implemented rendering of beads on abacus

src/Abacus/App/Widgets/Internal.hs

@@ -53,7 +53,13 @@ abacusLeft s =
       else ' '
 
 beads :: Abacus -> [(String, String)]
-beads = undefined
+beads a = map
+  ( \n ->
+    ( replicate (getNumBeads a - n) 'O'
+    , replicate n 'O'
+    )
+  )
+  (rungList a)
 
 abacusRight :: AppState -> [String]
 abacusRight = undefined