complete command names

we really need to make TAB and Return work for keyboard-selecting
a proffered completion

command.fnl

@@ -129,22 +129,27 @@
      (if result.active "commander" "echo-area"))))
 
 (fn on-input [self str]
-  (match self.state
-    {:command c :this-param param-name}
-    (let [parent self.completions-widget
-          { : completer}  (. c.params param-name)
-          completions (completer str)]
-      (parent:foreach #(parent:remove $1))
-      (each [text _w (pairs completions)]
-        (parent:add
-         (Gtk.Button {
-                      :label text
-                      :on_clicked
-                      #(update-widget-state self (self:on-input-finished text))
-                      })))
-      (parent:show_all)
-      )))
+  (let [parent self.completions-widget
+        set-completions
+        (fn [completions]
+          (parent:foreach #(parent:remove $1))
+          (each [text _w (pairs completions)]
+            (parent:add
+             (Gtk.Button {
+                          :label text
+                          :on_clicked
+                          #(update-widget-state self (self:on-input-finished text))
+                          })))
+          (parent:show_all))]
+    (match self.state
+      {:command c :this-param param-name}
+      (let [{ : completer}  (. c.params param-name)]
+        (set-completions (completer str)))
 
+      {:command nil}
+      (set-completions
+       (collect [k _ (pairs  commands)]
+         (if (= (k:find str 1 true) 1) (values k k)))))))
 
 (fn activate [{: state : entry : prompt &as self}]
   (tset state :active true)