Added set-nib! for variable width lines.

resources/cljs/tittle.cljs

@@ -1,6 +1,6 @@
 (ns tittle)
 
-            (def turtle (atom {:theta 0 :x 0 :y 0 :pen :up :ink "blue"}))
+(def turtle (atom {:theta 0 :x 0 :y 0 :pen :up :nib 3 :ink "blue"}))
 
 (defn log-turtle!
   "Prints the state of the turtle to the browser console."
@@ -105,6 +105,7 @@
           (.setAttribute elt "x2" x)
           (.setAttribute elt "y2" y)
           (.setAttribute elt "stroke" (or (:ink @turtle) "blue"))
+          (.setAttribute elt "stroke-width" (or (:nib @turtle) 3))
           (.appendChild playing-field elt)))
       (swap! turtle assoc :x x :y y))))
 
@@ -151,6 +152,12 @@
   (when (string? colour)
     (swap! turtle assoc :ink colour)))
 
+(defn set-nib!
+  "Set the nib (width) of the pen to this `n`, which should be a number."
+  [n]
+  (when (number-or-error! n)
+    (swap! turtle assoc :nib n)))
+
 (defn draw-tree!
   "Draw a tree. This is a fairly crude tree-drawing algorithm; 
                  there's lots of ways it can be improved, consider it a place