now it can turn left as well as right

rover.fnl

@@ -22,7 +22,12 @@
               :s :w
               :w :n
               }
-          )]
+          :l {
+              :n :w
+              :w :s
+              :s :e
+              :e :n
+              })]
     (. chooser direction)))
 
 
@@ -34,6 +39,7 @@
          :w (merge rover {:x (- rover.x 1)})
          :e (merge rover {:x (+ rover.x 1)}))
     :r (merge rover {:direction (rotate rover.direction :r)})
+    :l (merge rover {:direction (rotate rover.direction :l)})
     _ (assert false (. "unrecognised command " string))))
 
 (fn execute [rover [cmd & cmds]]
@@ -85,6 +91,10 @@
   (expect "Rotates to south when pointing east and asked to turn right"
           (r:execute [:r]) {:x 2 :y 4 :direction :s}))
 
+(let [r (rover 2 4 :s)]
+  (expect "Rotates to east when pointing south and asked to turn left"
+          (r:execute [:l]) {:x 2 :y 4 :direction :e}))
+
 (let [r (rover 2 4 :w)]
   (expect "Rotates to north when pointing west and asked to turn right"
           (r:execute [:r]) {:x 2 :y 4 :direction :n}))