extract function "command"

rover.fnl

@@ -1,6 +1,7 @@
 (local { : view } (require :fennel))
 (local { : merge } (require :lume))
 
+;; who needs a test framework when you have lisp macros?
 (macro expect [text actual expected]
   `(let [actual# ,actual]
      (or (match actual#
@@ -12,13 +13,15 @@
                               :actual actual#
                               })))))
 
+(fn command [rover command]
+  (match rover.direction
+    :n (merge rover {:y (+ rover.y 1)})
+    :s (merge rover {:y (- rover.y 1)})
+    :w (merge rover {:x (- rover.x 1)})
+    :e (merge rover {:x (+ rover.x 1)})))
+
 (fn execute [rover [cmd & cmds]]
-  (let [r1
-        (match rover.direction
-          :n (merge rover {:y (+ rover.y 1)})
-          :s (merge rover {:y (- rover.y 1)})
-          :w (merge rover {:x (- rover.x 1)})
-          :e (merge rover {:x (+ rover.x 1)}))]
+  (let [r1 (command rover)]
     (if (next cmds)
         (r1:execute cmds)
         r1)))