Parse out command-line arguments

--help, --repl, and the sort.

contact.scm

@@ -15,14 +15,17 @@
 
 (import scheme
         (chicken base)
+        (chicken condition)
         (chicken file)
+        (chicken pathname)
         (chicken io)
         (chicken repl)
-        (chicken repl)
+        (chicken process-context)
         (chicken string)
         (chicken time)
         srfi-1
         srfi-18
+        (prefix getopt-long getopt:)
         nrepl
         qt-light
         (prefix uri-common uri:)
@@ -35,6 +38,9 @@
 
 ;; Start & run the application.
 (define (init)
+  (let [(cli-args (parse-cli-args (command-line-arguments)))]
+    (if (alist-ref 'help cli-args)
+        (cli-usage))
     ;; Set up some global state, prepare the QT app.
     (set! qt-app (qt:init))
     (set! qt-win (create-window))
@@ -43,11 +49,45 @@
     (let ;; Start QT loop.
          [(qt-thread (thread-start! qt-loop))
           ;; Kick off the remote-REPL…
-       (nrepl-thread (thread-start! (lambda () (nrepl 1234))))]
+          (nrepl-thread
+           (if (alist-ref 'repl cli-args)
+               (thread-start!
+                (lambda ()
+                  (nrepl (string->number (alist-ref 'repl cli-args)))))))]
        ;; … and also provide a local REPL.
        (repl)
        ;; Wait for the QT program, even after stdin is closed off.
-    (thread-join! qt-thread)))
+       (thread-join! qt-thread))))
+
+
+;; Print a “usage” help message, telling the user how to run the program.
+(define (cli-usage)
+  (print "usage: " (pathname-file (program-name)) " [-h] [--repl PORT]")
+  (print)
+  (print (pathname-file (program-name)) " is a simple contacts program for managing")
+  (print "vCard-format contacts.")
+  (print)
+  (print (getopt:usage cli-args-grammar))
+  (exit))
+
+
+;; Parse out command-line args into an alist.
+;;    '("dad" "-h" "--repl=12" "mm") → '(("dad" "mm") (help #t) (repl 12))
+(define (parse-cli-args args)
+  (handle-exceptions
+      exn
+      (and
+        (print ((condition-property-accessor 'exn 'message) exn))
+        '((help . #t)))
+    (getopt:getopt-long args cli-args-grammar)))
+
+
+;; Definition of our command-line arguments, in getopt-long’s format.
+(define cli-args-grammar
+  '((help "display this help message"
+          (single-char #\h))
+    (repl "start a TCP-accesible REPL at the given port"
+          (value #t))))
 
 
 ;; Loop through QT’s processing, again and again.
@@ -145,4 +185,7 @@
        vcard-alist))
 
 
+
+
+
 (init)