command-line.startup: adding version argument.

$ ./factor -version
Factor 0.99

basis/command-line/startup/startup.factor

@@ -1,14 +1,19 @@
 ! Copyright (C) 2011 Joe Groff.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: command-line eval io io.pathnames kernel namespaces
+USING: combinators command-line eval io io.pathnames kernel
-sequences system vocabs.loader ;
+namespaces system vocabs.loader ;
 IN: command-line.startup
 
-: cli-usage ( -- )
+: help? ( -- ? )
+    "help" get "h" get or
+    os windows? [ script get "/?" = or ] when ;
+
+: help. ( -- )
 "Usage: " write vm-path file-name write " [Factor arguments] [script] [script arguments]
 
 Factor arguments:
     -help               print this message and exit
+    -version            print the Factor version and exit
     -i=<image>          load Factor image file <image> (default " write vm-path file-stem write ".image)
     -run=<vocab>        run the MAIN: entry point of <vocab>
         -run=listener   run terminal listener
@@ -35,13 +40,15 @@ from within Factor for more information.
 
 " write ;
 
-: help? ( -- ? )
+: version? ( -- ? ) "version" get ;
-    "help" get "h" get or
+
-    os windows? [ script get "/?" = or ] when ;
+: version. ( -- ) "Factor " write vm-version print ;
 
 : command-line-startup ( -- )
-    (command-line) parse-command-line
+    (command-line) parse-command-line {
-    help? [ cli-usage ] [
+        { [ help? ] [ help. ] }
+        { [ version? ] [ version. ] }
+        [
             load-vocab-roots
             run-user-init
             "e" get script get or [
@@ -50,7 +57,8 @@ from within Factor for more information.
             ] [
                 "run" get run
             ] if
-    ] if
+        ]
+    } cond
 
     output-stream get [ stream-flush ] when*
     0 exit ;