Simplify adding event listeners

src/Main.purs

@@ -180,18 +180,19 @@ update = do
   newNode <- importNode svgNode true document
   appendChild newNode svgContainer
 
+addUpdateListener :: Document -> String -> Effect Unit
+addUpdateListener doc id = do
+  listener <- eventListener updateEvent
+  element <- myGetElementById doc id
+  addEventListener (EventType "input") listener true (Element.toEventTarget element)
+
 main :: Effect Unit
 main = do
   w <- window
   d <- document w
   let dd = HTMLDoc.toDocument d
 
-  listener <- eventListener updateEvent
-
-  inputElement <- myGetElementById dd "ticks"
-  addEventListener (EventType "input") listener true (Element.toEventTarget inputElement)
-
-  tickSizeEl <- myGetElementById dd "tick-size"
-  addEventListener (EventType "input") listener true (Element.toEventTarget tickSizeEl)
+  addUpdateListener dd "ticks"
+  addUpdateListener dd "tick-size"
 
   update