add visit-location command

though it does hardcode the URL, making it less than generally useful

buffer.fnl

@@ -31,5 +31,6 @@
           (let [b (new-buffer name)]
             (tset buffers name b)
             b))
+   :current (fn [] (let [k (next buffers)] (. buffers k)))
    :find (fn [self term] (. buffers term))
    })

command.fnl

@@ -1,15 +1,33 @@
 (local { : Gtk  } (require :lgi))
+(local { : view } (require :fennel))
 
 (local commands {})
+(local Buffer (require :buffer))
+
+;; when a command is invoked from a binding, the binding may provide
+;; some or all of the parameter values. when there are missing params,
+;; or when invoked from the commander, `invoke` prompts for the
+;; missing params, offering default values which were specified by
+;; define-command
 
 (fn define-command [name function params]
+  ;; required parameter names and default arguments
   (let [v {:name name :function function :params params}]
     (tset commands name v)))
 
 (define-command "quit-browser" #(Gtk.main_quit) {})
 
+(define-command
+ "visit-location"
+ (fn [{:url url :buffer buffer}]
+   (buffer:visit url))
+ {:buffer (fn [] (Buffer.current))
+  :url #(do "http://www.example.com")
+  })
+
 (fn prompt-missing-args [params explicit-args]
-  explicit-args)
+  (collect [k v (pairs params)]
+    (values k (or (. explicit-args k) (v)))))
 
 (fn invoke [s args]
   (match (. commands s)

frame.fnl

@@ -44,9 +44,7 @@
            :content contentwidget
            :show-buffer (fn [self b]
                           (each [_ w (pairs (contentwidget:get_children))]
-                            (print "hide " w)
                             (w:hide))
-                          (print "show " (view b))
                           (contentwidget:pack_start b.webview true true 0)
                           (b.webview:show))
            }]