command-line argument
+(define (normalize-long-option A rest specs)
+  (define (return-empty-arg) (values rest (re-present A)))
+  (define (return-arg-with-value)
+    (values (cdr rest) (string-append (re-present A) (car rest))))
+  (cond
+   ((string-index A #\=)
+    ;; The argument is already in the canonical form.
+    (values rest A))
+   ((find-spec-long specs A)
+    => (λ (spec)
+          (if (cond ((null? rest) #f)
+                    ((option-spec->predicate spec)
+                     => (λ (pred) (pred (car rest))))
+                    (else
+                      (case (option-spec->value-policy spec)
+                        ((#f) #f)
+                        ((optional) 
+                         (not (eqv? (string-ref (car rest) 0) #\-)))
+                        ((#t)
+                         (or (string->number (car rest))
+                             (not (eqv? (string-ref (car rest) 0) #\-)))))))
+              (return-arg-with-value)
+              (return-empty-arg))))
+   (else
+    ;; We know nothing about this option, abort operations.
+    (fatal-error "no such option: --~a" (isolate-long-name A)))))
+
+
+
+;;  This procedure does whatever is necessary to put the (ostensibly)
+;;  first item on the command-line into the canonical form
+;;  '--item=value'; this may mean consuming the next item of the
+;;  command-line (the first item of /rest/) to get the value.  Note that
+;;  the value may be missing, but the '=' sign will always be there in
+;;  the return.  The first item (/A/) will always be exactly two
+;;  characters, and the first character will be "-", i.e. we are
+;;  processing an isolated short option.
+;;
+;;  A          IN   string               The first argument on the command-line
+;;  rest       IN   list of strings      The remaining items of the command-line
+;;  specs      IN   list of option-spec  Options specification
+;;  remnant    OUT  list of strings      The unprocessed command line
+;;  processed  OUT  string               New command-line argument
+(define (normalize-free-short-option A rest specs)
+  (define (return-empty-arg) (values rest (double-up A specs)))
+  (define (return-arg-with-next-value)
+    (values (cdr rest) (string-append (double-up A specs) (car rest))))
+  (let* ((name (string-ref A 1))
+         (spec (find-spec-short specs name)))
+    (if (cond ((not spec) (fatal-error "no such option: -~a" name))
+              ((null? rest) #f)
+              ((option-spec->predicate spec)
+               => (λ (pred) (pred (car rest))))
+              (else (case (option-spec->value-policy spec)
+                      ((optional) (not (eq? (string-ref (car rest) 0) #\-)))
+                      (else => identity))))
+        (return-arg-with-next-value)
+        (return-empty-arg))))
+
+
+
+;; The /sequence/ is a string of characters from the command line, and
+;; the task is to decide if those characters are a viable clumped option
+;; sequence, possibly using some of the trailing characters as option
+;; values, or not.
+(define (viable-short sequence specs)
+  (cond ((eq? 0 (string-length sequence)) #t)
+        ((find-spec-short specs (string-ref sequence 0))
+         => (λ (spec)
+               (cond ((option-spec->predicate spec)
+                      => (λ (pred) (pred (substring sequence 1))))
+                     (else
+                      ;; If this optionʼs /value-policy/ allows the
+                      ;; option to take a value then this string is
+                      ;; viable as the remainder can be taken as that
+                      ;; value.  Otherwise we must assert the viability
+                      ;; of the rest of the line by recursion.
+                      (or (not (eq? #f (option-spec->value-policy spec)))
+                          (viable-short (substring sequence 1) specs))))))
+        (else #f)))
+
+
+
+;;  This procedure does whatever is necessary to put the (ostensibly)
+;;  first item on the command-line into the canonical form
+;;  '--item=value'.  Note that the value may be missing, but the '='
+;;  sign will always be there in the return.  The first item (/A/) will
+;;  always be *more* than two characters, and the first character will
+;;  be "-", i.e. we are processing a short option which is either
+;;  clumped with other short options, or is clumped with its value.
+;;
+;;  NOTE that, contrary to the other normalize procedures, the return
+;;  value of /processed/ can be #f, with the expectation that the
+;;  modified /remnant/ will be re-processed.
+;;
+;;  A          IN   string               The first argument on the command-line
+;;  rest       IN   list of strings      The remaining items of the command-line
+;;  specs      IN   list of option-spec  Options specification
+;;  remnant    OUT  list of strings      The unprocessed command line
+;;  processed  OUT  string               New command-line argument
+(define (normalize-clumped-short-option A rest specs)
+  (define (declump-arg) (values (cons* (string-append "-" (substring A 1 2))
+                                       (string-append "-" (substring A 2))
+                                       rest)
+                                #f))
+  (define (construct-arg-from-clumped-value)
+    (values rest (string-append (double-up A specs) (substring A 2))))
+  (unless (char-alphabetic? (string-ref A 1)) (values rest A))
+  (let ((spec (find-spec-short specs (string-ref A 1))))
+    (if (cond ((not spec) (fatal-error "no such option: -~a" (string-ref A 1)))
+              ((option-spec->predicate spec)
+               => (λ (pred) (pred (substring A 2))))
+              (else (case (option-spec->value-policy spec)
+                      ((optional) (not (viable-short (substring A 2) specs)))
+                      (else => identity))))
+        (construct-arg-from-clumped-value)
+        (declump-arg))))
+
+
+
+;;  Return a version of the command-line /args/ in which all options are
+;;  represented in long form with an equals sign (whether they have a
+;;  value or not).
+(define (normalize args specs stop-at-first-non-option?)
