define command parameters as array not kv table

a command should be able to say in which order it wants to ask for
unsupplied parameter values

command.fnl

@@ -5,22 +5,36 @@
 
 (local Buffer (require :buffer))
 
-(fn define-command [name function params]
+(fn by-pairs [a]
+  (let [iter (fn [_ a]
+               (match a
+                 [k v & rest] (values rest k v)
+                 _ nil))]
+    (values iter a a)))
+
+(fn define-command [name function ordered-params]
   ;; required parameter names and default arguments
-  (let [v {:name name :function function :params params}]
+  (let [param-names (icollect [_ name val (by-pairs ordered-params)]
+                      name)
+        params (collect [_ name val (by-pairs ordered-params)]
+                 (values name val))
+        v {: name
+           : function
+           : param-names
+           : params}]
     (tset commands name v)))
 
 (define-command
  "quit-browser"
- #(Gtk.main_quit) {})
+ #(Gtk.main_quit) [])
 
 (define-command
  "visit-location"
  (fn [{:url url :buffer buffer}]
    (let [b (Buffer.find buffer)] (: b :visit url)))
- {:buffer (fn [] (. (Buffer.current) :name))
+ [:buffer (fn [] (. (Buffer.current) :name))
   :url #(do "http://www.example.com")
-  })
+  ])
 
 (fn find-command [name]
   (. commands name))
@@ -38,7 +52,7 @@
 
 (fn next-param [command params]
   (accumulate [v nil
-               k _ (pairs command.params)
+               _ k (ipairs command.param-names)
                &until v]
     (if (. params k) nil k)))
 

test/command.fnl

@@ -5,12 +5,12 @@
 (var happened false)
 (fn before [] (set happened false) (Command.reset-state))
 
-(Command.define-command "no-args-command" #(set happened true))
+(Command.define-command "no-args-command" #(set happened true) [])
 
 (Command.define-command
  "multiply"
  (fn [{: a : b }] (set happened (* (tonumber a) (tonumber b))))
- {:a #(do "3") :b #(do "2")})
+ [:a #(do "3") :b #(do "2")])
 
 (before)
 (let [(ok err)