Add a new module to let the user get help for commands

module/guile-wm/module/help.scm

@@ -0,0 +1,22 @@
+(define-module (guile-wm module help)
+  #:use-module (guile-wm command)
+  #:use-module (guile-wm shared)
+  #:use-module (language command spec))
+
+(use-wm-modules message menu)
+
+(define-command (help)
+  "List all the commands and show documentation for the one selected
+by the user"
+  (menu "Select a command:"
+        (map (lambda (c) (cons (symbol->string c) (command-documentation c)))
+             (hash-map->list (lambda (k v) k) commands))
+        (lambda (doc)
+          (if doc (message doc) (message "Not documented")))))
+
+(define-command (document (cmd #:symbol))
+  "Display docstring for command CMD"
+  (or
+   (and=> (command-documentation cmd) message)
+   (message (format #f "No command with name ~a" cmd))))
+