add objects and object types

examples/08_Type_Annotations.mers

@@ -46,16 +46,20 @@ double := x -> {
 // Define custom types:
 // `[[MyType] TypeDefinition]`
 
-[[City] (Int, Int, Int)]
+[[City] {
+  population: Int
+  pos_x: Int
+  pos_y: Int
+}]
 
 get_coords := city -> [(Int, Int)] {
   // only works with values of type City
-  (_, x, y) := [City] city
+  { population: _, pos_x: x, pos_y: y } := [City] city
   // return the coords
   (x, y)
 }
 
-test_city := (56000, 127, -12)
+test_city := { population: 56000, pos_x: 127, pos_y: -12 }
 
 ("Coords: ", test_city.get_coords).concat.println