mes: Support -c EXPR.

* mes/module/mes/boot-0.scm.in: Support -c EXPR.

mes/module/mes/boot-0.scm.in

@@ -212,6 +212,7 @@
   (define (parse-opts args)
     (let* ((option-spec
             '((no-auto-compile)
+              (command (single-char #\c) (value #t))
               (compiled-path (single-char #\C) (value #t))
               (help (single-char #\h))
               (load-path (single-char #\L) (value #t))
@@ -224,6 +225,7 @@
   (let* ((s-index (list-index source-arg? %argv))
          (args (if s-index (list-head %argv (+ s-index 2)) %argv))
          (options (parse-opts args))
+         (command (option-ref options 'command #f))
          (main (option-ref options 'main #f))
          (source (option-ref options 'source #f))
          (files (if s-index (list-tail %argv (+ s-index 1))
@@ -240,6 +242,7 @@
 Evaluate code with Mes, interactively or from a script.
 
   [-s] FILE            load source code from FILE, and exit
+  -c EXPR              evalute expression EXPR, and exit
   --                   stop scanning arguments; run interactively
 
 The above switches stop argument processing, and pass all
@@ -262,10 +265,16 @@ General help using GNU software: <http://gnu.org/gethelp/>
 " (or (and usage? (current-error-port)) (current-output-port)))
           (exit (or (and usage? 2) 0)))
      options)
-    (if main (set! %main main))
     (and=> (option-ref options 'load-path #f)
            (lambda (dir)
              (setenv "GUILE_LOAD_PATH" (string-append dir ":" (getenv "GUILE_LOAD_PATH")))))
+    (when command
+      (let* ((prev (set-current-input-port (open-input-string command)))
+             (expr (read-input-file-env (current-module)))
+             (set-current-input-port prev))
+        (primitive-eval expr)
+        (exit 0)))
+    (when main (set! %main main))
     (cond ((pair? files)
            (let* ((file (car files))
                   (port (if (equal? file "-") 0