+  (call/ec
+    (λ (return)
+      (let loop ((args args) (processed '()))
+        (when (null? args) (return (reverse processed)))
+        (define A (car args))
+        (define L (string-length A))
+        (define (when-loop cond normalizer)
+          (when cond
+            (receive (remainder-args processed-arg)
+                     (normalizer A (cdr args) specs)
+                     (loop
+                       remainder-args
+                       (if processed-arg
+                           (cons processed-arg processed)
+                           processed)))))
+        (when (string=? "--" A)
+          (return (append (reverse processed) args)))
+        (when-loop (and (> L 2) (string=? (substring A 0 2) "--"))
+          normalize-long-option)
+        (when-loop (and (eqv? L 2) (eqv? (string-ref A 0) #\-))
+          normalize-free-short-option)
+        (when-loop (and (> L 1) (eqv? (string-ref A 0) #\-))
+          normalize-clumped-short-option)
+        (if stop-at-first-non-option?
+            (return (append (reverse processed) args))
+            (loop (cdr args) (cons A processed)))))))
+
+
+
+;;  Check that all the rules inherent in the /specs/ are fulfilled by
+;;  the /options/.
+(define (verify-specs-fullfilled specs options)
+  (for-each
+    (λ (spec)
+      (let* ((name (option-spec->name spec))
+             (value (assq-ref options (string->symbol name))))
+        (when (and (option-spec->required? spec) (not value))
+          (fatal-error "option must be specified: --~a" name))
+        (let ((policy (option-spec->value-policy spec)))
+          (when (and (eq? policy #t) (eq? value  #t))
+            (fatal-error "option must be specified with argument: --~a" name))
+          (when (and (eq? policy #f) (string? value))
+            (fatal-error "option does not support argument: --~a" name)))
+        (let ((pred (option-spec->predicate spec)))
+          (when (and pred (string? value) (not (pred value)))
+            (fatal-error "option predicate failed: --~a" name)))))
+   specs))
+
+
+
+;;  Check that all the options are matched by a specification.
+(define (verify-options options specs)
+  (for-each
+    (λ (value)
+      (unless (or (null? (car value))
+                  (find-spec-long specs (symbol->string (car value))))
+        (fatal-error "no such option: --~a" (car value))))
+   options))
+
+
+
+;;  This procedure will simply return if the options and the specs
+;;  conform with each other, or else will bail out with an error
+;;  message.
+(define (check-compliance options specs)
+  (verify-specs-fullfilled specs options)
+  (verify-options options specs))
+
+
+
+(define full-option-re (make-regexp "^--([^=]+)=(.+)?$"))
+
+;; The /normal-args/ are a normalized command line in which all
+;; options are expressed long-form, and the task here is to construct an
+;; /options/ object: an associative array of option names onto values
+;; (or #t if there is no value).
+(define (extract-options normal-args stop-at-first-non-option?)
+  (let loop ((args normal-args)
+             (options '())
+             (non-options '()))
+       (cond
+         ((null? args) (acons '() (reverse non-options) options))
+         ((string=? (car args) "--")
+          (acons '() (append (reverse non-options) (cdr args)) options))
+         ((regexp-exec full-option-re (car args))
+          => (λ (match)
+                (loop (cdr args)
+                      (acons (string->symbol (match:substring match 1))
+                             (or (match:substring match 2) #t)
+                             options)
+                      non-options)))
+         (stop-at-first-non-option?
+          (acons '() (append (reverse non-options) args) options))
+         (else
+           (loop (cdr args) options (cons (car args) non-options))))))
+
+
+
+(define* (getopt-long program-arguments option-desc-list
+                      #:key stop-at-first-non-option)
+  "- Scheme Procedure: getopt-long PROGRAM-ARGUMENTS OPTION-DESC-LIST
+                                 [#:stop-at-first-non-option]
+
+Process options, handling both long and short options, similar to
+the glibc function 'getopt_long'.  PROGRAM-ARGUMENTS should be a value
+similar to what (program-arguments) returns.  OPTION-DESC-LIST is a
+list of option descriptions.  Each option description must satisfy the
+following grammar:
+
+    <option-spec>           :: (<name> . <attribute-ls>)
+    <attribute-ls>          :: (<attribute> . <attribute-ls>)
+                               | ()
+    <attribute>             :: <required-attribute>
+                               | <arg-required-attribute>
+                               | <single-char-attribute>
+                               | <predicate-attribute>
+                               | <value-attribute>
+    <required-attribute>    :: (required? <boolean>)
+    <single-char-attribute> :: (single-char <char>)
+    <value-attribute>       :: (value #t)
+                               (value #f)
+                               (value optional)
+    <predicate-attribute>   :: (predicate <1-ary-function>)
+
+    The procedure returns an alist of option names and values.  Each
+option name is a symbol.  The option value will be '#t' if no value
+was specified.  There is a special item in the returned alist with a
+key of the empty list, (): the list of arguments that are not options
+or option values.
+    By default, options are not required, and option values are not
+required.  By default, single character equivalents are not supported;
+if you want to allow the user to use single character options, you need
+to add a ‘single-char’ clause to the option description."
+  (parameterize ((program-name (car program-arguments)))
+    (let* ((specs (map parse-option-spec option-desc-list))
+           (options (extract-options
+                      (normalize (cdr program-arguments)
+                                 specs
+                                 stop-at-first-non-option)
+                      stop-at-first-non-option)))
+      (check-compliance options specs)
+      options)))
+
+
+
+(define (option-ref options key default)
+  "Return value in OPTIONS (as returned from getopt-long), using KEY--
+a symbol--, or DEFAULT if not found.  The value is either a string or
+‘#t’, or whatever DEFAULT is."
+  (or (assq-ref options key) default))
+
+
+;;; getopt-long.scm ends here
-- 
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